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  • 1
    Electronic Resource
    Electronic Resource
    The crystal and molecular structure of N-(methylsulfonyl)-N-(2,6)-(dimethylphenyl)methanesulfonamide (1994)
    Springer
    Journal of chemical crystallography 24 (1994), S. 759-762 
    Details
    ISSN: 1572-8854
    Keywords: Sulfonamide ; methanesulfonanilide ; crystal structure ; molecular structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The title compound, crystallizes in the triclinic space group $$P\bar 1$$ witha=8.232(4),b=9.159(2),c=10.230(3)Å. α=74.07(3)°, β=72.50(4)°, γ=63.65(3)° andZ=2. The structure was solved by direct methods and refined by full matrix least squares methods toR=0.054 for 1817 observed reflections. The plane containing the nitrogen and sulfur atoms is perpendicular to the aromatic plane. One of the S−O bonds in each methanesulfonyl group is in nearly eclipsed conformation with the N−C bond.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01666966
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  • 2
    Electronic Resource
    Electronic Resource
    The crystal structure of calcium succinate monohydrate (1994)
    Springer
    Journal of chemical crystallography 24 (1994), S. 437-440 
    Details
    ISSN: 1572-8854
    Keywords: Ca(C4H4O4)·H2O ; pentagonal pyramid ; calcium succinate ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The crystal structure of calcium succinate monohydrate, Ca(C4H4O4)·H2O, has been determined by single crystal X-ray diffraction. The crystals are monoclinic witha=11.952(2),b=9.691(2),c=11.606(2)Å, β=108.81(1)°, space group C2/c,Z=8,V=1272.49 Å3,d m =1.80, andd c =1.818 Mg m−3. The structure was refined by full-matrix least-squares techniques toR=0.027,R w =0.040, for 829 reflections with1≥3δ(I). Ca is coordinated to seven oxygen atoms, and the coordination polyhedron is best described as a pentagonal bipyramid. One carboxylate group in the succinate ion is bonded to three different Ca ions, forming a four-membered chelate ring with one Ca ion is bonded to three different Ca ions, forming a four-membered chelate ring with one Ca ion and unidentate bridge bonds to two other Ca ions. The other carboxylate group is bonded to two Ca ions through unidentate bonds. The structure is highly polymeric. The general structural features are nearly identical to those of calcium adipate monohydrate.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01666091
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  • 3
    Electronic Resource
    Electronic Resource
    The W2Cl4(NHCMe3)2(PR 3)2 molecules (R 3=Me3, Et3, Pr n 3, Me2Ph) I. Their isomeric forms, interconversion proeesses, crystalline forms, and detailed molecular structures (1994)
    Springer
    Journal of cluster science 5 (1994), S. 11-36 
    Details
    ISSN: 1572-8862
    Keywords: Tungsten ; isomeric forms ; crystal structure ; triple bonds ; interconversion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract A thorough study of compounds with the formula W2Cl4(NHCMe3)2(PR3)2, withR 3=Me3, Et3, Prg n 3 Me2,Ph, is reported. In addition to the previously reported crystalline compounds, namely Ia,trans-W2Cl4(NHCMe3)2(PMe3)2 in space group Pmmn;3a,trans-W2Cl4(NHCM3)2(PEt3)2 in space group P21/a (or P21/c); and4,cis-W2Cl4(NHCMe3)2(PMe2Ph)2 in Pna21, we have obtained and structurally characterized the following new substances,1b,trans-W2Cl4,(NHCMe3)2(PMe2)2, space group P21/c,a= 12.233 (4) Å,b= 12.872 (4) Å,c=17.095 (5) Å,β=93.52 (2)°,Z=4,V=2687 (1) Å3 2,cis-W2Cl4(NHCMe3)2(PMe3)2, P21/c,a=9.673 (4) Å,b=17.249 (4) Å,c=16.244 (5) Å,β=99.63 (3),Z = 4 ,V=2669 (1) Å.3b,trans-W2Cl4(NHCMe3)2(PEt3)2, Pl,a=16.850 (3) Å,b=17.797 (3) Å,c= 11.459 (2)Å,α= 101.02 (1),β= 103.13°, y=84.23 (1)°,Z=4,V= 3279 (1) Å5,trans-W2Cl4(NHCM3)2(PMe2Ph)2, Fdd2,a=39.563 (8) Å at 20°C; 39.325 (10) Å at -6O°C,b = 57.543 (17) Å at 20°C; 57.186 (16) Å at -60°C,c= 8.810 (1) Å at 20°C; 8.770 (1) Å at - 60°C ,Z=24,V=20057 (7) Å3 (20°C), 19723 (8) Å3 ( - 60°C) .6,trans-W2Cl4(NHCMe3 2(PPrn 3)2, Pl,a= 17.287 (2) Å (20°C); 17.077 (5) Å (-60°C),b= 19.119 (2) Å (20°C); 18.952 (6) Å (-60°C),c= 12.713 (1) Å (20°C); 12.668 (4) Å (-60°C),Z=4,V= 3980 (1) Å3 (20°C), 3898 (2) ,Å3 ( - 60°C). In addition, the structure of3a was re-determined and refined so that the disorder ratio was a refined parameter, leading to a value of 0.520:0.480 instead of being arbitrarily fixed at 0.50:0.50. In all of the structures the molecules are held in eclipsed (but very distorted) rotational conformations and the W-W distances are all within the range of 2.305-2.330 Å. As will be shown in a later paper, for all phosphines, thecis andtrans isomers are of similar stability and an equilibrium mixture exists in solution. It is also shown that1a and3a do not contain unexpectedly short W-N bonds as previously reported.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01165490
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  • 4
    Electronic Resource
    Electronic Resource
    A new platinum-osmium alkyne complex from the reaction of Pt2Os4(CO)18 with PhC ≡ CPh: The synthesis, characterization, and crystal structure of Pt2Os4(CO)8 (μ3-PhC2Ph)3(μ4-PhC2Ph) (1994)
    Springer
    Journal of cluster science 5 (1994), S. 317-326 
    Details
    ISSN: 1572-8862
    Keywords: Mixed metal cluster ; alkyne ; diphenylacetylene ; platinum ; osmium ; 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 new platinum-osmium alkyne cluster complex Pt2Os4(CO)8(μ3-PhC2Ph)3 (μ 4-PhC2Ph),2, was obtained from the reaction of Pt2Os4(CO)18,1b, with PhC2Ph and was characterized by IR.1H NMR and single-crystal X-ray diffraction analyses. The cluster of compound2 consists of an osmium capped Pt2Os3 square pyramid. It aLso contains three triply bridging and one quadruply bridging diphenylacetylene ligands. Crystal data for2: space group PI,a = 12.530(2) Å,b = 21.565(4) Å,c = 11.284(2) Å,α = 100.31(2),β = 111.89(1),β = 76.78(2),Z = 2, 3879 reflections,R = 0.032.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01170715
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  • 5
    Electronic Resource
    Electronic Resource
    Synthesis, structure and IR characterization of disodium tetra(9,10-dihydro-9-oxo-10-acridineacetato)zincate(II) bis(ethanol) heptahydrate (1994)
    Springer
    Journal of chemical crystallography 24 (1994), S. 731-737 
    Details
    ISSN: 1572-8854
    Keywords: Synthesis ; crystal structure ; IR data
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The synthesis, crystal structure and IR data are reported for Na2[Zn(CMA)4]·2EtOH·7H2O, where CMA− is the 9,10-dihydro-9-oxo-10-acridinacetate ion. The complex crystallizes in the monoclinic space group P2/n, with cell dimensionsa=17.335(9),b=8.440(5),c=21.875(12) Å, β=91.94(5)°,Z=2. The structure was solved by direct methods and refined to a finalR value of 0.0363 for 3022 non-zero reflections. The Zn2+ ion occupies twofold axis and is coordinated to four carboxylate ligands, the ZnO4 tetrahedron is considerably distorted with Zn−O distances of 1.978(3) and 1.961(3)Å. Each Na+ cation interacts with two water, one ethanol, and three carboxylate O atoms comprising distorted octahedron. The Zn2+ and Na+ cations are linked through monooxygen and syn-syn carboxylate bridges forming a trinuclear, mixed-metal cluster. The Zn...Na separation is 3.267(2)Å and Na...Na distance equals 3.520(2)Å. All oxygen bonded H-atoms are utilized in hydrogen bonds. The acridone rings overlap in the crystal with the 3.5 Å interlayer separations. The compound has been characterized by IR spectroscopy.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01666961
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  • 6
    Electronic Resource
    Electronic Resource
    Synthesis, characterization, and crystal structure of 1,3,7,9-tetramethylpyrido-[2,3-d∶6,5-d′]-dipyrimidine-2,4,6,8-tetrone (1994)
    Springer
    Journal of chemical crystallography 24 (1994), S. 465-468 
    Details
    ISSN: 1572-8854
    Keywords: Pyrimidine ; uracil ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract A new and easy method for the preparation of 1,3,7,9-tetramethylpyrido-[2,3-d∶6,5-d′]-dipyrimidine-2,4,6,8-tetrone is described. The structure of this compound has been solved by means of X-ray diffraction methods. The chemical characterization by spectral (mass, ultraviolet, infrared, and proton nuclear magnetic resonance) and thermal (thermogravimetry and differential scanning calorimetry) method is also reported. The compound is monoclinic, space groupP21/c,a=12.720(5),b=13.688(7),c=8.079(2) Å, β=107.06(4)°,Z=4. The structure consists of discrete tricyclic molecules, stacking playing an important role in crystal packing.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01666096
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  • 7
    Electronic Resource
    Electronic Resource
    Crystal structure oftrans-carbonylchlorobis-(tricyclohexylphosphine)iridium(I),trans-Ir(CO)Cl-[P(cyclo-C6H11)3]2, a disordered species (1994)
    Springer
    Journal of chemical crystallography 24 (1994), S. 557-560 
    Details
    ISSN: 1572-8854
    Keywords: Centrosymmetric ; symmetry ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The title compound crystallizes in the centrosymmetric triclinic space group $$P\bar 1$$ (C 1 l ; No.2) witha=9.9143(10) Å,b=10.2616(11) Å,c=10.7715(10) Å, α=113.887(8)°, β=109.197(8)°, γ=90.699(9)°,V=932.78(17) Å3 andZ=1. A total of 4869 data were collected and merged to a set of 2450 independent reflections; the structure was solved and refined toR=1.42% andwR=1.94%. The molecule lies on a site of $$\bar 1$$ symmetry and is disordered, with obvious scrambling of carbonyl and chloride ligands. Resulting bond lengths include Ir−P=2.339(1) Å, Ir−Cl=2.398(4) Å and Ir−CO=1.808(15) Å.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01666737
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  • 8
    Electronic Resource
    Electronic Resource
    The synthesis and structural analysis of the new high nuclearity platinum-ruthenium cluster complex Pt2Ru8(CO)18(μ3−EtC2Et)2(μ4−EtC2Et) containing three alkyne ligands (1994)
    Springer
    Journal of cluster science 5 (1994), S. 551-564 
    Details
    ISSN: 1572-8862
    Keywords: Mixed metal ; platinum ; ruthenium ; alkyne ; 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: Abstarct The ten metal cluster complex Pt2Ru8(CO)23(µ3−H)2, 1 was found to react with EtC2Et to form a new ten metal tris-alkyne complex Pt2Ru8(CO)18(µ3−EtC2Et)2 (µ4−EtC2Et),2 in 35% yield. Complex 2 was characterized by IR,1H NMR , and single crystalx-ray diffraction analyses. The cluster can be viewed as a dodecahedron of eight metal atoms capped with two ruthenium carbonyl groups, two triply bridging EtC2Et ligands and one quadruply bridging EtC2Et ligand. Application of the standard electron counting procedures indicate that this is an unusual complex in which the 18 electron rule applies and the polyhedral skeletal electron pair theory does not. Crystal Data for 2 2.0.5 CH2CI2: space group = P21,a = 12.759(2) A,b=18.438(2)Å,c = 20.197(3) Å,β = 91.59(1)°, Z. = 4, 6394 reflections,R = 0.037.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01171385
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  • 9
    Electronic Resource
    Electronic Resource
    Studies of crystalline native celluloses using potential energy calculations (1994)
    Springer
    Cellulose 1 (1994), S. 161-168 
    Details
    ISSN: 1572-882X
    Keywords: cellulose I ; molecular mechanics ; crystal structure ; molecular ; modelling
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Energies for various trial packing arrangements of unit cells for the Iα and Iβ phases of native cellulose discovered by Sugiyamaet al. were evaluated. Both a rigid-ring method, PLMR, and the full-optimization, molecular mechanics program, MM3(90), were used. For both phases the models that had the lowest PLMR energy also had the lowest MM3 energy. Both calculated models have the chains packed ‘up’, O6s intg positions, and the same sheets of hydrogen-bonded chains. The Iβ structure model is essentially identical to that proposed previously for ramie cellulose by Woodcock and Sarko. It is also the same as the best parallel model previously proposed that was based on the X-ray data of Mann, Gonzalez and Wellard, once the various unit cell conventions are considered. Also, the energies from both methods for all three celluloses, Iα, Iβ and II, are in the order that rationalizes their relative stabilites.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00819665
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  • 10
    Electronic Resource
    Electronic Resource
    Age-related changes in the haematology of young koalas (Phascolarctos cinereus) up to one year old (1994)
    Springer
    Comparative clinical pathology 4 (1994), S. 146-151 
    Details
    ISSN: 1433-2981
