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
  • 1995-1999  (189)
  • 1890-1899
  • 1850-1859
  • 1998  (55)
  • 1997  (134)
  • crystal structure
  • 1
    Electronic Resource
    Electronic Resource
    Structure of a 1:1 complex between the anthelmintic drug mebendazole and propionic acid (1998)
    Springer
    Journal of chemical crystallography 28 (1998), S. 11-15 
    Details
    ISSN: 1572-8854
    Keywords: Mebendazole–propionic acid complex ; molecular complex ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Recrystallization of the anthelmintic drug mebendazole from propionic acid yields a 1:1 molecular complex which crystallizes in the triclinic system space group $${P\bar 1}$$ , a = 5.928(2), b = 11.066(2), c = 14.337(6)Å, α = 94.89(3), β = 101.56(3), γ = 96.18(2)°, and Z = 2 complex units in the unit cell. An x-ray diffraction study revealed an R 2 2 (8) hydrogen bonding system in the complex, involving the unprotonated imidazole N and amide N–H function of the drug and the acid carboxylic group. Complex molecules form centrosymmetric dimers by intermolecular N–H···O hydrogen bonding involving the protonated imidazole N atom and the benzoyl O atom of the drug molecule.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1021766300133
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Crystal structure and EPR spectra of glycilglycilglycinocopper(II)bromide sesquihydrate (1998)
    Springer
    Journal of chemical crystallography 28 (1998), S. 61-68 
    Details
    ISSN: 1572-8854
    Keywords: Cu(II) complex ; crystal structure ; EPR spectra
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The title compound, Cu(glyglygly)Br·1·5H2O, crystallizes in the space group C2/c, with a = 21.468(7), b = 6.716(5), c = 16.166(6) Å, β = 98.39°, and Z = 8. The tripeptide is bonded to one Cu(II) ion through the nitrogen [Cu–N=1.97(1)Å] and oxygen [Cu–O=2.019(8)Å] atoms of the amino end glycine residue and to another Cu(II) through one oxygen atom [Cu–O=1.931(9)Å] of the terminal carboxyl group. This give rise to covalently bonded and infinite ···–Cu–tripeptide–Cu–··· chains. These chains are linked to one another by a network of H-bonds involving the water molecules and bromide ions. The Cu(II) ion is in a distorted tetragonal pyramidal coordination polyhedron. At the corner of the base of the pyramid are the terminal glycine nitrogen and oxygen atoms of one tripeptide, a carboxylic oxygen of another tripeptide and a bromide ion. The fivefold coordination is completed with a water molecule at the top of the pyramid [Cu–Ow=2.286(9)Å]. For all orientations of the applied magnetic field the single crystal EPR spectra display a single anisotropic exchange collapsed resonance without hyperfine structure. Its position was measured in three perpendicular planes and the crystal g-tensor evaluated from the data. This tensor is interpreted in terms of the contributing Cu(II) complexes in the unit cell to deduce the principal values g1 = 2.273, g2 = 2.050 and g3 = 2.131 for the molecular gyromagnetic tensor. We also discuss the magnitude of the exchange interaction between neighboring copper ions in the lattice on the basis of the features in the EPR spectra and the structural information.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1021734820606
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Reaction of 2-methylnaphthalene with hexachlorocyclopentadiene and structural characterization of a new addition-substitution product (1998)
    Springer
    Journal of chemical crystallography 28 (1998), S. 787-790 
    Details
    ISSN: 1572-8854
    Keywords: 2-Methylnaphthalene ; hexachlorocyclopentadiene ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract 2-Methylnaphthalene undergoes Diels-Alder addition and substitution with hexachlorocyclopentadiene to give two products, 1,2,3,4,5,6,7,8,13,13,14,14-dodecachloro-1,4,4a,4b,5,8,8a,12b-octahydro-10-methyl-1,4;5,8-dimethanotriphenylene 1 and 1,2,3,4,5,6,7,8,13,13,14,14-dodecachloro-1,4,4a,4b,5,8,8a,12b-octahydro-10-(1′,2′,3′,4′,5′-pentachlorocyclopentadienyl)methyl-1,4;5,8-dimethanotriphenylene 2. The molecular structure of 2 has been characterized by X-ray crystallography: C26H9Cl17, monoclinic, space group P21/c, with a = 15.316(3), b = 13.698(3), c = 16.116(3) Å, β = 96.113(3)°, and Z = 4.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1021819518557
    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 and crystal structure of [(PhenH)(PhenH2)][BiCl6]·2H2O with different o-phenanthroline protonations (1998)
    Springer
    Journal of chemical crystallography 28 (1998), S. 791-796 
    Details
    ISSN: 1572-8854
    Keywords: Halobismuthate(III) ; phenanthroline ; synthesis ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The reaction between bismuthate oxide and phen (1,10-phenanthroline) in acid medium led to the isolation of the unusual [(PhenH)(PhenH2)][BiCl6]·2H2O derivative, which has been characterized by X-ray analysis and IR spectroscopy. The compound crystallizes in the triclinic space group $$[\text[P\bar 1]]$$ with a = 8.313(2), b = 9.349(2), c = 9.807(3) Å, α = 86.39(3), β = 110.27(3) and γ = 106.48(3)°. The crystal structure is made of [BiCl6]3− anions and [(PhenH)(PhenH2)]3+ cations. A network of hydrogen bond interactions involving the two clathrated water molecules, the phenanthroline moiety and the chlorines characterizes the entire structure.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1021871502627
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    Tris-(thiocyanato)-bis-(hexamethylenetetramine)-nona-(aquo) lanthanum(III): synthesis, crystal structure, IR and Raman characterization (1998)
    Springer
    Journal of chemical crystallography 28 (1998), S. 879-884 
    Details
    ISSN: 1572-8854
    Keywords: Lanthanum complex ; hexamethylenetetramine ; IR spectra ; thiocyanates ; coordination number nine ; tricapped trigonal prism ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The title compound (LaC15H42N11O9S3) was prepared and characterized by means of X-ray, IR and Raman measurements. The crystals are orthorhombic: Pnma (No. 62), a = 21.117(2), b = 14.736(2), c = 10.082(1) Å, and Z = 4. The structure consists of polyhedra with a La(III) ion in the center of them and hexamethylene molecules, which link these polyhedra. Each La(III) ion coordinates seven molecules of water and two thiocyanate ions via nitrogen atoms. The IR and Raman spectra, which have been obtained and interpreted, are in good agreement with X-ray results.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1022846402229
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    Preparation and crystal structures of the Ce(IV) β-diketonates, [Ce(tmhd)4] and [Ce(pmhd)4] (tmhd =2,2,6,6-tetramethylheptane-3,5-dionate and pmhd = 1-phenyl-5-methylhexane-1,3-dionate) (1998)
    Springer
    Journal of chemical crystallography 28 (1998), S. 267-276 
    Details
    ISSN: 1572-8854
    Keywords: Cerium(IV) ; β-diketonate ; volatility ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The cerium(IV) β-diketonate compounds [Ce(β-diket)4] [where β-diket = tmhd (2,2,6,6-tetramethylheptane-3,5-dionate) 1, pmhd (1-phenyl-5-methylhexane-1,3-dionate) 2] were prepared by reacting cerium(IV) ammonium nitrate [CAN; Ce(NH4)2(NO3)6] with the respective Na(β-diket) compound in ethanol, and structurally characterized by single crystal X-ray diffraction. Compound 1 crystallizes in the triclinic space group $$P \bar 1$$ with a = 12.472(4), b = 19.972(5), c = 21.436(3) Å, α = 97.05(7), β = 90.16(2), γ = 106.55(3)°, V = 5076(2) Å3, Z = 4, T = 150(2) K. Compound 2 crystallizes in the monoclinic space group P21/n. with a = 14.817(6), b = 17.123(6), c = 19.146(3) Å, β = 105.46(4)°, V = 4682(3) Å3, Z = 4, T = 150(2) K. Crystals of 1 contain two independent [Ce(tmhd)4] molecules, with four chelating tmhd ligands bonded to each metal in a distorted dodecahedral arrangement; the cerium atom in 2 is also bonded to four chelating pmhd ligands but in this case the coordination geometry is closer to square antiprism. Both complexes are air and moisture stable. Sublimation studies reveal that 1 sublimes almost quantitatively, while 2 is comparatively involatile.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1021897102260
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    Molecular structure and spectral characteristics of bis(S-methyl-N-(2-pyridyl)methylendithiocarbazato)nickel(II), (Ni(NNS)2) (1998)
    Springer
    Journal of chemical crystallography 28 (1998), S. 871-874 
    Details
    ISSN: 1572-8854
    Keywords: Nickel(II) complex ; crystal structure ; Schiff base
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract A nickel(II) complex of the pyridine-2-aldehyde Schiff base of S-methyldithiocarbazate (HNNS) has been synthesized and characterized by means of elemental analysis, IR and UV-vis spectra. The crystal structure of the complex has been determined by single-crystal X-ray diffraction. The complex crystallizes in the monoclinic, space P21/c, with a = 14.092(2), b = 16.886(2), c = 8.857(2)Å; β = 105.78(3) °, V = 2028.2(6) Å3, and Z = 4. The nickel atom is octahedrally coordinated by two uninegatively charged tridentate Schiff base in a mer-configuration via the pyridine nitrogen atom, azomethine nitrogen atom, and mecaptide sulfur atom.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1022842301321
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 8
    Electronic Resource
    Electronic Resource
    Benztropine mesylate: crystal structure and kinetics of dehydration (1998)
    Springer
    Journal of chemical crystallography 28 (1998), S. 885-892 
    Details
    ISSN: 1572-8854
    Keywords: Benztropine mesylate ; crystal structure ; thermal analysis ; dehydration kinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The crystal structure of benztropine mesylate has been determined. It is orthorhombic, Pbca, with a = 12. 885(8)Å, b = 32.012(9)Å, and c = 10.027(3) Å. It exhibits similar packing to that seen in the previously reported crystal structure of benztropine mesylate monhydrate. X-ray powder diffraction patterns have been used to identify the anhydrous and monohydrate forms. The dehydration of the monohydrate follows a first-order reaction mechanism with activation energy of 92(8) kJ mol−1.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1022898419067
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 9
    Electronic Resource
    Electronic Resource
    Synthesis and X-ray crystallographic characterization of [Cd(NO3)2(15-Crown-5)] and [Cd(NO3)2(18-Crown-6)] (1998)
    Springer
    Journal of chemical crystallography 28 (1998), S. 521-527 
    Details
    ISSN: 1572-8854
    Keywords: Cadmium ; crown ether ; 15-crown-5 ; 18-crown-6 ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Reaction of 15-crown-5 or 18-crown-6 in 3:1 (v/v) CH3CN:CH3OH with Cd(NO3)2·4H2O followed by slow evaporation produces [Cd(NO3)2(15-crown-5)] or [Cd(NO3)2(18-crown-6)]. Crystals of [Cd(NO3)2(15-crown-5)] are orthorhombic with space group Pbca and cell parameters a = 13.562(5), b = 15.941(9), and c = 15.011(7) Å at 295 K. [Cd(NO3)2(18-crown-6)] crystallizes in the monoclinic space group C2/c with a = 11.235(2), b = 11.196(5), c = 15.385(3) Å, and β = 99.89(2)° at 295 K. The metal center in [Cd(NO3)2(15-crown-5)] rests atop the macrocyclic donor array with two cis-bound nitrate anions and adopts a distorted tricapped trigonal prismatic geometry. [Cd(NO3)2(18-crown-6)] resides on an equatorial two-fold rotation axis with Cd2+ coordinated in the 18-crown-6 cavity and the nitrate anions oriented in twisted trans positions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1023239921542
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 10
    Electronic Resource
    Electronic Resource
    The crystal and molecular structure of (−)—Crinine (C16H17NO3) (1998)
    Springer
    Journal of chemical crystallography 28 (1998), S. 577-579 
    Details
    ISSN: 1572-8854
    Keywords: (−)—Crinine ; Pancratium ; alkaloid ; Amaryllidaceae ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract (−)—Crinine, C16H17NO3, is an alkaloid extracted from the bulbs of Pancratium maritimum L. (Amaryllidaceae). The compound crystallizes in the space group P212121 with cell dimensions a = 6.040(1), b = 12.382(1), c = 17.861(2) Å, with Z = 4. The molecule has five rings and an OH group. The N-containing, five-membered ring and the D ring have envelope conformations. The A and B rings have distorted chair and half-chair conformations, respectively.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1023256425176
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 11
    Electronic Resource
    Electronic Resource
    Crystal structure of 2,2,4,7,7-pentamethyl-3,6-dithiaoctane tetracarbonyl tungsten(0) (1998)
    Springer
    Journal of chemical crystallography 28 (1998), S. 217-220 
    Details
    ISSN: 1572-8854
    Keywords: Metal carbonyl complexes ; chelate complexes ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The x-ray crystal structure of the complex η2-PDOW(CO)4 (five-membered ring, PDO = 2, 2, 4, 7, 7-pentamethyl-3,6-dithiaoctane) is reported. The complex crystallizes in the monoclinic crystal system, space group P21/c, [#14] with unit cell parameters a = 14.002(14) Å, b = 9.340(10) Å, c = 15.094(12) Å, β = 92.67(4)°, V = 1972(3) Å3; Z = 4. The arrangement of the ligands around the metal atom is distorted from octahedral geometry. Large C–O bond distances and short W–C bond distances of the carbonyl groups located at a trans position with respect to PDO is indicative of a trans influence. The W–S(1) and W–S(2) bond distances of 2.545(3) and 2.545(2) Å, respectively, are shorter than observed for closely related complexes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1022478528825
    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 structure of tris(triphenylsiloxy)borane·triphenylsilanol (1:1) adduct (1998)
    Springer
    Journal of chemical crystallography 28 (1998), S. 277-281 
    Details
    ISSN: 1572-8854
    Keywords: Triphenylsiloxy ; silanol ; borane ; crystal structure ; adduct
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The title compound crystallizes in the triclinic space group $$P \bar 1$$ , with a = 14.458(6), b = 14.630(5), c = 14.721(8) Å, α = 79.75(2), β = 80.11(3), γ = 80.50(3)°, and Z = 2. The crystal structure consists of molecules of (Ph3SiO)3B and Ph3SiOH linked by an weak B···(silanol) acceptor-donor bond, additionally stabilized by OH(silanol)···O(siloxy) hydrogen bonds. The average B–O, Si–O distances and B–O–Si angle are 1.369, 1.649 Å and 137.2°, respectively.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1021849219098
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 13
    Electronic Resource
    Electronic Resource
    17α-acetoxy-17β-methyl-16β-phenyl-D-homo-4,6-pregnadiene-3,17a-dione: synthesis and crystal structure determination of a new rearranged pregnane derivative (1998)
    Springer
    Journal of chemical crystallography 28 (1998), S. 487-491 
    Details
    ISSN: 1572-8854
    Keywords: Steroid ; pregnadiene ; x-ray diffraction ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The title compound is C29H34O4, tetragonal, P43, a = b = 10.310(1), c = 23.871(2)Å. The A, B, C, and D rings adopt envelope, half-chair, chair, and distorted chair conformations, respectively. The phenyl ring is planar. The methyl substituents at the A/B, C/D, and at C(17) are axial; and the –OCOCH3 group at C(17) and phenyl ring at C(16) are equatorial. The molecules in the crystal are held together by van der Waals forces and several C–H···O hydrogen bond interactions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1021729007943
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 14
    Electronic Resource
    Electronic Resource
    Structure, absolute configuration, and conformation of the antimalarial compound, Artemisinin (1998)
    Springer
    Journal of chemical crystallography 28 (1998), S. 539-543 
    Details
    ISSN: 1572-8854
    Keywords: Antimalarial ; crystal structure ; peroxy bridge
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The crystal and molecular structure of the antimalarial compound Artemisinin (formerly known as Qinghaosu), C15H22O5 has been determined by direct methods. Crystals are orthorhombic colorless needles, space group P212121, Z = 4. D c = 1.299 g cm −3, with unit cell parameters a = 6.3543(9), b = 9.439(3), c= 24.066(4) Å. The molecule incorporates a fused ring system containing a six-membered ring C which includes an oxygen bridge and a peroxy-bridge. The ring C has a distorted boat conformation and the C - O - O - C torsion angle is 47.8(2)°. Rings A and D have symmetrical chair and distorted chair conformations, repectively. Ring junctions A/B, A/D, and C/D are cis, junction B/D is trans. All inter-molecular contacts are van der Waals. The absolute configuration of Artemisinin was determined from the refined value of the Flack x parameter. [The atomic coordinates given in a previous structure analysis, “Crystal Structure and Absolute Configuration of Qinghaosu,” Qinghaosu Research Group, Institute of Biophysics, Academica Sinica, Scientia Sinica, Vol. XXIII No. 3, 380 (1980), do not display the molecule in its absolute configuration.]
