Library

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
  • 1990-1994  (315)
  • 1915-1919
  • 1890-1899
  • 1993  (315)
  • Biochemistry  (180)
  • crystal structure  (135)
  • 1
    Electronic Resource
    Electronic Resource
    The synthesis and structural analysis of Pt2Ru4(CO)18 and the products obtained from its reactions with 1, 2-bis(diphenylphosphino)ethane (1993)
    Springer
    Journal of cluster science 4 (1993), S. 119-132 
    Details
    ISSN: 1572-8862
    Keywords: Platinum ; ruthenium ; crystal structure ; heteronuclear cluster
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract From the reaction of Ru(CO)5 and Pt(COD)2, COD = 1, 5-cyclooctadiene, the new platinum-ruthenium heteronuclear cluster complex Pt2Ru4(CO)18,1, was obtained in 60% yield.1 has a folded ladder-like structure with alternating pairs of ruthenium atoms and platinum atoms. The cluster of1 can be split to yield the known compound PtRu2(CO)8(η2-dppe),2, (54% yield) by reaction with 1, 2-bis(diphenylphosphino)ethane, dppe, at 25°C. When1 was treated with excess dppe at 40°C, thebis-diphos compound3, PtRu2(CO)6(μ-η2-dppe)2 was obtained (39% yield). Under the similar reaction conditions,2 was converted to3 in 44% yield. All these complexes were characterized by single crystal X-ray diffraction analyses. Compounds2 and3 both contain a triangular cluster of one platinum and two ruthenium atoms, but in2 the bidentate ligand, dppe, chelates the platinum atom and in3 the two dppe ligands bridge the two Pt-Ru metal-metal bonds. Crystal data for1: space group C2/c,a=12.542(2)Å,b=15.350(4)Å,c=15.252(3)Å, β=105.32(2)°,Z=4, 2192 reflections,R=0.025. For2: space group P21/c,a=14.351(2)Å,b=13.486(3)Å,c=19.218(3)Å, β=108.48(1)°,Z=4, 3029 reflections,R=0.027. For3: space group P21/c,a=18.836(6)Å,b=15.559(5)Å,c=23.259(7)Å, β=111.26(2)°,Z=4, 4204 reflections,R=0.038.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00702713
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Preparation and structural characterization of the hexatungsten cluster complex (EDTEH)2[W6(μ3-Cl)8Cl6], (EDTEH=(MeO2CCH2)2N(H)CH2CH2N(CH2CO2Me)2+ (1993)
    Springer
    Journal of cluster science 4 (1993), S. 271-277 
    Details
    ISSN: 1572-8862
    Keywords: Tungsten ; chloride ; hexatungsten ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract The hexanuclear tungsten cluster complex [W6(μ3-Cl)8Cl6]2−,1 was isolated as a salt of the cation (MeO2CCH2)2N(H)CH2CH2N(CH2CO2Me)2+, EDTEH+, by crystallization from methanol solvent of the product obtained from the reaction of (H3O)2[W6(μ3-Cl)8Cl3] with the disodium salt of ethylenediaminetetraacetic acid. The compound was charcterized by single-crystal X-ray diffraction analysis. The cluster anion contains an octahedral arrangement of six tungsten atoms with chloride ligands bridging the eight triangular faces of the cluster and one chloride ligand terminally coordinated to each of the six tungsten atoms. The cation (EDTEH)+ achieves its positive charge by protonation of one of the nitrogen atoms. Crystal data: space group = P21/a,a=10.689(2) Å,b=22.931(6) Å,c=12.093(3) Å, β=98.41(2)°,Z=2, 2476 reflections,R=0.028.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00703743
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Preparation and structural characterization of a hexanuclear molybdenum (II) cluster containing carboxylate ligands (Bu4N)2[Mo6(μ3-Cl)8(O2CMe)6] (1993)
    Springer
    Journal of cluster science 4 (1993), S. 151-157 
    Details
    ISSN: 1572-8862
    Keywords: Molybdenum ; acetate, carboxylate ; hexamolybdenum ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract The hexamolybdenum cluster complex [Mo6(μ3-Cl)8(O2CMe)6]2−, 1 was isolated as the Bu4N+ salt in 71% yield from the reaction of (Bu4N)2[Mo6(μ3-Cl)8Cl6] with AgO2CMe in CH2Cl2 solvent. The compound was characterized by single crystal X-ray diffraction analysis. The cluster contains an octahedral arrangement of six molybdenum atoms with eight chloride ligands bridging the eight trianglar faces and six carboxylate ligands terminally coordinated through one oxygen atom to each of the six molybdenum atoms. Crystal data: space group =P21/n,a=10.713(3)Å,b=14.43(1)Å,c=21.919(4)Å, β=94.37(2)°,Z=2, 1965 reflections,R=0.036.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00702715
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Synthesis, characterization and x-ray structure of V3(μ3-O)(μ-Cl)Cl6(μ-η1-η1-PhNHNH2)2(PhNHNH2)2(THF) · 6THF: A new binding mode for phenylhydrazine (1993)
    Springer
    Journal of cluster science 4 (1993), S. 439-451 
    Details
    ISSN: 1572-8862
    Keywords: Vanadium ; phenylhydrazine ; nitrogenase ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract Addition of phenylhydrazine to a mixture of VCl3 · THF/N,N-propyl-bis (salicyladimine) and sodium hydride yielded a trinuclear vanadium complex, V3(μ3-O)(μ-Cl)Cl6(μ-η1-η1PhNHNH2)2(PhNHN H2)2(THF), containing two bridging and two terminal phenylhydrazine ligands. The product has been crystallographically characterized (P21/n, a=12.949(2) Å,b=24.061(4) Å,c=22.504(4) Å, β=107.22(1) deg.,V=6697(2) Å3 withZ=4) and was found to contain the first example of bridging monosubstituted hydrazine (phenylhydrazine) ligands.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00703736
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    Effects of higher-order structure of poly(3-hydroxybutyrate) on its biodegradation. II. Effects of crystal structure on microbial degradation (1993)
    Springer
    Journal of polymers and the environment 1 (1993), S. 65-80 
    Details
    ISSN: 1572-8900
    Keywords: Biodegradable plastic ; microbial degradation ; bacterial poly(d-(−)-3-hydroxybutyrate) ; crystal structure ; physiological behavior
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Energy, Environment Protection, Nuclear Power Engineering , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract As one of a series of studies concerning the relationship between the higher-order structure and the biodegradability of a biodegradable plastic, the effects of the crystal structure of the plastic on microbial degradation were investigated. Bacterial poly(d-(−)-3-hydroxybutyrate) (PHB) films which had a wide range of crystallinity were prepared by the melt-quenching method. Results of the microbial degradation indicated that the development of crystallinity evidently depressed the microbial degradability. From scanning electron microscopy (SEM) observations, it is suggested that the microbial degradation proceeded in at least two manners. One was preferential degradation of the amorphous region leaving the crystalline lamellae intact, which was considered to be a homogeneous enzymatic degradation over the surface. The other was nonpreferential spherical degradation on the surface. The SEMs indicate that the spherical holes were the result of colonization by degrading bacteria. The holes varied in size and number with the change of crystal structure. Therefore, it is considered that the crystal structure of PHB also influenced the physiological behavior of the degrading bacteria on the PHB surface.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01457654
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    Adult-onset lysosomal storage disease in a Schipperke dog: clinical, morphological and biochemical studies (1993)
    Springer
    Acta neuropathologica 86 (1993), S. 306-312 
    Details
    ISSN: 1432-0533
    Keywords: Canine galactosialidosis ; Morphology ; Biochemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary An adult-onset lysosomal storage disorder was diagnosed in a 5-year-old Schipperke dog with progressive cerebellar and central vestibular signs. It was characterized by cerebellar atrophy with extensive loss of Purkinje and granular cells, and hydrocephalus. Enlarged and vacuolated neurons were observed in spinal cord and brain; pancreatic centrolobular and islet cells were also vacuolated. Ultrastructurally, enlarged secondary lysosomes laden with lamellated membrane structures were present in neurons and empty enlarged vacuoles were found in pancreatic centroacinar, ductal, and islet cells. On frozen sections neurons stained with Ricinus communis agglutinin-I and wheat germ agglutinin. On paraffin sections neurons stained with luxol fast blue, periodic acid-Schiff, Concanavalia ensiformis agglutinin, and were autofluorescent. These findings indicate an accumulation of glycolipids containing terminal β-galactosyl and α-sialyl residues, and N-linked oligosaccharides. Tissue activity of lysosomal β-galactosidase was 50% of normal and the activity of β-hexosaminidase was elevated. Brain lipid-bound sialic acid was twice normal, with a small increase of GM1-ganglioside, but there was a significant elevation of GM2 (GD2) and GM3 (GD3). In addition, significant elevations of sialylated and non-sialylated oligosaccharides were noted. These clinical, biochemical and pathological findings are similar to those observed in human patients with adult-onset galactosialidosis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00304147
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    Analysis of atomic displacement parameters and molecular motion in crystals. Part 2. X-ray crystal structure of K2Ru(SO4)2 * 6H2O at 160 K and 295 K (1993)
    Springer
    Structural chemistry 4 (1993), S. 23-31 
    Details
    ISSN: 1572-9001
    Keywords: Atomic displacement ; molecular motion ; vibrational analysis ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Atomic displacement parameters determined from a single-crystal X-ray-diffraction study on K2Ru(SO4)2 * 6H2O are analyzed in the molecular mean field approximation. The motion of SO2 2− can be described with a rigid-body model, whereas for [Ru(H2O)6]2+ internal stretching motion and coupling between stretching motion and overall translation are found to be necessary for explaining the observed atomic displacement parameters. Frequencies and force constants of internal motion are not significantly affected by such couplings. K2Ru(SO4)2 * 6H2O crystallizes in the monoclinic space groupP21/c (No. 14), witha = 6.1211(7)Å,b = 12.226(2) Å,c = 8.916(2)Å,β = 105.11(1)°,Z = 2 at 160 K anda = 6.1402(7)Å,b = 12.274(2)Å,c = 8.957(1)Å,β = 105.25(1)°,Z = 2 at 295 K. The structure was refined to a finalR(F) of 0.017 at 160 K and of 0.019 at 295 K for 1438 and 1299 observed reflections withF 0 〉 6σ(F0) and sin θ/λ 〉 0.617 Å1−.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00672096
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 8
    Electronic Resource
    Electronic Resource
    Synthesis and structural chemistry of novel heteropolymolybdates and -tungstates (1993)
    Springer
    Molecular engineering 3 (1993), S. 43-59 
    Details
    ISSN: 1572-8951
    Keywords: Heteropolymolybdates ; heteropolytungstates ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The chemistry of polynuclear oxometalate anions is dominated by molybdenum and tungsten in their highest oxidation state. During the past twenty years this class of compounds has attracted much attention because of their variable applications, e.g. as reagents in analytical procedures, as industrial catalysts and as potential anticancer drugs. In order to obtain model systems for the investigation of the catalytic activity of heteropolyanions we have synthesized and structurally characterized some organo derivatives of polyoxoanions. We secondly focus on Sb(III) and Bi(III) heteropolytungstates to examine the important influence of the unshared electron pair on the resulting structures and properties. Some of these compounds may be regarded as supramolecular aggregates showing inclusion phenomena. In 9 two [SbW9O33]9− anions are linked by a set of six sodium ions forming a nearly planar hexagon. The sodium ions are enveloped by an oxygen cage formed by terminal oxygen atoms of the polyanions and by water molecules. Furthermore, the four anions [Sb2W22O74(OH)2]12−, [Sb2W20Fe2O70(H2O)6]8−, [Sb2W20Co2O70(H2O)6]10− and [Bi2W20Fe2O68(OH)2(H2O)6]6− (in10, 11, 12, 13) may be regarded as transition metal complexes of novel [Sb2W20O70]14− or [Bi2W20O70]14− anions which are serving as ligands. The octahedral coordination sphere of each transition metal is formed by three oxygen atoms of the anion and completed by three water molecules. The Sb(III) heteropolyanion, [Na2Sb8W36O132(H2O)4]22− in (14) includes two sodium and four antimony ions besides four water molecules. Each anion consists of four β-B-SbW9-Keggin fragments linked together by four SbO4-groups, incorporating two sodium and four water molecules effecting an additional connection of the subunits.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00999623
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 9
    Electronic Resource
    Electronic Resource
    Redetermination of the cobaltocene crystal structure at 100 K and 297 K: Comparison with ferrocene and nickelocene (1993)
    Springer
    Structural chemistry 4 (1993), S. 91-101 
    Details
    ISSN: 1572-9001
    Keywords: Cobaltocene ; molecular geometry ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The molecular and crystal structures of the monoclinic modification of cobaltocene Cp2Co (P21/n, Z=2) was determined at 100 K and 297 K with new sets of X-ray diffraction data (MoKα radiation, 3995 and 6534 reflections, refinement toR = 0.026 and 0.030 using 1061 and 1299 independent observable reflections, respectively). At 297 K the structure is disordered (similar to the isomorphous ferrocene and nickelocene) with two distinct orientations of the ring, differing in occupancy factors (80% and 20%) and by a rotation angle in the ring plane of approximately 34°. Just as for nickelocene but in contrast to ferrocene, no sharp phase transition was found on cooling Cp2Co to 100 K, but an essential ordering of the Cp-ring position was detected with a decrease of the contribution of the second minor orientation to nearly 10%. On the basis of a careful analysis of the molecular geometry, crystal packing, and anisotropic atomic displacement parameters, a dynamic temperature-dependent nature of the disorder in Cp2Co is assumed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00677370
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 10
    Electronic Resource
    Electronic Resource
    Structural, immunocytochemical and initial biochemical characterization of NAOH-extracted gap junctions from an insect, Heliothis virescens (1993)
    Springer
    Cell & tissue research 274 (1993), S. 393-403 
    Details
    ISSN: 1432-0878
    Keywords: Gap junction ; Cell junction ; Immunocytochemistry ; Biochemistry ; Heliothis virescens (Insecta)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Subcellular fractions enriched in gap junctions with an ultrastructure similar to those in intact insect tissue have been obtained by extracting crude membranes from the tobacco budworm Heliothis virescens (Lepidoptera: Noctuidae) with 2.5 mM NaOH. n-Octyl-β-d-glucopyranoside (OG) was used to further purify integral membrane proteins in the NaOH-extracted fractions. A polyclonal antibody (R16) is described that specifically labels nonextracted and NaOH-extracted gap junctions in cell fractions by electron microscope immunocytochemistry. R16 immunostaining of sectioned Heliothis testis at the light-microscope level yields a pattern of immunoreactivity consistent with the distribution of gap junctions in the tissue. R16 identifies a 40-kDa protein as a candidate gap junction protein on immunoblots of crude membrane, NaOH-extracted and NaOH/OG-extracted fractions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00318758
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 11
    Electronic Resource
    Electronic Resource
    Polar bonds in π-complexes. Preparation and crystal structures of cyclopentadienylcarbonyl iron(II) and ruthenium(II) benzoates andp-fluorobenzoates (1993)
    Springer
    Russian chemical bulletin 42 (1993), S. 359-364 
    Details
    ISSN: 1573-9171
    Keywords: iron(II) and ruthenium(II) complexes ; synthesis ; carbonyl, cyclopentadienyl, benzoate ligands ; crystal structure ; X-ray diffraction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Complexes of Fe(II) and Ru(II) of the general formula Cp(OC)2MOC(O)C6H4X-p, where M=Fe, X=H, F (1, 2) or M=Ru, X=H, F (3, 4) have been prepared by reactingp-XC6H4COOAg with [CpFe(CO)2]2 or CpRu(CO)2I. The crystal structures of complexes1–3 have been determined using X-ray diffraction. Compounds1 and3 are isomorphous. The COO group in1–3 is coordinated as a monodentate ligand. As the latter and the CO ligands are electronically non-equivalent, the coordination of the Cp ligand to the metal is slightly asymmetric.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00697097
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 12
    Electronic Resource
    Electronic Resource
    Crystal and molecular structure of 1-(trimethylsilylmethyl)hexahydroazepine-2-thione and hexahydroazepine-2-thione (1993)
    Springer
    Russian chemical bulletin 42 (1993), S. 181-184 
    Details
    ISSN: 1573-9171
    Keywords: synthesis ; crystal structure ; azepinethiones ; trimethylsilyl derivative
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The title compounds were prepared and X-ray analysis was performed (R = 0.064 and 0.035 for 1309 and 1637 reflections, respectively). In the former the intramolecular S→Si coordination interactions are absent and the Si atom has undistorted tetrahedral coordination with an S...Si distance of 4.034 Å. Crystals of the latter are built of centrosymmetric dimeric H-complexes (S...H(N) 2.58 Å, the S...HN angle 168°).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00700005
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 13
    Electronic Resource
    Electronic Resource
    Thermal stability and crystal structure of potassium fluoride monoperoxosolvate KF·H2O2 (1993)
    Springer
    Russian chemical bulletin 42 (1993), S. 30-35 
    Details
    ISSN: 1573-9171
    Keywords: peroxosolvates ; potassium fluoride ; monoperoxosolvate ; thermal stability ; crystal structure ; hydrogen bond
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Potassium fluoride peroxosolvate KF-H2O2 was obtained upon action of a 30% aqueous solution of hydrogen peroxide on solid potassium fluoride dihydrate. As compared to other peroxosolvates, KF-H2O2 is characterized by the highest thermal stability: the decomposition rate constantk 1, at 120°C is 1.4 10−3 min−1, the enthalpy of H2O2 addition to KF is 8.1 kcal/ mol. The correlation between the high stability of KF-H2O2 and the absence of catalytic properties of KF towards H2O2, and the formation of strong intermolecular O-H...F and intramolecular O-H...O hydrogen bonds in the crystal is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00699969
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 14
    Electronic Resource
    Electronic Resource
    Crystal and molecular structure of the (N-Si) chelate of 2-(chlorodimethylsilylmethylthio)-1-pyrroline (1993)
    Springer
    Russian chemical bulletin 42 (1993), S. 173-176 
    Details
    ISSN: 1573-9171
    Keywords: synthesis ; crystal structure ; pentacoordinated silicon ; chelate cycle
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The X-ray diffraction structural study of the (N-Si)-chelate of 2-(chlorodimethyl-silylmethylthio)-1-pyrroline was carried out (R = 0.033 for 1894 reflections). The Si atom has a somewhat distorted trigonal bipyramidal coordination with the Cl and N atoms in axial positions. The Si-Cl and Si-N distances (2.423(1) and 1.945(1) Å) belong, respectively, to the longest and shortest known Si-Cl and Si-N distances in pentacoordinated silicon derivatives with an axial N-Si-Cl moiety.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00700003
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 15
    Electronic Resource
    Electronic Resource
    Structure of the neutral metal complex Pt(dddt)2 (1993)