    Keywords: Biochemistry ; Development ; Haematology ; Koala
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Haematology and biochemistry of captive pouch young and back young koalas from 165 days to one year old were studied. Distinct changes with age were observed. Packed cell volume, haemoglobin, erythrocyte count, MCV and total plasma protein where lowest in the youngest animals less than 180 days old. Reticulocytes were highest in this age group. Haematological values differed from those of adult animals. Lymphocytosis occurred, especially between 210–330 days of age. Intense erythropoiesis was indicated by reticulocytosis and the presence of erythrocyte granular inclusions, anisocytosis and poikilocytosis on blood films, particularly up to 330 days of age. Microcytosis present on blood films throughout the study period could not be explained by iron deficiency.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00798355
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  • 11
    Electronic Resource
    Electronic Resource
    Superconductivity in the tetragonal phase of La1.9Bi0.1CuO4+δ annealed under high oxygen pressure (1994)
    Springer
    Journal of superconductivity 7 (1994), S. 37-38 
    Details
    ISSN: 1572-9605
    Keywords: High-Tc superconductivity ; La1.9Bi0.1CuO4+δ ; excess oxygen ; crystal structure ; superconducting transition temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract We have investigated the relation between the crystal structure and superconductivity in La1.9Bi0.1CuO4+δ , in which the phase separation observed in La2CuO4+δ is suppressed. A phase diagram in theT−δ plane is given for La1.9Bi0.1CuO4+δ with excess oxygen. For very smallδ values, the crystal structure is orthorhombic, and an orthorhombic-tetragonal phase transition occurs markedly atδ ∼ 0.03 in the measured temperature range between 13 and 293 K. Superconductivity is observed in the range of 0.04〈δ〈0.11. This is clear evidence thathigh-T c superconductivity also appears in the tetragonal phase.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00730364
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  • 12
    Electronic Resource
    Electronic Resource
    Problems in the low-temperature synthesis of 92K Superconducting YBCO (1994)
    Springer
    Il nuovo cimento della Società Italiana di Fisica 16 (1994), S. 1671-1678 
    Details
    ISSN: 0392-6737
    Keywords: Effects of material synthesis ; crystal structure ; chemical composition ; Y-based compounds ; Conference proceedings
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Summary YBCO with high granulometric perfection and low dispersion can be obtained by a low-temperature reaction (≈800°C) of atomic-scale dispersed powders, produced through the thermal decomposition of liquid precursors. As reacted such powders are tetragonal and not superconducting, but they transform into the high-T c phase after optimized annealing treatments. We describe the method we developed and the characteristics of the materials we achieved, and we discuss the main features of the process in the light of the current know-how.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02462158
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  • 13
    Electronic Resource
    Electronic Resource
    Survey on the pharmacodynamics of the new antipsychotic risperidone (1994)
    Springer
    Psychopharmacology 114 (1994), S. 9-23 
    Details
    ISSN: 1432-2072
    Keywords: Risperidone ; Antipsychotics ; 5-HT2 antagonism ; D2 antagonism ; Pharmacology ; Receptor binding ; Biochemistry ; Review
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract This review reports on the pharmacodynamics of the new antipsychotic risperidone. The primary action of risperidone is serotonin 5-HT2 receptor blockade as shown by displacement of radioligand binding (Ki: 0.16 nM), activity on isolated tissues (EC50:0.5 nM), and antagonism of peripherally (ED50: 0.0011 mg/kg) and centrally (ED50:0.014 mg/kg) acting 5-HT2 receptor agonists in rats. Risperidone is at least as potent as the specific 5-HT2 receptor antagonist ritanserin in these tests. Risperidone is also a potent dopamine D2 receptor antagonist as indicated by displacement of radioligand binding (Ki: 1.4 nM), activity in isolated striatal slices (IC50: 0.89 nM), and antagonism of peripherally (ED50: 0.0057 mg/kg in dogs) and centrally acting D2 receptor agonists (ED50: 0.056–0.15 mg/kg in rats). Risperidone shows all effects common to D2 antagonists, including enhancement of prolactin release. However, some central effects such as catalepsy and blockade of motor activity occur at high doses only. Risperidone is 4–10 times less potent than haloperidol as a central D2 antagonist in rats and it differs from haloperidol by the following characteristics: predominant 5-HT2 antagonism; LSD antagonism; effects on sleep; smooth dose-response curves for D2 antagonism; synergism of combined 5-HT2/D2 antagonism; pronounced effects on amphetamine-induced oxygen consumption; increased social interaction; and pronounced effects on dopamine (DA) turnover. Risperidone displays similar activity at pre- and postsynaptic D2 receptors and at D2 receptors from various rat brain regions. The binding affinity for D4 and D3 receptors is 5 and 9 times weaker, respectively, than for D2 receptors; interaction with D1 receptors occurs only at very high concentrations. The pharmacological profile of risperidone includes interaction with histamine H1 and α-adrenergic receptors but the compound is devoid of significant interaction with cholinergic and a variety of other types of receptors. Risperidone has excellent oral activity, a rapid onset, and a 24-h duration of action. Its major metabolite, 9-hydroxyrisperidone, closely mimics risperidone in pharmacodynamics. Risperidone can be characterized as a potent D2 antagonist with predominant 5HT2 antagonistic activity and optimal pharmacokinetic properties.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02245439
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  • 14
    Electronic Resource
    Electronic Resource
    Muscle phosphoglycerate mutase (PGAM) deficiency in the first Caucasian patient: biochemistry, muscle culture and31P-MR spectroscopy (1994)
    Springer
    Journal of neurology 241 (1994), S. 289-294 
    Details
    ISSN: 1432-1459
    Keywords: PGAM deficiency ; Myopathy ; Biochemistry ; Muscle culture ; 31P-MR spectroscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Muscle phosphoglycerate mutase (PGAM) deficiency has been so far identified in only six patients, five of these being African Americans. We report the results of clinical, morphological, biochemical, muscle culture and31P-MR spectroscopy studies in the first Caucasian patient with muscle PGAM deficiency. A 23-year-old man had a 10-year history of cramps after physical exertion with one episode of pigmenturia. Neurological examination and EMG study were normal. ECG and echocardiography revealed hypertrophy of the interventricular septum and slight dilatation of the left chambers of the heart. Muscle biopsy revealed increased glycogen content and some accumulation of mitochondria. Muscle PGAM activity was markedly decreased (6.5% and 9.7% of control value in two different biopsies). Citrate synthase and other mitochondrial respiratory chain enzyme activities were much higher than normal. In contrast to the marked decrease of PGAM activity observed in muscle biopsy, total enzyme activity in the patient's aneural muscle culture was normal, being represented exclusively by BB isoenzyme. The deficiency of PGAM-MM isoenzyme was reproduced in the patient's innervated muscle culture. Muscle31P-MR spectroscopy showed accumulation of phosphomonoesters only on fast “glycolytic” exercise. On “aerobic” exercise, Vmax, calculated from the work-energy cost transfer function, showed an increase consistent with the morphological and biochemical evidence of mitochondrial proliferation. This might represent a sort of compensatory aerobic effort in an attempt to restore muscle power.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00868435
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  • 15
    Electronic Resource
    Electronic Resource
    Preparation and characterization of some metal(II) complexes of isocinchomeronic acid and X-ray crystal structure ofcis-diaquabis(hydrogen isocinchomeronato)manganese(II) (1994)
    Springer
    Structural chemistry 5 (1994), S. 165-170 
    Details
    ISSN: 1572-9001
    Keywords: Isocinchomeronic acid ; 2,5-pyridinedicarboxylic acid ; hydrogen isocinchomeronate ; manganese(II) complex ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The reactions between Mn(II), Co(II), Ni(II), and Zn(II) ions with isocinchomeronic acid (H2-isocin) afforded complexes of the general formula M(H-isocin)2-2H2O, whereas Fe(II) gives both red and deep red-brown products of the same formula. Various physical measurements suggest that the complexes of M = Co, Ni, Zn, and Fe (brown) are octahedrally coordinated by two aqua ligands and twotrans-N,O-bidentate H-isocin− anions with dimeric hydrogen bonding. Those for M = Mn and Fe (red) are the correspondingcis isomers. The structure of the manganese complex as determined by X-ray crystallography exhibitsC 2 molecular symmetry with Mn-N = 2.279(2), Mn-O(H-isocin)− = 2.196(2), and Mn-O(aqua) = 2.137(2) Å. Each aqua ligand forms two donor O-H ⋯ O hydrogen bonds with carboxy groups of different molecules in adjacent chains.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02262837
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  • 16
    Electronic Resource
    Electronic Resource
    Tris(pyrazol-1-yl)-s-triazine (TPT): X-ray crystallographic, computational, and gas-phase electron diffraction studies (1994)
    Springer
    Structural chemistry 5 (1994), S. 255-264 
    Details
    ISSN: 1572-9001
    Keywords: tris(pyrazol-1-yl)-s-triazine ; crystal structure ; electron diffraction ; AM1 semiempirical calculation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The conformation of the TPT molecule has been analyzed using experimental and computational techniques. The solid-state molecular structure shows similar conformational features to those in the 2-pyrimidine and phenyl derivatives although a different pattern of bond angles in the triazine ring was observed. The AM1 calculations predicted two conformations of comparable stability (ΔE=1.8 kcal/mol) differing in the orientation of one pyrazole ring. While the minimum energy conformation corresponds to a model displayingC 3h symmetry (φ 1=φ 2=φ 3=0°), the other minimum (φ 1=φ 2=0°,φ 3=180°) is close to that observed in the solid state. The electron diffraction results are consistent with a planar or nearly planar conformation in agreement with the preceding studies.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02275498
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  • 17
    Electronic Resource
    Electronic Resource
    Structure of TiO2 in TiO2-SiO2 prepared by a complexing agent-assisted sol-gel procedure (1994)
    Springer
    Journal of sol gel science and technology 1 (1994), S. 113-121 
    Details
    ISSN: 1573-4846
    Keywords: crystal structure ; complexing agent ; TiO2 ; TiO2-SiO2
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Many types of TiO2-SiO2 (Ti:Si=50:50 mol%) were prepared by the sol-gel procedure with and without 2-methyl-2, 4-pentanediol (MPD) as an organic ligand. The effect of MPD on the gel structure and the properties of the TiO2 crystals were studied by XRD and raman spectroscopy, and the effect of the sol standing time on the properties of the TiO2 crystals were also studied by XRD spectroscopy. In the gels with MPD, anatase of TiO2 appeared at approximately 580°C, and the crystal structures were similar despite the difference in the gel preparation procedure. The titania gels with MPD were presumed to be dispersed in the silica gel matrix without any Ti-O-Si bond. In the presence of MPD, the formation of titania gels is controlled and the specified TiO2 crystal is produced.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00490241
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  • 18
    Electronic Resource
    Electronic Resource
    A complex of buckminsterfullerene with sulfur, C60·2S8: synthesis and crystal structure (1994)
    Springer
    Russian chemical bulletin 43 (1994), S. 240-244 
    Details
    ISSN: 1573-9171