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1023244122450
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 15
    Electronic Resource
    Electronic Resource
    Cluster Complexes of Polythioether Macrocycles: The Synthesis and Molecular Structures of Ru6(CO)13(cis-SCH2 CHMe(CH2SCH2CHMe)2CH2)(μ6-C) and Ru6(CO)13(trans-SCH2 CHMe(CH2SCH2CHMe)2CH2)(μ6-C) (1998)
    Springer
    Journal of cluster science 9 (1998), S. 93-105 
    Details
    ISSN: 1572-8862
    Keywords: Ruthenium ; thioether macrocycle ; 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 reaction of a mixture of cis-3,7,11-trimethyl-1,5,9-trithiacyclododecane, cis-Me312S3, 1 and trans-3,7,11-trimethyl-l,5,9-trithiacyclododecane, trans-Me312S3, 2, with Ru6(CO)17(μ 6-C), 3, yielded three new cluster compounds Ru6(CO)13(μ-η3-cis-SCH2CHMe(CH2SCH2CHMe)2CH2)(μ 6-C) 4, and two isomers of Ru6(CO)13(μ-η3-cis-SCH2CHMe(CH2SCH2CHMe)2CH2)(μ 6-C) 5a and 5b. The molecular structures of 4 and 5b were established by single crystal X-ray diffraction analyses. In both complexes, the macrocycles have adopted tridentate coordination with one of the sulfur atoms in a bridging position. Two carbonyl ligands occupy bridging positions in each compound. Crystal Data for 4·Me2CO: space group=P21/n, a=11.295(1) Å, b=17.547(3) Å, c=20.318(3) Å, β=93.71(1)°, Z=4, 2900 reflections, R=0.025. Crystal Data for 5b·1.5 C6H6: space group=Pbca, a=31.8900(8) Å, b=23.4330(6) Å, c=21.6240(4) Å, Z=16, 12163 reflections, R=0.040.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1022681523508
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 16
    Electronic Resource
    Electronic Resource
    The First New Hydrogen-Bonded Heterohexanuclear Complex [(salen)Cu]4[(salen)Fe(H2O)2]2(ClO4)2: Molecular and Crystal Structure and Magnetic Properties (1998)
    Springer
    Journal of cluster science 9 (1998), S. 465-471 
    Details
    ISSN: 1572-8862
    Keywords: Mixed-metal cluster ; crystal structure ; magnetic properties
    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 preparation, magnetic properties, and crystal structure of [(salen)Cu]4[(salen)Fe(H2O)2]2(ClO4)2 via hydrogen bonding are described [salen=N,N′-ethylenebis (salicylideneiminate)]. Crystals are triclinic, of space group $$\rm P\bar 1$$ , with cell constants a=12.853(3), b=13.921(3), c=14.251(3) Å, α=68.68(3)°, β=87.86(3)°, γ=86.82(3)°, and Z=1. The structure was solved and refined to R=0.064 and R′=0.068. The structure comprises the hexanuclear units which result from the linking of four mononuclear fragments [(salen)Cu] and two mononuclear fragment [(salen)Fe(H2O)]+, through Cu -O ⋯ H -O -Fe -O -H ⋯ O -Cu hydrogen bonds of coordinating H2O. In this complex, FeIII ions are in almost square-planar surroundings. The temperature dependences of the magnetic susceptibilities of the complex have been studied in the 4.2–300 K range, indicating the presence of an antiferromagnetic interactions between metal ions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1021990516837
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 17
    Electronic Resource
    Electronic Resource
    Direct Evidence for Metal Triangle Mobility within a Relatively Rigid Ligand Polytope: Dynamic Disorder in the X-Ray Crystal Structures of Ru3(CO)11(L), L=CN t Bu, PMe3, and Ru3(CO)9{P(OMe)3}3 (1998)
    Springer
    Journal of cluster science 9 (1998), S. 505-528 
    Details
    ISSN: 1572-8862
    Keywords: Dynamic disorder ; crystal structure ; ruthenium 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 The disorder in the X-ray crystal structures of Ru3(CO)11(L), L=CN t Bu 1 and PMe3 3 has been re-examined. Crystallographic data for 1 at 100 K: C16H9NO11Ru3, space group P21/n, a=11.796(5), b=11.748(2), c=16.040(7) Å, β=109.81(3)°, Z=4, 6077 reflections, R=0.028. For 3 at 223 K: C14H9O11PRu3, space group P21/n, a=8.5971(15), b=12.391(7), c=40.345(8) Å, β=94.43(2)°, Z=8, 7966 reflections, R=0.031. The disorder present in 1 and 3 at room temperature disappears reversibly on cooling, showing that it is dynamic in origin. The ligator atoms of the isonitrile and phosphine ligands move by a maximum of ∼0.8 Å, indicating that the whole cluster does not rotate intact within the crystal lattice, but rather that the Ru3 triangle effectively oscillates within a relatively rigid ligand polyhedron. The crystal structure of Ru3(CO)9{P(OMe)3 3} 7, which crystallizes in triclinic (7-t) and monoclinic (7-m) modifications is also reported. Both modifications have two independent molecules in the asymmetric unit, and both modifications display dynamic disorder in the metal framework. Crystalllographic data for 7-t at 173 K: C18H27O18P3Ru3, space group P-1, a=11.8085(18), b=15.915(2), c=17.350(3) Å, α=99.929(14), β=101.811(14), γ=90.630(12)°, Z=4, 11242 reflections, R=0.048. For 7-m at 120 K: C18H27O18P3Ru3, space group P21/c, a=11.708(8), b=15.922(5), c=33.950(10) Å, β=99.29(4), Z=8, 10191 reflections, R=0.027.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1021946701816
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 18
    Electronic Resource
    Electronic Resource
    Electroless deposition of Ni–B, Co–B and Ni–Co–B alloys using dimethylamineborane as a reducing agent (1998)
    Springer
    Journal of applied electrochemistry 28 (1998), S. 559-563 
    Details
    ISSN: 1572-8838
    Keywords: electroless Ni–Co–B alloy ; dimethylamineborane ; complexing agent ; deposition rate ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Electrical Engineering, Measurement and Control Technology
    Notes: Abstract Fundamental aspects of electroless Ni–B, Co–B and Ni–Co–B alloys have been systematically examined. The composition, crystal structure and deposition rate of the alloys were determined as a function of the concentration of reducing agent (dimethylamineborane) and complexing agents (tartrate, citrate, malonate and succinic acid), bath pH and Ni2+/Co2+ ratio. Changes in the deposition rate and metallurgical features of the alloys induced by the change in plating parameters are discussed, based on electrochemical polarization data and the formation enthalpy of the nickel and cobalt borides.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1003233715362
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 19
    Electronic Resource
    Electronic Resource
    Structural and magnetic properties of a syn-anti carboxylate bridged one-dimensional copper(II) complex with ferromagnetic exchange interaction (1998)
    Springer
    Journal of chemical crystallography 28 (1998), S. 771-777 
    Details
    ISSN: 1572-8854
    Keywords: Copper ; 1,10-phenanthroline ; trifluoroacetate ; crystal structure ; magnetic exchange
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The compound [Cu(phen)(O2CCF3)2]n (phen = 1,10-phenanthroline) has been synthesized and its crystal structure determined. It crystallizes in monoclinic space group C2/c, with a = 19.229(7), b = 11.281(5), c = 7.621(2) Å, β = 104.305(12)°, and Z = 4. The crystal structure is polymeric, being built from infinite zigzag chains of trifluoroacetate bridged copper(II), with the phenanthroline ligands being stacked between the chains. The variable-temperature (13–300 K) magnetic susceptibility and ESR data are reported and a weak ferromagnetic exchange interaction is observed with the exchange parameter estimated as J = 2.9 cm−1.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1021820729518
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 20
    Electronic Resource
    Electronic Resource
    Crystal structure of chloro(dicarbonyl) bis(acetonitrile) (π-2-methallyl) molybdenum(II) (1998)
    Springer
    Journal of chemical crystallography 28 (1998), S. 839-841 
    Details
    ISSN: 1572-8854
    Keywords: π-allyl ; carbonyl ; nitrile ; chloro ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The title compound crystallizes in the monoclinic spacegroup P21/m with a = 6.796(9), b = 12.145(14), c = 7.749(8)Å, β = 101.86(1)°, and Z = 2. The crystal structure consists of molecules of [MoCl(CO)2(NCMe)2(η3-C3H4Me-2)] with crystallographically imposed Cs symmetry and has a pseudo-octahedral geometry, with the π-allyl group trans- to the chloro group and the two cis-carbonyl and acetonitrile groups occupying the equatorial plane.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1021836022191
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 21
    Electronic Resource
    Electronic Resource
    The true nature of a complex of 1,10-phenanthroline with the ammonium ion; crystal structure of bis-phenanthrolineprotium perchlorate (1998)
    Springer
    Journal of chemical crystallography 28 (1998), S. 611-619 
    Details
    ISSN: 1572-8854
    Keywords: 1,10-Phenanthroline ; bis-phenanthrolineprotium ; adduct ; crystal structure ; hydrogen bonding
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Herzog's reported bis-1,10-phenanthrolineammonium perchlorate, [(phen)2(NH4)](ClO4) is in fact the known 2:1 adduct of l,10-phenanthroline (phen) with perchloric acid, [(phen)2H](CIO4). Its crystal structure, mode of formation, and properties are described. The compound crystallizes in the triclinic space group with $$P\bar 1$$ , a = 7.2510(8), b = 13.120(2), c = 22.083(12) Å, α = 77.4550(12), β = 84.45(2), γ = 82.204(14)°, V = 2026.7(6) Å3, Z = 4, and D c = 1.510 g cm−3. It contains cationic columns of alternating 1,10-phenanthroline and its conjugate acid.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1022460909589
    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 cytotoxic marine alkaloid 2-bromoleptoclinidinone (1998)
    Springer
    Journal of chemical crystallography 28 (1998), S. 645-648 
    Details
    ISSN: 1572-8854
    Keywords: 2-Bromoleptoclinidinone ; marine alkaloid ; cytotoxic ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract 2-Bromoleptoclinidinone methanol solvate, C18H8BrN3O·CH4O, crystallizes in the orthorhombic space group Pbca with a = 15.7013(2), b = 7.3308(1), and c = 26.9326(1) Å. The molecule is essentially planar, with the largest deviations occurring at bromine (−0.21 Å), carbonyl oxygen O(l) (+0.19 Å) and in ring-A (C(9) −0.15 Å, C(10) −0.15 Å). Methanol occupies the 1,10-phenanthroline-like metal binding site of the title compound.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1022421328245
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 23
    Electronic Resource
    Electronic Resource
    Synthesis and crystal structure of N 12-(7-chloro-4-quinolinyl)-N 1,N 1-diethy1-1,12-diaminododecane (AQ-40) (1998)
    Springer
    Journal of chemical crystallography 28 (1998), S. 925-929 
    Details
    ISSN: 1572-8854
    Keywords: Quinoline ; chloroquine ; antimalarial ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The preparation of N12-(7-chloro-4-quinolinyl)-N 1,N 1-diethyl-1,12-diaminododecane, AQ-40, was accomplished by a five-step process in 80% overall yield from 12-aminododecanoic acid and 4,7-dichloroquinoline. AQ-40 crystallizes as a monohydrate from reagent grade chloroform/ diethyl ether mixtures in the triclinc space group P-1 with a = 8.667(2), b = 8.9425(10), c = 17.217(3) Å, α = 99.34(1), β = 99.89(2), γ = 91.56(1)°, V = 1295.0 Å3 and Z = 2. The l2-(N 1,N 1-diethylamino)dodecyl side chain is in the fully extended conformation and the water molecule forms hydrogen bonds to the two tertiary nitrogen atoms as well as with the secondary amino group. The nitrogen of the secondary amino group bound to the four-position of the quinoline moiety is virtually planar. This together with the rather short C–N distance of 1.347(3) Å to the quinoline moiety suggests involvement of the lone pair on this nitrogen with the π system of the ring.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1022810821793
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 24
    Electronic Resource
    Electronic Resource
    Molecular structure of trans-[Co(NH3)4(NH2CH3)Cl](ClO4)2 (1998)
    Springer
    Journal of chemical crystallography 28 (1998), S. 69-72 
    Details
    ISSN: 1572-8854
    Keywords: Co(III) complex ; crystal structure ; kinetics ; steric effects
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The title compound crystallizes in the orthorhombic space group Pnma, with a = 7.9209(5), b = 9.818(1), c = 16.867(2) Å, and Z = 4. The structure was solved employing 1864 independent x-ray reflections with I〉2σ(I) by Patterson and difference Fourier techniques and refined by full-matrix least-squares to R = 0.036. The trans-[CO(NH3)4(NH2CH3)Cl](ClO4)2 molecule is on a crystallographic mirror plane. The cobalt ion is in an elongated octahedral coordination with four equatorial ammonia ligands [average Co–N distance equal to 1.966(2) Å], an axial methylamine [Co–N=1.965(3)Å], and an axial chlorine ion [Co–Cl=2.2771(9)Å]. Kinetic steric effects of the complex are interpreted in terms of structural results.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1021786804676
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 25
    Electronic Resource
    Electronic Resource
    Crystal structure of NH3(CH2)2NH3BiCl5·2H2O (1998)
    Springer
    Journal of chemical crystallography 28 (1998), S. 209-212 
    Details
    ISSN: 1572-8854
    Keywords: Bismuth ; crystal structure ; inorganic polymer
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The ethylenediammonium pentachlorobismuthate(III) dihydrate salt is monoclinic with the following unit cell dimensions: a = 10.902(8)Å, b = 7.926(6)Å, c = 15.199(6)Å, β = 96.40(1)°, space group P21/n with Z = 4. The structure shows a layer arrangement parallel to the $$\vec a$$ axis: planes of the [Bi2Cl10]4− bioctahedra alternate with planes of [NH3(CH2)2NH3]2+ dications. The [Bi2Cl10]4− bioctahedra are connected through O(W)–H··· Cl hydrogen bonds, so that infinite unidimensional chains of composition [Bi2Cl10(H2O)2] n 4n− are formed in the structure parallel to the $$\vec a$$ axis. These chains are themselves interconnected by means of the N–H···Cl bonds originating from the [NH3(CH2)2NH3]2+ entities, forming a three-dimensional network.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1022474327917
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 26
    Electronic Resource
    Electronic Resource
    The synthesis and X-ray structure of [Sr2(OSiPh3)4(NH3)5]·0.5C7H8 (1998)
    Springer
    Journal of chemical crystallography 28 (1998), S. 221-226 
    Details
    ISSN: 1572-8854
    Keywords: Strontium ; triphenylsiloxy ; crystal structure ; ammonia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The title complex [Sr2(OSiPh3)4(NH3)5]·0.5C7H8 was prepared by the reaction of strontium metal granules with triphenylsilanol in an ammoniacal-toluene solution at −40°C. It crystallizes in monoclinic space group P21/n with a = 14.465(3), b = 20.715 (6), c = 25.199(6) Å, β = 95.98(2)°, and Z = 4. The complex has a dimeric structure with one terminal and three bridging triphenylsiloxy ligands, the remaining coordination sites being occupied by five ammonia molecules. The central Sr2O4N5 moiety adopts a distorted M2X9 face-sharing bioctahedral arrangement.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1022430612896
    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 mixed rubidium–ammonium hydrogen sulfate Rb0.7(NH4)0.3HSO4 at room temperature (1998)
    Springer
    Journal of chemical crystallography 28 (1998), S. 335-338 
    Details
    ISSN: 1572-8854
    Keywords: Mixed rubidium–ammonium acid sulfate ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The structure of Rb0.7(NH4)0.3HSO4 has been determined by X-ray analysis. The mixed compound crystallizes in the monoclinic space group P21/n with unit cell parameters a = 14.374(6) Å, b = 4.618(6) Å, c = 14.412(2) Å, β = 118.03(2)°, V = 844.4(4) Å3, and D cal = 1.536 g cm−3 for Z = 8. The mixed compound Rb0.7(NH4)0.3HSO4 is a chain-based structure. The Rb+ and NH4 + cations are intercalated between chains, formed of HSO4 - groups linked with OH⋯O hydrogen-bonding. Rb0.7(NH4)0.3HSO4 presents a new type of structural arrangement different from those of pure RbHSO4 and NH4HSO4.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1022451822967
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 28
    Electronic Resource
    Electronic Resource
    The crystal and molecular structures of isoperezone, aminoperezone, and isoaminoperezone: a comparative study of their crystal packing (1998)
    Springer
    Journal of chemical crystallography 28 (1998), S. 529-537 
    Details
    ISSN: 1572-8854
    Keywords: 2-[1,5-Dimethyl-4-hexenyl]-6-hydroxy-5-methyl-1,4-benzoquinone ; 2-[1,5-dimethyl-4-hexenyl]-6-amino-3-hydroxy-5-methyl-1,4-benzoquinone ; 2-[1,5-dimethyl-4-hexenyl]-3-amino-6-hydroxy-5-methyl-1,4-benzoquinone ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The crystal structures of isoperezone (1), aminoperezone (2), and isoaminoperezone (3) have been determined by single-crystal X-ray diffraction. Compound (1) yields orange crystals, orthorhombic space group P212121 with unit cell dimensions a = 6.271(6), b = 30.373(7), c = 7.257(1) Å, and Z = 4; compound (2) yields purple crystals, orthorhombic space group P212121 with unit cell dimensions a = 6.498(3), b = 7.500(1) c = 29.200(6) Å, and Z = 4; compound (3) yields purple crystals, monoclinic space group P21 with unit cell dimensions a = 7.354(1), b = 7.511(1), c = 13.283(1) Å, β = 102,07(1)°, and Z = 2. The side chains in (1)–(3) are oriented out of the plane of the quinone ring at an angle of 124, 144, and 97°, respectively. The molecules in the crystal are held together by hydrogen-bonding networks and van der Waals interactions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1023292005612
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 29
    Electronic Resource
    Electronic Resource
    Crystal structure of [WI2(CO)3{P(OMe)3}2] (1998)
    Springer
    Journal of chemical crystallography 28 (1998), S. 639-643 
    Details
    ISSN: 1572-8854
    Keywords: Tungsten(II) ; diiodo ; carbonyl ; trimethylphosphite ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract [WI2(CO)3{P(OMe)3}2]crystallizes in the orthorhombic space group Pca21, with a = 26.924(5), b = 10.726(2), c = 14.136(3) Å, and Z = 8. There are two molecules in the asymmetric unit, the metal atoms in each case being seven-coordinate with a capped fac-(CO)3 octahedral geometry. The molecular dimensions in the two molecules are nearly identical. The W–P distance to the capping atom 2.397 Å (average) is significantly shorter than the other W–P distance, 2.525 Å (average).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1022469211406
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 30
    Electronic Resource
    Electronic Resource