    Springer
    Russian chemical bulletin 42 (1993), S. 1149-1151 
    Details
    ISSN: 1573-9171
    Keywords: Pt(dddt)2 ; organic conductors ; 5,6-dihydro-1,4-dithiin-2,3-dithiolate((dddt)2−) ; sulfur-containing platinum complexes ; crystal structure ; synthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A neutral metal complex, [Pt(dddt)2]° (1), has been obtained by oxidation of the [Pt(dddt)2]− anion with excess (Bu4N)AuBr4 in nitrobenzene. Crystallographic data for 1∶a=17.854(9) Å,b=18.409(9) Å,c=4.717(5) Å, γ=68.83(2)°, space group P21/n,Z=4,d calc=2.55 g/cm3. In1 two independent centrosymmetric [Pt(dddt)2]° molecules are packed in stacks that form layers parallel to the (110) plane. The molecules of1 in the layers have shortened S...S contacts 3.491(9) Å, and 3.594(10) Å. The average bond lengths Pt-S 2.242(7) Å, S-C 1.71(2) Å and C=C 1.40(3) Å, together with the square-planar coordination of Pt in PtS4, suggest considerable conjugation in the metal cycles.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00701993
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 16
    Electronic Resource
    Electronic Resource
    Crystal structure of 4-ethylvanadatrane-1-one (1993)
    Springer
    Russian chemical bulletin 42 (1993), S. 1415-1417 
    Details
    ISSN: 1573-9171
    Keywords: vanadatrane ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract An X-ray diffraction study of a substituted vanadatrane-1-one (space groupPna21,R= 0.019 for 1394 reflections, the absolute structure was determined) showed that the geometry of its atrane framework is similar to that of the Si- and Ge-analogs. The bond lengths are: V=O, 1.614(2) Å; V←N, 2.329(2) Å; V-O, 1.800–1.806(2) Å. The deviation of the V atom having distorted trigonal bipyramidal coordination from the equatorial plane of the O atoms is 0.35 Å, the 0=V←N bond angle is 179.4(1)°.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00699945
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 17
    Electronic Resource
    Electronic Resource
    Crystal and molecular structure of organosilicon titanium(iv) derivatives: (Me3Si)3SiTi(NEt2)3 and ClTi[N(SiMe3)2]3 (1993)
    Springer
    Russian chemical bulletin 42 (1993), S. 1411-1414 
    Details
    ISSN: 1573-9171
    Keywords: titanasilanes ; titanasilazanes ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract An X-ray structural study of two titanium-containing organosilicon compounds, (Me3Si)3SiTi(NEt2)3 (1) and ClTi[N(SiMe3)2]3 (2), has been performed. The conformation of molecule1 in a crystal is staggered (approximate inherentC 3 symmetry), the Ti-Si and Ti-N bond lengths are 2.671(2) and 1.874–1.890(5) Å, respectively. A crystal of1 consists of one type of enantiomers (the space group is P41212; the absolute configuration has been determined). The structure of2 studied previously has been refined to the value of R=0.029 on the basis of 3442 reflections (the absolute structure has been determined), the Ti-Cl and Ti-N bond lengths are 2.260(1) and 1.926(1) Å, respectively. The strong distortions in the symmetry of the valence environment of the N atoms in the molecules of1, 2, and related structures are caused by electronic effects, in which the conformation of the relevant molecular fragments plays a determining role.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00699944
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 18
    Electronic Resource
    Electronic Resource
    Chain folding in single crystals of tetrafluoroethylene copolymers (1993)
    Springer
    Colloid & polymer science 271 (1993), S. 50-55 
    Details
    ISSN: 1435-1536
    Keywords: Polytetrafluoroethylene ; copolymer ; crystal structure ; chain folding
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Molecular-mechanics calculations are performed on model folds proposed in the literature for single crystals of polytetrafluoroethylene crystallized in the phase stable below 19°C, in order to evaluate how they are modified when a fluorine atom is substituted by a bulky group, as occurs in fluorinated copolymers of tetrafluoroethylene. Only intramolecular effects are taken into account (isolated-chain model). An exhaustive analysis has been carried out of tetrafluoroethylene-hexafluoropropylene copolymer. Moreover, the lower energy folds found for such a copolymer have been examined for copolymers with chlorotrifluoroethylene and perfluoroalkylvinylethers, as comonomers. Our calculations show that all the considered comonomers can be arranged in the model folds proposed for the homopolymer, according to the imposed geometric constraints.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00652302
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 19
    Electronic Resource
    Electronic Resource
    Crystal structure of the complex of human α-thrombin and nonhydrolyzable bifunctional inhibitors, hirutonin - 2 and hirutonin - 6 (1993)
    New York, NY : Wiley-Blackwell
    Proteins: Structure, Function, and Genetics 17 (1993), S. 252-265 
    Details
    ISSN: 0887-3585
    Keywords: thrombin ; bifunctional inhibitor ; crystal structure ; hirutonis ; drugdesing ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The crystal structure of the complexes of hirutonin-2 and hirutonin-6 with human α-thrombin have been solved and refined to R-factors of 0.169 (2.0 Å resolution) and 0.162 (201Å), respectively. Hirutonins belong to a family of bifunctional inhibitors bearing a noncleavable moiety mimicking the scissile bond. Hirutonin-2 is an analog of (D)Phe-Pro-Arg-Gly-hirudin49-65; hirutonin-6 has the same N-terminal tripeptide connected to a shortened fibrinogen exosite-binding part by a short, non-peptidyl linker. The hirutonin-6 molecule is well defined in the electron density with the exception of the C-terminal Leu-h61. The linker follows near the bottom of the canyon connecting the active site with the exosite, forms a short antiparallel β-sheet-like arrangement with Leu-40-Leu41 and makes van der Waals contacts with Glu39-Leu40-Leu41 of thrombin. In the thrombin-hirutonin-2 complex, the N- and C-terminal parts of the inhibitor are well or dered (except the C-terminal Gln-h65) while the central portion of the linker is partially disordered. The glycine analog in the P1′ position of hirutonin-2 assumes a conformation similar to that of the canonical form (Bode and Huber (1992) Eur. J. Biochem. 204 : 433-451) and supports the identification of the S1′ site as restricted by His57, Trp60D, Lys60F, and the Cys42-Cys58 disulfide bridge. The carbonyl oxygen of the P1 arginine residue is located in the oxyanion hole formed by the NH groups of Gly193 and Ser195, while the carbonyl carbon is positioned within a short distance, 2.8 Å, from the Oγ of Ser195. This resembles the conformation of the substrate-like inhibitors bound to other serine proteases. The N-terminal (D)Phe-pro-Arg fragment common to both inhibitors binds to thrombin in a fashion very similar to that of other inhibitors having this motif. The binding of the C-terminus of hirutonins to the fibrinogen-binding exosite is similar to that observed in hirudin and hirulog complexes. © 1993 Wiley-Liss, Inc.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prot.340170304
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 20
    Electronic Resource
    Electronic Resource
    Calcium-independent subtilisin by design (1993)
    New York, NY : Wiley-Blackwell
    Proteins: Structure, Function, and Genetics 16 (1993), S. 205-213 
    Details
    ISSN: 0887-3585
    Keywords: calcium binding ; crystal structure ; protein stability ; site-directed mutagenesis ; subtilisin ; X-ray crystallography ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: A version of subtilisin BPN′ lacking the high affinity calcium site (site A) has been produced through genetic engineering methods, and its crystal structure refined at 1.8 Å resolution. This protein and the corresponding version containing the calcium A site are describedand compared. The deletion of residues 75-83 was made in the context of four site-specific replacements previously shown to stabilize subtilisin. The helix that in wild type is interrupted by the calcium binding loop, is continuous in the deletion mutant, with normal geometry. A few residues adjacent to the loop, principally those that were involved in calcium coordination, are repositioned and/or destabilized by the deletion. Because refolding is greatly facilitated by the absence of the Caloop, this proteinoffers a new vehicle for analysis and dissection of the folding reaction. This is among the largest internal changes to a protein to be described at atomic resolution. © Wiley-Liss, Inc.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prot.340160207
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 21
    Electronic Resource
    Electronic Resource
    Twelve-membered crown ethers: Crystal structures of benzo-12-crown-4 and naphtho-12-crown-4 (1993)
    Springer
    Journal of inclusion phenomena and macrocyclic chemistry 15 (1993), S. 79-89 
    Details
    ISSN: 1573-1111
    Keywords: 12-membered crown ethers ; crystal structure ; conformation peculiarities ; X-ray analysis ; CH...O contacts
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The crystal structures of two 12-membered crown ethers, benzo-12-crown-4 (1) and naphtho-12-crown-4 (2), have been determined by X-ray analysis. Both structures are molecular. Compound1 is monoclonic,P21/b,a=8.466(3),b=8.019(3),c=33.590(10) Å, γ=90.99(3)o. The unit cell contains two crystallographically independent molecules of1 with similar conformations. Compound2 is also monoclinic,P21/a,a=24.148(8),b=14.535(4),c=7.987(5) Å, γ=102.87(2)o. Two independent molecules in the unit cell have significantly different conformations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00706476
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 22
    Electronic Resource
    Electronic Resource
    Crystal structure of the complex of dibenzo-30-crown-10 with dysprosium isothiocyanate (1993)
    Springer
    Journal of inclusion phenomena and macrocyclic chemistry 15 (1993), S. 159-165 
    Details
    ISSN: 1573-1111
    Keywords: Dibenzo-30-crown-10 ; crystal structure ; complexation ; dysprosium isothiocyanate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Crystalline [Dy(NCS)3(dibenzo-30-crown-10)(H2O)2]·H2O·MeCN can be obtained by slowly evaporating a reaction mixture of Dy(NCS)3·nH2O with dibenzo-30-crown-10 in a solution of acetonitrile. The material crystallizes in the monoclinic space groupP21/n, the cell parameters area=11.450(5),b=23.284(4),c=18.424(6)Å, β=106.28(4)°,V=4715Å3,M=968.47,D x=1.36 g cm−1, μ=17.80 cm−1,F(000)=1972,Z=4.2740 independently observed [I≥3σI] reflections were used in the final least-squares refinement leading to an agreement index ofR=0.085. The Dy(III) ion coordination geometry approximates a square antiprism, involving two water oxygens and three dibenzo-30-crown-10 oxygen atoms and three isthiocyanate nitrogens. Hydrogen bonds are formed between the two water molecules and four uncoordinated crown ether oxygen atoms.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00710225
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 23
    Electronic Resource
    Electronic Resource
    Structural study of the 1:1 clathrate of an asymmetric calix[4]arene and acetone (1993)
    Springer
    Journal of inclusion phenomena and macrocyclic chemistry 15 (1993), S. 341-349 
    Details
    ISSN: 1573-1111
    Keywords: Molecular asymmetry ; calixarene ; acetone ; clathrate ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The crystal and molecular structure of the 1:1 clathrate of the asymmetric calix[4]arene,1, and acetone has been determined by X-ray analysis. The crystal data are: tetragonal, space groupP4/n,a=b=12.574(6),c=12.572(6) Å,V=1988(2) Å3,Z=2,D x =1.111 g cm−3,D m =1.108 g cm−3. Least-squares refinement based on 1131 observed reflections withF 0〉3σ(F 0) and anisotropic temperature factors led toR=0.096. In spite of the molecular asymmetric calixarene1 the crystal structure has high symmetry, because a part of the host and guest molecules are in disordered states.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00708751
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 24
    Electronic Resource
    Electronic Resource
    Helical tubulate inclusion compounds of ferrocene and squalene (1993)
    Springer
    Journal of inclusion phenomena and macrocyclic chemistry 15 (1993), S. 385-398 
    Details
    ISSN: 1573-1111
    Keywords: Hydrogen bonding ; alicyclic diol ; helical tubulate ; crystal structure ; ferrocene ; squalene
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The inclusion compounds of 2,8-dimethyltricyclo[5.3.1.13,9]dodecane-syn-2,syn-8-diol,3, with ferrocene and with squalene have been prepared. The crystal structures of these helical tubulate compounds: (3)3·(ferrocene)0.75 [P3121,a=b=13.7480(6),c=7.0312(5) Å,Z=1,R=0.038] and (3)3·(squalene)0.23 [P3121,a=b=13.677(1),c=7.0533(9) Å,Z=1,R=0.042] are described.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00708755
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 25
    Electronic Resource
    Electronic Resource
    Studies on werner clathrates. Part 131. Selective criteria in werner clathrates. Six crystal structures with bis(isothiocyanato)tetra(4-vinylpyridine)nickel(II) as host (1993)
    Springer
    Journal of inclusion phenomena and macrocyclic chemistry 16 (1993), S. 25-54 
    Details
    ISSN: 1573-1111
    Keywords: Werner clathrate ; nickel octahedral complex ; tetrahydrofuran ; crystal structure ; NMR ; molecular recognition ; hydrocarbon
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract This paper addresses the general question: what are the significant guest properties selected by this host when interacting with guest molecules in the liquid phase, resulting in cocrystallization of the host and guest? In particular, to what extent do π electrons in a guest molecule effect its potential as a guest? Werner clathrates of the host [Ni(NCS)2(4-ViPy)4] with mixtures of tetrahydrofuran (THF) and cyclic hydrocarbons as guests have been synthesised and their structures elucidated. Clathrate (1): [Ni(NCS)2(4-ViPy)4](1.78 THF)(0.22 cyclohexane), crystallizes in the orthorhombic space groupP bcn a=9.976(6),b=20.630(25),c=19.861 (4) Å,V=4087Å3,Z=4,R=0.087 for 1461 reflections; (2): [Ni(NCS)2(4-ViPy)4](1.76 THF)(0.24 cyclohexene),P bcn ,a=9.987(7),b=20.614(4),c=19.898(4)Å,V=4096Å3,Z=4,R=0.084 for 1304 reflections; (3): [Ni(NCS)2(4-ViPy)4](0.48 THF)(0.52 1,3-cyclohexadiene), tetragonalI41/a,a=16.898(3),b=16.898(3),c=26.463(6)Å,V=7556Å3,Z=8,R=0.120 for 1698 reflections; (4): [Ni(NCS)2(4-ViPy)4](0.36 THF)(1.04 1,4-cyclohexadiene),I41/a,a=16.986(4),b=16.986(4),c=25.896(15)Å,V=7472Å3,Z=8,R=0.103 for 2025 reflections; (5): [Ni(NCS)2(4-ViPy)4](0.35 THF)(1.05 benzene),I41/a,a=17.102(10),b=17.102(10),c=25.498(8)Å,V=7458Å3,Z=8,R=0.118 for 2200 reflections; (6): [Ni(NCS)2(4-ViPy)4](3 benzene), triclinicP1,a=10.432(24),b=11.155(9),c=21.581(7)Å, α=78.70(5), β=82.60(7), γ=74.09(13)°,V=2361Å3,Z=2,R=0.078 for 3427 reflections. Host-guest ratios and, for mixtures of guests, guest1/guest2 ratios, were elucidated by density and NMR. We show that the conformational freedom of the substituted pyridines is not the primary reason for the clathrating ability of Werner hosts. All six structures show no host-guest interaction at the level of van der Waals interactions. As non-bonding interactions are not observed between the host and guest, this study shows that the above host's selectivity by enclathration of particular guest molecules cannot be accounted for by solid state structural analysis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00708760
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 26
    Electronic Resource
    Electronic Resource
    Host-guest chemistry. 2. Amine inclusion compounds of 2-[o-(triphenylphosphoranylidenamino)benzyliden]amino-1H-2,3-dihydroindazol-3-one. X-ray structure of its 1∶1∶1 inclusion complex with isopropylamine and water (1993)
    Springer
    Journal of inclusion phenomena and macrocyclic chemistry 16 (1993), S. 155-168 
    Details
    ISSN: 1573-1111
    Keywords: Iminophosphoranes ; amine inclusion compounds ; 13C CPMAS NMR spectroscopy ; salt-like crystalline aggregates ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The crystal and molecular structure is reported for the inclusion compound 2-[o-(triphenylphosphoranylidenamino)benzyliden]amino-1H-2,3-dihydroindazol-3-one/isopropylamine/water3b. The crystal structure consists of discrete dimeric salt-like aggregates joined together by strong N+−H...−O−C hydrogen bonds between pairs of centrosymmetrically-related indazolonate anions and isopropylammonium cations. Six other inclusion compounds have been prepared and characterized by NMR [with propylamine (3a), withtert-butylamine (3c), withsec-butylamine (3d), withtert-pentylamine (3e), with 1-methylbutylamine (3f) and withiso-pentylamine (3g)]. Two different arrangements are found, both with the host being in the anionic form. The guests are either: (i) one protonated amine and one water molecule (3b and3f); or (ii) one protonated amine and the corresponding neutral amine (3a, 3c, 3d, 3e and3g).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00709149
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 27
    Electronic Resource
    Electronic Resource
    Crystal structure of [Yb (NO3)3 (phen) (H2O)] · (12-crown-4) (1993)
    Springer
    Journal of inclusion phenomena and macrocyclic chemistry 16 (1993), S. 267-272 
    Details
    ISSN: 1573-1111
    Keywords: Crown ether ; ytterbium nitrate ; phen ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The title complex was prepared by reacting Yb(NO3)3 (12-crown-4) with 1,10-phenanthroline (hereafter phen) in acetone. It crystallized in the triclinic space group $$P\bar 1$$ witha=10.095(5),b=17.415(4),c=8.710(2) Å α=92.45(2), β=115.83(3), γ=74.08(3)0 andD c=1.85 g cm−3;Z=2. The metal ion in this complex is nine-coordinated to three bidentate nitrate ions, two nitrogen atoms of a phen and a water molecule. The crown ligand is hydrogen bonded to the coordination water molecule. The symmetry change of the crown ether is also discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00708796
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 28
    Electronic Resource
    Electronic Resource
    Study of structure and polymerization of epitaxially grown SiPc(OH)2 thin films by high-resolution electron microscopy (1993)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 31 (1993), S. 1713-1723 
    Details
    ISSN: 0887-6266
    Keywords: phthalocyanine siloxane ; crystal structure ; epitaxial growth ; high-resolution electron microscopy ; molecular imaging ; polymerization ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Thin films of SiPc(OH)2 (Pc = phthalocyanine) were formed epitaxially on the (001) surface of mica by vacuum deposition and were then polymerized by heat treatment. The molecular packing of the SiPc(OH)2 was determined by electron diffraction and high-resolution electron microscopy as triclinic\documentclass{article}\pagestyle{empty}\begin{document}${\rm P\bar 1} $\end{document} having dimensions a = 0.727, b = 1.307, c = 0.688 nm, α = 102.5, β = 104.2, and γ = 97.4°. This monomer crystal grows with its c-axis parallel to the a-axis of the substrate mica and its bc-plane parallel to the (001) surface of mica. By heat treatment at 320°C, the SiPc(OH)2 polymerized with the c-axis of the polymer parallel to the c-axis of the monomer. At 420°C, the c-axis of the polymer became parallel to the a*-axis of the monomer (i.e., perpendicular to the film surface). From high-resolution electron microscopy of partially polymerized specimens, the polymerization was shown to start at the edges of small monomer crystals. This may be considered to be due to the volume expansion during the polymerization. © 1993 John Wiley & Sons, Inc.