    Keywords: C60·2S8 ; fullerene complexes ; synthesis ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The C60·2S8 complex was prepared by reaction of buckminsterfullerene C60 with sulfur in trichloroethylene and its single-crystal X-ray structure was studied at room temperature. Crystals of this compound are monoclinic, space groupC 2/c, a=20.90(1),b=21.10(1),c=10.537(9) Å, β=111.29(7)°,Z=4,d calc=1.89 g·cm−3. The crystal structure of the C60·2S8 complex consists of packed fullerene molecules that form hexagonal channels along thec axis with eight-membered crown-shaped S8 cyclic molecules inside the channels. The distances between the centers of neighboring fullerene molecules are 10.036(7), 10.636(7), and 10.537(9) Å. Each C60 molecule is linked to eight S8 molecules with ten shortened intermolecular contacts C...S 3.41(1)–3.52(2) Å. The average values of the C=C and C-C bond lengths are 1.32(3) and 1.47(3) Å, which attest to a significant degree of localization of electron density in the c60 molecule.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00695818
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  • 19
    Electronic Resource
    Electronic Resource
    Effects of Configuration Around the Chiral Carbon Atoms on the Crystal Properties of Ephedrinium and Pseudoephedrinium Salicylates (1994)
    Springer
    Pharmaceutical research 11 (1994), S. 1549-1556 
    Details
    ISSN: 1573-904X
    Keywords: ephedrine ; pseudoephedrine ; salicylate ; chirality ; salt formation ; homochiral crystal ; racemic compound ; racemic conglomerate ; crystal structure ; conformation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The physicochemical properties and crystal structures of the crystalline salts formed by the interaction of an achiral anion, salicylate, with homochiral and racemic ephedrinium and pseudoephedrinium cations were determined. The interaction of ephedrinium or pseudoephedrinium with salicylate in aqueous solution yielded crystalline salts with the notable exception of homochiral ephedrinium. Evaporation of the solvent from solutions of homochiral ephedrine and salicyclic acid in various organic solvents, as well as grinding together solid homochiral ephedrine and solid salicylic acid, yielded viscous semisolids suggesting that homochiral ephedrinium salicylate has a low melting point and/or a high aqueous solubility. Mixing of the two viscous solids, obtained by grinding each of the opposite enantiomers of ephedrine with equimolar salicylic acid, resulted in the formation of racemic ephedrine and subsequently, upon heating, in the formation of racemic ephedrinium salicylate. While racemic ephedrinium salicylate exists as a crystalline compound (P21/n space group) with an equal number of opposite enantiomers in the unit cell, its diastereomer, racemic pseudoephedrinium salicylate, exists as a conglomerate, i.e. a physical mixture, of the homochiral crystals of the opposite enantiomers (each P21 space group). The inability of homochiral ephedrinium to exist as a crystalline salicylate salt at 20–25°C is attributed to its high energy conformation and/or to the poor packing of homochiral ephedrinium salicylate molecules in the crystal lattice.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1018945401484
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  • 20
    Electronic Resource
    Electronic Resource
    Dicyclohexylamides as ionophores for li-selective electrodes. Crystal structures of a triamide ligand and its complex with lithium ion (1994)
    Springer
    Journal of inclusion phenomena and macrocyclic chemistry 20 (1994), S. 53-71 
    Details
    ISSN: 1573-1111
    Keywords: Lithium ionophores ; podand ; dicyclohexylamides ; Li-complex ; crystal structure ; X-ray analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The influence of structure and lipophilicity of dicyclohexylamides on the lithium selectivity in membrane electrodes is discussed. The crystal structures of the triamide podand1 and its complex with LiBr1b has been determined by X-ray analysis. Crystal data for ligand1: C48H83O6N3, triclinic,P1,a=10.749(2),b=12.097(3),c=19.123(6)Å, α=95.76(2),β=80.06(2), γ=100.27(2)0,V=2403(1) Ã3,Z=2. Crystal data for the lithium complex1b: C48H83O6N3·LiBr·x C2H5OH, monoclinic,P2 1/c,a=21.297(6),b=16.316(8),c=19.450(4) Å,β=110.87(2)0,V=6315(3) Å3,Z=4. In the complex the ligand adopts a conformation in which oxygen binding sites surrounding the Li+ cation form a slightly distorted trigonal prism.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00707612
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  • 21
    Electronic Resource
    Electronic Resource
    Cold adaption of enzymes: Structural comparison between salmon and bovine trypsins (1994)
    New York, NY : Wiley-Blackwell
    Proteins: Structure, Function, and Genetics 20 (1994), S. 149-166 
    Details
    ISSN: 0887-3585
    Keywords: crystal structure ; cold adaption ; catalytic efficiency ; protein stability ; anionic ; ectotherm ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The crystal structure of an anionic form of salmon trypsin has been determined at 1.82 Å resolution. We report the first structure of a trypsin from a phoikilothermic organism in a detailed comparison to mammalian trypsins in order to look for structural rationalizations for the cold-adaption features of salmon trypsin. This form of salmon trypsin (T II) comprises 222 residues, and is homologous to bovine trypsin (BT) in about 65% of the primary structure. The tertiary structures are similar, with an overall displacement in main chain atomic positions between salmon trypsin and various crystal structures of bovine trypsin of about 0.8 Å. Intramolecular hydrogen bonds and hydrophobic interactions are compared and discussed in order to estimate possible differences in molecular flexibility which might explain the higher catalytic efficiency and lower thermostability of salmon trypsin compared to bovine trypsin. No overall differences in intramolecular interactions are detected between the two structures, but there are differences in certain regions of the structures which may explain some of the observed differences in physical properties. The distribution of charged residues is different in the two trypsins, and the impact this might have on substrate affinity has been discussed. © 1994 Wiley-Liss, Inc.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prot.340200205
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  • 22
    Electronic Resource
    Electronic Resource
    Structure of trichosanthin at 1.88 Å resolution (1994)
    New York, NY : Wiley-Blackwell
    Proteins: Structure, Function, and Genetics 19 (1994), S. 4-13 
    Details
    ISSN: 0887-3585
    Keywords: trichosanthin ; ribosome-inactivating proteins ; crystal structure ; orthorhombic ; molecular replacement ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Trichosanthin (TCS) is one of the single chain ribosome-inactivating proteins (RIPs). The crystals of the orthorhombic form of trichosanthin have been obtained from a citrate buffer (pH 5.4) with KC1 as the precipitant. The crystal belongs to the space group P212121 with a = 38.31, b = 76.22, c = 79.21 Å. The structure was solved by molecular replacement method and refined using the programs XPLOR and PROLSQ to an R-factor of 0.191 for the reflections within the 6-1.88 Å resolution range. The bond length and bond angle in the protein molecule have root-mean-square deviations from ideal value of 0.013 Å and 3.3°, respectively. The refined model includes 247 residues and 197 water molecules. The TCS molecule consists of two structural domains. The large domain contains six α-helices, a six stranded sheet, and an antiparallel β-sheet. The small domain has a largest α-helix, which shows a distinct bend. The possible active site of the molecule located on the cleft between two domains was proposed. In the active site Arg-163 and Glu-160, Glu-189 and Arg-122 form two ion pairs, Glu-189 and Gln-156 are hydrogen bonded to each other. Three water molecules are bonded to the residues in the active site region. The structures of TCS molecule and ricin A-chain (RTA) superimpose quite well, showing that the structures of the two protein molecules are homologous. Comparison of the structures of the TCS molecule in this orthorhombic crystal with that in the monoclinic crystal indicates that there are no essential differences of the structures between the two protein crystals. © 1994 Wiley-Liss, Inc.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prot.340190103
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  • 23
    Electronic Resource
    Electronic Resource
    Phase and X-ray study of clathrate formation in the tetraisoamylammonium fluoride-water system (1994)
    Springer
    Journal of inclusion phenomena and macrocyclic chemistry 17 (1994), S. 137-148 
    Details
    ISSN: 1573-1111
    Keywords: Clathrate hydrate ; phase diagram ; crystal structure ; tetraisoamylammonium fluoride
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The phase diagram of the binary (i-C5H11)4NF-water system has been studied in the clathrate formation region. Three polyhydrates have been discovered, two of which (1∶38.9 and 1∶32.7) are the known orthorhombic and tetragonal phases:Pbmn,a=11.88,b=21.53,c=12.70 Å,ρ means=1.019 g cm-3 (0°C), m.p.=32.4°C andP42/m, a=23.729,c=12.466 Å,ρ means=1.062 g cm-3, (0°C), m.p.=31.2°C, respectively. A single crystal X-ray analysis of the novel clathrate hydrate (i-C5H11)4NF·27 H2O is reported. This new clathrate hydrate is tetragonal,I4I/a, witha=16.894(5),c=17.111(2) Å,Z=4, (−50°C), and m.p.=34.6°C. Each (i-C5H11)4N+ cation occupies a four-chamber cavity built of 15-hedra 71635942 (idealized description), with small vacant 5444 cavities filling the intervening space.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00711854
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  • 24
    Electronic Resource
    Electronic Resource
    X-ray structure and thermal analysis of a 1∶1 complex between sulfathiazole andβ-cyclodextrin (1994)
    Springer
    Journal of inclusion phenomena and macrocyclic chemistry 17 (1994), S. 187-201 
    Details
    ISSN: 1573-1111
    Keywords: β-Cyclodextrin ; sulfathiazole ; inclusion complex ; crystal structure ; thermal analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract An inclusion complex with the formula (β-cyclodextrin) (sulfathiazole) 8.3 H2O has been crystallized and characterized by physicochemical methods including single crystal X-ray analysis. The complex crystallizes in the monoclinic system, space group P21, witha=15.264(4),b= 16.500(6),c=15.559(5) Å,β=117.29(3)o andZ=2. The structure was solved using published co-ordinates forβ-cyclodextrin in an isomorphous complex. Refinement by block-diagonal leastsquares yieldedR=0.061 for 4706 unique observed reflections. Inclusion of sulfathiazole produces a slight ellipticity in the host conformation, but the guest adopts a conformation similar to that observed in its polymorphs. The guest is held in the macrocyclic cavity predominantly by hydrophobic forces, with the phenyl ring near the host primary hydroxyl side and the thiazole ring near the secondary hydroxyl side. The complex packs in layers parallel to theac-plane. Layers are linked by hydrogen bonding to water molecules which are located outside the cyclodextrin cavity. An extensive network of hydrogen bonds mediated chiefly by water molecules stabilizes the crystal structure.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00711858
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  • 25
    Electronic Resource
    Electronic Resource
    Inclusion complexes of the natural product gossypol. Recognition by gossypol of halogeno methanes. Structure of the dichloromethane complex of gossypol and single crystal conservation after decomposition (1994)
    Springer
    Journal of inclusion phenomena and macrocyclic chemistry 17 (1994), S. 317-324 
    Details
    ISSN: 1573-1111
    Keywords: Gossypol ; complex ; crystal structure ; single crystal ; desolvation ; polymorph
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The structures of gossypol complexes are extremely sensitive to the halogenomethane present as the guest; e.g. changing the number of Cl atoms in chloromethane derivatives changes the structure of the gossypol complex. The crystals of C30H30O8·CH2Cl2 are monoclinic, space groupC2/c,a=21.320(4),b=19.199(6),c=15.765(2)Å, β=113.05(2)o,V=5916(2)Å3,Z=8,D x=1.35 g/cm3,T=295 K. The structure has been solved by direct methods and refined to the finalR value of 0.084 for 1828 reflections. In the structure H-bonded gossypol molecules form columns, generating channels in the structure which are filled by guest molecules. After decomposition (desolvation) monocrystals of the complexes are conserved without destruction, in which there are rather wide and empty channels though slightly smaller than in the complex. An attempt is made to explain some peculiarities of the behavior of the gossypol polymorph formed on the basis of its structure with empty channels.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00707127
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  • 26
    Electronic Resource
    Electronic Resource
    Crystal structure of the product of a condensation reaction of (±)-gossypol with (R)-(+)-1-phenylethylamine. Why do diastereoisomeric diaminogossypols cocrystallize? (1994)
    Springer