    Asymmetric hetero-Diels-Alder reactions: X-ray structures of three novel chiral dihydropyrimidines (1998)
    Springer
    Journal of chemical crystallography 28 (1998), S. 663-671 
    Details
    ISSN: 1572-8854
    Keywords: Pyrimidine ; carboxamide ; sulfonyl ; chiral ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Three novel dihydropyrimidine compounds N8,6-di(4-nitrophenyl)-(3R)-ethyl-(7R)-methyl-5-oxo-2,3,6,7-tetrahydrooxazolo[3,2,c] pyrimidine-8-carboxamide (2), N8,6-di((4-methylphenyl)-sulfonyl)-(3R)-ethyl-5-oxo-(7R)-phenyl-2,3,6,7-tetrahydrooxazolo [3,2,c]pyrimidine-8-carboxamide (3) and N8,6-di ((4-methylphenyl)sulfonyl)-(3R)-ethyl-(7R)-methyl-5-oxo-2,3,6,7-tetrahydrooxazolo[3,2,c] pyrimidine-8-carboxamide (4) have been prepared (from 2-amino-1-butanol of 64.4% e.e.) and structurally characterized by X-ray crystallography. All three compounds contain stereogenic centers, but the crystal of (2) chosen was found to be racemic whilst those of (3) and (4) were found to be homochiral. Compound (2) crystallizes in the monoclinic space group P21/c, with a = 17.958(4), b = 12.431(2), c = 9.653(2) Å, β = 96.20(3)°, U = 2142.3(7) Å3, Z = 4, and D c = 1.449 g cm−3. Compounds (3) and (4) both crystallize in the monoclinic space group P21, with a = 9.349(2), b = 5.824(5), c = 26.513(8) Å, β = 99.43(2)°, U = 1424.1(13) Å3, Z = 2 and D c = 1.389 g cm−3 for (3), and a = 5.9526(9), b = 16.3521(10), c = 13.2263(11) Å, β = 92.81(12)°, U = 1285.9(2) Å3, Z = 2 and D c = 1.378 g cm−3 for (4).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1021791832534
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 31
    Electronic Resource
    Electronic Resource
    The synthesis and crystallographic characterization of the heterotrimetallic linear complex [Et4N][(Ph3P)2{CuS2MoS2Fe}Br2] (1998)
    Springer
    Journal of chemical crystallography 28 (1998), S. 713-716 
    Details
    ISSN: 1572-8854
    Keywords: Heterotrimetallic sulfido cluster ; linear ; synthesis ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The complex Cu(PPh3)3I reacts with [Et4N]2MoS4 and FeBr2 to give the heterotrimetallic complexes [Et4N][(Ph3P)2{CuS2MoS2Fe}Br2] (1). [Et4N][(Ph3P)2{CuS2MoS2Fe}Br2] (1) crystallizes in the triclinic space group P-1, a = 13.537(4), b = 15.316(4), c = 12.381(4) Å, α = 105.16(2), β = 93.27(3), γ = 101.18(2)°, and V = 2415.0(12) Å3 for Z = 2. The three metal atoms of the structure [Et4N][(Ph3P)2{CuS2MoS2Fe}Br2] (1) are nearly distributed along a line, where three metal atoms (Mo, Cu, Fe) are each in an approximate tetrahedral coordination, the lengths Mo-Fe and Mo-Cu distances are 2.772(2) and 2.798(2) Å, respectively.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1021756319330
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 32
    Electronic Resource
    Electronic Resource
    [CaSb2(EDTA)2(H2O)8]n: synthesis, crystal structure, and thermal behavior (1998)
    Springer
    Journal of chemical crystallography 28 (1998), S. 447-452 
    Details
    ISSN: 1572-8854
    Keywords: Bimetallic EDTA complex ; crystal structure ; antimony
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The synthesis and crystal structure of a new EDTA complex, [CaSb2(EDTA)2(H2O)8]n, are reported. This compound crystallizes in the monoclinic space group P21/n, with a = 7.132(1) Å, b = 21.893(3) Å, c = 10.891(2) Å, β = 91.15(2)°. Sb(EDTA) entities are connected through carboxylate bridges to the calcium atoms resulting in layers parallel to the (101) plane. These layers are linked through a weak Sb···O bond (3.171 Å). Pyrolysis of this complex under sulfur vapor, between 400 and 800°C, leads to a mixture of the monometallic sulfides. Pyrolysis in air above 700°C allows the easy preparation of the mixed oxide CaSb2O6.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1021716605217
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 33
    Electronic Resource
    Electronic Resource
    Crystal structure of (3,3′,4,4′-tetramethyl-1,1′-diphosphaferrocen-2-yl) carboxylic acid and its bis-[W(CO)5] complex·0.5C5H12: Conformation of 1,1′-diphosphaferrocenes (1998)
    Springer
    Journal of chemical crystallography 28 (1998), S. 621-628 
    Details
    ISSN: 1572-8854
    Keywords: 1-1′-Diphosphaferrocene conformation ; P···P secondary bonding ; bis-[W(CO)5](l,l′-diphosphaferrocene system) ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The structures of (3,3′,4,4′-tetramethyl-1,1′-diphosphaferrocen-2-yl)carboxylic acid (1) and its bis-[W(CO)5] pentane solvate complex (2) have been determined by X-ray analysis. The compound 1 crystallizes in the monoclinic P21 /n space group with Z = 4; a = 7.8404(9), b = 14.9441(16), c = 11.7730(14) Å, β = 92.773(10)°, V = 1377.8(3) Å3, and Dcalc = 1.553 g cm−3. The compound 2 crystallizes in the triclinic $$P\bar 1$$ space group with two complex molecules and one pentane molecule in the unit cell. Cell parameters: a = 10.7070(2), b = 12.577(2), c = 13.239(3) Å, α = 84.00(2), β = 77.58(1), γ = 66.06(1)°, V = 1591.0(5) Å3, and Dcalc = 2.100 g cm−3 .The fully eclipsed conformation of the phospholyl rings with P···P secondary bonding of 3.353(1) Å is observed in 1 and a partially eclipsed conformation is found in 2. The 10 possible conformations of 1,1′-diphosphaferrocenes were described as the function of conformational parameter θ and observed geometry of the phospholyl rings.7 We suppose that the earlier conclusions concerning the destabilizing nature of 1,1′-diphosphaferrocene conformations with θ 〈 100° cannot be considered as general. The mode of W – P coordination, the structural changes of 1 by W(CO)5 coordination, the structural effect of phospholyl rings substitution by the –COOH group, and hydrogen bonds are analyzed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1022413026427
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 34
    Electronic Resource
    Electronic Resource
    Crystal structure of [Co(o-SC6H4NH2){P(OMe)3}3]PF6 (1998)
    Springer
    Journal of chemical crystallography 28 (1998), S. 635-638 
    Details
    ISSN: 1572-8854
    Keywords: Cobalt(II) ; 2-aminobenzenethiol ; trimethylphosphite ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract A cobalt-thiolato-phosphite complex [Co(o-SC6H4NH2){P(OMe)3}3]PF6 has been prepared and characterized by X-ray crystallography. The complex crystallizes in the triclinic space group $$P\bar 1$$ with a = 10.590(4), b = 11.122(3), c = 13.577(5) Å, α = 101.85(1), β = 108.50(1), γ = 101.75(1)°, V = 1420.6(8) Å3, and Z = 2. The structure comprises discrete [Co(o-SC6H4NH2){P(OMe)3}3]+ cations and PF 6 − anions where the metal atom is coordinated in a highly distorted square-pyramidal environment by one chelate o-SC6H4NH 2 − (abt) and two P(OMe)3 ligands in the basal positions, and a third P(OMe)3 in the axial site with Co–N,, 1.847(5), Co–S, 2.166(2), Co–P, 2.157(2), 2.147(2), and 2.125(2) Å.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1022417127336
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 35
    Electronic Resource
    Electronic Resource
    Crystal Structure of the Sought-After Tetrameric [(PDBP)AgCl]4 Cluster (PDBP=5-Phenyldibenzophosphole) (1998)
    Springer
    Journal of cluster science 9 (1998), S. 547-554 
    Details
    ISSN: 1572-8862
    Keywords: Silver cluster ; crystal structure ; tetrameric 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 The sought-after member of the [(PDBP) n AgX] m (n, m=1,4; 2,2; 3,1; PDBP=5-Phenyldibenzophosphole, X=halides) series, the tetrameric [(PDBP)AgCl]4 cluster has been prepared and structurally characterized. The [P4Ag4Cl4] cluster core of [(PDBP)AgCl]4 bears striking similarity to that of [(Ph3P)AgCl]4.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1021950902725
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 36
    Electronic Resource
    Electronic Resource
    Crystal, Molecular, and Electronic Structure of 1-Acetyl-indoline and Derivatives (1998)
    Springer
    Structural chemistry 9 (1998), S. 365-373 
    Details
    ISSN: 1572-9001
    Keywords: 1-Acetyl-indoline ; crystal structure ; electronic structure ; AM1 calculation ; CI calculation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The crystal and molecular structures of the following molecules have been determined: 1-acetyl-indoline, 1-acetyl-5-nitro-indoline, l-acetyl-5-nitro-7-bromo-indoline, 1-acetyl-5-bromo-7-nitroindoline, and l-acetyl-5-bromo-7-nitro-indol. Molecular orbital calculations are performed for these compounds and two related species.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1022419111660
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 37
    Electronic Resource
    Electronic Resource
    Supramolecular Structure Formed from H-Bonding of Ferrocenyl Carbonyl Propanoic Acid and 4,4'-Bipyridine (1998)
    Springer
    Molecular engineering 8 (1998), S. 25-29 
    Details
    ISSN: 1572-8951
    Keywords: hydrogen bond ; ferrocenyl carbonyl proanoic ; supermolecule ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Selective recognition in the title compound, (C14H14FeO3)2 ċ (C10H8N2), between ferrocenyl carbonyl propanoic acid and 4,4'-bipyridine through strong O–-HċN intermolecular hydrogen bonds results in a novel supramolecular architecture. Its crystal structure has been solved by single-crystal X-ray diffraction methods while its characterization has been studied by IR and DSC.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008279517986
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 38
    Electronic Resource
    Electronic Resource
    Molecular Structure of a Chromatographic Chiral Selector Based on a Terguride Derivative (1998)
    Springer
    Structural chemistry 9 (1998), S. 39-45 
    Details
    ISSN: 1572-9001
    Keywords: Enantioselective chromatographic technique ; chiral selector ; ergot alkaloid derivative ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The structure of (+)1-(3-allylpropyl)-(5R,8S,10R)-N,N-diethyl-N′-[6-methylergolin-8-yl]urea, C22H33N4O (allyl-terguride), has been determined as part of a study on the chiral recognition mechanism of ergot alkaloids when they are used as the chiral stationary phase for the separation of racemic mixtures in liquid chromatographic methods. At the pH of the solution used for the crystallization, the molecules of allyl-terguride are protonated at N(6). All bond distances and angles are in the expected ranges. In the asymmetric unit one hydroxide ion is present. Hydrogen bonds join molecules of allyl-terguride in pairs along the b axis, connecting O(2) of the hydroxide ion to O(1) of one molecule and to N(2) and N(6) of another.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1022435615295
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 39
    Electronic Resource
    Electronic Resource
    Role of MnO on the Mullitization Behavior of Al2 O3-SiO2 Gels (1998)
    Springer
    Journal of sol gel science and technology 13 (1998), S. 987-990 
    Details
    ISSN: 1573-4846
    Keywords: mullite ; MnO ; crystal structure ; electronic paramagnetic resonance (EPR) ; sol-gel chemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Gels were synthesized from solutions of tetraethylorthosilicate (TEOS) and aluminium nitrate (with and without manganese nitrate). The structural evolution of the gels as a function of manganese content and heat-treatment temperature was studied by visible spectrophotometry (VIS), electron paramagnetic resonance (EPR), X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results show that the presence of manganese can induce mullitization at lower temperatures. However, the effect of manganese depends on its content and how it enters into the mullite structure.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008652129890
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 40
    Electronic Resource
    Electronic Resource
    Accuracy of Secondary Structure and Solvent Accessibility Predictions for a Clostridial Neurotoxin C-Fragment (1998)
    Springer
    The protein journal 17 (1998), S. 311-318 
    Details
    ISSN: 1573-4943
    Keywords: Artificial neural network ; crystal structure ; statistics ; tetanus toxin ; botulinum neurotoxin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Earlier studies used Rost and Sander's artificial neural network [(1993a), J. Mol. Biol. 232, 584–599] to predict the secondary structures [Lebeda and Olson (1994), Proteins 20, 293–300] and residue solvent accessibilities [Lebeda and Olson (1997), J. Protein Chem. 16, 607–618] of the clostridial neurotoxins. Because the X-ray crystal structure of the 50-kDa C-terminal half of the heavy chain of tetanus toxin was recently determined, this report evaluates the accuracy of these network-derived predictions. For this predominantly β-strand-containing fragment, predictions, on a per-residue basis, for both secondary structure and solvent accessibility were about 70% accurate. A more flexible and realistic analysis based on overlapping segments yielded accuracies of over 80% for the three-state secondary structure and for the two-state accessibility predictions. Because the accuracies of these predictions are comparable to those made by Rost and Sander using a dataset of 126 nonhomologous globular proteins, our predictions provide a quantitative foundation for gauging the results when building by homology the structures of related proteins.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1022599014617
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 41
    Electronic Resource
    Electronic Resource
    Identification of proton transfer pathways in the X-ray crystal structure of the bacterial reaction center from Rhodobacter sphaeroides (1998)
    Springer
    Photosynthesis research 55 (1998), S. 119-125 
    Details
    ISSN: 1573-5079
    Keywords: bacterial photosynthesis ; crystal structure ; electron transfer ; proton transfer
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Structural features that have important implications for the fundamental process of transmembrane proton transfer are examined in the recently published high resolution atomic structures of the reaction center (RC) from Rhodobacter sphaeroides in the dark adapted state (DQAQB) and the charged separated state (D+QAQB −); the latter is the active state for proton transfer to the semiquinone. The structures have been determined at 2.2 Å and 2.6 Å resolution, respectively, as reported by Stowell et al. (1997) [Science 276: 812–816]. Three possible proton transfer pathways (P1, P2, P3) consisting of water molecules and/or protonatable residues were identified which connect the QB binding region with the cytoplasmic exposed surface at Asp H224 & Asp M240 (P1), Tyr M3 (P2) and Asp M17 (P3). All three represent possible pathways for proton transfer into the RC. P1 contains an uninterrupted chain of water molecules. This path could, in addition, facilitate the exchange of quinone for quinol during the photocycle by allowing water to move into and out of the binding pocket. Located near these pathways is a cluster of electrostatically interacting acid residues (Asp-L213, Glu-H173, Asp-M17, Asp H124, Asp-L210 and Asp H170) each being within 4.5 Å of a neighboring carboxylic acid or a bridging water molecule. This cluster could serve as an internal ‘proton reservoir’ facilitating fast protonation of QB − that could occur at a rate greater than that attainable by proton uptake from solution.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006047519260
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 42
    Electronic Resource
    Electronic Resource
    Cytochrome c Oxidase (Heme aa 3) from Paracoccus denitrificans: Analysis of Mutations in Putative Proton Channels of Subunit I (1998)
    Springer
    Journal of bioenergetics and biomembranes 30 (1998), S. 89-97 
    Details
    ISSN: 1573-6881
    Keywords: Terminal oxidase ; redox coupling ; electrochemical gradient ; electron transport ; energy transduction ; proton translocation ; crystal structure ; site-directed mutagenesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Physics
    Notes: Abstract One of the challenging features of energy-transducing terminal oxidases, like the aa 3 cytochrome c oxidase of Paracoccus denitrificans, is the translocation of protons across the cytoplasmic membrane, which is coupled to the transfer of electrons to oxygen. As a prerequisite for a more advanced examination of the enzymatic properties, several amino acid residues, selected on the basis of recent three-dimensional structure determinations, were exchanged in subunit I of the Paracoccus enzyme by site-directed mutagenesis. The properties of the mutated oxidases were analyzed by different methods to elucidate whether they are involved in the coupled and coordinated transfer of protons via two different pathways either to the site of oxygen reduction or through the enzyme from the cytoplasm to the periplasmic side.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1020515713103
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 43
    Electronic Resource
    Electronic Resource
    Effect of M and M-Ca Substitution on the Structure and Superconductivity of GdBa2Cu3O7−δ [M = Mo, Hf ] (1998)
    Springer
    Journal of superconductivity 11 (1998), S. 285-290 
    Details
    ISSN: 1572-9605
    Keywords: GdBa2Cu3O7−δ ; Ca substitution ; Mo substitution ; Hf substitution ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract The structural and superconducting properties of (Gd1−x−y Ca y M x )Ba2Cu3O z with M = Mo, Hf are investigated using X-ray diffraction, electrical resistivity, and oxygen content measurements. The effect of increasing the Mo concentration in (Gd1−x Mo x )Ba2Cu3O z changes the structure from orthorhombic to tetragonal accompanied by a large increase in resistivity and a fast decrease in T c at the rate of 1.9 K per at.% of Mo, unlike that of Hf substitution in (Gd1−x Hf x )Ba2Cu3O z , which maintains the orthorhombic structure and decreases T c very slowly at the rate of 0.6 K per atm.% of Hf with nearly no change in resistivity. The suppression of T c by M = Mo, Hf can be counterbalanced by hole doping by Ca which increases T c with increasing Ca content showing maximum compensation for Mo. A comparative study of M = Mo, Hf doped samples in (Gd1−x−y Ca y M x )Ba2Cu3O z indicates that the valence of the dopant M = Mo4+,6+, Hf4+ and its ionic radius play an important role in controlling the structural and superconducting properties of the systems.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1022644203794
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 44
    Electronic Resource
    Electronic Resource