    Additional Material: 16 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/polb.1993.090311207
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 29
    Electronic Resource
    Electronic Resource
    poly(4,4′-oxybibenzoate): Polymerization, morphology, transitions, and crystal structures (1993)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 31 (1993), S. 1923-1940 
    Details
    ISSN: 0887-6266
    Keywords: poly(4,4′-oxybibenzoate) ; polymerization ; morphology ; transitions ; crystal structure ; disclination domains ; Iamellae ; single crystals ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: 4-Acetoxy 4′-carboxy biphenyl has been polymerized from solution, the bulk melt, and in constrained thin films, all below the melting point of the monomer as measured by differential scanning calorimetry (DSC). An isothermal sublimation-recrystallization-melting (and chemical change)-polymerization-crystallization process is proposed. From solution and in the thin films, single crystals consisting of ca. 100 Å thick lamellae are observed, with evidence for monomer addition-reaction on the end (top and bottom) surfaces. The bulk samples are fibrous, the “fibers” consisting of whisker-like single crystals. The polymer is highly heat and radiation (electron beam) resistant, with numerous successive electron diffraction (ED) patterns from the same crystal or sheared sample permitting comparison of the changes in ED patterns with transitions seen by DSC at ca. 350, 530, and 590°C. Phase I (a = 7.8, b = 5.5, c = 10.8 Å), a possible phase II (a = 15.6, b = 3.6 Å c = unknown), and a phase III (a = 9.0, b = 5.2 = √3a, c = 10.8 Å). Phases I and II are seen in samples polymerized at temperatures at and below 310°C; phase III is observed in samples polymerized at and above 350°C and in sheared samples. © 1993 John Wiley & Sons, Inc.
    Additional Material: 18 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/polb.1993.090311305
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 30
    Electronic Resource
    Electronic Resource
    Chronology of peroxidase activity in the developing rat parotid gland (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 235 (1993), S. 611-621 
    Details
    ISSN: 0003-276X
    Keywords: Peroxidase ; Parotid gland ; Salivary gland ; Rat ; Growth and development ; Biochemistry ; Cytochemistry ; Ultrastructure ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The course of development of salivary peroxidase, an enzyme that has an important role in oral defense mechanisms, has been well documented in rat submandibular glands. However, the only report on salivary peroxidase activity in the other major salivary glands of the rat has been a cytochemical study of the adult parotid gland. In the present investigation, the accumulation of salivary peroxidase activity in developing parotid glands of rats was followed both biochemically and cytochemically. Specific activity (units per mg protein) attributable to salivary peroxidase began at 1 day after birth, then rose rapidly but unevenly, with peaks at 21 and 70 days, and no difference between the sexes at any age. Activity per gland increased progressively to 42 days in both sexes and was significantly higher in males at 70 days. The cytochemical observations on peroxidase activity localized to the rough endoplasmic reticulum and secretory granules of the developing acini were well correlated with the biochemical findings. Peroxidase-negative cells occurred in immature acini at 1 and 7 days, but only in the intercalated ducts thereafter. This observation suggests that the acini are a source of some of the ductal cells, at least during early postnatal development. The developmental pattern of specific activity differed from those of other rat parotid secretory enzymes, indicating that control of their synthesis during development is noncoordinate. The patterns of specific activity of the parotid and submandibular glands were complementary, suggesting that their combined secretions may supply biologically significant peroxidase activity to the oral cavities of rats throughout postnatal development. © 1993 Wiley-Liss, Inc.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ar.1092350414
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 31
    Electronic Resource
    Electronic Resource
    Liquid crystalline main chain polymers with a poly(p-phenyleneterephthalate) backbone. 2. Fiber spinning and mechanical properties of polyesters with alkoxy side chains (1993)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 31 (1993), S. 1759-1767 
    Details
    ISSN: 0887-6266
    Keywords: rigid rod polymer ; thermotropic ; aromatic polyester ; fiber ; modulus ; crystal structure ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Fiber spinning and mechanical properties of four rigid polyesters with alkoxy substituents of different length and placement were evaluated. Properties of oriented fibers from the polymer with dodecyloxy substituents on the terephthalate moiety, PTA12HQ, were significantly affected by the crystal modification. At room temperature the following properties (tensile modulus E, tensile strength σb, and strain at break εb) could be obtained: E = 9.5 GPa, σb = 85 MPa and εb = 1.1% for phase Lf (the “frozen in layered mesophase”); E = 10.4 GPa, σb = 59 MPa and εb = 0.6% for modification A; E = 17.3 GPa, σb = 158 MPa and εb = 1.2% for modification B. Because of the higher amount of main chains per cross sectional area the polymer with hexyloxy side chains, PTA6HQ, showed better properties at a comparable degree of molecular orientation: E = 24 GPa, σb = 270 MPa, εb = 1.4%. Fibers obtained from the polyester with dodecyloxy substituents on the hydroquinone moiety, PTAHQ12, were too brittle to handle. The polyester with dodecyloxy substituents on both moieties, PTA12HQ12, was spun from the isotropic melt. Because of the obtained low degree of orientation, properties (E = 1 GPa, σb = 40 MPa, and εb = 6.3%) were governed by interactions between the chains (the main chains are not load-bearing). © 1993 John Wiley & Sons, Inc.
    Additional Material: 15 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/polb.1993.090311209
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 32
    Electronic Resource
    Electronic Resource
    Masthead (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 14 (1993) 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540140201
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 33
    Electronic Resource
    Electronic Resource
    3-D QSAR for intrinsic activity of 5-HT1A receptor ligands by the method of comparative molecular field analysis (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 14 (1993), S. 237-245 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: The affinity of a ligand for a receptor is usually expressed in terms of the dissociation constant (Ki) of the drug-receptor complex, conveniently measured by the inhibition of radioligand binding. However, a ligand can be an antagonist, a partial agonist, or a full agonist, a property largely independent of its receptor affinity. This property can be quantitated as intrinsic activity (1A), which can range from 0 for a full antagonist to 1 for a full agonist. Although quantitative structure-activity relationship (QSAR) methods have been applied to the prediction of receptor affinity with considerable success, the prediction of IA, even qualitatively, has rarely been attempted. Because most traditional QSAR methods are limited to congeneric series, and there are often major structural differences between agonists and antagonists, this lack of success in predicting IA is understandable. To overcome this limitation, we used the method of comparative molecular field analysis (CoMFA), which, unlike traditional Hansch analysis, permits the inclusion of structurally dissimilar compounds in a single QSAR model. A structurally diverse set of 5-hydroxytryptamine1A (5-HT1A) receptor ligands, with literature IA data (determined by the inhibition of 5-HT sensitive forskolin-stimulated adenylate cyclase), was used to develop a 3-D QSAR model correlating intrinsic activity with molecular structure properties of 5HT1A receptor ligands. This CoMFA model had a crossvalidated r2 of 0.481, five components and final conventional r2 of 0.943. The receptor model suggests that agonist and antagonist ligands can share parts of a common binding site on the receptor, with a primary agonist binding region that is also occupied by antagonists and a secondary binding site accommodating the excess bulk present in the sidechains of many antagonists and partial agonists. The CoMFA steric field graph clearly shows that agonists tend to be “flatter” (more coplanar) than antagonists, consistent with the difference between the 5-HT1A agonist and antagonist pharmacophores proposed by Hibert and coworkers. The CoMFA electrostatic field graph suggests that, in the region surrounding the essential protonated aliphatic amino group, the positive molecular electrostatic potential may be weaker in antagonists as compared to agonists. Together, the steric and electrostatic maps suggest that in the secondary binding site region increased hydrophobic binding may enhance antagonist activity. These results demonstrate that CoMFA is capable of generating a statistically crossvalidated 3-D QSAR model that can successfully distinguish between agonist and antagonist 5-HT1A ligands. To the best of our knowledge, this is the first time this or any other QSAR method has been successfully applied to the correlation of structure with IA rather than potency or affinity. The analysis has suggested various structural features associated with agonist and antagonist behaviors of 5-HT1A ligands and thus should assist in the future design of drugs that act via 5-HT1A receptors. © 1993 John Wiley & Sons, Inc.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540140211
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 34
    Electronic Resource
    Electronic Resource
    Optimal use of the recurrence relations for the evaluation of molecular integrals over Cartesian Gaussian basis functions (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 14 (1993), S. 30-36 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: We consider the tree search problem for the recurrence relation that appears in the evaluation of molecular integrals over Cartesian Gaussian basis functions. A systematic way of performing tree search is shown. By applying the result of tree searching to the LRL2 method of Lindh, Ryu, and Liu (LRL) (J. Chem. Phys., 95, 5889 1991), which is an auxiliary function-based method, we obtain significant reductions of the floating point operations (FLOPS) counts in the K4 region. The resulting FLOPS counts in the K4 region are comparable up to [dd|dd] angular momentum cases to the LRL1 method of LRL, currently the method requiring least FLOPS for [dd|dd] and higher angular momentum basis functions. For [ff|ff], [gg|gg], [hh|hh], and [ii|ii] cases, the required FLOPS are 24, 40, 51, and 59%, respectively, less than the LRL1 method in the K4 region. These are the best FLOPS counts available in the literature for high angular momentum cases. Also, there will be no overhead in either the K2 or K0 region in implementing the present scheme. This should lead to more efficient codes of integral evaluations for higher angular momentum cases than any other existing codes. © 1993 John Wiley & Sons, Inc.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540140107
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 35
    Electronic Resource
    Electronic Resource
    Off-lattice Monte Carlo method with constraints: Long-time dynamics of a protein model without nonbonded interactions (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 14 (1993), S. 19-29 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: A method is proposed to perform computer simulations of protein dynamics in the long-time regime. The method is based upon a Monte Carlo technique. The only molecular degrees of freedom considered are bond rotations. All other degrees of freedom including the amide plane torsions are kept rigid. These constraints approximately account for all interactions related to chemical bonding. An individual Monte Carlo step adopts the Go and Scheraga algorithm where local conformational changes in a small window of the protein backbone are performed. By using correlated rotations, the conformation of residues outside the window remains invariant. To test the reliability of the method, the nonbonded interactions are turned off in the present application. Exact statistical averages are compared with values obtained from data of computer simulation involving 2 × 106 scans of the window along the protein backbone. Time is related to the number of scans of the window along the protein backbone. End-to-end distance autocorrelation functions decay to 1/e of its initial value in about 103-104 scans of the window algorithm. Time decay follows a stretched exponential Kohlrausch decay law. © 1993 John Wiley & Sons, Inc.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540140106
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 36
    Electronic Resource
    Electronic Resource
    Force field for platinum binding to adenine (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 14 (1993), S. 45-53 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: The antitumor drug cis-diamminedichloroplatinum(II) (cisplatin) binds preferentially to GpG and ApG sequences of DNA, forming N7,N7 intrastrand chelates. Molecular modeling of the intrastrand adducts have been handicapped, so far, by the lack of force-field data describing the Pt-guanine and Pt-adenine binding. We used ab initio calculations with relativistic pseudopotentials to evaluate three important parameters for the platinum-adenine model complex [Pt(NH3)3(Ade)]2+: (1) the force constant for the Pt—N7 bond bending out of the adenine plane; (2) the energy profile for the torsion about Pt—N7; (3) a set of fractional atomic charges that reproduce the ab initio potential for a number of space points placed around the adduct. A population analysis and comparative study on the tetrammine complex [Pt(NH3)4]2+ have shown that for platinum adenine is a better σ-donor than NH3, but its capacity as a π-acceptor is weak. © 1993 John Wiley & Sons, Inc.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540140109
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 37
    Electronic Resource
    Electronic Resource
    Prediction of possible crystal structures for C-, H-, N-, O-, and F-containing organic compounds (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 14 (1993), S. 422-437 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: A procedure is reported for the prediction of dense crystal structures of C-, H-, N-, O-, and F-containing organic compounds in the primitive triclinic, monoclinic, and orthorhombic space groups with Z ≤ 4. The crystal environments of molecules in 242 crystal structures have been analyzed to determine the common coordination sphere pattens. This led to the development of the MOLPAK (MOLecular PAcKing) program, which uses a rigid-body molecular structure probe to build packing arrangements (possible crystal structures) in the various space groups. A MOLPAK search, which involves the investigation of all unique orientations of a central molecule and the construction of the appropriate coordination patterns about the central molecule, provides a 3-D map of minimum unit cell volume as a function of the orientation of the central molecule. MOLPAK uses a repulsion-only potential and a preset threshold to place molecules in contact with each other. The 5-10 smallest volume packing arrangements from a search are subjected to a lattice energy minimization refinement with the WMIN program to yield possible crystal structures. The results are described from the analyses of several known compounds starting with the crystal molecular structures as the MOLPAK search probes in the P1, P21, P21/c, and P212121 space groups. In addition, several examples are given in which the search probes were created by AM1 geometry optimization of preliminary molecular models. More extensive data are given in supplementary tables. © 1993 John Wiley & Sons, Inc.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540140406
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 38
    Electronic Resource
    Electronic Resource
    AMBERCUBE MD, parallelization of Amber's molecular dynamics module for distributed-memory hypercube computers (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 14 (1993), S. 312-329 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: A fully functional parallel version of the molecular dynamics (MD) module of AMBER3a has been implemented. Procedures parallelized include the calculation of the long-range nonbonded Coulomb and Lennard-Jones interactions, generation of the pairlist, intramolecular bond, angle, dihedral, 1-4 nonbonded interaction terms, coordinate restraints, and the SHAKE bond constraint algorithm. As far as we can determine, this is the first published description where a distributed-memory MIMD parallel implementation of the SHAKE algorithm has been designed to treat not only hydrogen-containing bonds but also all heavy-atom bonds, and where “shaken” crosslinks are supported as well. We discuss the subtasking and partitioning of an MD time-step, load balancing the nonbonded evaluations, describe in algorithmic detail how parallelization of SHAKE was accomplished, and present speedup, efficiency, and benchmarking results achieved when this hypercube adaptation of the MD module AMBER was applied to several variant molecular systems. Results are presented for speedup and efficiency obtained on the nCUBE machine, using up to 128 processors, as well as benchmarks for performance comparisons with the CRAY YMP and FPS522 vector machines. © 1993 John Wiley & Sons, Inc.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540140307
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 39
    Electronic Resource
    Electronic Resource
    Rapid approximation to molecular surface area via the use of Boolean logic and look-up tables (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 14 (1993), S. 349-352 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: We report the development of a new approximate method of calculating molecular surface areas. Our technique is based upon the method of Sharake and Rupley but incorporates several major advances. First, we represent the state of surface points as bits in a bit string so we can utilize Boolean operations to simultaneously turn off multiple test points in one Boolean AND operation. Second, we use a series of Boolean mask look-up tables to reduce the time complexity of the calculation of molecular surface area down to the same magnitude as doing a potential energy evaluation. When we use a 256 surface point sphere for all of the atoms in BPTI, a 454 nonhydrogen atom protein, and a 1.4-Å solvent probe, we in general underestimate the total solvent-accessible surface area (SASA) by approximately 1.25% with a correlation coefficient of 0.9990 over a wide range of conformations. The average CPU time required to calculate the SASA of a BPTI conformer is 0.58 s on an SGI 4D/220 workstation. We also describe a method by which we can calculate an approximate finite difference SASA gradient for BPTI in 0.79 of CPU time. © 1993 John Wiley & Sons, Inc.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540140309
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 40
    Electronic Resource
    Electronic Resource
    Announcements (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 14 (1993), S. 378-378 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540140313
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 41
    Electronic Resource
    Electronic Resource
    Path integral theory: An improved simulation for the forces in semiclassic systems (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 14 (1993), S. 728-735 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: A method is proposed for calculating the forces in path integral theory and tested on semiclassic systems. It takes the range of the classic and quantum interactions into account and uses a second table within the neighbors table for the nearest neighbors. This method is found to be much more efficient than either the standard direct method or the traditional neighbors table, the efficiency increasing with the size of the system. The method can also be applied to clusters whose interaction centers are much farther apart than the distances between two consecutive members of the cluster. © 1993 John Wiley & Sons, Inc.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540140614
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 42
    Electronic Resource
    Electronic Resource
    Masthead (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 14 (1993) 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540140701
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 43
    Electronic Resource
    Electronic Resource
    Development of a restricted Hartree - Fock program INDMOL on PARAM: A highly parallel computer (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 14 (1993), S. 445-451 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: Parallelization of the SCF method for closed-shell molecules on the highly parallel transputer-based system PARAM is described. The parallelization has been implemented on three different hardware and software environments: (1) a network of bare 64 transputers; (2) configuration 1 plus a back-end file system (BFS); and (3) configuration 2 with one INTEL i860 processor. The evaluation of electron repulsion integrals (ERIs) and setting up of the Fock matrix is carried out in parallel on 64 nodes using minimal communication strategies. A good load balance is achieved for ERI evaluation with the help of bounds, local symmetry features, and the shell concept, as well as a data randomization technique, resulting into almost linear speedup (for ERI evaluation). In configurations 2 and 3, BFS is used for parallel storage and retrieval of ERIs. Further, in 3 matrix operations are implemented as remote procedure calls on the i860 processor. Routine techniques of level shifting and extrapolation are used for accelerating SCF convergence. The resulting package, INDMOL, has been tested for some randomly selected molecules having up to 255 contractions. Using configuration 3, a factor of 2 to 5 in computation time is obtained over 1, for the systems for which the ERIs cannot be stored in the distributed core memory. In summary, a heterogeneous system, as in configuration 3, can indeed be optimally exploited for programming peculiar diverse requirements of the SCF procedure. © 1993 John Wiley & Sons, Inc.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540140408
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 44
    Electronic Resource
    Electronic Resource
    The ethylene group as a peptide bond mimicking unit: A theoretical conformational analysis (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 14 (1993), S. 471-477 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: One of the features of the polypeptide backbone is that it represents a flexible chain that contains almost rigid CO—NH peptide bonds. One may try to substitute one or more such bonds by another relatively rigid unit to maintain the overall conformational properties of the backbone and at the same time modify some other properties of the molecule (“pseudopeptide”), such as the ability to form hydrogen bonds. By a detailed conformational analysis, it is shown that the carbon—carbon double bond is quite isosteric with the peptide bond and for this reason suitable for such a substitution. This is accomplished by applying molecular mechanics in calculation of the φ, ψ maps for pseudopeptide analogs of the N-acetyl-Ala-NHMe molecule. © 1993 John Wiley & Sons, Inc.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540140411
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 45
    Electronic Resource
    Electronic Resource