    Journal of inclusion phenomena and macrocyclic chemistry 17 (1994), S. 365-376 
    Details
    ISSN: 1573-1111
    Keywords: Gossypol ; inclusion compounds ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The crystal structure of a compound obtained in a condensation reaction of (±)-gossypol with (R)-(+)-phenylethylamine has been determined by X-ray structure analysis. The crystals of C46H48O6N2·(C4H8O2)2 are monoclinic, space groupP21,a=21.243(3),b=8.666(1),c=28.651(4) Å, β=108.24(1)0,V=5009(3) β3,Z=4,D x=1.195 g cm−3, μ(CuK α)=0.66 mm−1,T=292 K. The structure has been solved by direct methods and refined to the finalR value of 0.091 for 4290 observed reflections and 1049 parameters. There are two diastereoisomeric molecules of the host and four solvent molecules in the asymmetric unit. The host molecules are H-bonded into chains with diastereoisomeric molecules alternating along the chain. The fact that the host prefers the association mode in which molecules with a different configuration of the 2,2′-binaphthyl moiety are H-bonded explains why separation of diastereoisomeric diaminogossypols by fractional crystallization has been unsuccessful. The 1,4-dioxane molecules are accommodated in infinite channels but only every second guest molecule in a channel is H-bonded to the host.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00707132
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  • 27
    Electronic Resource
    Electronic Resource
    A structural two-ring version of a tubular stack ofβ-rings in crystals of a cyclic D,L-hexapeptide (1994)
    Springer
    Journal of inclusion phenomena and macrocyclic chemistry 18 (1994), S. 27-36 
    Details
    ISSN: 1573-1111
    Keywords: D,L-hexapeptide ; cyclic ; crystal structure ; stacks ; tubular ; β-rings ; channels
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract An X-ray analysis of single crystals (from MeOH) of cyclo(-D-Leu-L-MeLeu-D-Leu-L-MeLeu-D-Leu-L-MeLeu-) has been carried out. The analysis reveals that the molecules of the cyclopeptide occur in the crystals with two slightly different, almost hexagonal backbone conformations of the β-type, and that pairs of molecules with the same conformation interact through their nonmethylated face, forming dimeric units (units A and B) with six interannular H-bonds. This kind of pairing reproduces well that expected for a two-ring element in a stack of antiparalleβ-rings. The X-ray analysis has also revealed the presence in the A units of two water molecules, each at one of two equivalent sites located on the 3-fold axis of the units and equidistant from the center of gravity, and the presence in the B units of one water molecule at the center of the units. This provides experimental support for the idea that stacks ofβ-rings can serve as molecular channels.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00706936
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  • 28
    Electronic Resource
    Electronic Resource
    N(nPr)4[B5O6(OH)4][B(OH)3]2 and N(nBu)4[B5O6(OH)4][B(OH)3]2: Clathrates with a diamondoid arrangement of hydrogen-bonded pentaborate anions (1994)
    Springer
    Journal of inclusion phenomena and macrocyclic chemistry 18 (1994), S. 161-175 
    Details
    ISSN: 1573-1111
    Keywords: Pentaborate ; boric acid ; clathrate ; diamond-related network ; hydrogen bonding ; tetrapropy-lammonium ; tetrabutylammonium ; crystal structure ; 11B MAS NMR ; 13C MAS NMR ; thermogravimetry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Single-crystal X-ray structure analyses of N(nPr)4[B5O6(OH)4][B(OH)3]2,1, and N(nBu)4 [B5O6(OH)4][B(OH)3]2,2, reveal that these materials are novel clathrates, the isotypic host structures of which are three-dimensional assemblies of hydrogen-bonded [B5O6(OH)4]− ionsand B(OH)3 molecules. The assembly of only the pentaborate anions is a distorted (i.e., along [102] elongated) fourconnected diamond-related network. The N(nPr) 4 + and N(nBu) 4 + ions are trapped within the complex three-dimensional channel systems of the host frameworks. Both1 and2 crystallize monoclinically with space groupP21/c andZ=4. The cell constants are:1:a=13.592(5),b=12.082(2),c=17.355(6) Å, β=106.60(2)° (298K);2:a=13.874(3),b=12.585(1),c=17.588(4) Å, β=107.04(1)° (238 K). The results obtained by both11B and13C MAS NMR spectroscopy are discussed. Thermogravimetric studies under a flowing inert-gas atmosphere suggest that water, stemming from polycondensation of the hydrous borate species, is released from the clathrates at ca. 443 K (1) and 398 K (2) before the decomposition of the organic cations starts at ca. 603 K (1) and 603 K (2).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00705819
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  • 29
    Electronic Resource
    Electronic Resource
    X-ray crystallographic studies of tricarbonylchromium complexes of calix[4]arene conformers: On an unusual conformation which appears in cone conformers (1994)
    Springer
    Journal of inclusion phenomena and macrocyclic chemistry 19 (1994), S. 227-236 
    Details
    ISSN: 1573-1111
    Keywords: Calixarenes ; arenetricarbonylchromium ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The structures of three arene-tricarbonylchromium complexes prepared from cone and 1,3-alternate-25, 26,27,28-tetrapropoxycalix[4]arene(1) and Cr(CO)6 were determined by single crystal X-ray studies. Crystal data for 1,3-alternate-1·Cr(CO)3 are space groupP21/a,a=19.496(3)Å,b=11.118(2)Å,c=19.121(2)Å, β=109.95°(1) andV=3895Å3. The structure was refined toRw=0.068. Crystal data for cone-1·Cr(CO)3 are space groupP21/a,a=21.457(4)Å,b=12.184(1)Å,c=14.816(2)Å, β=91.61°(1) andV=3872Å3. The structure was refined toRw=0.077. Crystal data for cone-1·2Cr(CO)3 are space groupP21/a,a=18.019(3)Å,b=41.347(4)Å,c=11.743(2)Å, β=97.39°(1) andV=8676Å3. The single crystal included two similar but slightly different structures but the data were successfully refined toRw=0.092. The structure of 1,3-alternate-1·Cr(CO)3 differs only slightly from that of the regular 1,3-alternate calix[4]arene. In contrast, cone-1·Cr(CO)3 and cone-1·2Cr(CO)3 show an unusual conformation with a pair of faced gablelike roofs, which is considerbly distorted from the regular cone calix[4]arene. The origin of this distortion is discussed in combination with the spectral studies.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00708984
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  • 30
    Electronic Resource
    Electronic Resource
    12-Membered crown ethers. Lipophilic derivatives of benzo- and naphtho-12-crown-4 and their membrane electrode properties. Crystal structures of benzo-12-crown-4 NaI and KI complexes (1994)
    Springer
    Journal of inclusion phenomena and macrocyclic chemistry 20 (1994), S. 335-351 
    Details
    ISSN: 1573-1111
    Keywords: 12-Membered crown ethers ; ion-selective membrane electrodes ; complexes ; crystal structure ; X-ray analysis ; conformation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Lipophilic derivatives of benzo-12-crown-4 and naphtho-12-crown-4 have been synthesized. The behavior of the parent compounds and their derivatives in membrane ion-selective electrodes have been studied. Selectivity changes have been observed with the rise in lipophilicity. Crystal structures of the NaI and KI complexes of benzo-12-crown-4 (1 and2) have been determined by X-ray analysis. The alkali metal and iodide ions are in direct contact in2 but not in1. Compound1 [Na(benzo-12-crown-4)2]·I is triclinic, witha=13.368(8),b=10.727(7),c=10.325(4) Å; α=73.56(4),β=77.73(4), γ=108.70(5)°;Z=2, space group is $$P\bar 1$$ . Compound2 [K(benzo-12-crown-4)2·I] is monoclinic, witha=15.807(8),b=12.043(4),c=15.601(6) Å,β=117.74(3)°;Z=4, space groupC2/c. In both compounds the cations interact with all oxygen atoms of two crown ether molecules. Correlation of the crystal structures and behavior of the crown ethers in ion-selective membrane electrodes is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00708878
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  • 31
    Electronic Resource
    Electronic Resource
    Synthesis and crystal structure of an organic semiconductor (ET)4[Hg2I6] (1994)
    Springer
    Russian chemical bulletin 43 (1994), S. 1175-1179 
    Details
    ISSN: 1573-9171
    Keywords: organic conductors ; ion-radical salts ; bis(ethylenedithio)tetrathiafulvalene ; mercury iodides ; crystal structure ; electrochemical synthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A new cation-radical salt (ET)4[Hg2I6] (1), where ET is bis(ethylenedithio)tetrathiafulvalene, has been synthesized in the system ET-HgI3 −-PhCl. An X-ray study of 1 (a=41.02(5),b=23.01(1),c=8.233(2) Å,V=7772(3) Å3, space groupPc21 b,Z=4,d calc=2.308 g cm−3) has established its composition, chemical formula, and the main structural features. The ET cation-radicals are packed in the conducting layer, the type of packing is α″; the [Hg2I6]2− anion has a dimeric structure. The temperature dependence of the conductivity of the (ET)4[Hg2I6] crystals (σ300=6 Ohm−1 cm−1) has a semiconducting character.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00698238
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  • 32
    Electronic Resource
    Electronic Resource
    Synthesis and crystal structure of cyclotris-(4,4′-thiodiphenylene ketone) (1994)
    Springer
    Russian chemical bulletin 43 (1994), S. 1384-1389 
    Details
    ISSN: 1573-9171
    Keywords: synthesis ; macrocyclic thiophenylene ketone ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The side reaction of macrocyclization that occurs during the synthesis of poly-(1,4-phenylenesulfide ketone) by polycondensation of a 4,4-dihalobenzophenone with sodium sulfide was studied. It was found that the major product of this reaction is a cyclic trimer, cyclotris-(4,4"-thiodiphenylene ketone) (1). Despite the fact that ketone bridges are more rigid than sulfide bridges, the yield of the macrocycle is rather high, as it is in the synthesis of poly-(1,4-phenylenesulfide), and reaches 20% under high dilution conditions. The structure of 1 was investigated by X-ray diffraction analysis (R = 0.069 on 3138 reflections). Macrocycle 1 is strongly flattened in the crystal; the conformation observed is determined by the packing, since stereochemical analysis indicates high flexibility of the macrocycle. The solvate acetone molecules incorporated in the crystal are disordered, nevertheless, they are strongly fixed in the cavities and channels of the crystal structure.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00703700
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  • 33
    Electronic Resource
    Electronic Resource
    Analysis of structure and properties of poly(ethylene terephthalate) fibers (1994)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 32 (1994), S. 2289-2306 
    Details
    ISSN: 0887-6266
    Keywords: poly(ethylene terephthalate) ; fiber ; x-ray diffraction ; crystal structure ; three-phase model ; modulus ; tenecity ; shrinkage ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The structure of four semicrystalline poly(ethylene terephthalate) fibers were analyzed with full-pattern (two-dimensional Rietveld) x-ray diffraction refinement, small-angle x-ray scattering, and thermal mechanical analysis, and compared to some of their known mechanical properties. The classical two-phase model of crystal and amorphous phases were unable to correlate structure and properties. We found that there must be a third phase, an oriented, intermediate phase, located mainly between the fibrils. About 1/3 of the intensity of fiber diffraction of the analyzed samples was contributed from such intermediate phase. For some fiber properties the intermediate phase plays a similar role as proposed for “taut tie molecules.” A simple model for the description of structure-insensitive properties of PET fibers was developed, based on this quantitaitve separation into three phases. The oriented intermediate phase changes the definition and calculation of the basic parameters of the fiber structure, such as crystallinity and orientation. Based on small-angle x-ray evidence, the crystallites are assumed to be separated by layers of largely amorphous material, both surrounded by the intermediate phase. The initial modulus of the fiber is determined mainly by the amount and orientation of the intermediate phase which has a maximum modulus of about 500 g/d on full orientation instead of the earlier predicted 150 g/d for fully oriented semicrystalline fibers. Based on the relationship between tenactity and average orientation function, the maximum tenacity for PET fibers of a structure like the ones analyzed may reach 20-45 g/d instead of earlier predictions of 10 g/d. The additional information needed to understand the structure-sensitive property of shrinkage is discussed. Presently easily accessible parameters have no quantitative predictive capabilities. © 1994 John Wiley & Sons, Inc.