    A general method of domain closure is applied to phosphoglycerate kinase and the result compared with the crystal structure of a closed conformation of the enzyme (1998)
    New York, NY : Wiley-Blackwell
    Proteins: Structure, Function, and Genetics 30 (1998), S. 372-380 
    Details
    ISSN: 0887-3585
    Keywords: protein modeling ; crystal structure ; conformation change ; prediction ; mechanism ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The occurrence of large domain motions associated with the mechanism of action of many proteins is well established. We present a general method of predicting domain closure applicable to proteins containing domains separated by an apparent hinge. The method attempts to allow for natural directional bias within the closing protein by repeatedly applying a weak pulling force over a short distance between pairs of atoms chosen at random in the two domains in question. Appropriate parameters governing the pulling function were determined empirically. The method was applied to the bi-lobal protein PGK and a closed-form activated ternary complex generated for Bacillus stearothermophilus PGK. This model was compared with the recently determined crystal structure of closed-form Trypanosoma brucei PGK. The model predicts the correct hinge regions, although the magnitude of movement at one hinge point was overestimated, and provides a reasonable representation of the closed-form ternary complex. Proteins 30:372-380, 1998. © 1998 Wiley-Liss, Inc.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 45
    Electronic Resource
    Electronic Resource
    Full-matrix least-squares refinement of lysozymes and analysis of anisotropic thermal motion (1998)
    New York, NY : Wiley-Blackwell
    Proteins: Structure, Function, and Genetics 30 (1998), S. 232-243 
    Details
    ISSN: 0887-3585
    Keywords: turkey lysozyme ; human lysozyme ; crystal structure ; protein structure ; structure refinement ; protein crystal ; atomic resolution ; rigid-body motion ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Crystal structures of turkey egg lysozyme (TEL) and human lysozyme (HL) were refined by full-matrix least-squares method using anisotropic temperature factors. The refinement converged at the conventional R-values of 0.104 (TEL) and 0.115 (HL) for reflections with Fo 〉 0 to the resolution of 1.12 Å and 1.15 Å, respectively. The estimated r.m.s. coordinate errors for protein atoms were 0.031 Å (TEL) and 0.034 Å (HL). The introduction of anisotropic temperature factors markedly reduced the R-value but did not significantly affect the main chain coordinates. The degree of anisotropy of atomic thermal motion has strong positive correlation with the square of distance from the molecular centroid. The ratio of the radial component of thermal ellipsoid to the r.m.s. magnitude of three principal components has negative correlation with the distance from the molecular centroid, suggesting the domination of libration rather than breathing motion. The TLS model was applied to elucidate the characteristics of the rigid-body motion. The TLS tensors were determined by the least-squares fit to observed temperature factors. The profile of the magnitude of reproduced temperature factors by the TLS method well fitted to that of observed Beqv. However, considerable disagreement was observed in the shape and orientation of thermal ellipsoid for atoms with large temperature factors, indicating the large contribution of local motion. The upper estimate of the external motion, 67% (TEL) and 61% (HL) of Beqv, was deduced from the plot of the magnitude of TLS tensors determined for main chain atoms which were grouped into shells according to the distance from the center of libration. In the external motion, the translational portion is predominant and the contribution of libration and screw motion is relatively small. The internal motion, estimated by subtracting the upper estimate of the external motion from the observed temperature factor, is very similar between TEL and HL in spite of the difference in 54 of 130 amino acid residues and in crystal packing, being suggested to reflect the intrinsic internal motion of chicken-type lysozymes. Proteins 30:232-243, 1998. © 1998 Wiley-Liss, Inc.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 46
    Electronic Resource
    Electronic Resource
    Role of water in plasticity, stability, and action of proteins: The crystal structures of lysozyme at very low levels of hydration (1998)
    New York, NY : Wiley-Blackwell
    Proteins: Structure, Function, and Genetics 32 (1998), S. 229-240 
    Details
    ISSN: 0887-3585
    Keywords: active-site geometry ; crystal structure ; enzyme action ; protein hydration ; protein mobility ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Earlier studies involving water-mediated transformations in lysozyme and ribonuclease A have shown that the overall movements in the protein molecule consequent to the reduction in the amount of surrounding water are similar to those that occur during enzyme action, thus highlighting the relationship among hydration, plasticity, and action of these enzymes. Monoclinic lysozyme retains its crystallinity even when the level of hydration is reduced further below that necessary for activity (about 0.2 gram of water per gram of protein). In order to gain insights into the role of water in the stability and the plasticity of the protein molecule and the geometrical basis for the loss of activity that accompanies dehydration, the crystal structures of monoclinic lysozyme with solvent contents of 17.6%, 16.9%, and 9.4% were determined and refined. A detailed comparison of these forms with the normally hydrated forms show that the C-terminal segment (residues 88-129) of domain I and the main loop (residues 65-73) in domain II exhibit large deviations in atomic positions when the solvent content is reduced, although the three-dimensional structure is essentially preserved. Many crucial water bridges between different regions of the molecule are conserved in spite of differences in detail, even when the level of hydration is reduced well below that required for activity. The loss of activity that accompany dehydration appears to be caused by the removal of functionally important water molecules from the active-site region and the reduction in the size of the substrate binding cleft. Proteins 32:229-240, 1998. © 1998 Wiley-Liss, Inc.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 47
    Electronic Resource
    Electronic Resource
    Crystal Structure of a p-Benzylcalix[5]arene- pyridine Complex (1998)
    Springer
    Journal of inclusion phenomena and macrocyclic chemistry 31 (1998), S. 357-365 
    Details
    ISSN: 1573-1111
    Keywords: calixarenes ; crystal structure ; supramolecular assembly
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract p-Benzylcalix[5]arene.3py (py = pyridine) (1) crystallizes in the triclinic space group P1, a = 10.641(3), b = 13.975(3), c = 24.052(12) Å, α = 94.60(4), β = 91.51(4), γ = 111.46(2)°, V = 3312(4) Å3, Z = 2. Refinement led to a final conventional R value of 0.065 for 5457 reflections. The calixarene is in a distorted cone conformation. Two pyridine molecules are hydrogen bonded to phenolic oxygen atoms and one of them is included in the hydrophobic cavity of the neighboring calixarene molecule along the a axis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1007964510691
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 48
    Electronic Resource
    Electronic Resource
    A New Clathrate: Synthesis and Crystal Structure of the [36]ene-O6N8/THF (1:2) Clathrate (1998)
    Springer
    Journal of inclusion phenomena and macrocyclic chemistry 30 (1998), S. 13-19 
    Details
    ISSN: 1573-1111
    Keywords: THF clathrate ; Schiff base macrocycle ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A new clathrate inclusion compound of 2,3:11,12:20,21:29,30-tetrabenzo-1,13,16,19,31,34-hexaoxa-5,6,8,9,23,24,26,27- octaaza-7,25-dithioketone-2,3:4,5:9,10:11,12:22,23:27,28:29,30-cyclo-[36]ene([ 36]eneO6N8), which contains THF, has been prepared and crystallizes in the monoclinic space group P21/n with a = 9.829(5)Å, b = 24.23(1)Å, c = 10.181(9)Å, β = 92.93(5)-. Each unit cell contains two [36]ene-O6N8 molecules and four THF molecules. The [36]ene-O6N8 molecule lies on the crystallographic centre of symmetry and a pair of the THF molecules with half-chair conformation are located within rectangular channels formed by the macrocycle molecules.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1007904912978
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 49
    Electronic Resource
    Electronic Resource
    Morphology and crystal structure of a recombinant silk-like molecule, SLP4 (1998)
    New York : Wiley-Blackwell
    Biopolymers 45 (1998), S. 307-321 
    Details
    ISSN: 0006-3525
    Keywords: morphology ; crystal structure ; recombinant silk-like molecule ; silk I ; wide angle x-ray scattering ; electron diffraction ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Morphology and crystal structure of a recombinant silk-like molecule, SLP4, were studied. Wide angle x-ray scattering (WAXS) and electron diffraction revealed that SLP4 lyophilized powder and thin films were isomorphic with the silk I crystal structure. Transmission electron microscopy of SLP4 thin films demonstrated a morphology of flat, variable width, crystallites that may aggregate in an epitaxial manner. Theoretical diffraction patterns from silk I crystal structure models were critically compared with SLP4 WAXS data. The analysis concluded that while the crankshaft model is capable of describing details of the SLP4 structural data well, the out-of-register model does not explain the experimental results. In particular, the predicted intensities of the crystallographic reflections for the out-of-register model are inconsistent with the SLP4 WAXS data. © 1998 John Wiley & Sons, Inc. Biopoly 45: 307-321, 1998
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 50
    Electronic Resource
    Electronic Resource
    Conformational behaviour of Cα,α-diphenylglycine: folded vs. extended structures in DφG-containing tripeptides (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Peptide Science 4 (1998), S. 21-32 
    Details
    ISSN: 1075-2617
    Keywords: Cα,α-disubstituted amino acids ; crystal structure ; molecular dynamics ; conformation ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The crystal structures of three fully protected tripeptides containing the Dφg residue (Cα,α-diphenylglycine) in the central position are reported, namely Z-Gly-Dφg-Gly-OMe (a), Z-Gly-Dφg-Aib-OMe (b) and Z-Aib-Dφg-Aib-OMe (c). The molecular conformations are quite unusual because the Dφg residue adopts a folded conformation in the 310-helical region when the following residue adopts a folded conformation of opposite handedness (peptidesbandc). In contrast, the Dφg residue adopts the more frequently observed fully extended conformation when the following residue adopts a semi-extended conformation (peptidea). These findings are in agreement with the theoretical calculations on Ac-Dφg-Aib-NHCH3 and Ac-Aib-Dφg-NHCH3 also reported in this work. © 1998 European Peptide Society and John Wiley & Sons, Ltd.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 51
    Electronic Resource
    Electronic Resource
    X-ray and NMR investigation of 25,27-dihydroxy-26,28-bis(diethoxyphosphoryloxy)-tert-butylcalix[4]arene in the 1,2-alternate conformation (1998)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 11 (1998), S. 63-70 
    Details
    ISSN: 0894-3230
    Keywords: calixarenes ; complexes ; conformation ; crystal structure ; 1H NMR ; 13C NMR ; Chemistry ; Theoretical, Physical and Computational Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The crystal structure of 25,27-dihydroxy-26,28-bis(diethoxyphosphoryloxy)-tert-butylcalix[4]arene (1) (hexane solvate, 1:1) was determined by x-ray crystallography. The crystal data are P21/n, a  =  12.652(1) Å, b  =  12.564(2) Å, c  =  18.781(4) Å, β  =  105.56(1)°, V  =  2876.0(8) Å3, Z  =  2. In this complex the molecule adopts a 1,2-alternate conformation. Both the calixarene and hexane molecules are centrosymmetric. The phenol units in the asymmetric part of the calix are inclined with respect to the main macrocyclic plane by 115.46(6)° and 128.01(7)° for the phosphorylated and the non-phosphorylated ring, respectively. Self-inclusion of the ethyl chains in the half-cavities is observed. One intramolecular O - H…O and several intermolecular C - H…O hydrogen bonds are present. In the 1H NMR spectrum one average AX spin system for methylene bridge protons can be interpreted as fast (on the NMR time-scale) interconversion of non-phosphorylated phenol fragments. © 1998 John Wiley & Sons, Ltd.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 52
    Electronic Resource
    Electronic Resource
    1:1 Crystal complex of 2′,6′-dimethoxyflavone and 2,6-dimethoxybenzoic acid. Relationship of pKa to x-ray hydrogen bond data (1998)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 11 (1998), S. 751-755 
    Details
    ISSN: 0894-3230
    Keywords: 2′,6′-dimethoxyflavone-2,6-dimethoxybenzoic acid complex ; crystal structure ; pKa values ; hydrogen bonds ; Chemistry ; Theoretical, Physical and Computational Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The crystal structure of the 2′,6′-dimethoxyflavone-2,6-dimethoxybenzoic acid complex was determined. Owing steric hindrance of the methoxy groups, the two H-bonded molecules are twisted. Earlier results were used to establish a relationship between the pKa values of different acids and their hydrogen bond distances in complexes with 2′,6′-dimethoxyflavone. © 1998 John Wiley & Sons, Ltd.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 53
    Electronic Resource
    Electronic Resource
    Some new synthetic low-dimensional semiconductors based on inorganic units (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Advanced Materials for Optics and Electronics 8 (1998), S. 263-267 
    Details
    ISSN: 1057-9257
    Keywords: semiconductors ; low-dimensional systems ; crystal structure ; optical properties ; photoluminescence ; Raman spectra ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: The structural, optical and related properties (i.e. photoluminescence and resonance Raman spectra) of some synthetic (i.e. unconventional) low-dimensional semiconductor systems such as K2Cd3S4, [CH3SC(NH2)=NH2]3PbI5 and [H3N(CH2)6NH3]BiI5 are reported. They are compared with the properties of the corresponding higher-dimensionality systems. A blue shift of the excitonic bands and an enhancement of their binding energy and intensity were observed by decreasing the dimensionality or the size of the materials active part. The results are similar to those obtained from conventional semiconductors by decreasing the dimensionality or the size and are attributed to quantum confinement of excitons. © 1998 John Wiley & Sons, Ltd.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 54
    Electronic Resource
    Electronic Resource
    α-Hydroxymethylserine as a peptide building block: synthetic and structural aspects (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Peptide Science 4 (1998), S. 46-57 
    Details
    ISSN: 1075-2617
    Keywords: α-hydroxymethylserine peptides ; isopropylidene protecting group ; crystal structure ; peptide conformation ; peptide synthesis ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A synthetic methodology has been developed for peptide bond formation with α-hydroxmethylserine as the carboxyl or amino component and also for the preparation of homo-sequences. The key intermediate, O,O-protected α-hydroxymethylserine in the form of an isopropylidene derivative, is easily accessible and represents the first example of a heterocyclic Cα,α-disubstituted amino acid containing an 1,3-dioxane ring. The use of this intermediate facilitates protection of the sterically hindered amino and carboxyl groups and is advantageous for the coupling and deprotection steps. X-ray structure determination of Z-HmS(Ipr)-Ala-OMe revealed that the two crystallographically independent molecules present in the asymmetric unit adopt an S-shaped conformation. In the one molecule the achiral HmS(Ipr) residue has the torsion angle values (φ==61.4°,ψ=40.8°) in the left-handed helical region of the Ramachandran map, while in the second molecule the negative torsion angles (φ=-60.1°, ψ=-44.4°) are associated with the right-handed helix. © 1998 European Peptide Society and John Wiley & Sons, Ltd.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 55
    Electronic Resource
    Electronic Resource
    Synthesis, characterization and biological activities of some triarylantimony dichrysanthemates and crystal structure of Ph3Sb(O2CCHCMe2CMe2)2 (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 12 (1998), S. 31-38 
    Details
    ISSN: 0268-2605
    Keywords: triarylantimony dichrysanthemate ; plant growth-regulating activity ; crystal structure ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A series of triarylantimony dichrysanthemate compounds of the type Ar3Sb(O2CR)2 [Ar=C6H5, 4-CH3C6H4, 3-CH3C6H4, -CH3C6H4, 4-ClC6H4; R=4-ClC6H4CH(i-Pr), cis-Cl2C:CH trans-Cl2C:CH] have been synthesized and characterized by elemental analysis, infrared spectra, 1H NMR spectra and mass spectra. Some activities of these compounds in plant growth regulation have been determined. Their results indicate that the derivatives of cis-dichlorochrysanthemic acid and trans-dichlorochrysanthemic acid significantly promote rooting of excised cucumber cotyledons at 10 ppm. An X ray structure determination has been carried out as follows for Ph3Sb(O2CCHCMe2CMe2)2: orthorhombic, space group Pbcn, Z=4, structure solution with 2385 independent reflections, R=0.035. Lattice dimensions at 26 °C: a=15.616(3) Å, b=10.275(2) Å, c=20.201(5) Å, V=3241(2) Å3, ρ=1.302 g cm-3. © 1998 John Wiley & Sons, Ltd.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 56
    Electronic Resource
    Electronic Resource
    Synthesis and Characterization of the Isocyanide Ligated Centered Zirconium Halide Cluster [(Zr6Be)Cl12(CNXyl)6] (1997)
    Springer
    Journal of cluster science 8 (1997), S. 521-531 
    Details
    ISSN: 1572-8862
    Keywords: Zirconium clusters ; isocyanide ; synthesis ; 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 first isocyanide ligated hexanuclear zirconium halide cluster is reported. The unoxidized [(Zr6Be)Cl12(CNXyl)6] (CNXyl = 2,6-dimethylphenyl isocyanide) was obtained from the solid state precursor K3Zr6Cl15Be by dissolution in CH3CN in the presence of CNXyl. The CNXyl ligands occupy all the axial positions on the cluster. The compound was recrystallized from CH2Cl2 and Et2O. [(Zr6Be)Cl12(CNXyl)6].2CH2Cl2 crystallizes in the space group $${\text{P}}\overline {\text{1}} $$ (#2) with a = 12.092(5) Å, b=12.728(5) Å, c = 14.102(8) Å, α = 104.98(4)°, β =107.11°, γ = 100.94°, V = 1919(2) Å3, Z = l, R = 11.3% and R W = 27.0%. For the bound isocyanide ligands, v CN increases to 2140 cm−1.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1022605113866