    Minimization of empirical energy functions in proteins including hydrophobic surface area effects (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 14 (1993), S. 510-521 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: We present analytical expressions to calculate the gradient of the water-accessible surface area of proteins with respect to Cartesian coordinates and dihedral angles. A detailed mathematical analysis leads to corrected equations for the gradient calculation used previously in the ANAREA program. To study the hydrophobic effect of solvent-protein interactions, our expressions have been implemented to further improve the program package FANTOM. We used this version of FANTOM to minimize the ECEPP/2 and the hydrophobic energy of tendamistat. © 1993 John Wiley & Sons, Inc.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540140503
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 46
    Electronic Resource
    Electronic Resource
    Comparative study between ab initio and semiempirical electrostatic potentials on molecular surfaces (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 14 (1993), S. 530-540 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: The electrostatic potentials of 21 molecules containing different functional groups has been computed at the ab initio RHF/6-31G* level on a series of solvent accessible surfaces and compared with MNDO, AM1, and PM3-derived pontentials. We analyzed in detail the distribution of electrostatic potentials on the surfaces around their maximum and minimum values and found out that consistently MNDO gives results similar to ab initio potentials. The actual values of the MNDO electrostatic potentials show a systematic deviation from the “correct” results, but the pattern of the MEP distribution on the surface is similar to that of the ab initio results. In contrast, PM3 fails in some cases to give even the correct number or distribution of “hot spots” of potential (low MEP) on the surface. AM1 behaves somewhere between these two semiempirical methods. As a conclusion, MNDO would be suggested as the best approach to analyses requiring a fast and efficient mapping of electrostatic potentials on simplified models of molecular surfaces. © 1993 John Wiley & Sons, Inc.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540140505
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 47
    Electronic Resource
    Electronic Resource
    Loop closure via bond scaling and relaxation (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 14 (1993), S. 556-565 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: We describe, test, and apply a new computational algorithm for generating protein loop conformations subject to distance and secondary structure constraints. The algorithm is based upon initial scaling and subsequent relaxation of covalent bond lengths. The scaling-relaxation procedure needs no additional energy terms and can be readily incorporated into existing molecular modeling packages. The algorithm uses an all-atom energy function from the outset in a straightforward way so that about 60% of the generated loop conformations are free of severe distortions of covalent bond lengths and angles. An extensive application to the major loop conformations of TFIIIA-type zinc fingers (Zif268 and ADR1) is presented, as well as preliminary calculations on hypervariable loops of two immunoglobulins (MCPC603 and Bence-Jones). © 1993 John Wiley & Sons, Inc.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540140508
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 48
    Electronic Resource
    Electronic Resource
    Cumulative and discrete similarity analysis of electrostatic potentials and fields (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 14 (1993), S. 928-933 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: A new index suitable for computing molecular similarity based upon the similarity of molecular properties such as electrostatic potentials or electrostatic fields is presented in two forms. For one form of the present index, general conditions are established for which a linear measure of similarity is obtained. An illustrative example is provided in which the electrostatic field and electrostatic potential of guanine obtained from different wave functions are compared. © 1993 John Wiley & Sons, Inc.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540140808
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 49
    Electronic Resource
    Electronic Resource
    Conformational analysis of cocaine, the potent analog 2β-carbomethoxy-3β-(4-fluorophenyl)tropane (CFT), and other dopamine reuptake blockers (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 14 (1993), S. 934-943 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: Using the MM2-87 program and parameter set, conformational analyses have been performed on cocaine (1), the potent analog 2β-carbomethoxy-3β-(4-fluorophenyl)tropane (CFT, 2), and a group of dopamine reuptake blockers that contain two phenyl rings. The latter includes LU 19-005 (3), a 1-amino-4-phenyltetralin (4), a hexahydropyrrolo[2,1-a]isoquinoline (5), diclofensine (6), and a hexahydro[1,2-b]pyridine (7). Using different values for the dielectric constant, the global minimum of 1 and 2 is a conformer in which there is a favorable electrostatic interaction between the ammonium hydrogen and the carbonyl of the carbomethoxy group. The N-methyl groups in 1 and 2 are found to strongly prefer the equatorial position of the piperidine ring. These results were also related to four crystal structures of 1 and its close derivatives. Compounds 3-7 are found to have a common conformation that was used to define the pharmacophore for dopamine reuptake blockers including the required orientation of the ammonium hydrogen. The pharmacophore provides an explanation for why the tertiary amine analogs of 3 and 4 are less potent than the secondary amines because the added N-methyl group occupies the position required for the ammonium hydrogen. This explanation, however, does not work for 7, in which the tertiary amine is again less active than the secondary amine. However, this last series appears to have a number of anomalous features. Superposition of 2 with the pharmacophore suggests that its carbomethoxy may occupy the same region of the receptor as the second phenyl ring in compounds 3-7. © 1993 John Wiley & Sons, Inc.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540140809
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 50
    Electronic Resource
    Electronic Resource
    Multipole correction of atomic monopole models of molecular charge distribution. I. Peptides (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 14 (1993), S. 970-976 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: The defects in atomic monopole models of molecular charge distribution have been analyzed for several model-blocked peptides and compared with accurate quantum chemical values. The results indicate that the angular characteristics of the molecular electrostatic potential around functional groups capable of forming hydrogen bonds can be considerably distorted within various models relying upon isotropic atomic charges only. It is shown that these defects can be corrected by augmenting the atomic point charge models by cumulative atomic multipole moments (CAMMs). Alternatively, sets of off-center atomic point charges could be automatically derived from respective multipoles, providing approximately equivalent corrections. For the first time, correlated atomic multipoles have been calculated for N-acetyl, N′-methylamide-blocked derivatives of glycine, alanine, cysteine, threonine, leucine, lysine, and serine using the MP2 method. The role of the correlation effects in the peptide molecular charge distribution are discussed. © 1993 John Wiley & Sons, Inc.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540140812
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 51
    Electronic Resource
    Electronic Resource
    Masthead (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 14 (1993) 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540140901
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 52
    Electronic Resource
    Electronic Resource
    AQUARIUS2: Knowledge-based modeling of solvent sites around proteins (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 14 (1993), S. 1007-1018 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: The program AQUARIUS2 calculates probable positions for water molecules within the first hydration shell of any protein for which atomic coordinates are known. Like its predecessor, AQUARIUS, it uses a knowledge of water molecules sites from crystallographically determined protein structures. Energy calculations are not employed. It differs substantially from the original program in that a 3-D probability map (for solvent sites) is generated around the surface of the protein instead of the previously used discrete points. The accuracy of the program has been gauged by comparison with experimentally derived water molecule positions for proteins not used in the knowledge base of the program. It has also been tested by combining the probability density maps with crystallographically determined electron density maps for the protein porphobilinogen deaminase. This procedure filters the most likely solvent electron density peaks from the background noise and has been used in the determination of the solvent structure around the protein nerve growth factor. © John Wiley & Sons, Inc.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540140902
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 53
    Electronic Resource
    Electronic Resource
    New method for the derivation of net atomic charges from the electrostatic potential (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 14 (1993), S. 1036-1041 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: Net atomic charges are derived from a least-squares fitting to electrostatic potentials at atomic sites. The method treats atoms in the molecule as having spherically averaged Hartree-Fock densities, the atomic densities overlapping with one another. The method has the advantage of best reproducing the electrostatic potentials at the atomic nuclei and avoiding the arbitrariness in choosing the points used in the fitting. We have written a FORTRAN program, CHELPN92 (Z. Su, Chemistry Department, SUNY at Buffalo, Buffalo, NY, 1992), based on the method and applied it to deuterated benzene, l-alanine, d,l-histidine, 2-methyl-4-nitroaniline, and deuterated pyridinium-1-dicyanomethylide using the molecular geometry and electrostatic potentials from analysis of accurate X-ray diffraction data. The derived charges are used to calculate the molecular dipole moments. While the charges from this method are in general significantly different from those from the kappa refinement [P. Coppens, T.N. Guru Row, P. Leung, E.D. Stevens, P.J. Becker, and Y.W. Yang, Acta Cryst. A, 35, 63 (1979)], the dipole moments obtained with the new method agree well with those from the kappa refinement. © John Wiley & Sons, Inc.
    Additional Material: 6 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540140905
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 54
    Electronic Resource
    Electronic Resource
    Conformational searching methods for small molecules. I. Study of the sybyl search method (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 14 (1993), S. 1050-1065 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: Several methods are available in the literature for the conformational analysis of small molecules. Each of these methods has some advantages and some disadvantages. Also, each of these methods may be expected to perform better or worse on different types of molecules. There is no clear calibration of each of these methods against a “standardized” set of molecules available in the literature. Such a reference work would be useful to the community because it would allow the choice of methods to be based on some facts. We attempted to provide a start to such a calibration in this article with an examination of the SYBYL SEARCH method. Methods for evaluating the performance of this method are described in detail and will be applied to all other available conformational analysis methods in future papers. © John Wiley & Sons, Inc.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540140907
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 55
    Electronic Resource
    Electronic Resource
    Announcement (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 14 (1993), S. 1123-1123 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540140913
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 56
    Electronic Resource
    Electronic Resource
    Continuous similarity measure between nonoverlapping X-ray powder diagrams of different crystal modifications (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 14 (1993), S. 1125-1135 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: The problem of quantifying similarity between crystal structures is transformed into the problem of comparing the associated X-ray powder diagrams. A smooth similarity measure between two powder diagrams, termed a “fold,” is defined. In contrast to conventional comparison methods, the introduced method is still applicable when the peaks of the spectra to be compared have no overlap. The main areas of application of the method are the construction of a molecular crystal structure when only the experimental powder diagram is available and the analysis of possible crystal packings predicted on the basis of molecular information only. A suitable empirical parameterization of the fold has been derived from a large set of experimental and force-field-generated crystals. The analysis of the outcome of an ab initio packing of a flexible molecule is given as an example. The algorithmic details of the method are given as a FORTRAN 77 code. © John Wiley & Sons, Inc.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540141002
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 57
    Electronic Resource
    Electronic Resource
    CONCEPTS: New dynamic algorithm for de novo drug suggestion (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 14 (1993), S. 1184-1193 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: We describe a new method for de novo design of molecules that bind to protein active sites. The method, CONCEPTS (Creation of Novel Compounds by Evaluation of Particles at Target Sites), places a group of atom-like particles in the site. The particles are free to move within the site to improve binding to the protein. A key innovation of this technique is that covalent connections are made among the particles in a stochastic and dynamically reversible manner. These changes in the topology are either accepted or rejected depending on their ability to improve the total energy of the enzyme-inhibitor complex. The method is applied to two test systems: The FK506 binding protein (FKBP-12) and HIV-1 aspartyl protease. In both cases, we are able to predict, de novo, drugs that have striking similarities to known potent inhibitors and that can successfully be used to generate “hits” of the known inhibitors from a data base. © John Wiley & Sons, Inc.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540141008
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 58
    Electronic Resource
    Electronic Resource
    Long-Range multicenter integrals with slater functions: Gauss transform-based methods (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 14 (1993), S. 1203-1211 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: The separation of the short- and long-range terms in the potentials generated by pairs of Slater functions is reformulated in the context of the Gauss transform method. Analytic expressions of the long-range potentials (in closed form) are derived for equal exponents and generalized (as expansion series) for different exponents. Additionally, the representation of these potentials from small sets of charges or lowest-order multipoles is examined, paying special attention to their values and optimal positions. Finally, numerical tests of the formal developments are presented. It is concluded that the long-range three- and four-center integrals can be calculated with high accuracy in a simple and relatively inexpensive manner. © John Wiley & Sons, Inc.
    Additional Material: 7 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540141010
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 59
    Electronic Resource
    Electronic Resource
    Masthead (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 14 (1993) 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540141101
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 60
    Electronic Resource
    Electronic Resource
    Comparison of two force fields by molecular dynamics simulations of glucose crystals: Effect of using ewald sums (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 14 (1993), S. 1281-1289 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: To compare the GROMOS force field with one designed by Ha et al., molecular dynamics simulations of α-D-glucose anhydrate and monohydrate crystals were performed. Also, the long-range interactions were calculated both with a cutoff approximation and with Ewald summations. The results are compared with results obtained experimentally by neutron and X-ray diffraction. The force-field parameters had been optimized with the cutoff approximation; this apparently led to worse results when the Ewald summations were used. However, in all simulations the symmetry was roughly preserved and the mean atomic coordinates and thermal parameters, bond angles, and dihedrals without hydrogen atoms were rather well reproduced. The dihedrals with hydrogen atoms exhibited conformational transitions, which resulted in a disordered hydrogen bonding scheme. In general, the GROMOS force field performed better than the Ha force field. © John Wiley & Sons, Inc.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540141104
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 61
    Electronic Resource
    Electronic Resource
    Optimization and application of lithium parameters for PM3This article is dedicated to Prof. Dr. A.R. Katritzky on the occasion of his 65th birthday. (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 14 (1993), S. 1301-1312 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: Lithium parameters have been optimized for Stewart's standard PM3 method. The average deviation of the heats of formation calculated for 18 reference compounds is 6.2 kcal/mol from the experimental or high-level ab initio data; the average deviation with Li/MNDO is 18.9 kcal/mol. The average error in bond lengths is also reduced by a factor of two to three. Ionization potentials and dipole moments are reproduced with comparable accuracy than Li/MNDO. However, the mean deviation for the heats of formation of both methods increases when being applied to other systems, especially to small inorgnic molecules. The applicability of the new parameter set is demonstrated further for various compounds not included in the reference set, for the calculation of the activation barriers of several lithiation reactions, as well as for the estimation of oligomerization energies of methyl lithium (including the tetramer). Li/PM3 gives reliable results even for large dimeric complexes, like [{4-(CH3CR)C5H4N}Li]2, containing TMEDA or THF as coligands and reproduces the haptotropic interaction between Li+ and π-systems (e.g., in benzyl lithium) as well as the relative energies and structural features of compounds with “hypervalent” atoms (e.g., in lithiated sulfones). © John Wiley & Sons, Inc.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540141106
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 62
    Electronic Resource
    Electronic Resource
    Prediction of peptide conformation by multicanonical algorithm: New approach to the multiple-minima problem (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 14 (1993), S. 1333-1338 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: We apply a recently developed method, the multicanonical algorithm, to the problem of tertiary structure prediction of peptides and proteins. As a simple example to test the effectiveness of the algorithm, metenkephalin is studied and the ergodicity problem, or multiple-minima problem, is shown to be overcome by this algorithm. The lowest-energy conformation obtained agrees with that determined by other efficient methods such as Monte Carlo simulated annealing. The superiority of the present method to simulated annealing lies in the fact that the relationship to the canonical ensemble remains exactly controlled. Once the multicanonical parameters are determined, only one simulation run is necessary to obtain the lowest-energy conformation and further the results of this one run can be used to calculate various thermodynamic quantities at any temperature. The latter point is demonstrated by the calculation of the average potential energy and specific heat as functions of temperature. © John Wiley & Sons, Inc.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540141110
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 63
    Electronic Resource
    Electronic Resource
    Ab initio molecular orbital calculations for 3,6-dihydro-1,2-dithiin and 3,6-dihydro-1,2-dioxin (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 14 (1993), S. 1376-1384 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: Optimized geometries and total energies for the conformers of 3,6-dihydro-1,2-dithiin (2) and 3,6-dihydro-1,2-dioxin (3) were calculated at several ab initio MO levels: RHF/3-21G(*), RHF/6-31G*, MP2/6-31G*, and MP2/6-31G*/ /RHF/3-21G(*). For the dioxin, in addition to the above levels the corresponding nonextended basis sets ab initio methods were also carried out. The dithiin results are compared with those of simple disulfanes, HSSH and (CH3)2S2, whose optimized geometries agree closely with the observed structures, which is the gauche (C2 symmetry). For the disulfanes, the gauche geometries from RHF/3-21G(*) are in good agreement with the observed structure while the RHF/3-21G results best fit the dioxin. Pertinent structural data at the RHF/3-21G(*) for the half-chair (C2) dithiin are: bond lengths, —SS—, —CS—, —CC=, and —C=C—, 2.050, 1.817, 1.515, and 1.317 Å, respectively; bond angles, CSS, =CCS, and C=CS, 98.0, 114.2, and 127.8°, respectively; CSSC dihedral angle of 63.2°; and twist angle of 36.5°. The total energy for half-chair dithiin at MP2/6-31G*//RHF/3-21G(*) is less than the planar (C2v) and the half-boat (Cs) structures by 69.67 and 29.05 kJ/mol, respectively. The calculated structural data (vs. observed) at RHF/3-21G for the half-chair dioxin are: bond lengths, —OO—, —CO—, —CC=, and C=C, 1.464 (1.463), 1.454, 1.509, and 1.313 Å (1.338 Å), respectively; bond angles, COO, =CCO, and C=CO, 105.0, 109.8 (110.3), and 120.7° (119.9°), respectively; COOC dihedral angle of 79.7° (80 ± 2°); and twist angle of 39.0 (38.3°). The total energy for half-chair dioxin at MP2/6-31G//RHF/3-21G is less than the planar and the half-boat structures by 70.35 and 42.85 kJ/mol, respectively. The total energies calculated at the extended basis sets (*) ab initio levels for the C2 symmetry dioxin are much lower than those of the nonextended basis sets. © John Wiley & Sons, Inc.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540141114
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 64
    Electronic Resource
    Electronic Resource
    Grid positioning independence and the reduction of self-energy in the solution of the Poisson - Boltzmann equation (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 14 (1993), S. 1417-1422 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: A common problem in the solution of the Poisson-Boltzmann equation using finite difference methods is the self-energy of the system, also known as the grid energy. Because atoms are typically modeled as a point charge, the infinite self-energy of a point charge is likewise modeled. In this article, a simple, alternate treatment of atomic charge is described where each atom is represented as a sphere of uniform charge. Unlike the point charge model, this method converges as the grid spacing is reduced. The uniform charge model generates the same electrostatic field outside the atoms. In addition, the use of fine grids reduces the variations in the potential due to variations in the position of atoms relative to the grid. Calculations of Born ion solvation energies, small-molecule solvation energies, and the electrostatic field of superoxide dismutase are used to demonstrate that this method yields the same results as the point charge model. © John Wiley & Sons, Inc.