    Additional Material: 8 Ill.
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    URL: http://dx.doi.org/10.1002/polb.1994.090321316
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    Surface studies of tetraalkylammonium bromides and iodides using atomic force microscopy (1994)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 32 (1994), S. 2653-2659 
    Details
    ISSN: 0887-6266
    Keywords: tetraalkylammonium halide ; atomic force microscopy ; crystal structure ; surface structure ; hextriacontane ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The surface structures of two series of tetra-n-alkylammonium halides, N(CxH2×+1)4I and N(CxH2x+1)4 Br have been investigated with atomic force microscopy (AFM) and compared to hexatriacontane (C36H74). The surfaces could be imaged with atomic resolution. The observed primitive, square surface-patterns of tetra-n-butyl chloride and bromide are in good accord with x-ray single-crystal structure. For n 〉 4, x-ray powder diffraction showed that increasing the alkyl chain-length leads mainly to an appropriate increase of the unit cell along the c-axis, which suggests similar layer structures for all long-chain salts beyond the butyl homologue. Within the centers of the molecular layers of these crystals reside the halide anions and the quaternary nitrogens. The surfaces accessible for AFM consist of methyl end-groups. As the number of carbon atoms increases beyond four, the surface symmetry changes to the face-centered square patterns characteristic of many paraffins. The chains of the tetraalkyl ammonium salts pack, however, less dense than paraffins. © 1994 John Wiley & Sons, Inc.
    Additional Material: 9 Ill.
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    URL: http://dx.doi.org/10.1002/polb.1994.090321611
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    Liquid crystalline main chain polymers with a poly(p-phenylene-terephthalate) backbone: 7. Thermal expansion of oriented films of the polyester with dodecyloxy side chains (1994)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 32 (1994), S. 851-857 
    Details
    ISSN: 0887-6266
    Keywords: rigid rod polymer ; thermotropic ; aromatic polyester ; oriented film ; thermal expansion ; crystal structure ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The linear thermal expansion coefficients of oriented films of poly(p-phenylene-2,5-didodecyloxy-terephthalate) in the three structures B, A, and Lf are reported. The results are interpreted in terms of a molecular laminate model in which the rigid main-chain layers are separated by the aliphatic side chains. In a film oriented unidirectionally the rigid mainchain layers provide a negative contribution to the thermal expansion coefficient, while the side chains supply a positive contribution. Therefore, the resulting expansion coefficient α depends on the details of the main- and side-chain packing and low-temperature values between α = +0.3 × 10-5 K-1 (A and Lf and α = -1.2 × 10-5 K-1 (B) are found in highly oriented films. Measurements on undrawn films are in accordance with the molecular laminate model. © 1994 John Wiley & Sons, Inc.
    Additional Material: 7 Ill.
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    URL: http://dx.doi.org/10.1002/polb.1994.090320508
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    Comparison of NDDO and quasi-ab initio approaches to compute semiempirical molecular electrostatic potentials (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 15 (1994), S. 12-22 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: The suitability of the two most widely used strategies to compute semiempirical MEPs is examined. For this purpose, MEP minima, electrostatic charges, and dipoles for a large number of molecules were computed at the AM1, MNDO, and PM3 levels using both the NDDO strategy developed by Ferenczy, Reynolds, and Richards and our own quasi-ab initio method. Results demonstrate that the quasi-ab initio is preferred over the NDDO method for the computation of MEP minima. It is also found that the best set of semiempirical charges and dipoles are obtained using either the AM1 NDDO or the MNDO quasi-ab initio methods. In these two cases, the quality of the results is fully comparable with 6-31G* values. © 1994 by John Wiley & Sons, Inc.
    Additional Material: 6 Tab.
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    URL: http://dx.doi.org/10.1002/jcc.540150103
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    Newton-Raphson optimization of the explicitly correlated Gaussian functions for calculations of the ground state of the helium atom (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 15 (1994), S. 54-60 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: Explicitly correlated Gaussian functions have been used in variational calculations on the ground state of the helium atom. The major problem of this application, as well as in other applications of the explicitly correlated Gaussian functions to compute electronic energies of atoms and molecules, is the optimization of the nonlinear parameters involved in the variational wave function. An effective Newton-Raphson optimization procedure is proposed based on analytic first and second derivatives of the variational functional with respect to the Gaussian exponents. The algorithm of the method and its computational implementation is described. The application of the method to the helium atom shows that the Newton-Raphson procedure leads to a good convergence of the optimization process. © 1994 by John Wiley & Sons, Inc.
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/jcc.540150107
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    General parameterization of a reaction field theory combined with the boundary element method (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 15 (1994), S. 90-104 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: We described various technical aspects in applying reaction field theories using continuum models to practical problems. It was investigated how solvent-dependent properties of solute molecules are influenced by the following factors: difference in quantum-chemical description of solute-solvent (continuum dielectric) interaction, difference in values of empirically determinable parameters such as atomic radii to define a size of a cavity created in a dielectric to accommodate a solute, and difference in the sophistication level of molecular orbital calculation, including electron correlation and different parameter sets (MNDO, AM1, and PM3). Through these investigations, the better parameter sets were found to evaluate accurately physicochemically important parameters such as hydration enthalpy. © 1994 by John Wiley & Sons, Inc.
    Additional Material: 8 Ill.
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    URL: http://dx.doi.org/10.1002/jcc.540150111
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    Conformation and reactivity of α-oxo-ketenes: Ab initio and semiempirical (AM1, PM3) calculations (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 15 (1994), S. 132-143 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: Ab initio MP2/6-31G*//MP2/6-31G* and semiempirical AM1 and PM3 calculations on a series of differently substituted α-oxo-ketenes are used to investigate E/Z-isomerism and rotational barriers in these molecules. Sterically crowded derivatives are found to exist solely as s-E conformers. The unusual stability of these derivatives thus can be attributed to their inability to adopt the s-Z conformation required for the normal α-oxo-ketene reactions. With respect to structures and energies, the PM3 method (especially in the case of highly crowded molecules) is found to be less reliable than AM1. Ab initio HF/3-21G and PM3 vibrational frequencies appear to be of sufficient accuracy for a distinction between s-Z and s-E conformers. In this respect, the AM1 method appears less reliable. © 1994 by John Wiley & Sons, Inc.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/jcc.540150203
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  • 40
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    Atomic charges derived from a fast and accurate method for electrostatic potentials based on modified AM1 calculations (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 15 (1994), S. 200-207 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: Atomic charges derived from a recently described approach to the very rapid computation of AM1 electrostatic potentials (ESP) accurately parallel, but are ca. 20% smaller than, the corresponding HF/6-31G* values. The dipole moments computed from the AM1 charges are virtually identical to those derived directly from the wave function and in rather better agreement with the experimental values than those computed using the HF/6-31G* charges. Unlike other approaches to the semiempirical calculation of ESP-derived charges, the present method also yields near HF/6-31G* quality potentials close to the molecular periphery. For medium-sized organic molecules (40-100 basis functions), the method is approximately two orders of magnitude faster than those involving prior deorthogonalization of AM1 wave function and explicit computation of the full ESP integral matrix. © 1994 by John Wiley & Sons, Inc.
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/jcc.540150210
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    A ring-bracing approach to computer-assisted ligand design (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 15 (1994), S. 233-240 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: Rigid inhibitors suffer a smaller loss of conformational entropy when they bind to a macromolecular receptor than their acyclic counterparts. They can also be useful for elucidating pharmacophores due to their reduced conformational space and may be more amenable to synthesis. Computational approaches to rational drug design should therefore take these factors into consideration when suggesting possible compounds. We describe how an acyclic chain which links two parts of a receptor site can be ‘braced’ using ring templates. The acyclic chains may be produced from a number of sources, including lattices or the structures of known inhibitors. The resulting structures contain a rich variety of isolated and fused ring systems, which provide many useful molecular skeletons for subsequent inhibitor design. © 1994 by John Wiley & Sons, Inc.
    Additional Material: 7 Ill.
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    URL: http://dx.doi.org/10.1002/jcc.540150213
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  • 42
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    Force field calculations (MM3) on glyoxal, quinones, and related compounds (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 15 (1994), S. 251-268 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: A general force field type of calculation has been devised in connection with MM3 to treat 1,2- and 1,4-diketones, both when they are not conjugated (as in derivatives of glyoxal) and when they are conjugated (as in derivatives of ortho- and para-benzoquinone). The molecular structures, moments of inertia, dipole moments, and vibrational spectra have been examined for about 15 compounds, some in several conformations. Ab initio calculations (6-31G*) have been used to determine quantities that have not been previously defined by experiment. In general, the force field permits the calculation of the structures with high accuracy, and the spectroscopic and conformational energy data with fair accuracy. © 1994 by John Wiley & Sons, Inc.