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 57
    Electronic Resource
    Electronic Resource
    Reactions of the Dirhenium(II) Complexes Re2 X 4(μ-dppm)2 (X=Cl, Br; dppm=Ph2PCH2PPh2) with Isocyanides. Part XV: A Fifth Structural Isomer of the [Re2Cl3(μ-dppm)2(CO)(CNXyl)2]+ Cation (Xyl = 2, 6-Dimethylphenyl) (1997)
    Springer
    Journal of cluster science 8 (1997), S. 547-551 
    Details
    ISSN: 1572-8862
    Keywords: Rhenium ; dirhenium complexes ; rhenium–rhenium multiple bonds ; isocyanide ligands ; carbonyl ligand ; structural isomers ; 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 reaction of the unsymmetrical, coordinatively unsaturated dirhenium(II) complex [(XylNC)(OC)CIRe(μ-dppm)2ReCl2]O3SCF3 (dppm = Ph2PCH2PPh2) with one equivalent of XylNC in CH2Cl2 affords a fifth structural isomer of the [Re2Cl3(μ-dppm)2(CO)(CNXyl)2] + cation; this is believed to have a CO-bridged structure of the type [(XylNC)ClRe(μ-Cl)(μ-CO)(μ-dppm)2ReCl(CNXyl)]+. The latter complex reacts with a further equivalent of XylNC in the presence of Tl+ to form the [Re2Cl2(μ-dppm)2(CO)(CNXyl)3]2+ cation, which has been shown by IR spectroscopy, and by the X-ray crystallographic characterization of its neutral congener Re2Cl2(μ-dppm)2(CO)(CNXyl)3, to contain a very weak and unsymmetrical CO bridge.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1022609214775
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 58
    Electronic Resource
    Electronic Resource
    Thermal latent coordination compounds (1997)
    Springer
    Journal of thermal analysis and calorimetry 50 (1997), S. 569-586 
    Details
    ISSN: 1572-8943
    Keywords: crystal structure ; metal(II) picolinate and quinaldinate ; thermal degradation of imidazole and pyrazole complexes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Complexes of the type M(Pa)2(HAz)2 and M(QA)2(HAz)2 (M=cobalt(II) and nickel(II); HPa=picolinic acid, HQa=quinaldic acid; HAz=azoles like imidazole (Him), pyrazole (HPz), benzimidazole (HBzIm) etc.) show a similar thermal behaviour. In the first step of decomposition the corresponding azolinium picolinates or quinaldinates (H2AzPa, H2AzQa) are split off with formation of polymeric mixed ligand complexes M(Pa)(Az) or M(Qa)(Az). X-ray analysis of Co(Qa)2(HBzIm)2 XIIIa illustrates a proton transfer and a subsequent thermal removal of benzimidazolinium quinaldinate (H2BzImQa): Hydrogen bridges from pyrrole nitrogen of the benzimidazole to the non-coordinated oxygen of the quinaldinate predetermine the thermal initiated proton transfer. The high volatility of the heterocyclic acids and the nitrogen coordination are responsible for the formation of the mixed ligand complex Co(Qa)(BzIm) XIVa. Exceptions are the complexes M(Pa)2(HPz)2 XIa-b and M(Qa)2(HIm)2 XVIIa-b. Pyrazole is eliminated from the complexes XIa-b with formation of the solvent-free inner complex M(Pa)2 XIIa-b. From compounds XVIIIa-b quinaldic acid or their decomposition products are split off and a high temperature modification of M(Im)2 XVIIIa-b is formed at elevated temperature. XVIIIa-b are decomposed to the cyanides M(CN)2 similarly to the thermal behaviour of Cu(Im). In the first step the thermal degradation of imidazole and pyrazole adducts of copper(II) picolinates and quinaldinates is characterized by the elimination of azoles. The reason for this thermal behaviour is the weaker coordination of the azole heterocycles in copper chelate compounds.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01979029
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 59
    Electronic Resource
    Electronic Resource
    Structures and tautomeric interconversions of anthraquinone imine derivatives (1997)
    Springer
    Structural chemistry 8 (1997), S. 197-204 
    Details
    ISSN: 1572-9001
    Keywords: Tautomerism ; anthraquinone ; crystal structure ; semiempirical computations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Substituted 1-hydroxy-9,10-anthraquinone-9-imines have been found to exhibit tautomeric interconversions between the 9,10- and 1,10-quinonoid forms in the solid state as well as in solution. Single-crystal X-ray crystallography was used to study the structures of 4-(N-acetyl-p-tolylamino)-9-amino-1,10-anthracenedione and 4-hydroxy-1-phenylamino-10-mesitylimino-9(10H)-anthracenone at ambient and low temperatures. The former compound gave crystals belonging to the monoclinic space group P2l/c and, at 295 K,a=9.684(2),b=16.371(3),c=12.097(2) å,Β=110.41(1)
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02263507
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 60
    Electronic Resource
    Electronic Resource
    Synthesis and structure of 5-methoxy-4-methylbenzopsoralen (1997)
    Springer
    Structural chemistry 8 (1997), S. 453-457 
    Details
    ISSN: 1572-9001
    Keywords: Benzopsoralen ; photochemotherapeutic agent ; crystal structure ; molecular mechanics ; AM1 theoretical calculations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract 5-Methoxy-4-methyl-2H-benzofuro[3,2-g]benzo-1-pyran-2-one was synthesized and its crystal structure was determined and compared with the optimal conformation arrived at by MM and AM1 theoretical calculations. The latter indicated that the tetracyclic skeleton is planar with total length (C2–C8) 9.23 å, and that the line joining the conters of the terminal-benzene and furan rings makes an angle of 30.5
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02311704
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 61
    Electronic Resource
    Electronic Resource
    The crystal and molecular structures of cellulose I and II (1997)
    Springer
    Glycoconjugate journal 14 (1997), S. 677-690 
    Details
    ISSN: 1573-4986
    Keywords: molecular dynamics ; crystal structure ; cellulose I and II
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The paper describes molecular dynamics (MD) simulations on the crystal structures of the Iβ and II phases of cellulose. Structural proposals for each of these were made in the 1970s on the basis of X-ray diffraction data. However, due to the limited resolution of these data some controversies remained and details on hydrogen bonding could not be directly obtained. In contrast to structure factor amplitudes in X-ray diffraction, energies, as obtained from MD simulations, are very sensitive to the positions of the hydroxyl hydrogen atoms. Therefore the latter technique is very suitable for obtaining such structural details. MD simulations of the Iβ phase clearly shows preference for one of the two possible models in which the chains are packed in a parallel orientation. Only the parallel-down mode (in the definition of Gardner and Blackwell (1974) J Biopolym 13: 1975-2001) presents a stable structure. The hydrogen bonding consists of two intramolecular hydrogen bonds parallel to the glycosidic linkage for both chains, and two intralayer hydrogen bonds. The layers are packed hydrophobically. All hydroxymethyl group are positioned in the tg conformation. For the cellulose II form it was found that, in contrast to what seemed to emerge from the X-ray fibre diffraction data, both independent chains had the gt conformation. This idea already existed because of elastic moduli calculations and 13C-solid state NMR data. Recently, the structure of cellotetraose was determined. There appear to be a striking similarity between the structure obtained from the MD simulations and this cellotetraose structure in terms of packing of the two independent molecules, the hydrogen bonding network and the conformations of the hydroxymethyl group, which were also gt for both molecules. The structure forms a 3D hydrogen bonded network, and the contribution from electrostatics to the packing is more pronounced than in case of the Iβ structure. In contrast to what is expected, in view of the irreversible transition of the cellulose I to II form, the energies of the Iβ form is found to be lower than that of II by 1 kcal mol-1 per cellobiose.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1018509231331
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 62
    Electronic Resource
    Electronic Resource
    The molecular complex of dibenz[a,c]anthracene and trinitrobenzene (1997)
    Springer
    Structural chemistry 8 (1997), S. 141-147 
    Details
    ISSN: 1572-9001
    Keywords: Dibenzanthracene ; trinitrobenzene complex ; trinitrobenzene complex ; π-complex ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The crystal structure of the complex between the polycyclic aromatic hydrocarbon di-benz[a,c]anthracene and 1,3,5-trinitrobenzene is reported. The crystals are triclinic, space group P¯1 with unit cell dimensionsa=7.277(2) å,b=11.237(6) å, andc=13.902(5) å,α= 104.13(4)
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02262849
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 63
    Electronic Resource
    Electronic Resource
    Large differences are observed between the crystal and solution quaternary structures of allosteric aspartate transcarbamylase in the R state (1997)
    New York, NY : Wiley-Blackwell
    Proteins: Structure, Function, and Genetics 27 (1997), S. 110-117 
    Details
    ISSN: 0887-3585
    Keywords: small-angle scattering ; x-rays ; allosteric enzymes ; crystal structure ; rigid body modeling ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Solution scattering curves evaluated from the crystal structures of the T and R states of the allosteric enzyme aspartate transcarbamylase from Escherichia coli were compared with the experimental x-ray scattering patterns. Whereas the scattering from the crystal structure of the T state agrees with the experiment, large deviations reflecting a significant difference between the quaternary structures in the crystal and in solution are observed for the R state. The experimental curve of the R state was fitted by rigid body movements of the subunits in the crystal R structure which displace the latter further away from the T structure along the reaction coordinates of the T→R transition observed in the crystals. Taking the crystal R structure as a reference, it was found that in solution the distance between the catalytic trimers along the threefold axis is 0.34 nm larger and the trimers are rotated by 11° in opposite directions around the same axis; each of the three regulatory dimers is rotated by 9° around the corresponding twofold axis and displaced by 0.14 nm away from the molecular center along this axis. Proteins 27:110-117 © 1997 Wiley-Liss, Inc.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 64
    Electronic Resource
    Electronic Resource
    Bactericidal antibody recognition of a PorA epitope of Neisseria meningitidis: Crystal structure of a Fab fragment in complex with a fluorescein-conjugated peptide (1997)
    New York, NY : Wiley-Blackwell
    Proteins: Structure, Function, and Genetics 29 (1997), S. 113-125 
    Details
    ISSN: 0887-3585
    Keywords: bactericidal antibody ; crystal structure ; Neisseria meningitidis ; peptide-fluorescein conjugate ; PorA outer membrane protein ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Class 1 outer membrane protein PorA of Neisseria meningitidis is a vaccine candidate against bacterial meningitis. Antibodies against PorA are able to induce complement-mediated bacterial killing and thereby play an important role in protection against meningococcal disease. Bactericidal antibodies are all directed against variable regions VR1 and VR2 of the PorA sequence, corresponding to loops 1 and 4 of a two-dimensional topology model of the porin with eight extracellular loops. We have determined the crystal structure to 2.6 Å resolution of the Fab fragment of bactericidal antibody MN12H2 against meningococcal PorA in complex with a linear fluorescein-conjugated peptide TKDTNNNL derived from the VR2 sequence of sero-subtype P1.7,16 (residues 180-187) from meningococcal strain H44/76. The peptide folds deeply into the binding cavity of the Fab molecule in a type I β-turn, with the minimal P1.16 epitope DTNNN virtually completely buried. The structure reveals H-bonds and van der Waals interactions with all minimal epitope residues and one essential salt bridge between Asp-182 of the peptide and His-31 of the MN12H2 light chain. The key components of the recognition of PorA epitope P1.16 by bactericidal antibody MN12H2 correspond well with available thermodynamic data from binding studies. Furthermore, they indicate the structural basis of an increased endemic incidence of infection by group B meningococci in England and Wales since 1981 associated with the occurrence of an Neisseria meningitidis escape mutant (strain MC58). The observed three-dimensional conformation of the peptide provides a rationale for the development of a synthetic peptide vaccine against meningococcal disease. Proteins 29:113-125, 1997. © 1997 Wiley-Liss, Inc.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 65
    Electronic Resource
    Electronic Resource
    Computational, pulse-radiolytic, and structural investigations of lysine-136 and its role in the electrostatic triad of human C u,Z n superoxide dismutase (1997)
    New York, NY : Wiley-Blackwell
    Proteins: Structure, Function, and Genetics 29 (1997), S. 103-112 
    Details
    ISSN: 0887-3585
    Keywords: Brownian dynamics ; molecular recognition ; site-directed mutagenesis ; facilitated diffusion ; crystal structure ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Key charged residues in Cu,Zn superoxide dismutase (Cu,Zn SOD) promote electrostatic steering of the superoxide substrate to the active site Cu ion, resulting in dismutation of superoxide to oxygen and hydrogen peroxide. Lys-136, along with the adjacent residues Glu-132 and Glu-133, forms a proposed electrostatic triad contributing to substrate recognition. Human Cu,Zn SODs with single-site replacements of Lys-136 by Arg, Ala, Gln, or Glu or with a triple-site substitution (Glu-132 and Glu-133 to Gln and Lys-136 to Ala) were made to test hypotheses regarding contributions of these residues to Cu,Zn SOD activity. The structural effects of these mutations were modeled computationally and validated by the X-ray crystallographic structure determination of Cu,Zn SOD having the Lys-136-to-Glu replacement. Brownian dynamics simulations and multiple-site titration calculations predicted mutant reaction rates as well as ionic strength and pH effects measured by pulse-radiolytic experiments. Lys-136-to-Glu charge reversal decreased dismutation activity 50% from 2.2 × 109 to 1.2 × 109 M-1 s-1 due to repulsion of negatively charged superoxide, whereas charge-neutralizing substitutions (Lys-136 to Gln or Ala) had a less dramatic influence. In contrast, the triple-mutant Cu,Zn SOD (all three charges in the electrostatic triad neutralized) surprisingly doubled the reaction rate compared with wild-type enzyme but introduced phosphate inhibition. Computational and experimental reaction rates decreased with increasing ionic strength in all of the Lys-136 mutants, with charge reversal having a more pronounced effect than charge neutralization, implying that local electrostatic effects still govern the dismutation rates. Multiple-site titration analysis showed that deprotonation events throughout the enzyme are likely responsible for the gradual decrease in SOD activity above pH 9.5 and predicted a pKa value of 11.7 for Lys-136. Overall, Lys-136 and Glu-132 make comparable contributions to substrate recognition but are less critical to enzyme function than Arg-143, which is both mechanistically and electrostatically essential. Thus, the sequence-conserved residues of this electrostatic triad are evidently important solely for their electrostatic properties, which maintain the high catalytic rate and turnover of Cu,Zn SOD while simultaneously providing specificity by selecting against binding by other anions. Proteins 29:103-112, 1997. © 1997 Wiley-Liss, Inc.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 66
    Electronic Resource
    Electronic Resource
    The crystal structure of 1,4-benzenedithiol by rietveld analysis and studies on the mechanism of solid-state addition polymerization of 1,4-benzenedithiol to 1,4-diethynylbenzene (1997)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 35 (1997), S. 1621-1625 
    Details
    ISSN: 0887-624X
    Keywords: 1,4-benzenedithiol ; 1,4-diethynylbenzene ; crystal structure ; solid-state polymerization ; layer structure ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The crystal structure of 1,4-benzenedithiol (BDT) was determined by the Rietveld method based on the calculation of the atomic coordinates of the BDT molecule using the Molecular Mechanics Program (MMP2). The refined crystal structure of BDT was monoclinic P21/c with dimensions, a = 7.795, b = 7.290, c = 5.955 Å, β = 92.16°, z = 2. The R factor of the refined structure was 0.038. Using above results, the mechanism of solid-state addition polymerization of BDT to 1,4-diethynylbenzene (DEB) was studied. Sublimed BDT piles up onto glass plate substrate and forms the layer structure along with the a axis. An inclination angle of the piled BDT column was 60° toward the substrate surface. DEB crystal structure was also monoclinic P21/c with a = 4.007, b = 6.018; c = 15.340 Å, β = 91.42°, z = 2. Sublimation of equimolar mixture of BDT and DEB gave a crystal having 1 : 1 composition, in which DEB column is situated between the columns of BDT. Relative arrangement of both monomers was suitable for the addition of —SH and —C=CH groups, since the distance between the two groups is 3.3 Å by CERIUS II calculation. Therefore, the addition polymerization of BDT to DEB easily proceeded by UV irradiation and the resulting polymer had a highly layer structure along with the a axis of BDT crystal. Tentatively estimated crystal structure of polymer obtained is monoclinic with a = 7.73, b = 7.30, c = 5.95 Å, β = 92.16°. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 1621-1625, 1997
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 67
    Electronic Resource
    Electronic Resource
    Crystal Structures of 1,3-Calix[4]-bis-crown-6·3CH3CN and 1,3-Calix[4]-bis-(benzo-crown-6)·3 CH3CN (1997)
    Springer
    Journal of inclusion phenomena and macrocyclic chemistry 27 (1997), S. 169-178 
    Details
    ISSN: 1573-1111