    Additional Material: 5 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540141202
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 65
    Electronic Resource
    Electronic Resource
    Algorithm to test the structural plausibility of a proposed elementary reaction (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 14 (1993), S. 1454-1459 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: An algorithm is introduced that tests whether a proposed elementary reaction can be realized within a specified number of cleavages and formations of covalent bonds. This is related to the problem of computing the minimum chemical distance of a given stoichiometry, but differs from it in important ways that are exploited in the algorithm design. One application of the algorithm is as a filter in MECHEM - a computer aid for the elucidation of reaction pathways. In that application, reaction steps implying more changes to covalent bonds than a given threshold are ruled implausible, and in practice such tests need to be carried out many thousands of times. Future applications of the algorithm can be expected because the question addressed is a fundamental one: What elementary reactions can occur? © 1993 by John Wiley & Sons, Inc.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540141207
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 66
    Electronic Resource
    Electronic Resource
    Improved strategy in analytic surface calculation for molecular systems: Handling of singularities and computational efficiency (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 14 (1993), S. 1272-1280 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: Computer methods for analytic surface calculations of molecular systems suffer from numerical instabilities and are CPU time consuming. In this article, we present proposals toward the solution of both problems. Singularities arise when nearly collinear triples of neighboring atoms or multiple vertices are encountered during the calculation. Topological decisions in analytic surface calculation algorithms (accessibility of vertices and arcs) are based upon the comparison of distances or angles. If two such numbers are nearly equal, then currently used computer programs may not resolve this ambiguity correctly and can subsequently fail. In this article, modifications in the analytic surface calculation algorithm are described that recognize singularities automatically and treat them appropriately without restarting parts of the computation. The computing time required to execute these alterations is minimal. The basic modification consists in defining an accuracy limit within which two values may be assumed as equal. The search algorithm has been reformulated to reduce the computational effort. A new set of formulas makes it possible to avoid mostly the extraction of square roots. Tests for small-and medium-sized intersection circles and for pairs of vertices with small vertex height help recognize fully buried circles and vertex pairs at an early stage. The new program can compute the complete topology of the surface and accessible surface area of the protein crambin in 1.50-4.29 s (on a single R3000 processor of an SGI 4D/480) depending on the compactness of the conformation where the limits correspond to the fully extended or fully folded chain, respectively. The algorithm, implemented in a computer program, will be made available on request. © John Wiley & Sons, Inc.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540141103
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 67
    Electronic Resource
    Electronic Resource
    Generalized morse analytic function for the “true” diatomic potential of the RKR type (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 14 (1993), S. 1320-1325 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: The problem of the representation of the RKR (or IPA) diatomic potential by a simple analytic function is considered. This old problem has for a fairly good solution the Coxon-Hajigeorgiou function U(x) = D[1 - exp-fn(x)]2 with fn(x) = Σm = 1n amxm. The problem of the determination of the disposable parameters a1 … an [in order that U(r) fits the given RKR potential] is reduced to that of a set of linear equations in am where a standard least-squares technique is used. The application to several states (ground or excited) of several molecules shows that a fairly “good” fit is obtained for n ∼ 10, even for the state XOg - I2 bounded by 109 vibrational levels, for which the RKR potential is defined by the coordinates of 219 points. It is shown that the percentage deviation |U(r)RKR - U(r)| throughout the range of r values is about 0.04% for XΣ—Li2, 0.0005% for XΣ—HCl, 0.06% for XOg—I2, and 0.05% for BOu—I2 (as examples). This approach shows the same success for deep and shallow potentials. The comparison of the computed Ev (vibrational energy) and Bv (rotational constant) with their corresponding experimental values shows that a good agreement is reached even for high vibrational levels close to the dissociation. © John Wiley & Sons, Inc.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540141108
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 68
    Electronic Resource
    Electronic Resource
    General atomic and molecular electronic structure system (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 14 (1993), S. 1347-1363 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: A description of the ab initio quantum chemistry package GAMESS is presented. Chemical systems containing atoms through radon can be treated with wave functions ranging from the simplest closed-shell case up to a general MCSCF case, permitting calculations at the necessary level of sophistication. Emphasis is given to novel features of the program. The parallelization strategy used in the RHF, ROHF, UHF, and GVB sections of the program is described, and detailed speecup results are given. Parallel calculations can be run on ordinary workstations as well as dedicated parallel machines. © John Wiley & Sons, Inc.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540141112
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 69
    Electronic Resource
    Electronic Resource
    Characterization of force fields for lipid molecules: Applications to crystal structures (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 14 (1993), S. 1066-1076 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: The nonbonded portion of a force field for lecithins was characterized by application to the study of the crystal packing geometry and energetics of eight different molecules. The molecules were either lecithin fragments or chosen to isolate particular intermolecular features to test the accuracy of the force field specifically for those interactions. In particular, the hydrocarbon interactions, hydrogen bonding, electrostatics, and phosphate interactions were critiqued. The results support previous findings that indicated that this force field is reasonably accurate for lecithins. For all molecules, a minimum was found near the experimentally determined crystal structure. Using D-glucitol as an example, it is shown that the structural effect of hydrogen bonding is better represented by a nonelectrostatic force-field model than by a purely electrostatic model. Results obtained with glycerylphosphocholine and four smaller organic phosphate molecules suggest that further study of nonbonded interactions of phosphate groups is needed. © John Wiley & Sons, Inc.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540140908
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 70
    Electronic Resource
    Electronic Resource
    Masthead (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 14 (1993) 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540141001
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 71
    Electronic Resource
    Electronic Resource
    Computation of the mean residence time of water in the hydration shells of biomolecules (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 14 (1993), S. 1396-1406 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: An algorithm is presented within the context of the calculation of the time-relaxation behavior of the hydration shells around atomic sites in biomolecules. We report a calculation of the time-relaxation behavior of the first and second hydration shells of polar, hydrophobic, and charged groups in a protein, crambin. The water mean residence times around protein groups are obtained from averages over configurations sampled during a 325-ps molecular dynamics simulation of crambin in solution. A convolution arising in the calculation of the mean relaxation time is implemented using a parallel prefix operator. A new characterization is given of the parallel prefix operator as a linear transformation, and this formulation enables us to derive efficient factorization of the convolution as a product of two parallel prefix operations. The parallel prefix operations are implemented in logarithmic time. © John Wiley & Sons, Inc.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540141116
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 72
    Electronic Resource
    Electronic Resource
    Distributed data parallel coupled-cluster algorithm: Application to the 2-hydroxypyridine/2-pyridone tautomerism (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 14 (1993), S. 1429-1439 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: The recently developed parallel coupled-cluster algorithm of Rendell, Lee, and Lindh [Chem. Phys. Lett., 194, 84 (1992)] is extended to allow four-indexed quantities containing one or two indices in the virtual orbital space to be stored across the global memory of distributed-memory parallel processors. Quantities such as the double-excitation amplitudes can now be distributed over multiple nodes, with blocks of data retrieved from remote nodes by the use of interrupt handlers. As an application of the new code, we have investigated the potential energy surface of the 2-hydroxypyridine/2-pyridone tautomers. Using large basis sets, the structure of each tautomer and the transition state connecting the two minima has been determined at the SCF level. The relative energy difference and the activation energy were then redetermined using the MP2, CCSD, and CCSD(T) methods. All calculations have been performed on Intel distributed-memory supercomputers. The largest coupled-cluster calculations contained over 2 million double-excitation amplitudes. © John Wiley & Sons, Inc.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540141204
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 73
    Electronic Resource
    Electronic Resource
    Estimation of pKa for organic oxyacids using calculated atomic charges (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 14 (1993), S. 1460-1467 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: A method for the estimation of pKa from empirically calculated atomic charges has been developed and tested on a diverse set of organic oxyacids. The approach involves a comparison of the atomic charges calculated for both the acid and the negative ion that is formed after loss of the acidic proton. These charges have been used in conjunction with the familiar concepts of induction and resonance to develop an accurate formula to predict pKa. Results for a set of 135 compounds, including alcohols, phenols, and carboxylic acids, yielded a fit of pKa with r = 0.993 and an rms error of 0.455. © John Wiley & Sons, Inc.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540141208
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 74
    Electronic Resource
    Electronic Resource
    Neubestimmung von Struktur und Eigenschaften isotyper Natriumtetraamidometallate des Aluminiums und Galliums (1993)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 619 (1993), S. 381-386 
    Details
    ISSN: 0044-2313
    Keywords: Sodium tetraamido aluminate ; sodium tetraamido gallate ; crystal structure ; IR spectra ; thermal behaviour ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Redetermination of Structure and Properties of the Isotypic Sodium Tetraamido Metallates of Aluminium and GalliumCrystals for x-ray structure determination of NaAl(NH2)4 and NaGa(NH2)4 were obtained by the reaction of the metals with ammonia in autoclaves at 100°C and P(NH3) = 60 bar within 7 days. The compounds crystallize isotypic in the space group P21/c with Z = 4 NaAl(NH2)4 a = 7.328(2) Å, b = 6.047(2) Å, c = 13.151(3) Å, β = 94.04(1)° NaGa(NH2)4 a = 7.4087(8) Å, b = 6.0917(5) Å, c = 12.855(2) Å, β = 92.10(1)°The structures were refined inclusively all H-positions of the amide ions. The ternay amides are furthermore characterized by their IR spectra and their thermal behaviour.
    Notes: Für röntgenographische Strukturbestimmungen geeignete Kristalle von NaAl(NH2)4 und NaGa(NH2)4 wurden durch Umsetzung der Metalle mit NH3 in Autoklaven bei 100°C und P(NH3) = 60 bar in 7d erhalten. Die Verbindungen kristallisieren isotyp in der Raumgruppe P21/c mit Z = 4 NaAl(NH2)4 a = 7,328(2) Å, b = 6,047(2) Å, c = 13,151(3) Å, β = 94,04(1)° NaGa(NH2)4 a = 7,4087(8) Å, b = 6,0917(5) Å, c = 12,855(2) Å, β = 92,10(1)°Die Strukturen wurden einschließlich aller H-Lagen der NH2--Ionen bestimmt. Die ternären Amide werden außerdem IR-spektroskopisch und bezüglich ihres thermischen Verhaltens charakterisiert.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19936190224
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 75
    Electronic Resource
    Electronic Resource
    Über eine neu entdeckte Dimorphie an BaCoEr2O5 (1993)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 619 (1993), S. 421-423 
    Details
    ISSN: 0044-2313
    Keywords: Barium, cobalt, erbium, oxide ; crystal structure ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: On a New Observed Dimorphism of BaCoEr2O5Single crystals of BaCoEr2O5 were prepared by CO2-LASER technique under N2-atmosphere and investigated by X-ray single crystal methods. It crystallizes with orthorhombic symmetry, space group D2h16-Pnma (a = 12.2787, b = 5.6826, c = 7.0344 Å; Z = 4). The so far unknown crystal structure of BaCoEr2O5 belongs to the BaCuLn2O5 type forming the dimorphic substance to the previously described Ni type of BaCoEr2O5.
    Notes: BaCoEr2O5 wurde mit CO2-LASER-Technik in Stickstoffatmosphäre einkristallin dargestellt und röntgenographisch untersucht. Es kristallisiert orthorhombisch, Raumgruppe D2h16-Pnma, mit den Gitterkonstanten a = 12,2787, b = 5,6826, c = 7,0344 Å; Z = 4. Die hier untersuchten Einkristalle von BaCoEr2O5 gehören zum BaCuLn2O5-Typ und bilden die dimorphe Form zum früher beschrieben Ni - Typ von BaCoEr2O5.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19936190230
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 76
    Electronic Resource
    Electronic Resource
    Zur Kenntnis der Dialkalimetalldichalkogenide β-Na2S2, K2S2, α-Rb2S2, β-Rb2S2, K2Se2, Rb2Se2, α-K2Te2, β-K2Te2 und Rb2Te2 (1993)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 619 (1993), S. 476-488 
    Details
    ISSN: 0044-2313
    Keywords: Dialkali metal dichalcogenides ; preparation ; crystal structure ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: On Dialkali Metal Dichalcogenides β-Na2S2, K2S2, α-Rb2S2, β-Rb2S2, K2Se2, Rb2Se2, α-K2Te2, β-K2Te2 and Rb2Te2The first presentation of pure samples of α- and β-Rb2S2, α- and β-K2Te2, and Rb2Te2 is described. Using single crystals of K2S2 and K2Se2, received by ammonothermal synthesis, the structure of the Na2O2 type and by using single crystals of β-Na2S2 and β-K2Te2 the Li2O2 type structure will be refined. By combined investigations with temperature-dependent Guinier-, neutron diffraction-, thermal analysis, and Raman-spectroscopy the nature of the monotropic phase transition from the Na2O2 type to the Li2O2 type will be explained by means of the examples α-/β-Na2S2 and α-/β-K2Te2. A further case of dimorphic condition as well as the monotropic phase transition of α- and β-Rb2S2 is presented. The existing areas of the structure fields of the dialkali metal dichalcogenides are limited by the model of the polar covalence.
    Notes: Die erstmalige Darstellung phasenreiner Proben von α- und β-Rb2S2, von α- und β-K2Te2 und von Rb2Te2 wird beschrieben. Mit Hilfe von ammonothermal synthetisierten Einkristallen des K2S2 und des K2Se2 wird die Struktur des Na2O2-Typs, mit Einkristallen des β-Na2S2 und des β-K2Te2 die des Li2O2-Typs verfeinert. Durch kombinierte temperaturabhängige Guinier-, Neutronenbeugungs-, thermoanalytische und Raman-spektroskopische Untersuchungen wird die Natur des monotropen Phasenübergangs vom Na2O2-Typ zum Li2O2-Typ an Hand der Beispiele α-/β-Na2S2 und α-/β-K2Te2 aufgeklärt. Ein weiterer Fall von Dimorphie, der ebenfalls monotrope Übergang von α-Rb2S2(Rb2O2-Typ) zu β-Rb2S2(Na2O2-Typ), wird vorgestellt. Die Existenzgebiete der Strukturfelder bei den Dialkalimentalldichalkogeniden werden mittels des Modells der polaren Kovalenz gegeneinander abgegrenzt.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19936190309
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 77
    Electronic Resource
    Electronic Resource
    Synthese und Kristallstruktur von CaBiVO5 (1993)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 619 (1993), S. 521-524 
    Details
    ISSN: 0044-2313
    Keywords: Calcium ; bismuth ; vanadium ; oxide ; crystal structure ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthesis and Crystal Structure of CaBiVO5Single crystals of the hitherto unknown compound CaBiVO5 were prepared and investigated by X-ray work. It crystallizes with orthorhombic symmetry, space group D2h15—Pbca, a = 11.2022, b = 5.4283, c = 15.5605 Å, Z = 8. The crystal structure is characterized by layers of the edge-linked CaO7 polyhedra, isolated VO4 tetrahedra and an asymmetric surrounding of Bi3+ by oxygen.
    Notes: Die bisher unbekannte Verbindung CaBiVO5 wurde einkristallin dargestellt und röntgenographisch untersucht. Sie kristallisiert orthorhombisch in der Raumgruppe D2h15-Pbca mit a = 11,2022, b =5,4283, c = 15,5605 Å, Z = 8. Die Kristallstruktur ist durch Schichten aus CaO7-Polyedern, isolierte VO4-Tetraeder und asymmetrisch koordinierte Bi3+-Ionen charakterisiert.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19936190315
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 78
    Electronic Resource
    Electronic Resource
    Zwei neue Verbindungen mit Zink in tetragonal pyramidaler Koordination: BaZnDy2O5 und Ba1,25ZnHo2O5,25 (Ba5Zn4Ho8O21) (1993)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 619 (1993), S. 529-533 
    Details
    ISSN: 0044-2313
    Keywords: Barium-zinc-rare earth metal-oxide ; crystal structure ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: New Compounds with Zinc in Square Pyramidal Coordination: BaZnDy2O5 and Ba1.25ZnHo2O5.25 (Ba5Zn4Ho8O21).Single crystals of (I): BaZnDy2O5 and (II): Ba5Zn4Ho8O21 were prepared by high temperature reactions and investigated by X-ray technique. (I) belongs to the BaCuLn2O5 type, space group D2h16-Pbnm; a = 7.084; b = 12.368; c = 5.728 Å, Z = 4. (II) is isotypic to Ba5Mn4Ln8O21, space group C4h5-I4/m; a = 13.779; c = 5.707 Å, Z = 2. The two different structure types are caused by the small difference in the composition of 0.25 BaO. Analogies and differences will be discussed. In addition the lattice constants of powder samples of Ba5Zn4Ln8O21 (Ln = Eu, Gd, Dy, Ho, Er and Y) are given.
    Notes: Mit Hochtemperaturreaktionen wurden Einkristalle von (I): BaZnDy2O5 und (II): Ba5Zn4Ho8O21 dargestellt und röntgenographisch untersucht. (I) gehört zum BaCuLn2O5-Typ, Raumgruppe D2h16-Pbnm mit a = 7,084; b = 12,368; c = 5,728 Å, Z = 4. (II) ist isotyp zum Ba5Mn4Ln8O21-Typ, Raumgruppe C4h5-I4/m, mit a = 13,779; c = 5,707 Å, Z = 2. Der geringe Unterschied von 0,25 BaO führt zu zwei verschiedenen Strukturtypen. Gemeinsamkeiten und Unterschiede werden diskutiert. Weitere Verbindungen vom Typ Ba5Zn4Ln8O21 mit Ln = Eu, Gd, Dy, Ho, Er und Y wurden mikrokristallin dargestellt und die Gitterkonstanten bestimmt.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19936190317
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 79
    Electronic Resource
    Electronic Resource
    Zur Kristallchemie von Ba3In2Zn5O11. Ein tOxoindat/zinkatsol;zinkat mit Zn10O20- und In4O16-Makropolyedern und erstmals O2- in tetraedrischer Koordination durch Zn2+ (1993)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 619 (1993), S. 559-562 
    Details
    ISSN: 0044-2313
    Keywords: Barium ; indium ; zinc ; oxide ; crystal structure ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: On the Crystal Structure of Ba3In2Zn5O11. An Oxoindate/zincatesol;zincate with Zn10O20 and In4O16 Macropolyhedra with Zn2+ in Tetrahedral Coordination by O2-Ba3In2Zn5O11 was prepared for the first time by a flux technique and investigated by single crystal X-ray work. It crystallizes with cubic symmetry, space group T2d-F43m, a = 13.3588 Å, Z = 8. Zn2+ show tetrahedral coordination by O2-, forming Zn10O20 macropolyhedra. In addition the nZn/Osol;O part of the crystal structure is made up of Zn10O20 parts. Edge connection of four InO6 octahedra results in In4O16 groups. The crystal structure will be shown and discussed.