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/jcc.540150302
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    A comparative study of effective core potential and full-electron calculations in Mo compounds. I. An analysis of topological properties of bond charge distribution (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 15 (1994), S. 313-321 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: Effective core potential (ECP) and full-electron (FE) calculations for MoS4-2, MoO4-2, and MoOCl4 compounds were analyzed. Geometry parameters, binding energies, charge distributions, and topological properties of the electronic density were studied for Mo—L bonds (L = S, O, Cl). Results clearly indicate that those approaches that include valence plus 4s and 4p electrons (ECP2 methods) are able to reproduce the topological properties of Mo—L bonds, charge distributions, and geometries with respect to those obtained by FE methods. ECP methods that consider only the 4d and 5s valence electrons (ECP1) fail in the calculation of molecular properties. The use of 5p functions in ECP1 approaches produces a negative Mulliken charge on Mo. Bader's charges give more consistent results than Mulliken's ones. A new parameter for measuring the degree of ionicity is proposed. © 1994 by John Wiley & Sons, Inc.
    Additional Material: 7 Tab.
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    URL: http://dx.doi.org/10.1002/jcc.540150306
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    Ab initio study of low-lying electronic states of the PF2 radical (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 15 (1994), S. 346-350 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: The equilibrium geometries, excitation energies, force constants, and vibrational frequencies of the low-lying electronic states X2B1, 2A1, 2B2, and 2A2 of the PF2 radical have been calculated at the MRSDCI level with a double zeta plus polarization basis set. Our calculated geometry, force constants, and vibrational frequencies for the X2B1 state are in good agreement with experimental data. The electronic transition moments, oscillator strengths for the 2A1 → X2B1 and 2A2 → X2B1 transitions, and radiative lifetimes for the 2A1 and 2A2 states are calculated based on the MRSDCI wave functions. © 1994 by John Wiley & Sons, Inc.
    Additional Material: 3 Tab.
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    URL: http://dx.doi.org/10.1002/jcc.540150309
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    Free energy perturbation calculations on parallel computers: Demonstrations of scalable linear speedup (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 15 (1994), S. 351-373 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: A coarse-grain parallel implementation of the free energy perturbation (FEP) module of the AMBER molecular dynamics program is described and then demonstrated using five different molecular systems. The difference in the free energy of (aqueous) solvation is calculated for two monovalent cations ΔΔGaq(Li+ Δ Cs+), and for the zero-sum ethane-to-ethane′ perturbation ΔΔGaq(CH3—methyl—X → X—methyl—CH3), where X is a ghost methyl. The difference in binding free energy for a docked HIV-1 protease inhibitor into its ethylene mimetic is examined by mutating its fifth peptide bond, ΔG(CO—NH → CH=CH). A potassium ion (K+) is driven outward from the center of mass of ionophore salinomycin (SAL-) in a potential of mean force calculation ΔGMeOH(SAL- · K+) carried out in methanol solvent. Parallel speedup obtained is linearly proportional to the number of parallel processors applied. Finally, the difference in free energy of solvation of phenol versus benzene, ΔΔGoct(phenol → benzene), is determined in water-saturated octanol and then expressed in terms of relative partition coefficients, Δ log(Po/w). Because no interprocessor communication is required, this approach is scalable and applicable in general for any parallel architecture or network of machines. FEP calculations run on the nCUBE/2 using 50 or 100 parallel processors were completed in clock times equivalent to or twice as fast as a Cray Y-MP. The difficulty of ensuring adequate system equilibrium when agradual configurational reorientation follows the mutation of the Hamiltonian is discussed and analyzed. The results of a successful protocol for overcoming this equilibration problem are presented. The types of molecular perturbations for which this method is expected to perform most efficiently are described. © 1994 by John Wiley & Sons, Inc.
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    URL: http://dx.doi.org/10.1002/jcc.540150310
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    Transferable semiempirical quadratic force fields: The case of polythiophene and shorter oligomers (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 15 (1994), S. 405-423 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: The vibrational spectra of oligomers of thiophene are treated theoretically with the main purpose of deriving information for the interpretation of the infrared and Raman spectra of the polymer and isotopic derivatives. We report the results of a series of semiempirical MNDO calculations on the structure and vibrational properties of oligothiophenes, and we compare the calculated MNDO Pulay scaled force field of the monomer with an empirical harmonic force field that we have obtained by least squares refinement on nine isotopic derivatives. The scaling factors obtained were transferred from thiophene for the computation of the vibrational spectrum and the phonon dispersion curves of the polymer. © 1994 by John Wiley & Sons, Inc.
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/jcc.540150405
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    Announcements (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 15 (1994), S. 475-475 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540150411
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    On the analytical calculation of van der Waals surfaces and volumes: Some numerical aspects (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 15 (1994), S. 507-523 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: A fast computer algorithm is presented for complete analytical calculation of van der Waals surfaces and volumes. Connolly's analytical algorithms, computing second- and third-order atomic spheres overlaps, are shown to give insufficient numerical approximations of the exact van der Waals surfaces and volumes. The presented algorithm computes overlaps of any order. Practical situations frequently involve six-order overlaps. Analytical computed surfaces and volumes of 63 chemicals are compared with Monte Carlo measured values. © 1994 by John Wiley & Sons, Inc.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/jcc.540150504
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    ICM - A new method for protein modeling and design: Applications to docking and structure prediction from the distorted native conformation (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 15 (1994), S. 488-506 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: An efficient methodology, further referred to as ICM, for versatile modeling operations and global energy optimization on arbitrarily fixed multimolecular systems is described. It is aimed at protein structure prediction, homology modeling, molecular docking, nuclear magnetic resonance (NMR) structure determination, and protein design. The method uses and further develops a previously introduced approach to model biomolecular structures in which bond lengths, bond angles, and torsion angles are considered as independent variables, any subset of them being fixed. Here we simplify and generalize the basic description of the system, introduce the variable dihedral phase angle, and allow arbitrary connections of the molecules and conventional definition of the torsion angles. Algorithms for calculation of energy derivatives with respect to internal variables in the topological tree of the system and for rapid evaluation of accessible surface are presented. Multidimensional variable restraints are proposed to represent the statistical information about the torsion angle distributions in proteins. To incorporate complex energy terms as solvation energy and electrostatics into a structure prediction procedure, a “double-energy” Monte Carlo minimization procedure in which these terms are omitted during the minimization stage of the random step and included for the comparison with the previous conformation in a Markov chain is proposed and justified. The ICM method is applied successfully to a molecular docking problem. The procedure finds the correct parallel arrangement of two rigid helixes from a leucine zipper domain as the lowest-energy conformation (0.5 Å root mean square, rms, deviation from the native structure) starting from completely random configuration. Structures with antiparallel helixes or helixes staggered by one helix turn had energies higher by about 7 or 9 kcal/mol, respectively. Soft docking was also attempted. A docking procedure allowing side-chain flexibility also converged to the parallel configuration starting from the helixes optimized individually. To justdy an internal coordinate approach to the structure prediction as opposed to a Cartesian one, energy hypersurfaces around the native structure of the squash seeds trypsin inhibitor were studied. Torsion angle minimization from the optimal conformation randomly distorted up to the rms deviation of 2.2 Å or angular rms deviation of l0° restored the native conformation in most cases. In contrast, Cartesian coordinate minimization did not reach the minimum from deviations as small as 0.3 Å or 2°. We conclude that the most promising detailed approach to the protein-folding problem would consist of some coarse global sampling strategy combined with the local energy minimization in the torsion coordinate space. © 1994 by John Wiley & Sons, Inc.
    Additional Material: 11 Ill.
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    URL: http://dx.doi.org/10.1002/jcc.540150503
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    Masthead (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 15 (1994) 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540150601
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    Direct search methods for the molecular conformation problem (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 15 (1994), S. 627-632 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: An important area of research in computational biochemistry is the design of molecules for specific applications. The design of these molecules, which depends on the accurate determination of their three-dimensional structure, can be formulated as a global optimization problem. In this article, we present results from the application of a new conformation searching method based on direct search methods. We compare these results to some earlier results using genetic algorithms and simulated annealing. © 1994 by John Wiley & Sons, Inc.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/jcc.540150606
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    Triazene proton affinities: A comparison between density functional, Hartree-Fock, and post-Hartree-Fock methods (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 15 (1994), S. 875-892 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: The consistency of three density functional computational implementations (DMol, DGauss, and deMon) are compared with high-level Hartree-Fock and Møller-Plesset (MP) calculations for triazene (HN=NNH2) and formyl triazene (HN=NNHCOH). Proton affinities on all electronegative sites are investigated as well as the geometries of the neutral and protonated species. Density functional calculations employing the nonlocal gradient corrections show agreement with MP calculations for both proton affinities and geometries of neutral and protonated triazenes. Local spin density approximation DMol calculations using numerical basis sets must employ an extended basis to agree with other density functional codes using analytic Gaussian basis sets. The lowest energy conformation of triazene was found to be nonplanar; however, the degree of nonplanarity, as well as some bond lengths, is dependent on the basis set, electron correlation treatment, and methods used for the calculation. © 1994 by John Wiley & Sons, Inc.This article is a U.S. Government work and, as such, is in the public domain in the United States of America.
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    URL: http://dx.doi.org/10.1002/jcc.540150809
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    Cluster analysis of molecular conformations (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 15 (1994), S. 899-916 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: We describe a method for locating clusters of geometrically similar conformers in ensembles of chemical conformations. We first calculate the pairwise interconformational distance matrix in either torsional or Cartesian space and then use an agglomerative, single-link clustering method to define a hierarchy of clusterings in the same space. Especially good clusterings are distinguished by high values of the separation ratio: the ratio of the shortest intercluster distance to the characteristic threshold distance defining the clustering. We also discuss other statistics. The method has been embodied in a program called XCluster, which can display the distance matrix, the hierarchy of clusterings, and the clustering statistics in a variety of formats. XCluster can also write out the clustered conformations for subsequent or simultaneous viewing with a molecular visualization program. We demonstrate the sorts of insight that this approach affords with examples obtained from conformational search and molecular dynamics procedures. © 1994 by John Wiley & Sons, Inc.
    Additional Material: 8 Ill.
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    URL: http://dx.doi.org/10.1002/jcc.540150811
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    D-CICADA: A software for conformational PES elucidation on network of workstationsThis work is dedicated to Professor M. Kratochvíl on the occasion of his seventieth birthday. (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 15 (1994), S. 937-946 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: The methodology of conformational potential energy (hyper)surface (PES) elucidation is the subject of this article. The decomposition of the recently developed software CICADA and its implementation in the distributed environment using PVM (parallel virtual machine) is presented. CICADA has been chosen for the parallelization because of its ability to elucidate systematically the low-energy areas of PES in polynomial time. This makes the method applicable on larger systems which are beyond the scope of the grid search. To show the level of parallelization, conformational PES of two molecules, cyclohexane and terminally blocked alanine, have been studied by the distributed version, D-CICADA, and results have been compared to those of the sequential version. D-CICADA was tested on several virtual machines composed of DEC and Sun workstations. The timing shows good efficiency for both the decomposition of the original algorithm and the PVM environment. © 1994 by John Wiley & Sons, Inc.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/jcc.540150904
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    Long-time overdamped Langevin dynamics of molecular chains (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 15 (1994), S. 997-1012 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: We present a novel algorithm of constrained, overdamped dynamics to study the long-time properties of peptides, proteins, and related molecules. The constraints are applied to an all-atom model of the molecule by projecting out all components of the nonbonding interactions which tend to alter fixed bond lengths and angles. Because the overdamped dynamical equations are first order in time, the constraints are satisfied by inversion of a banded matrix at each timestep, which is computationally efficient. Thermal effects are included through a Langevin noise term in the equation of motion. Because high-frequency components of the motion have been eliminated, the timestep of the algorithm is determined by the nonbonding forces, which are two to three orders of magnitude weaker than the bonding forces. Using polyalanine as a test example, we demonstrate that trajectories simulating a microsecond of motion can be run about 103 times faster than an equivalent molecular dynamics simulation. © 1994 by John Wiley & Sons, Inc.