    Keywords: Bridged calix[4]arene ; ditopic receptor ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The crystal structures of a new solvate of the ditopic receptor 1,3-calix[4]-bis-crown-6, Bis-C6, and of 1,3-calix[4]-bis-(benzo-crown-6), Bis-benzoC6, are reported. Bis-C6.3 CH3CN (1) crystallizes in the monoclinic space group P21/n, a = 14.388(3), b = 26.947(8), c = 14.707(4) Å, β = 113.19(3)°, V = 5241(5) Å3, Z = 4. Refinement led to a final conventional R value of 0.092 for 2723 reflections. The structure of (1) differs from the previously reported structure of Bis-C6.4 CH3CN by the conformation of one crown either chain. Two acetonitrile molecules are in the close neighbourhood of the crown ether cavities. Bis-benzoC6.3 CH3CN (2) crystallizes in the monoclinic space group P21/c, a = 10.391(4), b = 17.264(11), c = 30.426(9) Å, β = 94.62(3)°, V = 5440(7) Å3, Z = 4. Refinement led to a final conventional R value of 0.106 for 2965 reflections. Two acetonitrile molecules are located near the crown ether cavities, as in (1). One of the crown ether conformations is the same as in the binuclear caesium complex of Bis-benzoC6, supporting the hypothesis of a preorganization of this ligand towards the complexation of this ion; the second crown ether chain is partially disordered.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1007990208036
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 68
    Electronic Resource
    Electronic Resource
    X-Ray Structure and Proton NMR Study of a Hexacoordinated Lithium Complex (1997)
    Springer
    Journal of inclusion phenomena and macrocyclic chemistry 28 (1997), S. 125-140 
    Details
    ISSN: 1573-1111
    Keywords: X-ray ; crystal structure ; Li-complex ; triamides ; 1H-NMR
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The structure of the lithium complex with1,3,5-tris[oxymethylene(N,N-dicyclohexyl)carboxyamido]cyclohexanehas been determined by the X-ray method.The compound is triclinic, space group P¯1,a = 15.623(3), b = 19.279(4),c = 19.295(4)Å α = 102.32(3), β = 92.45(3),γ = 105.67(3)0, V = 5436(2)Å3, Z = 4. Itscomposition is represented by the formulaC48H82N3O6LiI 0.5H2O. The lithium cationis encapsulated in a polar pseudo-cavity of six oxygen atoms of the ligandmolecule and displays a distorted trigonal prism coordination. The conformationof the ligand in the solid state complex has been compared with the conformationof the complex in solution determined by 1H-NMR measurements. Supplementary data relevant to this publication have been deposited with the British Library, No. SUP 82224 (21 pages).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1007955923966
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 69
    Electronic Resource
    Electronic Resource
    Inclusion Compounds of NaI with 13-Membered Azo- and Azoxycrown Ethers (1997)
    Springer
    Journal of inclusion phenomena and macrocyclic chemistry 28 (1997), S. 17-32 
    Details
    ISSN: 1573-1111
    Keywords: Azocrown ether ; azoxycrown ether ; sodium complexes ; crystal structure ; X-ray analysis ; conformation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Sodium iodide complexes of 13-membered azo-(I)and azoxycrown ethers (II) have been synthesized. Compound I[Na(L1 trans)2]⋅I⋅H2O is triclinic witha = 11.53(2), b = 15.74(2), c = 19.17(2) Å,α = 98.93(9), β = 105.51(9),γ = 89.20(9) deg.; Z = 4, space groupP1. Compound II [Na(L2)2]⋅I is orthorhombic witha = 12.451(2), b = 13.796(3), c = 18.667(4)Å; Z = 4, space group P212121. In bothcomplexes the cation is coordinated tochain oxygen atoms and to one nitrogen atom of the azoor azoxy unit. The ability of bothligands to form complexes in relation to thegeometry of the azo or azoxy subunit of themacrocycle is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1007929726695
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 70
    Electronic Resource
    Electronic Resource
    Polymorphism of Inclusion Complexes and Unsolvated Hosts. II. Structure of the β-Dimorph of the Host-Guest Complex of Dianilinegossypol with Ethylacetate (1997)
    Springer
    Journal of inclusion phenomena and macrocyclic chemistry 27 (1997), S. 105-112 
    Details
    ISSN: 1573-1111
    Keywords: β-Dimorph ; crystal structure ; dianilinegossypol ethylacetate 1 : 1 clathrate ; packing motifs
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Depending on crystallization conditions, dianilinegossypol and ethylacetate form low (ambient temperature, α-phase) and high temperature (t = 35°C, β-phase) clathrate modifications. The structure of the α-phase has been discussed earlier [1]. Crystals of the 1 : 1 β-phase complex, C42H40O6N2·C4O2H8, are monoclinic, space group P21/c, a = 11.362(6), b = 19.479(9), c = 19.085(9) Å, β = 103.21(4)°, V = 4112(3)Å3, Z = 4, R = 0.084 for 3210 observed reflections. In these complexes centrosymmetric dimers of dianilinegossypol molecules formed via O(5)—H···O(3) hydrogen bonds are associated into columns by a weak O(8)—H···O(7) H-bond. A difference in the structure of these two phases is in the packing mode of the columns. The angle formed by intersecting host columns is about 126° for the α-phase and 104° for the β-modification. Guest molecules are hydrogen bonded to the host molecules via an O(1)—H···O(10) bond and are accommodated in channels in α-phase complex and in cavities in β-phase complex.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1007908530132
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 71
    Electronic Resource
    Electronic Resource
    Crystal Structure of a Uranyl/p-tert-Butylcalix[5]arene Complex (1997)
    Springer
    Journal of inclusion phenomena and macrocyclic chemistry 27 (1997), S. 13-20 
    Details
    ISSN: 1573-1111
    Keywords: Uranyl complexes ; calixarenes ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The synthesis and crystal structure of the inclusion complex between uranyl and p-tert-butylcalix[5]arene are reported. [UO2 (p-tert-butylcalix[5]arene-4H]2- · $${\text{2HNE}}_{{\text{t}}_{\text{3}} }^{\text{ + }} $$ &·2MeOH(1) crystallizes in the monoclinic space group C2/c, a = 30.06(2), b = 18.20(3), c = 31.35(2) Å, β = 128.51(6)°, V = 13423(40) Å3, Z = 8. Refinement led to a final conventional R value of 0.043 for 4155 reflections. The uranyl ion is bonded, in its equatorial plane, to the five oxygen atoms of the calixarene, four of which are deprotonated. A protonated triethylamine molecule is located inside the calixarene cavity and hydrogen bonded to a uranyl oxygen atom, and another one outside and hydrogen bonded to a calixarene oxygen atom. The calixarene conformation is the usual cone one.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1007938218723
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 72
    Electronic Resource
    Electronic Resource
    Synthesis, Structure and Alkali Metal Ion Binding Properties of a Podand Polyether Derived from Calix[4]arene, 5,11,17,23-tetra-tert-butyl-25,27-di(phenylmethoxy)-26,28-di(2‘-methoxyethoxy)-calix[4]arene (1997)
    Springer
    Journal of inclusion phenomena and macrocyclic chemistry 27 (1997), S. 291-302 
    Details
    ISSN: 1573-1111
    Keywords: Calix[4]arene ; polyether ; crystal structure ; alkali metal ion binding
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The ligand 5,11,17,23-tetra-t-butyl-25,27-di(phenylmethoxy)-26,28-di(2-methoxy-ethoxy)calix[4]arene,designed as an analogue of some calixcrown speciesin order to evaluate possible origins of their selectivity in alkali metal ion binding, has been synthesised and structurally characterised by X-ray crystallography. The crystals are monoclinic, P21/n, a = 15.940(6), b = 19.388(5), c = 20.020(5) Å,β = 109.10(2) deg., Z = 4, conventional R on |F| being 0.073 for 3454 independent, ’observed‘ (I 〉 3σ(I)) reflections. 1H-NMR studies in 1:1 CD3CN/CDCl3solvent have shown that the ligand exerts a strong preference for the lighteralkali metal ions (Li+ and Na+) contrary to the binding behaviour of knowncalixcrowns. This may reflect interactions restricted to the lower rim donor atoms without concomitant interaction with the calixarene π-electrons, perhaps because the latter interactions are substituted by those with the benzyl group π-electrons.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1007981710765
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 73
    Electronic Resource
    Electronic Resource
    Polymorphism of Inclusion Complexes and Unsolvated Hosts. V. Crystal Structure of the α-Dimorph of the 1 : 2 Dianilinegossypol–DMSO Complex and a 1 : 1 : 1 Inclusion Complex Based on a Mixed Dianilinegossypol/1,4-Dioxane Host Matrix and 1,2-Dichloroethane Guest (1997)
    Springer
    Journal of inclusion phenomena and macrocyclic chemistry 29 (1997), S. 23-32 
    Details
    ISSN: 1573-1111
    Keywords: Dianilinegossypol ; crystal structure ; host–guest complexes ; H-bond ; α- and β-dimorphs
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Dianilinegossypol forms a 1 : 2 host-guest complex with DMSO:monoclinic, space group P21/n, a = 8.522(3), b = 18.034(4), c= 28.462(6) Å, β = 94.14(2)°, V = 4362Å3, Z = 4, D x = 1.26 g cm-3, T = 295 K.Final R value is 0.102 for 1793 observed reflections. A 1 : 1 : 1 adduct ofdianilinegossypol with 1,4-dioxane and 1,2-dichloroethane is found to beisostructural with the dianilinegossypol complex with DMSO: monoclinic,space group P21/n, a = 8.281(2), b = 19.245(3), c = 27.970(7)Å, β = 95.18°, V = 4439 Å3, Z = 4, D x =1.28 g cm-3, T = 295 K. Final R value is 0.114 for 2458observed reflections.The host molecules are associated by O(4)—H ...O(3) H-bonds toinfinite chains running in the direction of the c-axis The chains areincorporated into layers through 1,4-dioxane or DMSO molecules havingH-bonds with dianilinegossypol molecules. Another DMSO or 1,2-dichloroethanemolecule is included as a guest in the channels formed between the layers.At 60 °C a cryptate-type inclusion complex of dianilinegossypol isformed with DMSO or 1,4-dioxane. It is isostructural with the acetonecomplex reported in Part IV of the present series.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1007992116261
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 74
    Electronic Resource
    Electronic Resource
    p-tert-Butylcalix[5]arene: a New Synthetic Pathway and Crystal Structure of the N,N-Dimethylformamide Complex (1997)
    Springer
    Journal of inclusion phenomena and macrocyclic chemistry 29 (1997), S. 175-185 
    Details
    ISSN: 1573-1111
    Keywords: p-tert-Butylcalix[5]arene ; synthesis ; complexation ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The formation of p-tert-butylcalix[5]arene by the opening ofp-tert-butyldihomooxacalix [4]arene and the addition of a monomer has beenstudied. Various facets, including the effects of bases and the nature ofthe monomer added to the p-tert-butyldihomooxacalix[4]arene, have beeninvestigated. p-tert-Butylcalix[5]arene can be prepared in yields up to30%. The structure of its 1 : 2 complex with DMF has been determinedby X-ray crystallography. Crystals are triclinic, space group P¯1, a =1428.2(3) pm, b = 1837.3(3) pm, c = 1276.1(2) pm, α = 108.98(1)°,β = 105.02(2)°, γ = 95.21(1)°, Z = 2, D c = 1.059 kg m-3,final R value = 0.087. The macrocycle adopts a cone conformation, one guestenclosed inside the cavity, the other one outside.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1007907525620
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 75
    Electronic Resource
    Electronic Resource
    Synthesis of Two New Glycophanes Comprised of Thioglucose Molecules Linked by Hydrocarbons (1997)
    Springer
    Journal of inclusion phenomena and macrocyclic chemistry 29 (1997), S. 335-346 
    Details
    ISSN: 1573-1111
    Keywords: Glycophane ; macrocycle ; carbohydrate ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Preparation of two new glycophanes is reported. These compounds arecomprised of two glucose molecules linked by hydrocarbon units at the 1,1′ and 3, 3′ or 3, 3′ and 6, 6′ positions. Thecrystal structure of one of the glycophanes is also described.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1007952822709
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 76
    Electronic Resource
    Electronic Resource
    Synthesis, conformation, and biological activity of two fMLP-OMe analogues containing the new 2-[2′-(methylthio) ethyl] methionine residue (1997)
    New York : Wiley-Blackwell
    Biopolymers 42 (1997), S. 415-426 
    Details
    ISSN: 0006-3525
    Keywords: chemotaxis ; conformation ; crystal structure ; Cα-tetrasubstituted amino acids ; formylpeptides ; 2-[2′-(methylthio)ethyl]methionine ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The new Cα-tetrasubstituted α-amino acid residue 2-[2′-(methylthio) ethyl]methionine (Dmt) has been introduced into the reference chemotactic tripeptide HCO-Met-Leu-Phe-OMe (fMLP-OMe) in place of the leucine or methionine, respectively. The biological activity of the new analogues [Dmt2] fMLP-OMe (2) and [Dmt1] fMLP-OMe (3) has been determined; whereas 2 is active toward human neutrophils, stimulating directed migration, superoxide anion generation, and lysozyme release, 3 results practically inactive in all tested assays. A conformational analysis on 2 and 3 has been performed in solution by using ir absorption and 1H-nmr. The conformation of 2 was also examined in the crystal by x-ray diffraction methods. Both 2 and 3 adopt fully extended conformation in correspondence with the Dmt residue. Biological and conformational results are discussed and compared with related previously studied models. © 1997 John Wiley & Sons, Inc. Biopoly 42: 415-426, 1997
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 77
    Electronic Resource
    Electronic Resource
    Role of two consecutive α,β-dehydrophenylalanines in peptide structure: Crystal and molecular structure of Boc-Leu-ΔPhe-ΔPhe-Ala-Phe-NHMe (1997)
    New York : Wiley-Blackwell
    Biopolymers 42 (1997), S. 373-382 
    Details
    ISSN: 0006-3525
    Keywords: x-ray diffraction ; crystal structure ; dehydrophenylalanine ; constrained peptides ; 310-helix ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An Nα-protected model pentapeptide containing two consecutive ΔPhe residues, Boc-Leu-ΔPhe-ΔPhe-Ala-Phe-NHMe, has been synthesized by solution methods and fully characterized. 1H-nmr studies provided evidence for the occurrence of a significant population of a conformer having three consecutive, intramolecularly H-bonded β-bends in solution. The solid state structure has been determined by x-ray diffraction methods. The crystals grown from aqueous methanol are orthorhombic, space group P212121, a = 11.503(2), b = 16.554(2), c = 22.107(3) Å, V = 4209(1) Å,3 and Z = 4. The x-ray data were collected on a CAD4 diffractometer using CuKa radiation (λ = 1.5418 Å). The structure was determined using direct methods and refined by full-matrix least-squares procedure. The R factor is 5.3%. The molecule is characterized by a right handed 310-helical conformation (〈φ〉 = -68.2°, 〈ψ〉 = -26.3°), which is made up of two consecutive type III β-bends and one type I β-bend. In the solid state the helical molecules are aligned head-to-tail, thus forming long rod like structures. A comparison with other peptide structures containing consecutive ΔPhe residues is also provided. The present study confirms that the -ΔPhe-ΔPhe-sequence can be accommodated in helical structures. © 1997 John Wiley & Sons, Inc. Biopoly 42: 373-382, 1997
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 78
    Electronic Resource
    Electronic Resource
    RNA crystallography (1997)
    New York : Wiley-Blackwell
    Biopolymers 44 (1997), S. 3-21 
    Details
    ISSN: 0006-3525
    Keywords: RNA ; x-ray crystallography ; crystal structure ; transfer RNA ; ribozyme ; catalytic RNA ; internal loop ; review ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The current state of three-dimensional structure analysis of RNA by x-ray crystallograpy is summarized. The methods of sample preparation, crystallization, data collection, and structure solution are discussed, followed by a review of the RNA structures that have been determined and of common structural features, and finally, an appraisal of future prospects for x-ray crystal structure analysis of RNA. © 1997 John Wiley & Sons, Inc. Biopoly 44: 3-21, 1997
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 79
    Electronic Resource
    Electronic Resource
    Crystalline structure of poly(methyl-n-propylsilane) (1997)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 35 (1997), S. 1533-1543 
    Details
    ISSN: 0887-6266
    Keywords: polysilane ; lamellar microstructure ; crystal structure ; crystallization kinetics ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The thermal behavior and physical structure of atactic poly(methyl-n-propylsilane) (PMPrS) have been investigated by complementary techniques. Temperature-dependent wide-angle X-ray scattering as well as thermal analysis clearly indicate that atactic PMPrS crystallizes below 40°C in a monoclinic lattice with PMPrS adopting an all-trans planar zigzag conformation. Above 40°C, the polymer is in the isotropic amorphous state. A restricted analysis of the structure factors of PMPrS has been performed, indicating that the zigzag planes most probably lie in (110) planes. The chains pack with little interpenetration, and the crystals may be considered as bundles of long, closely packed prisms. The restricted interlocking of neighboring chains results, in turn, in a poor register of the chains along the c-axis. Moreover, transmission electron microscopy reveals that the crystallized polymer adopts a lamellar microstructure, with parallel lamellae tending to form tight bundles. Both electron microscopy and small-angle X-ray scattering indicate crystal thicknesses of about 60 Å. Finally, PMPrS was found to crystallize with a nucleation-controlled type of kinetics. Avrami exponents were calculated as n ≈ 1, suggesting a fibrillar growth geometry compatible with the absence of spherulitic superstructure. A double-melting behavior is also observed for PMPrS. © 1997 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 35: 1533-1543, 1997
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 80
    Electronic Resource
    Electronic Resource
    Electron diffraction and computer modeling of poly(naphthalic anhydride) crystal structure (1997)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 35 (1997), S. 1575-1588 
    Details
    ISSN: 0887-6266