    Notes: Mit einer Schmelzmitteltechnik wurde erstmals Ba3In2Zn5O11 dargestellt und an Einkristallen röntgenographisch untersucht. Es kristallisiert kubisch, in der Raumgruppe T2d-F43m, mit a = 13,3588 Å und Z = 8. Zn2+ ist tetraedrisch von O2- koordiniert und bildet Zn10O20-Makropolyeder. Ferner wird der nZn/Osol;O-Teil der Kristallstruktur aus Zn10O20-Bausteinen zusammen-gesetzt. Die oktaedrisch koordinierten In3+-Ionen verknüpfen über Kanten zu In4O16-Baugruppen. Die Kristallstruktur wird vorgestellt und diskutiert.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19936190322
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 80
    Electronic Resource
    Electronic Resource
    Darstellung und Kristallstruktur eines Kalium - Magnesium-Oxocuprat/-vanadats: KMg2Cu2V3O12 (1993)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 619 (1993), S. 617-620 
    Details
    ISSN: 0044-2313
    Keywords: Potassium ; magnesium ; copper ; vanadium ; oxide ; crystal structure ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Preparation and Crystal Structure of Potassium Magnesium Oxocuprate/-vanadate: KMg2Cu2V3O12.Single crystals of KMg2Cu2V3O12 were prepared by solid state reactions below the melting point of the reaction mixture (K2CO3, MgCO3, CuO, V2O5). It crystallizes with monoclinic symmetry space group C2h6—C2/c, a = 12.1592 Å, b = 12.7204 Å, c = 6.8557 Å, β = 111.73°, Z = 4. The structure type is characterized by VO4 tetrahedra, twisted CuO4 square units, MgO6 octahedra and a special 2 + 4 + 2 coordination around the potassium ion.
    Notes: Einkristalle von KMg2Cu2V3O12 wurden durch Feststoffreaktionen, dicht unterhalb des Schmelzpunktes des Reaktionsgemenges (K2CO3, MgCO3, CuO, V2O5), erhalten. Die Verbindung kristallisiert mit monokliner Symmetrie, Raumgruppe C2h6—C2/c, a = 12,1592 Å, b = 12,7204 Å, c = 6,8557 Å, β = 111,73°, Z = 4. Die Kristallstruktur ist durch VO4-Tetraeder, tordierte CuO4-Baugruppen, MgO6-Oktaeder und Kalium, in einer besonderen 2 + 4 + 2 Koordination charakterisiert.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19936190402
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 81
    Electronic Resource
    Electronic Resource
    Crystallochemistry of some new niobium bromides with (Nb6Br18) units: Structures of CsErNb6Br18 and Cs2EuNb6Br18Dedicated to Professor Harald Schäfer in memoriam (1993)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 619 (1993), S. 621-627 
    Details
    ISSN: 0044-2313
    Keywords: Niobum bromides ; (Nb6Br18) units ; crystal structure ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Kristallchemie einiger neuer Niobbromide mit (Nb6Br18)-Einheiten: Die Strukturen von CsErNb6Br18 und Cs2EuNb6Br18.Zwei neue Reihen von Nb6-Bromiden, CsSENb6Br18 (SE = alle Lanthanoide außer Eu und Yb, + Y) (Typ H) und M2SENb6Br18 (M = Cs, Rb, Tl; SE = Eu, Yb) (Typ R) sind dargestellt worden. Die Kristallstrukturen von CsErNb6Br18 und Cs2EuNb6Br18, isotyp mit den entsprechenden Chloriden, wurden durch Einkristall-Röntgendaten bestimmt. Die Stabilität der (Nb6Br18)-Einheit hängt von der Art und der Ladung des Gegenkations ab. Ein Vergleich zwischen den entsprechenden Reihen der Chloride und Bromide wird anhand der chemischen Eigenschaften und der Größe des Halogens diskutiert.
    Notes: Two new series of Nb6 bromides, CsRENb6Br18 (RE = all the lanthanides excepted Eu and Yb, + Y) (type H) and M2RENb6Br18 (M = Cs, Rb, Tl; RE = Eu, Yb) (type R) have been isolated. The crystal structures of CsErNb6Br18 and Cs2EuNb6Br18, isotypic with the corresponding chlorides, have been determined by single crystal X-ray diffraction data. The (Nb6Br18) intra-unit strength is related to the nature and the charge of the counter cation. A comparison between the corresponding chlorides and bromides series, based on the chemical properties and the size of the halogen is discussed.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19936190403
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 82
    Electronic Resource
    Electronic Resource
    Ein neues Syntheseverfahren für Vanadiumbronzen. Die Kristallstruktur von β—Ag0,33V2O5. Verfeinerung der Kristallstruktur von ∊—Cu0,76V2O5Professor Hartmut Bärnighausen zum 60. Geburtstage gewidmet (1993)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 619 (1993), S. 287-292 
    Details
    ISSN: 0044-2313
    Keywords: Silver vanadium bronze ; copper vanadium bronze ; synthesis ; crystal structure ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: A Novel Means of Synthesis for Vanadium Bronzes. Crystal Structure of β—Ag0.33V2O5. Refinement of the Crystal Structure of ∊—Cu0.76V2O5Ag0.33V2O5 and Cu0.76V2O5 were obtained by heating equimolar mixtures of AgI + V2O5 (700°C) and CuI + V2O5 (525°C), respectively, in sealed quartz glass ampoules. In each case, one of the well-formed crystals served for an X-ray structure analysis. Ag0.33V2O5 has the structure known of the β phase of the vanadium bronzes, i. e. layers of edge-sharing, distorted VO6 octahedra are liked by certain common octahedron vertices, the Ag atoms randomly occupy two positions with occupation probabilities of 0.5. Cu0.76V2O5 has the previously determined structure of the ∊ phase, however, its space group is not Cm but C2/m.
    Notes: Ag0,33V2O2 und Cu0,76V2O5 wurden durch zweiwöchiges Erhitzen von äquimolaren Gemischen AgI + V2O5 (700°C) bzw. CuI + V2O (525°C) in einer Quarzglasampulle erhalten. Mit je einem der gut ausgebildeten Kristalle wurden eine Röntgenstrukturanalyse durchgeführt. Ag0,33V2O5 hat die für die β-Phase der Vanadiumbronzen bekannte Struktur, d. h. Schichten aus verzerrten, kantenverknüpften VO6-Oktaedern sind über bestimmte Oktaederecken verknüpft, die Ag-Atome nehmen statistisch zwei Atomlagen der Koordinationszahl 7 mit halber Besetzungswahrscheinlichkeit ein. Cu0,76V2O5 hat die früher bereits bestimmte Struktur der ∊-Phase, deren Raumgruppe jedoch nicht Cm sondern C2/m ist.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19936190211
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 83
    Electronic Resource
    Electronic Resource
    Verbesserte Darstellung, Kristallzüchtung und Strukturanalyse von P4O6S2 und P4O6S3Professor Hartmut Bärninghausen zum 60. Geburtstage gewidmet (1993)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 619 (1993), S. 281-286 
    Details
    ISSN: 0044-2313
    Keywords: Tetraphosphorus hexaoxide disulfide and trisulfide ; preparation ; crystal structure ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Improved Syntheses, Crystal Growth, and Crystal Structure Determination of P4O6S2 and P4O6S3Syntheses and single crystal growths of the title compounds are described. Both compounds crystallize in the space group P21/c (P4O6S2: a = 11.293(4); b = 6.457(3); c = 11.588(4) Å; β = 90.29(2)°, 2 450 diffractometer data, Rw = 0.035/P4O6S3: a = 15.611(5); b = 8,303(3); c = 9.697(4) Å; β = 127.12(2)°, 2 481 diffractometer data, Rw = 0.034). The structural data for the series P4O6Sn (n = 1 - 4) thus completed are compared to their oxide analogues P4O6On (n = 1 - 4). The changes in the geometry of the P4O6-cage in course of its successive oxidation are discussed.
    Notes: Darstellung und Einkristallzucht der Titelverbindungen werden beschrieben. Beide Verbindungen kristallisieren in der Raumgruppe P21/c (P4O6S2: a = 11,293(4); b = 6,457(3); c = 11,588(4) Å; β = 90,29(2)°, 2 450 Diffraktometerdaten, Rw = 0,035/P4O6S3: a = 15,611(5); b = 8,303(3); c = 9.697(4) Å; β = 127,12(2)°, 2 481 Diffraktometerdaten, Rw = 0,034). Durch die neu gelösten Strukturen werden die Daten für das System P4O6Sn (n = 1 - 4) komplettiert und können mit denen der analog aufgebauten Oxide P4O6On (n = 1 - 4) verglichen werden. Die Veränderungen der Molekülgeometrie des zentralen P4O6-Käfigs im Zuge der schrittweisen Oxidation werden diskutiert.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19936190210
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 84
    Electronic Resource
    Electronic Resource
    Li5B7S13 und Li9B19S33: Zwei Lithiumthioborate mit neuen hochpolymeren AnionengerüstenProfessor Hartmut Bärnighausen zum 60. Geburtstage gewidmet (1993)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 619 (1993), S. 293-302 
    Details
    ISSN: 0044-2313
    Keywords: Lithium thioborates ; preparation ; crystal structure ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Li5B7S13 and Li9B19S33: Two Lithium Thioborates with Novel Highly Polymeric Anion NetworksLi5B7S13 (C2/c; a = 17.304(2) Å, b = 21.922(3) Å, c = 12.233(2) Å, β = 134.91(1)°; Z = 8) and Li9B19S33 (C2/c; a = 23.669(9) Å, b = 14.361(3) Å, c = 12.237(3) Å, β = 103.77(2)°; Z = 4) were prepared by reaction of stoichiometric amounts of lithium sulfide, boron, and sulfur at 750°C (Li5B7S13) and 700°C (Li9B19S33) with subsequent annealing. The crystal structures consist of interpenetrating, polymeric boron sulfur anion networks which are formed by corner-sharing of B4S10 and B10S20 units (Li5B7S13), or B19S36 units (Li9B19S33). The lithium cations are situated in between with a strong disorder in Li9B19S33.
    Notes: Li5B7S13 (C2/c; a = 17,304(2) Å, b = 21,922(3) Å, c = 12,233(2) Å, β = 134,91(1)°; Z = 8 und Li9B19S33 (C2/c; a = 23,669(9) Å, b = 14,361(3) Å, c = 12,237(3) Å, β = 103,77(2)°; Z = 4 wurden durch Reaktion von stöchiometrischen Mengen Lithiumsulfid, Bor und Schwefel bei 750°C (Li5B7S13) und 700°C (Li9B19S33) mit anschließendem Tempern dargestellt. Die Kristallstrukturen bestehen aus sich durchdringenden, polymeren Bor-Schwefel-Anionengerüsten, die durch Eckenverknüpfung von B4S10- und B10S20-Einheiten (Li5B7S13) bzw. B19S36-Einheiten (Li9B19S33) gebildet werden. Dazwischen befinden sich die Lithiumkationen, wobei bei Li9B19S33 eine starke Fehlordnung beobachtet wird.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19936190212
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 85
    Electronic Resource
    Electronic Resource
    Über Neue Oxoruthenate vom Typ der 6 L-Perowskite: Ba3SrRu2-xTaxO9 (x = 0,8 und 1,4) mit einem Beitrag über Ba3CaRu2O9 (1993)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 619 (1993), S. 517-520 
    Details
    ISSN: 0044-2313
    Keywords: Alkaline Earth ; ruthenium ; oxygen ; crystal structure ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: On Novel Oxoruthenates of the 6 L-Perovskite Type: Ba3SrRu2-xTaxO9 (x = 0.8 and 1.4) with a Comment on Ba3CaRu2O9Single crystals of the phases Ba3SrRu2-xTaxO9 [(I): x = 0.8 and (II): x = 1.4] and the compound (III): Ba3CaRu2O9 were prepared by a BaCl2 flux and investigated by X-ray methods. (I)-(III) crystallizes with hexagonal symmetry space group P62c with lattice constants: (I) a = 6.003 Å; c = 15.227 Å; (II) a = 5.988 Å; c = 15.220 Å and (III) a = 5.891 Å; c = 14.571 Å. The crystal structures of these substances corresponds to the 6 layer perovskites with the stacking sequence (hcc)2. All of them show a so far not described slightly distorted oxygen framework caused by the Sr2+ and Ca2+ ions.
    Notes: Einkristalle der Phasen Ba2SrRu2-xTaxO9 [(I): x = 0,8 und (II): x = 1,4] sowie der Verbindung (III): Ba3CaRu2O9 wurden in einer BaCl2-Schmelze präpariert und mit Hilfe von Röntgenbeugungsmethoden untersucht. (I)-(III) kristallisieren in der hexagonalen Raumgruppe P62c mit den Gitterkonstanten: (I) a = 6,003 Å; c = 15,227 Å; (II) a = 5,988 Å; c = 15,220 Å und (III) a = 5,891 Å; c = 14,571 Å. Ihre Kristallstrukturen entsprechen den 6 L-Perowskiten mit der Stapelsequenz (hcc)2. Sie zeigen eine bislang noch nicht beschriebene leichte Verzerrung im Aufbau der Sauerstoffteilgitter, die auf die Sr2+ - bzw. Ca2+-Ionen zurückgeführt werden kann.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19936190314
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 86
    Electronic Resource
    Electronic Resource
    Ba2BiV3O11 mit Bismut in geschlossener Koordination (1993)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 619 (1993), S. 525-528 
    Details
    ISSN: 0044-2313
    Keywords: Barium-bismuth-oxovanadate ; crystal structure ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Ba2BiV3O11 containing Bismuth within closed CoordinationA new barium bismuth oxovanadate, Ba2BiV3O11, was prepared and investigated by X-Ray single crystal technique. It crystallizes with monoclinic symmetry space group C2h5 - P21/a, lattice constants a = 24.6473; b = 7.7347; c = 5.6375 Å, β = 103.16°; Z = 4. Octahedra arround Bi3+, tetrahedra and double tetrahedra arround V5+ form a tunnel structure. The tunnel positions are occupied by Ba(2).
    Notes: Ein neues Barium-Bismutoxovanadat, Ba2BiV3O11, wurde einkristallin dargestellt und röntgenographisch untersucht. Es kristallisiert monoklin, Raumgruppe C2h5 - P21/a, mit den Gitterkonstanten a = 24,6473; b = 7,7347; c = 5,6375 Å, β = 103,16°; Z = 4. Oktaeder um Bi3+, Tetraeder und Doppeltetraeder um V5+ vernetzen mit Ba(1) zu einer Tunnelstruktur. Ba(2) besetzt die Tunnelpositionen.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19936190316
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 87
    Electronic Resource
    Electronic Resource
    Zur Kenntnis von Ca3IrCuO6 (1993)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 619 (1993), S. 534-536 
    Details
    ISSN: 0044-2313
    Keywords: Calcium ; iridium ; copper ; oxide ; crystal structure ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: On Ca3IrCuO6Single crystals of Ca3IrCuO6 were prepared by a flux technique and investigated by single crystal X-ray work. It crystallizes with monoclinic symmetry, space group C2h6 - C12/c1; a = 9.032, b = 9.295, c = 6.466 Å, β = 91.35°, Z = 4. Ca3IrCuO6 is isotypic to Sr3IrCuO6. The square planare CuO4 polygones show probably a slightly deficit accompanied by an adequate part of iridium in the oxydation state Ir5+.
    Notes: Einkristalle von Ca3IrCuO6 wurden mit Hilfe von Schmelzmitteln dargestellt und röntgenographisch untersucht. Es kristallisiert mit monokliner Symmetrie in der Raumgruppe C2h6 - C12/c1, mit a = 9,032, b = 9,295, c = 6,466 Å, β = 91,35°, Z = 4. Ca3IrCuO6 ist mit Sr3IrCuO6 isotyp. Die planaren CuO4-Baugruppen zeigen wahrscheinlich ein geringes Defizit an Cu2+, welches durch einen adäquaten Teil von Ir5+ kompensiert wird.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19936190318
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 88
    Electronic Resource
    Electronic Resource
    Das erste Alkali-Erdalkalimetall-Oxo/Peroxo-Aurat(III): NaBa4AuO4(O2)2 (1993)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 619 (1993), S. 537-539 
    Details
    ISSN: 0044-2313
    Keywords: Sodium-barium-oxo/peroxo-aurate(III) ; crystal structure ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: On the first Alkaline-Alkaline-Earth-Oxo/Peroxo-Aurate(III): NaBa4AuO4(O2)2The hitherto unknown compound NaBa4AuO4(O2)2 was prepared by oxidizing of barium gold alloy with Na2O2 in closed Ag-bombs. X-ray single crystal investigation led to tetragonal symmetry space group D4h17I4/mmm, a = 5.939; c = 15.393 Å, Z = 2. NaBa4AuO4(O2)2 shows a distorted square antiprismatic surrounding of Ba2+ by four peroxo groups on one side and four O2- on the opposite. Au3+ shows the usual square planar polygons of AuO4. Na+ is coordinated by four O2- ions in the base of an octahedron and two peroxo groups in the apical positions.