    Additional Material: 9 Ill.
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    URL: http://dx.doi.org/10.1002/jcc.540150908
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    Decomposition analyses of the intermolecular interaction energies in two π—π stacking complexes: Quinhydrone and N,N,N′, N′-tetramethyl-P-diaminobenzene-chloranil complex (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 15 (1994), S. 1013-1018 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: Although there is a similarity in the orbital interaction scheme between quinhydrone and N,N,N′,N′-tetramethyl-p-diaminobenzene-chloranil complex, the stacking conformations are different from each other. The former prefers the half-stacked conformation, whereas the latter prefers the completely stacked conformation. We have done ab initio molecular orbital calculations and decomposition analyses of the intermolecular interaction energies to clarify the origin of the different stacking conformations. It was concluded that the main origin is the difference in the steric part of the interaction energies. © 1994 by John Wiley & Sons, Inc.
    Additional Material: 8 Ill.
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    URL: http://dx.doi.org/10.1002/jcc.540150909
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    A force field for monosaccharides and (1 → 4) linked polysaccharides (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 15 (1994), S. 1019-1040 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: A force field for monosaccharides that can be extended to (1 → 4) linked polysaccharides has been developed for the AMBER potential function. The resulting force field is consistent with the existing AMBER force field for proteins and nucleic acids. Modifications to the standard AMBER OH force constant and to the Lennard-Jones parameters were made. Furthermore, a 10-12 nonbonded term was included between the hydroxyl hydrogen of the saccharide and the water oxygen (TIP3P, SPC/E, etc.) to reproduce better the water-saccharide intermolecular distances. STO-3G electrostatic potential (ESP) charges were used to represent the electrostatic interactions between the saccharide and its surrounding environment. To obtain charges for polysaccharides, a scheme was developed to piece together saccharide residues through 1 → 4 connections while still retaining a net neutral charge on the molecule as a whole. Free energy perturbation (FEP) simulations of D-glucose and D-mannose in water were performed to test the resulting force field. The FEP simulations demonstrate that AMBER overestimates intramolecular interaction energies, suggesting that further improvements are needed in this part of the force field. To test further the reliability of the parameters, a molecular dynamics (MD) simulation of α-D-glucose in water was also performed. The MD simulation was able to produce structural and conformational results that are in accord with experimental evidence and previous theoretical results. Finally, a relaxed conformational map of β-maltose was assembled and it was found that the present force field is consistent with available theoretical and experimental results. © 1994 by John Wiley & Sons, Inc.
    Additional Material: 5 Ill.
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    URL: http://dx.doi.org/10.1002/jcc.540150910
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    A rapidly convergent simulation method: Mixed Monte Carlo/stochastic dynamics (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 15 (1994), S. 1302-1310 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: Although Monte Carlo and molecular dynamics are the primary methods used for free energy simulations of molecular systems, their application to molecules that have multiple conformations separated by energy barriers of ≥ 3 kcal/mol is problematic because of slow rates of convergence. In this article we introduce a hybrid simulation method termed MC-SD which mixes Monte Carlo (MC) and stochastic dynamics (SD). This new method generates a canonical ensemble via alternating MC and SD steps and combines the local exploration strengths of dynamics with the barrier-crossing ability of large-step Monte Carlo. Using calculations on double-well potentials and long simulations (108 steps of MC and 1 μs of SD) of the simple, conformationally flexible molecule n-pentane, we find that MC-SD simulations converage faster than either MC or SD alone and generate ensembles which are equivalent to those created by classical MC or SD. Using pure SD at 300 K, the conformational populations of n-pentane are shown to be poorly converged even after a full microsecond of simulation. © 1994 by John Wiley & Sons, Inc.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/jcc.540151111
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    Molecular mechanics calculations (MM2 and MM3) on enamines and aniline derivatives (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 15 (1994), S. 1321-1330 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: The MM2 and MM3 force fields have been extended to cover this class of compounds. Structures, vibrational spectra, and other data for 13 compounds were examined and can be reproduced satisfactorily by MM3. Except for the spectra, the other data can be reproduced somewhat less well by MM2. © 1994 by John Wiley & Sons, Inc.
    Additional Material: 14 Tab.
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    URL: http://dx.doi.org/10.1002/jcc.540151202
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    A variational biorthogonal valence bond method (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 15 (1994), S. 1357-1364 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: The details of a simple and efficient scheme for performing variational biorthogonal valence bond calculations are presented. A variational bound on the energy functional is obtained through the use of a complete configuration expansion in a well-chosen subset of orbitals. The resultant wave functions are clearly dominated by the covalent (spin-coupled) structures, with a negligible contribution from ionic structures. The orbitals obtained compare favorably with overlap enhanced atomic orbitals obtained by other valence bond approaches. The method is illustrated by calculations on water and dioxygen difluoride. © 1994 by John Wiley & Sons, Inc.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/jcc.540151205
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    Stability of two-dimensional crystalline aggregates of a protein studied by molecular dynamics (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 15 (1994), S. 1278-1290 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: Two-dimensional protein (ferritin) aggregates with a square lattice symmetry, which were formed within a thin liquid layer on a mercury surface, were studied by molecular dynamics (MD) simulation. For the simulation, the ferritin molecule was modeled by an assembly of 49 spheres, and the intermolecular interactions were given by simple formulae. During the simulation, molecules were confined within a layer, which corresponds to the thin liquid layer. An annealing MD simulation was done starting from a random molecular configuration within the layer, and aggregates with the square lattice symmetry were also obtained. To study the stability of aggregates, dissociation processes of the aggregates were analyzed using MD simulations at room temperature. Interactions between the nearest-neighbor molecules were regarded as bonds. Mean bond energies and correlation coefficients between the bond energies were calculated from the MD trajectories. A decay profile according to the dissociation was obtained, yielding a dissociation rate constant. Buried bonds were stronger than peripheral bonds. The larger the aggregate size, the stronger the bond for each of the buried and peripheral bonds. A simple theoretical account, which is applicable to a general bonded network, was introduced to analyze the dynamics of the aggregates. © 1994 by John Wiley & Sons, Inc.
    Additional Material: 7 Ill.
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    URL: http://dx.doi.org/10.1002/jcc.540151109
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    Linear dependency in the refinement of force constants with the Jacobian method (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 15 (1994), S. 1291-1301 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: The Jacobian method in the refinement of force constants is studied. Theoretical and experimental frequencies and other observables, νs, are matched by minimizing ΣsWs(νsexp - νsth)2, where s = 1, 2, 3,…, proceeds over all normal modes and isotopes, and Ws are weighting factors. Modification of the theoretical frequencies is accomplished with the Jacobian matrix, J, with elements Jsi = ∂νs/∂ki involving each force constant or associated parameter, ki, i = 1, 2, 3,…, by Δν = JΔk. The parameters are adjusted directly with Δk = (JTWJ)-1(JW) Δν, where W is a diagonal matrix which weights the frequencies. The linear dependence problem must be addressed prior to inversion of JTWJ. The approach entails diagonalization of JT WJ, analysis of the components of the eigenvectors associated with zero and small eigenvalues, identification of the linearly dependent parameters, successive elimination of selective parameters, and a repeat of this procedure until linear dependency is removed. The Jacobian matrices are obtained by differencing the frequencies when the parameters are varied and by numerical and analytical evaluation of the derivative of the potential. The unitary transformation, U, used to calculate J = UT (∂F/∂k)U or J = UT (ΔF/Δk)U, is obtained from the diagonalization of the Hessian, Fmn = ∂2ν/∂pm∂qn, where p, q = x, y, z are the Cartesian coordinates for atoms m, n = 1, 2, 3,…, at the initial value of ki, i = 1, 2, 3,⃜ The accuracy of and the ability to evaluate the Jacobian matrix by these methods are discussed. Applications to CH4, H2CO, C2H4, and C2H6 are presented. Linearly dependent and ill-conditioned parameters are identified and removed. The procedure is general for any observable quantity. © 1994 by John Wiley & Sons, Inc.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/jcc.540151110
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    Algorithms for clustering molecular dynamics configurations (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 15 (1994), S. 1331-1340 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: Two traditional clustering algorithms are applied to configurations from a long molecular dynamics trajectory and compared using two sets of test data. First, a subset of atoms was chosen to present conformations which naturally fall into a number of clusters. Second, a subset of atoms was selected to span a relatively continuous region of conformational space rather than form discrete conformational classes. Of the two algorithms used, the single linkage method is inappropriate for this kind of data. The divisive hierarchical method, based on minimizing the difference between cluster centroids and extrema, is successful but also prone to imposing clustering hierarchy where none can be justified. © 1994 by John Wiley & Sons, Inc.
    Additional Material: 8 Ill.
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    URL: http://dx.doi.org/10.1002/jcc.540151203
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    Application of a high-performance, special-purpose computer, GRAPE-2A, to molecular dynamics (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 15 (1994), S. 1372-1376 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: The special-purpose computer GRAPE-2A accelerates the calculation of pairwise interactions in many-body systems. This computer is a back-end processor connected to a host computer through a Versa Module Europe (VME) bus. GRAPE-2A receives coordinates and other physical data for particles from the host and then calculates the pairwise interactions. The host then integrates an equation of motion by using these interactions. We did molecular dynamics simulations for two systems of liquid water: System 1 (1000 molecules), and System 2 (1728 molecules). The time spent for one step of molecular dynamics was 3.9 s (System l), and 10.2 s (System 2). The larger the molecular system, the higher the performance. The speed of GRAPE-2A did not depend on the formula describing the pairwise interaction. The cost performance was about 20 times better than that of the fastest workstations available today, and GRAPE-2A cost only $22,000. © 1994 by John Wiley & Sons, Inc.
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/jcc.540151207
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    Hydrating peptides using a sprouting technique (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 15 (1994), S. 23-27 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: A scheme for generating water coordinates, whose proton orientations are random, and simultaneously generating side chain coordinates of peptides, preparatory to studying solvation of peptides using molecular dynamics schemes is presented in an X-PLOR context. Examples from the Integrin and Tropomyosin systems are used to illustrate the procedure. © 1994 by John Wiley & Sons, Inc.
    Additional Material: 6 Ill.
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    URL: http://dx.doi.org/10.1002/jcc.540150104
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    Simulations of the solution structure of HIV-1 protease in the presence and absence of bound zinc (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 15 (1994), S. 61-71 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: Zinc ions have been shown to inhibit human immunodeficiency virus type 1 (HIV-1) protease in vitro at neutral pH [Zhang et al. Biochemistry, 36, 8717 (1991)]. Kinetic data from this study support a reversible binding mechanism of zinc in the active site. Preliminary calculations of the ion-protein potential energy based on the geometry of the crystallographic structure [Wlodawer et al. Science, 245, 616 (1989)] are consistent with this proposed mechanism. To examine the structure of HIV-1 protease with zinc bound in the active site, molecular dynamics simulations in the presence and absence of zinc at this site have been carried out to 200 ps. These simulations suggest zinc remains stably bound to the catalytic aspartate residues without disruption of the dimer or significant alteration of the active site structure. These data are consistent with those observed by Zhang et al. (1991), and together give strong evidence that this is the binding site that leads to inactivation. A proposed model of zinc binding at the active site based on quantum mechanical calculations indicates Zn+2 coordination is monodentate with each catalytic aspartate, leaving at least two ligand positions potentially free (occupied by water molecules in the calculations). © 1994 by John Wiley & Sons, Inc.