    Keywords: poly(naphthalic anhydride) ; crystal structure ; electron diffraction ; confined thin film melt polymerization ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Single crystals of poly(naphthalic anhydride) (PNA) have been grown using our confined thin film melt polymerization technique. Lamellae, 70-100 Å thick, are found for the crystals polymerized at 180°C with thinner lamellae for a 200°C polymerization temperature. In addition, irregular lath-shaped crystals are found for both polymerization temperatures, apparently formed by a solid-state polymerization process within the original needle-like monomer crystals. The crystal structure of PNA has been studied by electron diffraction (ED) and computer modeling based on seven different zonal ED patterns. It is found that, in most cases, two or three different zonal patterns are superimposed with a common plane, suggesting variable chain tilting even in individual lamellae. Shearing of the material shortly after the initiation of polymerization, permitted obtaining an additional [010] zone ED pattern. A monoclinic unit cell with one chain, two repeat units is proposed based on measurements of 21 independent reflections; the space group is Pc11; a = 6.26 Å, b = 4.33 Å, c = 18.60 Å, and α = 122.5°. The computer-simulated (Cerius2) molecular conformation and chain packing are described with the corresponding simulated electron diffraction patterns being in good agreement with the observed ones. © 1997 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 35: 1575-1588, 1997
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 81
    Electronic Resource
    Electronic Resource
    Hexabromotricyclobutabenzene and Hexabromohexaradialene: Their Nickel-Mediated One-Pot Syntheses and Crystal Structure (1997)
    Weinheim : Wiley-Blackwell
    Chemistry - A European Journal 3 (1997), S. 208-210 
    Details
    ISSN: 0947-6539
    Keywords: crystal structure ; cyclobutenes ; nickel ; radialenes ; radical reactions ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reaction of hexakis(dibromomethyl)benzene with [(Bu3P)2-Ni(COD)] (COD = 1,5-cyclooctadiene) in DMF at 65-70°C yielded a mixture of the title compounds. The mixture was separated by column chromatography to yield hexabromotricyclobutabenzene (3 a) and hexabromohexaradialene (4) in 24 and 16% yields, respectively. 1H and 13C NMR spectroscopy suggest that 3 is obtained as the syn-all-trans isomer 3 a, and the symmetric anti-all-trans isomer 3 b is not obtained at all. The X-ray structures of 3 a and 4 are reported. The hexaradialene 4 has a chair conformation, and deviates from planarity by 43.6°. Heat or radical impurities cause the clean transformation of 3 a to 4.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chem.19970030207
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 82
    Electronic Resource
    Electronic Resource
    Two New Closely Related MoV Hydroxymonophosphates Built Up of Cd[Mo6P4O25(OH)6]2 And Cd[Mo6P4O26(OH)5]2 ClustersDedicated to Professor H. G. von Schnering on the occasion of his retirement (1997)
    Weinheim : Wiley-Blackwell
    Chemistry - A European Journal 3 (1997), S. 1797-1800 
    Details
    ISSN: 0947-6539
    Keywords: cadmium ; crystal structure ; hydrothermal synthesis ; hydroxyphosphate ; molybdenum ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Two new molybdenum(v) hydroxyphosphates have been synthesized hydrothermally, Na2Cd3(Mo2O4OH)6-(PO4)2(PO3OH)6[N(CH3)4]4·10H20 (1) and Cd9(Mo2O4OH)12(PO4)6(PO3OH)10-[N(CH3)4]8·15H2O (2). Their structures have been determined from single-crystal X-ray diffraction. The water molecules and hydroxyl groups have been deduced from valence calculations. Both compounds crystallize in the triclinic space group P1, with the cell parameters for 1 a = 12.340(2), b = 12.596(1), c = 14.717(2) Å, α = 107.24(1)°, β = 89.83(1)°, γ = 114.31(1)°, V = 1972.3(4) Å3, and for 2 a = 11.942(1), b = 13.339(2), c = 26.765(3) Å, α = 85.33(1)°, β = 86.87(1)°, γ = 64.08(1)°, V = 3821.3(9) Å3. The two frameworks can be described on the basis of similar [Mo6P4X31]n- (X = O, OH) anionic clusters, but 1 is a tridimensional structure, whereas 2 exhibits a monodimensional structure.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chem.19970031111
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 83
    Electronic Resource
    Electronic Resource
    Morphology, crystal structure, and orientation of poly-p-oxybenzoate on mica (1997)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 35 (1997), S. 1807-1820 
    Details
    ISSN: 0887-6266
    Keywords: poly(p-oxybenzoate) ; confined thin film melt polymerization ; epitaxy ; mica substrate ; morphology ; crystal structure ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Polymerization of p-acetoxybenzoic acid between mica sheets, from both the melt and dilute solution, in a wide range of polymerization temperatures (180-400°C) yields an epitaxial-like overgrowth of PpOBA on the mica cleavage surface. The PpOBA overgrowth forms long rows by lateral aggregation of ribbon crystals situated in three substrate directions rotated by 60°. The c-axes of the PpOBA phase I and II lattices are parallel to the 001 plane of the mica, coinciding with the a-axes of the mica hexagonal structure. The aI- and bII-axes lie predominantly on the mica surface. The surface-orienting effect is tentatively attributed to surface steps and or/polar effects; lattice matching does not occur. The recrystallization of bulk polymer samples previously prepared also leads to ordering between mica like that in melt or solution polymerization. © 1997 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 35: 1807-1820, 1997
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 84
    Electronic Resource
    Electronic Resource
    Structural transformation of ultra-high modulus and molecular weight polyethylene fibers by high-temperature wide-angle X-ray diffraction (1997)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 35 (1997), S. 623-630 
    Details
    ISSN: 0887-6266
    Keywords: ultra-high modulus and molecular weight polyethylene fibers (UHM-WPE) ; high-temperature wide-angle x-ray diffraction (HTWAXD) ; crystal structure ; orthorhombic/monoclinic/pseudohexagonal transformation ; annealing and thermal behavior ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Wide-angle x-ray diffraction (WAXD) of the ultra-high modulus and molecular weight polyethylene (UHMWPE) fibers at room temperature shows a predominantly orthorhombic structure with trace amount of nonorthorhombic crystals and very low amorphous contents. The calculated unit cell dimensions a and b of the orthorhombic crystals are 7.36 (±0.04) Å, and 4.89 (±0.04) Å, respectively. The apparent crystallite sizes perpendicular to the orthorhombic 110 and 200 reflection planes are 169.8 and 143.4 Å, respectively. The crystallite size perpendicular to the nonorthorhombic 010 reflection is 149.4 Å. The crystal density is calculated to be 1.02 g/cc. With increasing temperature, the thermal expansion coefficient in the a direction is much higher than that in the b direction which explains the structural transformation from the orthorhombic crystals to a pseudohexagonal form. Tension along the fiber axis while being heated during the high-temperature x-ray diffraction (HTWAXD) scanning has shown enhanced structural transformation from the orthorhombic form to the monoclinic form. Structural transformation from the orthorhombic form to the pseudohexagonal phase is not observed on the UHMWPE fibers under axial tension or annealing conditions in HTWAXD. © 1997 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys, 35: 623-630, 1997
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 85
    Electronic Resource
    Electronic Resource
    A study of the dilation of the unit cell of metallocene isotactic poly(propylenes): The monoclinic form (1997)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 35 (1997), S. 2511-2521 
    Details
    ISSN: 0887-6266
    Keywords: isotactic poly(propylenes) ; unit-cell density ; crystal structure ; unit-cell parameters ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The lattice parameters of a series of monoclinic metallocene poly(propylenes) of constant molecular weight are measured as a function of defect content, that vary between 0.3 and 2.35 total defects per 100 monomeric units. The parameters are also measured as a function of molecular weight for a fixed defect content and as a function of the crystallization temperature. The b axis is found to increase with decreasing isothermal crystallization temperature whereas only small changes are found for samples rapidly crystallized. The a and c axis showed basically no variation with crystallization temperature. The parameters of the unit cell were essentially constant with varying defect content in the poly(propylene) chain. Lack of observed effect on the dilation of the unit cell by increasing defects is a consequence of the rapid crystallization required to ensure formation of monoclinic crystals. The unit cell parameters increased as a mild function of the molecular weight. © 1997 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 35: 2511-2521, 1997
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 86
    Electronic Resource
    Electronic Resource
    Crystal structure of the bovine α-chymotrypsin:kunitz inhibitor complex. An example of multiple protein:protein recognition sitesThis paper is dedicated to Professor A. Ballio on the occasion of his 75th birthday. (1997)
    Chicester [u.a.] : Wiley-Blackwell
    Journal of Molecular Recognition 10 (1997), S. 26-35 
    Details
    ISSN: 0952-3499
    Keywords: bovine α-chymotrypsin ; bovine basic pancreatic trypsin inhibitor (Kunitz-type inhibitor) ; serine proteinase:Kunitz inhibitor complex ; crystal structure ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The crystal structure of bovine α-chymotrypsin (α-CHT) in complex with the bovine basic pancreatic trypsin inhibitor (BPTI) has been solved and refined at 2.8 Å resolution (R-factor=0.18). The proteinase:inhibitor complex forms a compact dimer (two α-CHT and two BPTI molecules), which may be stabilized by surface-bound sulphate ions, in the crystalline state. Each BPTI molecule, at opposite ends, is contacting both proteinase molecules in the dimer, through the reactive site loop and through residues next to the inhibitor's C-terminal region. Specific recognition between α-CHT and BPTI occurs at the (re)active site interface according to structural rules inferred from the analysis of homologous serine proteinase:inhibitor complexes. Lys15, the P1 residue of BPTI, however, does not occupy the α-CHT S1 specificity pocket, being hydrogen bonded to backbone atoms of the enzyme surface residues Gly216 and Ser217. © 1997 John Wiley & Sons, Ltd.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 87
    Electronic Resource
    Electronic Resource
    Metal-Template Electrophilic Substitution on Phenols: Synthesis and Crystal Structure of Bromomagnesium Phenolate and Its Reactive Complex with para-IsopropylbenzaldehydeDedicated to the memory of Professor Giuseppe Casnati on the 4th anniversary of his death (1997)
    Weinheim : Wiley-Blackwell
    Chemistry - A European Journal 3 (1997), S. 1269-1272 
    Details
    ISSN: 0947-6539
    Keywords: crystal structure ; electrophilic aromatic substitutions ; magnesium ; regioselectivity ; template synthesis ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The crystal structures of the bromomagnesium phenolate 5 and its complex 7 with para-isopropylbenzaldehyde are reported; for the first time it has been possible to demonstrate that the reactive complex 7, responsible for the complete ortho-regioselective control in the alkylation of phenoxymagnesium bromides with aldehydes, is not obtained by simple replacement of the ethereal ligand but by expansion of the metal coordination sphere from 4 (usual tetrahedral configuration) to 5. We infer from 1H NMR studies that the magnesium coordination of complex 7 in solution is analogous to that shown in the solid state, with a complexed ethereal molecule.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chem.19970030814
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 88
    Electronic Resource
    Electronic Resource
    Synthesis of Pyrazinoporphyrazine Derivatives Functionalised with Tetrathiafulvalene (TTF) Units: X-Ray Crystal Structures of Two Related ttf Cyclophanes and Two Bis(1,3-Dithiole-2-Thione) IntermediatesDedicated to Professor Fabian Gerson on the occasion of his retirement (1997)
    Weinheim : Wiley-Blackwell
    Chemistry - A European Journal 3 (1997), S. 1679-1690 
    Details
    ISSN: 0947-6539
    Keywords: crystal structure ; cyclophanes ; electrochemistry ; porphyrazines ; tetrathiafulvalenes ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The pyrazinoporphyrazine system 13 (metal-free, zinc and copper derivatives) has been synthesised by tetramerisation of 2,3-dicyanopyrazine monomer unit 10. The structure of 13a-c has been established by 1H NMR spectroscopy, UV/Vis spectrophotometry, MALDI-TOF mass spectrometry, cyclic voltammetry and differential pulse voltammetry. The electrochemical redox behaviour of 13a-c is strongly solvent dependent. The expected two-stage oxidation of the tetrathiafulvalene (TTF) units of 13a-c was observed in a range of solvents; in addition, oxidation and reduction of the pyrazinoporphyrazine core of the metal-free derivative 13a was detected in benzonitrile. On excitation of 13 in the Q-band region no fluorescence was observed, which is presumably the consequence of intramolecular charge transfer between the TTF moieties and the excited state of the central porphyrazine. Molecular modelling studies on 13a and 13c are reported. During the course of this work, the novel TTF macrocycles 11 and 20 were synthesised; their X-ray crystal structures reveal severely bent TTF units, the conformations of which are discussed in detail. The X-ray crystal structures of the bis(1,3-dithiole) systems 15 and 18 have also been determined.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chem.19970031018
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 89
    Electronic Resource
    Electronic Resource
    The Unusual Properties of 5-Methyl-4,5,6,7-Tetrahydro-1H-Indazole in the Solid State (1997)
    Weinheim : Wiley-Blackwell
    Chemistry - A European Journal 3 (1997), S. 121-126 
    Details
    ISSN: 0947-6539
    Keywords: crystal structure ; NMR spectroscopy ; proton transfer ; pyrazoles ; tautomerism ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The crystal structure of the title compound was determined by X-ray analysis at 200 K. Three independent molecules form a trimer joined by strong and linear N-H … N hydrogen bonds. There is another centrosymmetrically related trimer in the unit cell. Both tautomers (1H and 2H) are present in each trimer. Disorder of the NH protons involved in the N-H … N hydrogen bonds has been observed. Solid-state 13C CPMAS NMR was used to establish the dynamic nature of the NH-proton disorder, the title compound being the first example of proton transfer in a tautomeric mixture of pyrazoles with an equilibrium constant other than 1.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chem.19970030119
    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 von Bis(1,2-dimethyl-5-nitro-imidazol)dichlorocobalt(II) (1997)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 623 (1997), S. 1201-1202 
    Details
    ISSN: 0044-2313
    Keywords: Cobalt(II) complex ; 1,2-dimethyl-5-nitro-imidazole ligand ; crystal structure ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis and Crystal Structure of Bis(1,2-dimetyl-5-nitro-imidazole)dichlorocobalt(II)Bis(1,2-dimethyl-5-nitro-imidazol)dichlorocobalt(II) was obtained by reaction of CoCl2 · 6 H2O with 1,2-dimethyl-5-nitro-imidazole in methanol. The compound forms blue crystals which were characterized by IR and UV-vis spectroscopy and by an X-ray crystal structure determination. Co(C5H7N3O2)2Cl2: tetragonal, space group I42d, Z = 8, a = 1142.1(1) pm, c = 2577.3(2) pm. R = 0.036 for 670 independent reflexions. The Co atom is tetrahedrally surrounded by two chlorine and two N atoms at distances of 222.8(2) and 203.5(4) pm.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19976230802
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 91
    Electronic Resource
    Electronic Resource
    Tetraammin-Lithium-Kationen zur Stabilisierung phenylsubstituierter Zintl-Anionen: Die Verbindung [Li(NH3)4]2[Sn2Ph4] (1997)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 623 (1997), S. 1503-1505 
    Details
    ISSN: 0044-2313
    Keywords: Ditetraammine lithium tetraphenyldistannide ; synthesis ; single-crystals ; crystal structure ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Tetraammine Lithium Cations Stabilizing Phenylsubstituted Zintl-Anions: The Compound [Li(NH3)4]2[Sn2Ph4]Ruby-red, brittle single crystals of [Li(NH3)4]2[Sn2Ph4] were synthesized by the reaction of diphenyltin dichloride and metallic lithium in liquid ammonia at -35°C. The structure was determined from X-ray singlecrystal diffractometer data: Space group, P1, Z = 1, a = 9.462(2) Å, b = 9.727(2) Å, c = 11.232(2) Å, α = 66.22(3)°, β = 85.78(3)°, γ = 61.83(3)°, R1 (F02 ≥ 4σF02) = 5.13%, wR2 (F02 ≥ 4σF02) = 10.5%, N(F02 ≥ 4σF02) = 779, N(Var.) = 163.The compound contains to Sb2Ph4 isosteric centres [Sn2Ph4]2- as anions which are connected to rods by lithium cations in distorted tetrahedral coordination by ammonia. These rods are arranged parallel to one another in the b,c-plane, but stacked along [100].
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19976231006
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 92
    Electronic Resource
    Electronic Resource
    Bi13Pt3I7: Ein Subiodid mit einer pseudosymmetrischen Schichtstruktur (1997)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 623 (1997), S. 1535-1541 
    Details
    ISSN: 0044-2313
    Keywords: Bismuth platinum iodide ; subhalide ; crystal structure ; pseudo-symmetry ; stacking faults ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Bi13Pt3I7: A Subiodide with a Pseudo-Symmetric Layer StructureThe reaction of PtI2 with Bi and BiI at 630 K yields black, lustrous, air insensitive crystals of the subiodide Bi13Pt3I7. The layered crystal structure (triclinic, C1, a = 1581.0(2) pm, b = 912.6(1) pm, c = 2149.6(6) pm, α = 90.03(2)°, β = 96.96(2)°, γ = 90.11(1)°, V = 3078.6 · 106 pm3) contains edge-sharing [PtBi8/2] cubes, which form nets of Kagomé type. Iodine atoms fill the hexagonal-prismatic voids therein. These ∞2[(PtBi8/2)3I] layers are alternately separated by layers of iodine atoms or ∞1[BiI4-] zigzag-chains. The marked pseudo-symmetry of the structure favours stacking faults, which cause streaks of diffuse scattering in the diffraction pattern.