    Notes: Die bisher unbekannte Verbindung NaBa4AuO4(O2)2 wurde durch Reaktion einer Barium-Gold-Legierung mit Na2O2 im geschlossenen Silberbömbchen dargestellt. Die Kristallstruktur wurde röntgenographisch an Einkristallen untersucht. NaBa4AuO4(O2)2 kristallisiert tetragonal, Raumgruppe D4h17-I4/mmm, a = 5,939; c = 15,393 Å, Z = 2. Ba2+ ist verzerrt quadratisch antiprismatisch von vier Peroxogruppen auf der einen und vier O2--Ionen auf der Gegenseite koordiniert. Au3+ zeigt quadratisch planare Koordination von O2- und Na+ ist von vier O2--Ionen in der Oktaederbasisfläche und zwei Peroxogruppen in trans-Stellung dazu koordiniert.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19936190319
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 89
    Electronic Resource
    Electronic Resource
    Synthese, Charakterisierung und Struktur von P7(t-Bu3Si)3 („Tris(supersilyl)heptaphosphan(3)“)Professor Hartmut Bärnighausen zum 60. Geburtstage gewidmet (1993)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 619 (1993), S. 453-460 
    Details
    ISSN: 0044-2313
    Keywords: Tris(tri-tert-butylsilyl)heptaphosphonortricyclane P7(t-Bu3Si)3 ; synthesis ; 31P{1H} NMR data ; crystal structure ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthesis, Characterization, and Structure of P7(t-Bu3Si)3 („Tris(supersilyl)heptaphosphane(3)“Tris(tri-tert-butylsilyl)heptaphosphanortricyclane P7(t-Bu3Si)3 1 is obtained from the reaction of (t-Bu)3Si—Si(t-Bu)3 with white phosphorus and forms colorless to pale yellow thermostable crystals. 1 is identified by the complete analysis of its 31P{1H} NMR spectrum (A[MX]3 spin system) as well as by a single crystal structure determination (space group Pca21, a = 170.76(2)pm, b = 131.14(3)pm, c = 426.61(5)pm, α = β = γ= 90°, Z = 8 formula units in the elementary cell). The steric demand of the (t-Bu)3Si-Groups causes an increase of the exocyclic bond angles at the equatorial phosphorus atoms Pe, while it does not particularly influence the P7-skeleton. Chlorine (r.t.) and bromine (70°C) degrade the P7-cage of 1 with formation of PX3 and (t-Bu)3SiX (X = Cl, Br).
    Notes: Tris(tri-tert-butylsilyl)-heptaphosphanortricyclan P7(t-Bu3Si)3 1 entsteht durch Umsetzung von (t-Bu)3Si—Si(t-Bu)3 mit weißem Phosphor und bildet farblose bis blaßgelbe thermostabile Kristalle. Die Identität von 1 wird durch die vollständige Analyse des 31P{1H}-NMR-Spektrums (A[MX]3-Spinsystem) sowie durch eine Kristallstrukturbestimmung belegt. 1 kristallisiert in der Raumgruppe Pca21 mit Z = 8 Formeleinheiten; a = 170,76(2)pm, b = 131,14(3)pm, c = 426,61(5)pm, α = β = γ= 90°. Der erhöhte Raumbedarf der (t-Bu)3Si-Gruppen führt zu einer Aufweitung der exocyclischen Bindungswinkel an den äquatorialen Phosphoratomen Pe ohne das P7-Gerüst besonders zu beeinflußen. Chlor (Raumtemperatur) und Brom (70°C) bauen den P7-Käfig von 1 unter Bildung von PX3 und (t-Bu)3SiX (X = Cl, Br,) ab.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19936190305
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 90
    Electronic Resource
    Electronic Resource
    Synthese und Kristallstruktur einer Neuen hexagonalen Modifikation von Al2S3 mit fünffach koordiniertem AluminiumProfessor Heinrich Nöth zum 65. Geburtstage gewidmet (1993)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 619 (1993), S. 983-988 
    Details
    ISSN: 0044-2313
    Keywords: Aluminum sulfide ; crystal structure ; chemical transport ; five-coordinated aluminum ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthesis and Crystal Structure of a Novel Hexagonal Modification of Al2S3 with Five-coordinated AluminumA new hexagonal high temperature modification of Al2S3 could be prepared by chemical vapour transport with iodine (860 → 750°C) or by annealing of α -Al2S3 at 550°C. According to the single crystal X-ray structure determination the novel form of Al2S3 crystallizes in space group P 61 (No. 169) with a = 6.491(1), c = 17.169(4) Å, V = 626.5 Å3, Z = 6; R = 0.0253. In this modification one half of the aluminum atoms are tetrahedrally coordinated [d(Al—S): 2.226-2.267 Å], whereas the other half are in trigonal bipyramidal coordination of five S atoms with bond lengths of 2.272-2.315 Å (equatorial) and 2.495-2.521 Å (axial).Aluminum in AlS5 coordination is observed for the first time in this compound. The crystal structure is isotypic to In2Se3 and AlInS3. In addition, results of a refinement of the α -Al2S3 crystal structure are reported which were obtained on crystals prepared also by chemical vapour transport with iodine.
    Notes: Eine bisher noch nicht beschriebene hexagonale Hochtemperatur-Modifikation von Al2S3 konnte in reiner Form entweder durch chemischen Transport mit Iod (860 → 750°C) oder durch Tempern von α -Al2S3 oberhalb 550°C erhalten und durch eine Einkristall-Röntgenstrukturanalyse charakterisiert werden.Die neue Form des Al2S3 kristallisiert in der Raumgruppe P 61 (Nr. 169) mit a = 6,491(1), c = 17,169(4) Å, V = 626,5 Å3, Z = 6; R = 0,0253. In dieser Modifikation liegt die eine Hälfte der Aluminiumatome tetraedrisch koordiniert vor [d(Al—S): 2,226-2,267 Å], während die andere Hälfte trigonal-bipyramidal von fünf S-Atomen mit Al—S-Bindungslängen von 2,272 bis 2,315 Å (äquatorial) und 2,495-2,521 Å (axial) umgeben ist.Aluminium in AlS5-Koordination ist bisher unbekannt und wird hier zum ersten Mal beobachtet. Die Struktur ist isotyp zu In2Se3 und AlInS3. Zusätzlich wird über die Verfeinerung der Kristallstruktur α von -Al2S3 an Einkristallen berichtet, die ebenfalls durch chemischen Transport mit Iod hergestellt wurden.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19936190604
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 91
    Electronic Resource
    Electronic Resource
    Zur Kenntnis eines Erdalkalimetall-Oxopalladats(II) mit ringförmigen Pd6O12-Baugruppen: CaBa2Pd3O6Professor Heinrich Nöth zum 65. Geburtstage gewidmet (1993)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 619 (1993), S. 1004-1006 
    Details
    ISSN: 0044-2313
    Keywords: Alkaline-Earth ; palladium ; oxide ; crystal structure ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: On an Alkaline-Earth Oxopalladate containing Pd6O12 Rings: CaBa2Pd3O6CaBa2Pd3O6 was prepared for the first time and investigated by X-ray single crystal technique. It is isotypic to NaBa2Cu3O6 and crystallizes with orthorhombic symmetry, space group D2h23-Fmmm, a = 8.717, b = 11.47, c = 14.933 Å; Z = 2. Typical features of the crystal structure are edge connected square planar PdO4 polygones, forming isolated Pd6O12 rings.
    Notes: CaBa2Pd3O6 wurde erstmals dargestellt und röntgenographisch an Einkristallen untersucht. Es ist isotyp mit NaBa2Cu3O6 und kristallisiert mit orthorhombischer Symmetrie, Raumgruppe D2h23-Fmmm, a = 8,717, b = 11,47, c = 14,933 Å; Z = 2. Charakteristische Strukturmerkmale sind kantenverknüpfte planare PdO4-Polygone, die isolierte Pd6O12-Ringe ausbilden.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19936190608
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 92
    Electronic Resource
    Electronic Resource
    Synthese sowie Kristall- und Molekülstruktur von Tetrafluoro[2-(pyrrolidinio)ethyl]silicatProfessor Ulrich Wannagat zum 70. Geburtstage gewidmet (1993)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 619 (1993), S. 1012-1016 
    Details
    ISSN: 0044-2313
    Keywords: Zwitterionic λ5-organofluorosilicate ; pentacoordinate silicon ; crystal structure ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthesis and Crystal and Molecular Structure of Tetrafluoro[2-(pyrrolidinio)ethyl]silicateThe zwitterionic tetrafluoro[2-(pyrrolidinio)ethyl]silicate (4) was synthesized by reaction of trimethoxy(2-pyrrolidinoethyl)silane (5) with hydrogen fluoride in ethanol/hydrofluoric acid at 0°C. The crystal and molecular structure of 4 was studied at -100°C by single-crystal X-ray diffraction. In addition, 4 was characterized by solution-state NMR studies (CD3CN: 1H, 13C).
    Notes: Das zwitterionische Tetrafluoro[2-(pyrrolidinio)ethyl]silicat (4) wurde durch Reaktion von Trimethoxy(2-pyrrolidinoethyl)silan (5) mit Fluorwasserstoff in einem Ethanol/Flußsäure-Gemisch bei 0°C synthetisiert. Die Kristall- und Molekülstruktur von 4 wurde bei - 100°C mittels einer Einkristall-Röntgenstrukturanalyse untersucht. Außerdem wurde 4 durch NMR-Untersuchungen in Lösung charakterisiert (CD3CN: 1H, 13C).
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19936190610
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 93
    Electronic Resource
    Electronic Resource
    The crystal structure of β-Thallium perrhenateDedicated to Professor Hartmut Bärnighausen on his 60th Birthday (1993)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 619 (1993), S. 1017-1022 
    Details
    ISSN: 0044-2313
    Keywords: Thallium perrhenate ; room-temperature modification ; crystal structure ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Die Kristallstruktur von β-ThalliumperrhenatDie Raumtemperaturmodifikation von Thalliumperrhenat, β-TlReO4, wurde durch Röntgenbeugung an Einkristallen untersucht. β-TlReO4 kristallisiert in der monoklinen Raumgruppe P1121/a mit a = 5,636(1), b = 17,428(3), c = 13,353(3) Å, γ = 89,86(2)° und Z = 12. Die Strukturverfeinerung endete bei R = 0,063 (wR = 0,053), wobei 2 020 absorptionskorrigierte Reflexdaten verwendet wurden. β-TlReO4 läßt sich als eine Verwachsung von β-CsReO4- und Scheelit-Einheiten auf Elementarzellniveau beschreiben.Die Struktur von β-TlReO4, besteht aus isolierten ReO4-Tetraedern, die durch TlO8- und TlO9-Polyeder miteinander verknüpft sind. Auf der Basis gruppentheoretischer Überlegungen werden die strukturellen Beziehungen zwischen β-TlReO4, β-CsReO4, α-CsReO4 und Scheelit-Typ diskutiert.
    Notes: β-TlReO4, the room temperature modification of thallium perrhenate, has been investigated by means of single crystal X-ray diffraction. It crystallizes in the monoclinic space group P1121/a with a = 5.636(1), b = 17.428(3), c = 13.353(3) Å, γ = 89.86(2)° and Z = 12. The structure has been refined to R = 0.063 (wR = 0.053) using 2 020 absorption-corrected reflections. The title compound can be described as an intergrowth of β-CsReO4 and scheelite type blocks at unit cell level. The structure of β-TlReO4 consists of isolated ReO4 tetrahedra linked together by TlO8 and TlO9 polyhedra. Based upon group theoretical considerations the structural relationships between β-TlReO4, β-CsReO4, α-CsReO4 and scheelite type are discussed.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19936190611
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 94
    Electronic Resource
    Electronic Resource
    Polysulfonylamine. XLI. Ein Silber(I)-Hydrat ungewöhnlicher Zusammensetzung: Röntgenstrukturanalytische und thermochemische Charakterisierung von Tetrakis(dimesylamido)aquatetrasilber(I) [Ag4(N(SO2CH3)2}4(H2O)] (1993)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 619 (1993), S. 1027-1036 
    Details
    ISSN: 0044-2313
    Keywords: Polysulfonyl amines ; silver(1) dimesylarnide ; tetrakis(dimesylamido)aquatetrasilver(l) ; crystal structure ; thermal analysis ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Polysulfonyl Amines. XLI. A Silver(I) Hydrate with an Unusual Composition: Characterization of Tetrakis(dimesylamido)aquatetrasilver(I) [Ag4(N)SO2CH3)2}4(H2O)] by X-Ray Diffraction and Thermal AnalysisThe title compound is obtained by crystallizing AgN(SO2CH3)2 from water at room temperature. Crystallographic data (at -95°C): Triclinic space group P1, a = 864.6(4), b = 1 211.2(5), c = 1 399.1(5) pm, α = 90.97(3), β = 90.90(3), γ = 98.25(4)°, V = 1.4496 nm3, Z = 2, Dx = 2.608 Mg m-3. The four independent silver atoms and the water molecule form zigzag chains Ag(1)-Ag(2)-(μ-H2O)-Ag(3) … Ag(4) … Ag(1′) with distances Ag(1)-Ag(2) 309.7, Ag(2)-O(w) 241.8, O(w)-Ag(3) 241.4, Ag(3) … Ag(4) 342.9, Ag(4) … Ag(1′) 361.4 pm. The catenated silver atoms are further connected by the dimesylamide anions acting as tridentate bridging (α-O, N, ω-O)-ligands. The resulting strands are interconnected into layers through one O(S)-Ag′ contact (247 pm) and one hydrogen bond O(w)-H(l) … O′(S) per repeating unit. Between the layers, a weak O(S) … Ag″ interaction (271 ptn) and a hydrogen bond O(w)-H(2) … O(S) per repeating unit are observed. The silver atoms Ag(l) to Ag(4) display the coordination numbers 5 [NO,Ag(2), distorted trigonal bipyramid], 5[NO2,O(w)Ag(I), distorted trigonal bipyramid], 5[O4,O(w), trigonal bipyramid], and 2 + 1 (N2, li-near; plus a secondary Ag … 0 contact). The dehydration of the title compound and a solid-solid phase transformation in anhydrous AgN(SO2CH3)2, were quantitatively investigated by thermoconductometry and time- and temperature-resolved X-ray diffractometry (TXRD).
    Notes: Die Titelverbindung entsteht durch Kristallisation von AgN(SO2CH3)2 aus Wasser bei Raumtemperatur. Kristallographische Daten (bei -95°C): Trikline Raumgruppe P1, a = 864,6(4), b = 1 211,2(5), c = 1 399,1(5) pm, α = 90,97(3), β = 90,90(3), γ = 98,25(4)°, V = 1,4496 nm3, Z = 2, Dx = 2,608 Mg m-3. Die vier unabhängigen Silberatome und das Wassermolekül bilden Zickzack-Ketten Ag(1)-Ag(2)-(μ-H2O)-Ag(3) … Ag(4) … Ag(1′) mit den Abständen Ag(1)-Ag(2) 309,7, Ag(2)-O(W) 241,8 O(W)-Ag(3) 241,4, Ag(3) … Ag(4) 342,9, Ag(4) … Ag(1′) 361,4 pm. Die Silberatome in der Kette werden durch die Dimesylamid-Anionen miteinander verklammert, die innerhalb der so resultierenden Stränge als dreizähnig-verbrückende (α-O, N, ω-O)-Liganden wirken. Die Stränge sind pro Repetiereinheit durch einen Kontakt O(S)-Ag′ (247 pm) und eine Wasserstoffbrücke O(W)-H(1) …O′(S) zu Schichten verknüpft. Zwischen den Schichten bestehen je Strang-Repetiereinheit eine schwache Wechselwirkung O(S) … Ag″ (271 pm) und eine Wasserstoffbrücke O(W)-H(2) … O″(S). Die Silberatome besitzen in der Reihenfolge Ag(1) bis Ag(4) die Koordinationszahl 5 [NO3Ag(2), verzerrt trigonal-bipyramidal], 5 [NO2O(W)Ag(1), verzerrt trigonal-bipyramidal], 5 [O4O(W), trigonal-bipyramidal], 2 + 1 (N2, linear; ein zusätzlicher Sekundärkontakt Ag … O). Die Dehydratation der Titelverbindung und eine fest-fest-Phasenumwandlung des wasserfreien AgN(SO2CH3)2 wurden durch Thermokonduktometrie sowie zeit- und temperaturaufgelöste Röntgendiffraktometrie (TXRD) quantitativ untersucht.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19936190613
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 95
    Electronic Resource
    Electronic Resource
    Penicillamin-Komplexe des Nickels, Chroms und Molybdäns  -  Strukturelle Besonderheiten und biologische/medizinische Relevanz (1993)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 619 (1993), S. 1037-1046 
    Details
    ISSN: 0044-2313
    Keywords: Nickel ; chromium ; molybdenum ; penicillamine ; complexes ; synthesis ; crystal structure ; antidot ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Penicillamine Complexes of Nickel, Chromium, and Molybdenum  -  Structural Particularity and Biological/Medical RelevanceThe compounds Tl2[NiII(H2O)6][NiII(D-pen)(L-pen)]2[NiII(SCN)2(H2O)4] 1, Tl[NiII(D-pen)2H] · H2O 2, Tl[CrIII(D-pen)2] 3, and Na2[Mo2VO4(pen)2] · 3 CH3OH · 3 H2O 4 have been prepared by the reaction of nickel nitrate (for 1), nickel acetate (for 2), potassium chromate (for 3), and sodium molybdate (for 4) with D- and D, L-penicillamine, respectively. They were characterized by single-crystal X-ray structure analysis and other physical methods. Whereas penicillamine acts as a bidentate (N, S)-ligand in 1 and 2, CrIII (in 3), and MoV (in 4) are coordinated to the three ligand atoms N, O, and S. The presence of three different types of NiII-complexes a cationic, a neutral, and an anionic one in 1 is remarkable.For crystal data see Inhaltsübersicht.