    Notes: Aus der Reaktion von PtI2 mit Bi und BiI bei 630 K erhält man schwarze, metallisch glänzende und luftbeständige Kristalle des Subiodids Bi13Pt3I7. In der schichtartig aufgebauten Kristallstruktur (triklin, C1, a = 1581,0(2) pm, b = 912,6(1) pm, c = 2149,6(6) pm, α = 90,03(2)°, β = 96,96(2)°, γ = 90,11(1)°, V = 3078,6 · 106 pm3) liegen Kagomé-Netze aus kantenverknüpften [PtBi8/2]-Würfeln vor, deren hexagonal-prismatische Lücken mit Iodatomen gefüllt sind. Diese ∞2[(PtBi8/2)3I]-Schichten sind abwechselnd durch eine Lage von Iodatomen oder eine Schicht aus parallel angeordneten ∞1[BiI4-]-Zickzackketten getrennt. Die in der Struktur stark ausgeprägte Pseudosymmetrie begünstigt Stapelfehler, welche sich auch in diffusen Streifen im Beugungsbild äußern.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19976231011
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 93
    Electronic Resource
    Electronic Resource
    Zur Kristallstruktur von CaZn2(OH)6 · 2 H2O (1997)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 623 (1997), S. 1287-1289 
    Details
    ISSN: 0044-2313
    Keywords: Calcium hexahydroxodizincate dihydrate ; synthesis ; crystal structure ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Crystal Structure of CaZn2(OH)6 · 2 H2OThe electrochemical oxidation of zinc in a zinc/iron-pair leads in an aqueous NH3 solution of calciumhydroxide at room temperature to colourless crystals of CaZn2(OH)6 · 2 H2O. The X-ray structure determination was now successful including all hydrogen positions.P21/c, Z = 2, a = 6.372(1) Å, b = 10.940(2) Å, c = 5.749(2) Å, β = 101.94(2)° N(F2o ≥ 3σF2o) = 809, N(Var.) = 69, R/RW = 0.011/0.012The compound CaZn2(OH)6 · 2H2O contains Zn2+ in tetrahedral coordination by OH- and Ca2+ in octahedral coordination by four OH- and two H2O. The tetrahedra around Zn2+ form corner sharing chains, three-dimensionally linked by isolated polyhedra around Ca2+. Weak hydrogen bridge bonds result between H2O as donor and OH-.
    Notes: Die elektrochemische Oxidation von Zink in einem Zink/Eisen-Paar führt in einer wäßrigen NH3-Lösung von Calciumhydroxid bei Raumtemperatur zu farblosen Kristallen von CaZn2(OH)6 · 2 H2O. An ihnen wurde röntgenographisch die Struktur jetzt einschließlich aller H-Lagen bestimmt.P21/c, Z = 2, a = 6,372(1) Å, b = 10,940(2) Å, c = 5,749(2) Å, β = 101,94(2)° Z(F2o ≥ 3σF2o) = 809, Z(Var.) = 69, R/RW = 0,011/0,012In CaZn2(OH)6 · 2 H2O ist Zn2+ tetraedrisch von OH- und Ca2+ oktaedrisch von vier OH- und zwei H2O umgeben. Die Tetraeder um Zn2+ bilden Ketten über gemeinsame Ecken, die durch voneinander isolierten Oktaedern um Ca2+ dreidimensional verknüpft werden. Es liegen schwache H-Brückenbindungen von H2O als Donator zu OH- vor.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19976230819
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 94
    Electronic Resource
    Electronic Resource
    Pseudoelementverbindungen. XI. [1] Untersuchungen zum Komplexbildungsverhalten von Cyanamidonitrat [NO2NCN]-Professor Wolfgang Beck zum 65. Geburtstag gewidmet (1997)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 623 (1997), S. 1299-1305 
    Details
    ISSN: 0044-2313
    Keywords: Pseudoelement compounds ; cyanamidonitrate ; copper(I) ; silver(I) ; platinum(II) ; crystal structure ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Pseudoelement Compounds. XI. [1] Investigations on the Coordination Behaviour of Cyanamidonitrate [NO2NCN]-With the ionic, potentially ambidentate ligand cyanamidonitrate complexes of the types [MX(PPh3)3], [MX(PPh3)2]2 (M=CuI, AgI) and trans-[Pt(H)X(PPh3)2] (X-=[NO2NCN]-) are introduced. The new compounds are characterized by 1H NMR, 31P NMR, and IR spectroscopy. The crystal structures of [Cu(NO2NCN)(PPh3)2]2 and [Ag(NO2NCN)(PPh3)2]2 are reported. In the complexes [MX(PPh3)3] and trans-[Pt(H)X(PPh3)2] cyanamidonitrate is unidentately coordinated through the nitrile group end-on. In the dimeric complexes [MX(PPh3)2]2 the anion acts bidentately as a bridging ligand. Surprisingly, both coordinative bonds are formed through nitrogen atoms of the NCN group.
    Notes: Es werden mit dem ionischen, potentiell ambidenten Liganden Cyanamidonitrat Komplexe der Typen [MX(PPh3)3], [MX(PPh3)2]2 (M=CuI, AgI) sowie trans-[Pt(H)X(PPh3)2] (X-=[NO2NCN]-) vorgestellt. Die Verbindungen wurden 1H-NMR-, 31P-NMR- und IR-spektroskopisch charakterisiert. Für [Cu(NO2NCN)(PPh3)2]2 und [Ag(NO2NCN)(PPh3)2]2 liegen Kristallstrukturanalysen vor.Cyanamidonitrat wird in den Komplexen [MX(PPh3)3] und trans-[Pt(H)X(PPh3)2] einzähnig über das endständige N-Atom der Nitrilgruppe koordiniert. In den dimeren Komplexen [MX(PPh3)2]2 liegt das Anion als zweizähniger Brükkenligand vor. Überraschend werden beide koordinativen Bindungen über die Stickstoffatome der NCN-Gruppe ausgebildet.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19976230821
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 95
    Electronic Resource
    Electronic Resource
    Kristallstruktur der Tieftemperaturmodifikation von RuTe2 (1997)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 623 (1997), S. 1657-1660 
    Details
    ISSN: 0044-2313
    Keywords: Ruthenium ; chalcogenide ; chemical transport ; crystal structure ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Crystal Structure of the Low Temperature Modification of RuTe2Black shining, platelet like single crystals of α-RuTe2 were obtained by chemical transport reaction with Cl2/AlCl3 (crystal dimensions up to 1 mm). The crystal structure of this low temperature modification of α-RuTe2 hitherto only known from powder measurements, was redetermined at room temperature by single crystal X-ray diffraction on a four-circle diffractometer. α-RuTe2 crystallizes in the marcasit structure typ in the orthorhombic spacegroup Pnnm (No. 58) with the lattice constants a = 528.12(13), b = 639.43(19), c = 400.85(13) pm.
    Notes: Durch chemischen Transport mit dem Transportmittel Cl2/AlCl3 konnten schwarzglänzende, plattenartige Einkristalle von α-RuTe2 erhalten werden (Kantenlänge bis zu 1 mm). Die Kristallstruktur dieser bisher nur aus Pulverdaten bekannten Tieftemperaturmodifikation von RuTe2 wurde röntgenographisch an einem Einkristall auf einem Vierkreisdiffraktometer bei Raumtemperatur neu bestimmt. α-RuTe2 kristallisiert im Markasit-Strukturtyp in der orthorhombischen Raumgruppe Pnnm (Nr. 58) mit den Gitterkonstanten a = 528,12(13), b = 639,43(19), c = 400,85(13) pm.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19976231029
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 96
    Electronic Resource
    Electronic Resource
    Mesityloxomolybdän- und -wolfram-Verbindungen. I. Die Struktur von LiMoO2Me2Mes(OEt2)2 (1997)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 623 (1997), S. 1661-1664 
    Details
    ISSN: 0044-2313
    Keywords: Organo molybdenum compounds ; oxo complexes ; crystal structure ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Mesityl Oxo Molybdenum and Tungsten Compounds. I. Structure of LiMoO2Me2Mes(OEt2)2LiMoO2Me2Mes(OEt2)2 2 is prepared by literature method [2] from MoO2Mes2 1 and LiMe. Its x-ray structure and NMR-spectral data are presented. 2 adopts a dimer structure in which two [MoO2Me2Mes]- anions are linked via two bridging [Li(OEt2)2]+ cations bonded to the oxo ligands. The resulting [‥OMoOLi‥]2 ring is planar.
    Notes: Die Struktur der bekannten, aus MoO2Mes2 1 und LiMe dargestellten Verbindung LiMoO2Me2Mes(OEt2)2 2 [2] sowie ihre NMR-spektroskopischen Daten werden mitgeteilt. 2 bildet ein in der Raumgruppe P1 kristallisierendes Dimer durch Verknüpfung zweier [MoO2Me2Mes]--Anionen über Oxo-Liganden durch zwei Kationen [Li(OEt2)2]+. Der gebildete [‥OMoOLi‥]2- Achtring ist eben.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19976231030
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 97
    Electronic Resource
    Electronic Resource
    Die 3-(N,N-Dimethylamino)prop-1-enyl-Gruppe als Chelatligand in Organoindium-Verbindungen (1997)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 623 (1997), S. 1679-1683 
    Details
    ISSN: 0044-2313
    Keywords: Organoindium compounds ; chelate complexes ; crystal structure ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: The 3-(N,N-Dimethylamino)prop-1-enyl Group as a Chelate Ligand in Indium OrganylsInBr3 reacts with Me2NCH2CH=CHMgCl (molar ratio 1 : 2) to form (Me2NCH2CH=CH)2InBr (1) as the first indium alkenyl compound with amino-functionalized alkenyl groups. The X-ray structure determination shows the formation of a chelate complex. 1 crystallizes in the orthorhombic space group Fddd with the unit cell parameters a = 14.904(2) Å, b = 17.140(1) Å and c = 21.035(2) Å. By reaction of Me2InBr with Me2NCH2CH=CHMgCl (molar ratio 1 : 1) (Me2NCH2CH=CH)InMe2 (2) is formed as a colorless, at room temperature liquid, monomeric compound. The n.m.r. and mass spectra are discussed.
    Notes: InBr3 reagiert mit Me2NCH2CH=CHMgCl (Molverhältnis 1 : 2) in Diethylether als Lösungsmittel zu (Me2NCH2CH=CH)2InBr (1), der ersten Indium-Alkenylverbindung mit aminofunktionalisierten Alkenylresten. Die Röntgenkristallstrukturanalyse zeigt das Vorliegen eines Chelatkomplexes an. 1 kristallisiert orthorhombisch in der Raumgruppe Fddd mit Z = 16, a = 14,904(2) Å, b = 17,1405(14) Å und c = 21,035(2) Å. Aus Me2InBr und Me2NCH2CH=CHMgCl (Molverhältnis 1 : 1) wurde (Me2NCH2CH=CH)InMe2 (2) als farblose, bei Raumtemperatur flüssige, monomere Verbindung erhalten. Die 1H- und 13C-NMR-Spektren sowie Massenspektren werden mitgeteilt.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19976231033
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 98
    Electronic Resource
    Electronic Resource
    Contributions on thermal behaviour and crystal chemistry of anhydrous phosphates. XIX. Tri-chromium(II)-bis-phosphate Cr3(PO4)2 (≙ Cr6(PO4)4) - A transition metal(II)-orthophosphate with new structure type (1997)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 623 (1997), S. 1672-1678 
    Details
    ISSN: 0044-2313
    Keywords: Chromium(II)-orthophosphate ; crystal growth ; crystal structure ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Beiträge zum thermischen Verhalten und zur Kristallchemie von wasserfreien Phosphaten. XIX. Tri-chrom(II)-bis-phosphat Cr3(PO4)2 (≙ Cr6(PO4)4) - Ein Übergangsmetall(II)- Orthophosphat mit neuem StrukturtypIntensiv blau-violette Kristalle des bislang unbekannten Tri-chrom(II)-bis-phosphats, Cr3(PO4)2, entstehen bei der Reduktion von CrPO4 mit Chrom oberhalb von 1050°C (evakuierte Quarzglasampullen, wenige mg NH4I oder I2 als Mineralisator). Die Kristallstruktur von Cr3(PO4)2 enthält sechs kristallographisch unabhängige Cr2+ in der Elementarzelle (P212121, Z = 8, a = 8,4849(10) Å, b = 10,3317(10) Å, c = 14,206(3) Å). Davon sind fünf in der ersten Koordinationssphäre von vier Sauerstoffatomen leicht verzerrt quadratisch-planar umgeben (1,96 Å ≤ d(Cr—O) ≤ 2.15 Å). Deren Koordination wird vervollständigt durch zwei bzw. drei weiter entfernte Sauerstoffatome (2,32 Å ≤ d(Cr—O) ≤ 3,21 Å). Das sechste Cr2+-Ion ist stark verzerrt oktaedrisch koordiniert (d(Cr—O): 1,97, 2,04, 2,15, 2,28, 2,29, 2,53 Å).Die vier kristallographisch unterschiedlichen [PO4]-Gruppen zeigen nur geringe Abweichungen von der Geometric eines idealen Tetraeders (1,51 Å ≤ d(P—O) ≤ 1,57 Å; 104,3° ≤ ∠(O—P—O) ≤ 114,4°).Für die Cr2+ wurde mit μexp = 4,28(2) μB (θP = -54,8(5) K) ein ungewöhnlich niedriges mittleres magnetische Moment gefunden.
    Notes: Deep blue-violet single crystals of hitherto unknown chromous orthophosphate have been obtained reducing CrPO4 by elemental Cr at temperatures above 1050°C in evacuated silica ampoules (NH4I or I2 as mineraliser). The complex structure of Cr3(PO4)2 (P212121, Z = 8, a = 8.4849(10) Å, b = 10.3317(10) Å, c = 14.206(2) Å) contains six crystallographically independent Cr2+ per unit cell. Five of them are coordinated by four oxygen atoms which form a distorted (roof shaped) square plane as first coordination sphere at interatomic distances 1.96 Å ≤ d(Cr—O) ≤ 2.15 Å. Their coordination is completed by additional oxygen atoms (2 or 3) at distances 2.32 Å ≤ d(Cr—O) ≤ 3.21 Å. The sixth Cr2+ shows six-fold octahedral coordination with strong radial distortion (d(Cr—O): 1.97, 2.04, 2.15, 2.28, 2.29, 2.53 Å).The four different [PO4] groups exhibit only minor deviations from ideal tetrahedral geometry (1.51 Å ≤ d(P—O) ≤ 1.57 Å, 104.3° ≤ ∠(O—P—O) ≤ 114.4°).An unusually low magnetic moment μexp = 4.28(2) μB (θP = -54.8(5) K) has been observed for Cr2+.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19976231032
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 99
    Electronic Resource
    Electronic Resource
    Über den Einfluß von Temperatur, Druck und Substitution auf die Kristallstruktur von ARh2P2 (A = Ca, Sr, Eu, Ba)Professor Welf Bronger zum 65. Geburtstag gewidmet (1997)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 623 (1997), S. 1418-1424 
    Details
    ISSN: 0044-2313
    Keywords: Ternary Rhodium phosphides ; crystal structure ; phase transition ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: About the Effect of Temperature, Pressure, and Substitution on the Crystal Structure of ARh2P2 (A = Ca, Sr, Eu, Ba)Four compounds ARh2P2 (A = Ca, Sr, Eu, Ba) were prepared by heating mixtures of the elements and investigated by means of single crystal X-ray methods. They crystallize in the ThCr2Si2 type structure (I4/mmm; Z = 2) with P—P distances along [001] reaching from 2.26 Å (CaRh2P2) to 3.74 Å (BaRh2P2). With increasing temperature (EuRh2P2) or increasing pressure (SrRh2P2) a first order phase transition occurs with strong changes of the P—P distances. Substitution of the atoms changes the bond lengths of the compounds too.
    Notes: Vier Verbindungen ARh2P2 (A = Ca, Sr, Eu, Ba) wurden durch Erhitzen entsprechender Elementgemenge dargestellt und hinsichtlich ihrer Kristallstruktur mit Hilfe von Einkristallmethoden charakterisiert. Sie kristallisieren in der tetragonalen ThCr2Si2-Struktur (I4/mmm; Z = 2) und unterscheiden sich im wesentlichen durch ihre P—P-Abstände längs [001]. Diese reichen von 2,26 Å bei CaRh2P2 bis 3,74 Å bei BaRh2P2 und verändern sich drastisch im Zuge von Phasenumwandlungen 1. Ordnung durch Temperaturerhöhung bei EuRh2P2 sowie unter erhöhtem Druck bei SrRh2P2. Substitution übt ebenfalls einen großen Einfluß auf den Strukturfeinbau der Verbindungen aus.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19976230917
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 100
    Electronic Resource
    Electronic Resource
    Zur Kristallstruktur von Tb2Se3 (1997)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 623 (1997), S. 1744-1746 
    Details
    ISSN: 0044-2313
    Keywords: Terbium sesquiselenide ; chemical transport ; crystal structure ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Crystal Structure of Tb2Se3Single crystals of Tb2Se3 could be prepared by chemical transport reaction with AlCl3. By starting from TbSe1.9 and terbium metal black needles of Tb2Se3 in the U2S3 type structure with the space group Pnma and a = 1113,0(1) pm, b = 402,4(1) pm and c = 1095,1(3) pm were obtained.
    Notes: Einkristalle von Tb2Se3 konnten durch chemischen Transport mit AlCl3 dargestellt werden. Ausgehend von pulverförmigem TbSe1,9 und Terbiummetall wurden schwarze, nadelförmige Einkristalle von Tb2Se3 im U2S3-Strukturtyp mit der Raumgruppe Pnma und a = 1113,0(1) pm, b = 402,4(1) pm und c = 1095,1(3) pm erhalten.
    Additional Material: 5 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19976231113
    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...