    Notes: Die Verbindungen Tl2[NiII(H2O)6][NiII(D-Pen)(L-Pen)]2[NiII(SCN)2(H2O)4] 1, Tl[NiII(D-Pen)2H] · H2O 2, Tl[CrIII(D-Pen)2] 3 und Na2[Mo2VO4(Pen)2] · 3 CH3OH · 3 H2O 4 wurden durch Umsetzung von Nickelnitrat (für 1), Nickelacetat (für 2), Kaliumchromat (für 3) und Natriummolybdat (für 4) mit D- bzw. D, L-Penicillamin in wäßriger Lösung dargestellt und durch Einkristallstrukturanalyse und andere physikalische Methoden charakterisiert. Während in den Ni-Pen-Komplexen von 1 und 2 Penicillamin als zweizähniger Ligand (N, S) fungiert, sind CrIII in 3 und MoV in 4 über N, O und S koordiniert. Bemerkenswert ist, daß in 1 drei verschiedene Ni-Komplexe und zwar ein kationischer, ein neutraler und ein anionischer in einer Elementarzelle vorliegen.1: C2/m, a = 1 484,6(4), b = 1 358,7(4), c = 1 204,7(3) pm, β = 103,75(2)°, V = 2 360,4(11) ° 106 pm3, R = 0,042 für 1 633 unabhängige Reflexe (Fo〉 4,0σ(Fo)), Z = 2.2: C2, a = 2 279,9(7), b = 613,1(1), c = 1 275,2(3) pm, β = 110,94(2)°, V = 1 664,8(6) · 106 pm3, R = 0,056 für 1 413 unabhängige Reflexe (Fo〉 4,0σ(Fo)), Z = 4.3: C2, a = 2 054,0(3), b = 592,1(1), c = 606,7(1) pm, β = 92,89(1)°, V = 736,95(17) · 106 pm3, R = 0,028 für 862 unabhängige Reflexe (Fo〉 4,0σ(Fo)), Z = 2.4: P1, a = 996,2(4), b = 1 222,2(7), c = 1 395,3(7) pm, = 114,27(4), β = 104,55(4), γ = 95,63(4)°, V = 1 459,4(13) · 106 pm3, R = 0,072 für 3 763 unabhängige Reflexe (Fo〉 4,0σ(Fo)), Z = 2.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19936190614
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 96
    Electronic Resource
    Electronic Resource
    Schwermetall-π-Komplexe. IX. Die Kettenpolymere ∞1[(1,2- (CH3)2C6H4BiCl3)2], ∞1[(1,3) (CH3)2C6H4BiCl3)2] und ∞1[(1,4- (CH3)2C6H4BiCl3)2] (1993)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 619 (1993), S. 1073-1082 
    Details
    ISSN: 0044-2313
    Keywords: Bismuth arene π-complexes ; bismuth xylene complexes ; preparation ; crystal structure ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Heavy Metal π-Complexes. IX. The Chain Polymers ∞1[(1,2- (CH3)2C6H4BiCl3)2], ∞1[(1,3- (CH3)2C6H4BiCl3)2] and ∞1[(1,4- (CH3)2C6H4BiCl3)2]In the crystal structures of the three solid state complexes (C6H4(CH3)2BiCl3 (C6H4(CH3)2 = o-xylene: 1, m-xylene: 2, p-xylene: 3) quasi-dimeric units of almost undistorted, arene coordinated BiCl3 fragments can be found that are further associated via additional Bi—Cl contacts to form one-dimensional polymeric chains. Whereas the chains of 2 and 3 are constituted by Bi2Cl2 four-membered rings only, further Cl-bridging in 1 leads to additional trigonal-bipyramidal arrangements with Bi atoms exhibiting coordination numbers of 3 + 3 + 1 and 3 + 2 + 1, respectively (prim. + sec. Cl contacts + arene). The arene-metal bonding is characterized by Bi-arene distances in the range from 297 - 306 pm, including ring slippages of 24 -41 pm and 73 pm with the Bi atoms being six and seven coordinated, respectively. The direction of this slipping with respect to the arene's methylation sites cannot be understood in terms of electronic influences but is shown to be caused by steric demands. The values IP1 of the arenes prove to determine the colours of the complexes.
    Notes: In den Festkörperstrukturen der drei Komplexe (C6H4(CH3)2)BiCl3 (C6H4(CH3)2 = o-Xylol: 1, m-Xylol: 2, p-Xylol: 3) findet man quasidimere Einheiten fast unverzerrter, arenkoordinierter BiCl3-Fragmente, die über zusätzliche Bi—Cl-Kontakte zu eindimensionalen polymeren Ketten assoziiert sind. Während die Ketten von 2 und 3 nur aus Bi2Cl2-Vierringsegmenten bestehen, führt eine weitere Verbrückung in 1 zusätzlich zu trigonal-bipyramidalen Anordnungen mit Bi-Atomen der Koordinationszahlen 3 + 3 + 1 bzw. 3 + 2 + 1 (prim. + sek. Cl-Kontakte + Aren). Die Bindung des Arens an das Metall ist durch Bi-Aren-Abstände zwischen 297 und 306 pm charakterisiert. Die „ring slippage“ beträgt 24-41 bzw. 73 pm bei den sechsfach bzw. siebenfach koordinierten Bi-Atomen. Die Richtung dieser Verschiebung in bezug auf die Lage der Methylgruppen des Arens kann nicht auf elektronischer Basis interpretiert werden, sondern ist sterisch verursacht. Für die Farbe der Komplexe erweist sich IP1 des Arens als bestimmend.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19936190618
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 97
    Electronic Resource
    Electronic Resource
    The Tetraphenylester of the μ-Imido-Dithiodiphosphoric Acid and its palladium complex  -  crystal structures (1993)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 619 (1993), S. 1147-1153 
    Details
    ISSN: 0044-2313
    Keywords: O,O′,O″,O‴-tetraphenyl μ-imido-dithiodiphosphate ; N-(O,O′-diphenylthiophosphoryl)-O″,O‴-diphenylthiophosphorimidate ; Bis(O,O′,O″,O‴-tetraphenyl μ-imido-dithiodiphosphato) palladium chelate ; Bis[N-O,O′-diphenylthiophosphoryl-O″,O‴-diphenylthiophosphorimidato] palladium chelate ; preparation ; crystal structure ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Der Tetraphenylester der μ-Imido-dithiodiphosphorsäure und sein Palladiumkomplex  -  KristallstrukturenDie Darstellung der Verbindung [(C6H5O2PS]2NH (SS) und ihres Palladiumkomplexes [Pd{C6H5O)2P(S)NP(S)(OC6H5) 2}2] (PDSS) wird beschrieben. Die Verbindungen werden elementaranalytisch, durch NMR- und Massenspektrometrie sowie mittels Röntgen-Kristallstrukturanalyse charakterisiert. Die Struktur von SS enthält zwei unabhängige Moleküle in einer asymmetrischen Einheit, die über N … H … S Wasserstoffbrücken zu Dimeren verbunden sind. SS ist eine Br⊘nsted-Säure, die mit PdII zu einem neutralen Chelatkomplex reagiert. Die Struktur von PDSS besteht aus isolierten Molekülen mit dem Pd-Atom als Symmetriezentrum. Das Pd ist an 4 S-Atome in einer verzerrt quadratisch-planaren Anordnung mit einem mittleren Abstand Pd—S von 2,345(6) Å und Winkel S—Pd—S von 98,29(4)° gebunden.
    Notes: The preparations of [(C6H5O)2PS]2NH (SS) and its Pd complex [Pd{C6H5O2P(S)NP(S)(OC6H5) 2}2] (PDSS) are described. The compounds were characterized by elemental analysis, NMR, and mass spectra and X-ray structure analysis. The structure of SS contains two independent molecules in an asymmetric unit which are joined into dimers via N … H … S hydrogen bonds. SS is a Br⊘nsted acid And reacts with PdII to a neutral chelate complex. The structure of PDSS is composed of isolated molecules with Pd atom in the center of symmetry. The Pd atom is coordinated by 4 S atoms in a distorted square-planar arrangement with average distance Pd—S 2.345(6) Å and an angle S—Pd—S 98.29(4)°.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19936190630
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 98
    Electronic Resource
    Electronic Resource
    On the proton-acceptor properties of [TeMo6O24]6- in Na4(NH4)2[TeMo6O24] · 16H2O (1993)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 619 (1993), S. 1132-1136 
    Details
    ISSN: 0044-2313
    Keywords: Hexamolybdotellurate(VI) ; crystal structure ; hydrogen bonding ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Über das Protonenakzeptorverhalten von [TeMo6O24]6- in Na4(NH4)2[TeMo6O24] · 16H2OFarblose Einkristalle von Na4(NH4)2[TeMo6O24] · 16H2O wurden in wäßriger Lösung gezüchtet (Raumgruppe P1, a = 1 075,3(1), b = 1 074,2(1), c = 1 089,8(1) pm, = 96,259(9), β = 118,556(7), γ = 113,355(8)°, Z = 1, 295 K, 311 Parameter, 3 689 Reflexe, Rg = 0,0197). Es liegen zwei kristallographisch unabhängige Na+ Kationen vor. Na(1) ist oktaedrisch von vier Wassermolekülen und zwei Sauerstoffatomen des zentrosymmetrischen [TeMo6O24]6--Anions umgeben. Na(2) ist in stark verzerrt trigonal-bipyramidaler Weise von fünf Wassermolekülen koordiniert. Je zwei dieser Na(H2O)5+-Bipyramiden sind mit zwei NH4+-Kationen über Wasserstoffbrückenbindungen zu zentrosymmetrischen kationischen Clustern verknüpft. Mit Ausnahme von O(10) wirken alle Sauerstoffatome des [TeMo6O24]6--Anions ungeachtet ihrer unterschiedlichen Bindigkeit bezüglich Mo bzw. Te als annähernd gleichwertige Protonenakzeptoren in Wasserstoffbrückenbindungen zu den NH4+-Kationen und den Kristallwassermolekülen.
    Notes: Colourless triclinic single crystals of Na4(NH4)2[TeMo6O24] · 16H2O were grown in aqueous solution (space group P1, a = 1 075.3(1), b = 1 074.2(1), c = 1 089.8(1) pm, = 96.259(9), β = 118.556(7), γ = 113.355(8)°, Z = 1, 295 K, 311 parameters, 3 689 reflections, Rg = 0.0197). There are two crystallographically independent Na+ cations. Na(1) is coordinated octahedrally by four water molecules and two oxygen atoms of the centrosymmetric [TeMo6O24]6- anion. Na(2) is bound to five water molecules in a considerably distorted trigonally bipyramidal fashion. These bipyramids are linked with NH4+ by hydrogen bonds to yield centrosymmetric cluster cations consisting of two NH4+ and two Na(H2O)5+ each. Hydrogen bonds envolving all except one (O(10)) of the oxygen atoms of the [TeMo6O24]6- anion as almost equivalent proton acceptors regardless of their bonding mode to Te and Mo, respectively, establish further connections to NH4+ and the water of crystallization.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19936190628
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 99
    Electronic Resource
    Electronic Resource
    Water-rich molybdotellurates: Preparation and crystal structure of Li6[TeMo6O24] · 18 H2O and Li6[TeMo6O24] · Te(OH)6 · 18 H2O (1993)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 619 (1993), S. 1137-1146 
    Details
    ISSN: 0044-2313
    Keywords: Molybdotellurate(VI) ; crystal structure ; differential thermal analysis ; hydrogen bonding ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Wasserreiche Molybdotellurate: Darstellung und Kristallstruktur von Li6[TeMo6O24] · 18 H2O und Li6[TeMo6O24] · Te(OH)6 · 18 H2OLi6[TeMo6O24] · 18 H2O kristallisiert in der triklinen Raumgruppe P1 (a = 1 041,7(1), b = 1 058,6(1), c = 1 070,8(1) pm, α = 61,08(1), β = 60,44(1), γ = 73,95(1)°. Die Einkristallröntgenstrukturanalyse (Z = 1, 295 K, 317 Parameter, 3 973 Reflexe, Rg = 0,0250) zeigte, daß eine verzweigte, unendliche Kette aus kantenverknüpften Li-Koordinationspolyedern das markante Strukturmerkmal dieser Verbindung ist. Eines der vier kristallographisch unabhängigen Li+-Kationen ist oktaedrisch koordiniert. Bei den übrigen Li+-Kationen liegt verzerrt trigonal-bipyramidale Koordination vor. Lediglich drei kristallographisch unabhängige Sauerstoffatome (O(9), O(10), O(12)) des zentrosymmetrischen [TeMo6O24]6--Anions sind an Li+ koordiniert. Die übrigen Positionen in den Li+-Koordinationssphären sind durch Wassermoleküle besetzt. Die Sauerstoffatome des [TeMo6O24]6--Anions treten in intermolekularen Wasserstoffbrückenbindungen ungeachtet ihrer unterschiedlichen Bindigkeit bezüglich Mo und Te als annähernd gleichwertige Protonenakzeptoren auf.Li6[TeMo6O24] · Te(OH)6 · 18 H2O kristallisiert in der monoklinen Raumgruppe P21/n mit Z = 4, a = 994,1(3), b = 2 344,8(10), c = 1 764,9(4) pm und β = 91,36(4)°. Die Einkristallröntgenstrukturbestimmung mit 627 Parametern und 5900 Reflexen (295 K) konvergierte bei Rg = 0,0324. Es liegen sechs kristallographisch unabhängige Li+-Kationen vor. Die Koordinationspolyeder von Li(1), Li(2), Li(3) und Li(4) sind über gemeinsame Kanten zu einem achtgliedrigen, zentrosymmetrischen Strang verknüpft. Die Koordinationspolyeder von Li(5) und Li(6) sind über eine gemeinsame Ecke zu Zweiergruppen verbunden. Sämtliche Sauerstoffatome des eingeschlossenen Te(OH)6-Moleküls, aber nur drei Sauerstoffatome (0(13), 0(18), O(23)) des [TeMo6024]6--Anions, welches hier über keine kristallographische Symmetrie verfügt, sind an Li+ koordiniert. Die Sauerstoffatome des Anions treten in Wasserstoffbrückenbindungen von überwiegend mittlerer Stärke als Protonenakzeptoren auf. Kurze intermolekulare Wasserstoffbrückenbindungen verbinden die [TeMo6O24]6--Anionen mit den Te(OH)6-Molekülen zu unendlichen Ketten.
    Notes: Li6[TeMo6O24] · 18 H2O is triclinic (space group P1, a = 1 041.7(1), b = 1 058.6(1), c = 1 070.8(1) pm, α = 61.08(1), β = 60.44(1), γ = 73.95(1)°). Single crystal X-ray structure analysis (Z = 1, 295 K, 317 parameters, 3 973 reflections, Rg = 0.0250) revealed an infinite branched chain of edge-sharing Li coordination polyhedra to be the prominent structural feature. One of the four crystallographically independent Li+ is coordinated octahedrally. The coordination polyhedra of the remaining Li+ are distorted trigonal bipyramids. Only three unique oxygen atoms (O(9), O(10), O(12)) of the centrosymmetric [TeMo6O24]6- anion are bound to Li+. The further positions in the coordination spheres of the Li+ are occupied by water molecules. Intermolecular hydrogen bonds involve mainly oxygen atoms of the [TeMo6O24]6- anion as nearly equivalent proton acceptors without regard to their different bonding modes to Te and Mo, respectively.Li6[TeMo6O24] · Te(OH)6 · 18 H2O crystallizes monoclinically in space group P21/n with Z = 4, a = 994.1(3), b = 2 344.8(10), c = 1 764.9(4) pm, and β = 91.36(4)°. Single crystal structure analysis with least squares refinement of 627 parameters (5 900 reflections, 295 K) converged to Rg = 0.0324. There are six unique Li+ cations. The coordination polyhedra of Li(1), Li(2), Li(3), and Li(4) are linked by common edges to yield an eight membered centrosymmetric strand. The coordination polyhedra of the remaining two Li+ sites (Li(5), Li(6)) are connected to a dimeric unit via a common corner. All oxygen atoms of the Te(OH)6 molecule are involved in the coordination of Li+. However, only three oxygen atoms (O(13), O(18), O(23)) of the [TeMo6O24]6- anion which lacks crystallographic symmetry are involved in the coordination of Li+. The oxygen atoms of the anion act as proton acceptors in hydrogen bonds of predominantly medium strength. Te(OH)6 molecules and [TeMo6O24]6- anions connected by strong hydrogen bonds form an infinite chain.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19936190629
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 100
    Electronic Resource
    Electronic Resource
    Darstellung und Kristallstruktur von SnTl4Te3 und PbTl4Te3Professor Dietrich Mootz zum 60. Geburtstage gewidmet. (1993)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 619 (1993), S. 1155-1160 
    Details
    ISSN: 0044-2313
    Keywords: Tin tetrathalliumtritelluride ; lead tetrathalliumtritelluride ; preparation ; crystal structure ; Cr5B3 type ; In5Bi3 type ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Preparation and Crystal Structure of SnTl4Te3 and PbTl4Te3.We describe the synthesis and crystal structure of two ternary derivatives MTl4Te3 of the parent phase Tl5Te3. Both the derivatives, SnTl4Te3 and PbTl4Te3, crystallize with the In5Bi3 type of structure: space group I4/mcm, Z = 4. The cell constants of SnTl4Te3(PbTl4Te3) are as follows: a = 8.819(2) Å (8.841(2)Å), c = 13.013(3) Å (13.056(3) Å), c/a = 1.47 (1.48). Short M—Te distances of 3.25 Å (3.26 Å) are obtained in ∞1[MTe2/2] chains, which run along [001]. The M atoms are further surrounded by additional tellurium atoms in such a way that octahedra occur, which share common vertices to build up a three dimensional infinite network ∞3[MTe6/2]. The remaining thallium atoms span cubes around the octahedra: ∞3[MTe6/2]Tl8/2 = MTl4Te3.An alternative structure description takes into account bent fragments Tl2Te with Tl—Te distances of 3.15 Å (3.17 Å) as the constitutional elements of M-centered, slightly distorted rhombic dodecahedra as the only polyhedra of the structure. Along [001] they share common vertices, whereas in the tetragonal a-a-plane they are interconnected via common faces.
    Notes: Die Darstellung und die Kristallstruktur der zwei ternären Abkömmlinge SnTl4Te3 und PbTl4Te3 werden beschrieben. Beide kristallisieren isotyp zu ihrer Mutterphase Tl5Te3 im In5Bi3-Typ, der seinerseits eine isopuntale Unterfamilie des Cr5B3-Typs bildet. Die Raumgruppe ist I4/mcm, die Zahl der Formeleinheiten beträgt 4. Die Gitterkonstanten für SnTl4Te3(PbTl4Te3) lauten a = 8,819(2) Å (8,841(2) Å), c = 13,013(3) Å (13,056(3) Å), das c/a-Verhältnis beträgt 1,47 (1,48).In zwei Fragmenten des dreidimensionalen Verbandes treten kurze M—Te—Abstände auf (M = Sn, Pb, Tl). Je nachdem, welchem Fragment man mehr Aufmerksamkeit schenkt, sind zwei alternative, aber gleichwertige Strukturbeschreibungen möglich: Die erstere lehnt sich an die bei der Mutterphase Tl5Te3 gewählte an und betont die kurzen Sn—Te— bzw. Pb—Te—Abstände in den parallel zur [001]-Richtung verlaufenden linearen Ketten ∞1[MTe2/2](Sn—Te: 3,25 Å, Pb—Te: 3,26 Å). Die M-Atome der Ketten werden durch weitere Tellur-Atome zu einem allseits spitzenverknüpften Oktaederverband ∞1[MTe6/2] komplettiert. Die Oktaeder werden würfelförmig von den Thallium-Atomen umgeben: ∞3[MTe6/2]Tl8/2 = MTl4Te3.De zweite betont die gewinkelten Fragmente Tl2Te(Tl—Te in SnTl4Te3: 3,15 Å, Tl—Te in PbTl4Te3: 3,16 Å). Die Tl2Te-Fragmente sind Teile verzerrter Tl2Te2-Rhomben. Diese Rhomben bauen M-zentrierte Rhombendodekaeder auf (M = Sn, Pb), die das einzige zum Strukturaufbau nötige Polyeder sind.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19936190702
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...