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    URL: http://dx.doi.org/10.1002/jcc.540150108
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    Masthead (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 15 (1994) 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540150201
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    Parallel algorithm for calculating ro-vibrational states of diatomic molecules (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 15 (1994), S. 144-148 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: In this article, we develop and implement an algorithm for calculating the rovbrational states of diatomic molecules optimized for multiple instructions multiple data computers of distributed memory. The method is based upon the p-version of the finite element method and has been implemented on an INTEL iPSC/2 machine with 16 processors. © 1994 by John Wiley & Sons, Inc.
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    URL: http://dx.doi.org/10.1002/jcc.540150204
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    Derivation of class II force fields. I. Methodology and quantum force field for the alkyl functional group and alkane molecules (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 15 (1994), S. 162-182 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: A new method for deriving force fields for molecular simulations has been developed. It is based on the derivation and parameterization of analytic representations of the ab initio potential energy surfaces. The general method is presented here and used to derive a quantum mechanical force field (QMFF) for alkanes. It is based on sampling the energy surfaces of 16 representative alkane species. For hydrocarbons, this force field contains 66 force constants and reference values. These were fit to 128,376 quantum mechanical energies and energy derivatives describing the energy surface. The detailed form of the analytic force field expression and the values of all resulting parameters are given. A series of computations is then performed to test the ability of this force field to reproduce the features of the ab initio energy surface in terms of energies as well as the first and second derivatives of the energies with respect to molecular deformations. The fit is shown to be good, with rms energy deviations of less than 7% for all molecules. Also, although only two atom types are employed, the force field accounts for the properties of both highly strained species, such as cyclopropane and methylcyclopropanes, as well as unstrained systems. The information contained in the quantum energy surface indicates that it is significantly anharmonic and that important intramolecular coupling interactions exist between internals. The representation of the nature of these interactions, not present in diagonal, quadratic force fields (Class I force fields), is shown to be important in accounting accurately for molecular energy surfaces. The Class II force field derived from the quantum energy surface is characterized by accounting for these important intramolecular forces. The importance of each 4.2 to 18.2%. This fourfold increase in the second derivative error dramatically demonstrates the importance of bond anharmonicity in the ab initio potential energy surface. The Class II force field derived from the quantum energy surface is characterized by accounting for these important intramolecular forces. The importance of each of the interaction terms of the potential energy function has also been assessed. Bond anharmonicity, angle anharmonicity, and bond/angle, bond/torsion, and angle/angle/ torsion cross-term interactions result in the most significant overall improvement in distorted structure energies and energy derivatives. The implications of each energy term for the development of advanced force fields is discussed. Finally, it is shown that the techniques introduced here for exploring the quantum energy surface can be used to determine the extent of transferability and range of validity of the force field. The latter is of crucial importance in meeting the objective of deriving a force field for use in molecular mechanics and dynamics calculations of a wide range of molecules often containing functional groups in novel environments. © 1994 by John Wiley & Sons, Inc.
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    URL: http://dx.doi.org/10.1002/jcc.540150207
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    Darstellung und Struktur von Tetraethylcyclotetraarsoxan-Komplexen von Kupfer(I)-Halogeniden (1994)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 620 (1994), S. 334-342 
    Details
    ISSN: 0044-2313
    Keywords: Copper(I) halide complexes ; tetraethylcyclotetraarsoxane copper(I) complexes ; preparation ; crystal structure ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Preparation and Structure of Tetraethylcyclotetraarsoxane Complexes of Copper(I) HalidesThe polymeric complexes [Cu4Cl4{cyclo-(C2H5AsO)4}3]n (1), [Cu3Br3{cyclo-(C2H5AsO)4}2]n (2) and [Cu6I6{cyclo-(C2H5AsO)4}3]n (3) were prepared by the reaction of (C2H5AsO)n and CuX (X = Cl, Br, I) in acetonitrile and characterised by X-ray analysis. All three complexes contain only tetramers (C2H5AsO)4 as ligands, in which the As4O4 ring systems coordinate between two and four Cu-atoms. In each case one As4O4 ring with a crown-shaped conformation is observed, which coordinates either four (in 1) or three (in 2 and 3) axially sited Cu-atoms. In addition there are further (C2H5AsO)4 ligands, which display either a boat-chair- (in 1) or a twist-chair-conformation (in 1-3). The individual building units are connected to one another via Cu—X—Cu bridges (in 2 and 3) and/or centrosymmetric As4O4 ring systems (in 1-3) into chain (1) or layer structures (2 und 3).
    Notes: Die polymeren Komplexe [Cu4Cl4{cyclo-(C2H5AsO)4}3]n (1), [Cu3Br3{cyclo-(C2H5AsO)4}2]n (2) und [Cu6I6{cyclo-(C2H5AsO)4}3]n (3) wurden durch die Umsetzung von (C2H5AsO)n und CuX (X = Cl, Br, I) in Acetonitril dargestellt und durch Röntgenstrukturanalyse charakterisiert. Alle drei Komplexe enthalten lediglich Tetramere (C2H5AsO)4 als Liganden, wobei die As4O4-Ringsysteme zwischen zwei und vier Cu-Atomen koordinieren. Es wird jeweils ein As4O4-Ring mit Kronenkonformation beobachtet, der entweder vier (in 1) oder drei (in 2 und 3) Cu-Atome axial koordiniert. Außerdem liegen weitere (C2H5AsO)4-Liganden in boat-chair- (in 1) oder twist-chair-Konformation (in 1-3) vor. Die einzelnen Baueinheiten werden über Cu—X—Cu-Brücken (in 2 und 3) und/oder zentrosymmetrische As4O4-Ringsysteme (in 1-3) zu Ketten-(1) oder Schichtstrukturen (2 und 3) verknüpft.
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    URL: http://dx.doi.org/10.1002/zaac.19946200222
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    Über die Reaktion von Cp2TiCl2 mit [C(NMe2)3][(CO)4FeC(O)NMe2] - Kristallstruktur von [C(NMe2)3]2[FeCl4] (1994)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 620 (1994), S. 343-345 
    Details
    ISSN: 0044-2313
    Keywords: Hexamethyl guanidinium cation ; tetrachloro iron(II) anion ; crystal structure ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Concerning the Reaction of Cp2TiCl2 with [C(NMe2)3][(CO)4FeC(O)NMe2] - Crystal Structure of [C(NMe2)3]2[FeCl4]The title compound forms by the reaction of Cp2TiCl2 with [C(NMe2)3][(CO)4FeC(O)NMe2] in THF solution. It crystallizes in the space group Pbcn with a = 1 566.6(3); b = 976.4(2); c = 1 580.4(4) pm; Z = 4; R = 3.8%. Each [FeCl4]2- in is surrounded by eight cations. Two cations each are connected with one Cl atom by relatively short H … Cl contacts leading to a distortion of the tetrahedral geometry of the anion.
    Notes: Die Titelverbindung entsteht bei der Umsetzung von Cp2TiCl2 mit [C(NMe2)3][(CO)4FeC(O)NMe2] in THF-Lösung. Sie kristallisiert in der Raumgruppe Pbcn mit a = 1 566,6(3); b = 976,4(2); c = 1 580,4(4) pm; Z = 4; R = 3,8%. Jedes [FeCl4]2- Ion ist von acht Kationen umgeben. Je zwei Kationen sind über relativ kurze H … Cl Kontakte mit einem Cl-Atom verbunden, was zu einer Verzerrung der Tetraedergeometrie des Anions führt.
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/zaac.19946200223
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    Preparation and x-ray structure of 1,4,2,3,5,6-Dithiatetrazine (1994)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 620 (1994), S. 495-497 
    Details
    ISSN: 0044-2313
    Keywords: Dithiatetrazine ; synthesis ; crystal structure ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Darstellung und Röntgenstrukturanalyse von 1,4,2,3,5,6-DithiatetrazinDie Umsetzung von Schwefeldichlorid mit sym-EtO2CNHNHCO2Et 1 ergibt S2[N(CO2Et)]4 2, das analytisch, durch NMR und röntgenographisch charakterisiert wird. Die Strukturanalyse von 2 zeigt, daß der S2N4-Ring Sessel-Konformation hat mit allen vier Estergruppen in pseudoaxialen Positionen. Die Bindungslängen und -winkel werden mit denen in 1 und S4(NR)2 verglichen.
    Notes: Reaction of sulfur dichloride with sym-EtO2CNHNHCO2Et 1 gives the title ring system which has been characterised by microanalyses, nmr, and X-Ray crystallography. The X-ray structure of S2[N(CO2Et)]4 2 reveals that the S2N4 ring adopts a chair conformation with all four ester groups in pseudo-axial positions. Bond lengths and angles are compared with 1 and S4(NR)2.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/zaac.19946200316
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  • 73
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    o-1λ5,3λ5-Diphosphaphenylen-bis(diphenylphosphan) und seine chelatbildenden Eigenschaften (1994)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 620 (1994), S. 483-488 
    Details
    ISSN: 0044-2313
    Keywords: o-1λ5,3λ5-Diphosphaphenylene-bis(diphenylphosphane) ; nickel(II) chloride chelate complex ; crystal structure ; NMR, Ir spectra ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: o-1λ5,3λ5-Diphosphaphenylene-bis(diphenylphosphane) and its Chelating PropertiesBis(diphenylphosphanyl)acetylene and 1,1′,3,3′-tetrakis(dimethylamino)-1λ5,3λ5-diphosphete react at higher temperatures to yield the title compound 5, which forms easily the chelate complex 6 with nickel(II) chloride.
    Notes: Bis(diphenylphosphanyl)acetylen und 1,1′,3,3′-Tetrakis(dimethylamino)-1λ5,3λ5-diphosphet reagieren bei höheren Temperaturen zur Titelverbindung 5, die mit Nickel(II)-chlorid leicht den Chelatkomplex 6 bildet.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/zaac.19946200314
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  • 74
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    Pb3Al2F12: Crystal structure of a cyclo-fluoroaluminate related to Ba3Al2F12 (1994)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 620 (1994), S. 1449-1454 
    Details
    ISSN: 0044-2313
    Keywords: Lead fluoroaluminate ; preparation ; crystal structure ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Pb3Al2F12: Kristallstruktur eines mit zu Ba3Al2F12 verwandten cyclo-FluoroaluminatDas Fluoroaluminat Pb3Al2F12 wurde in Form von Einkristallen durch Hydrothermal-Synthese erhalten und kristallisiert monoklin in P 21/n mit a = 9,435(6) Å, b = 9,610(5) Å, c = 10,100(9) Å, β = 90,59(5)°, V = 915,7(2) Å3, Z = 4, MoKα, λ = 0,71073 Å, R = 0,0463, Rw = 0,0465, 3 044 symmetrieunabhängige gemessene Reflexe. Die Struktur zeigt tetramere, isolierte, von einem Unternetzwerk unabhängiger Fluoridpolyeder eingeschlossene Oktaeder und ist mit Ba3Al2F12 verwandt. Existenz und Struktur der A3M2F12-Verbindungen werden diskutiert.
    Notes: Pb3Al2F12 is a fluorometalate obtained in single-crystal form by hydrothermal synthesis. It crystallizes in the monoclinic system, space group P 21/n, with a = 9.435(6) Å, b = 9.610(5) Å, c = 10.100(9) Å, β = 90.59(5)°, V = 915.7(2) Å3, Z = 4. The structure was solved from single crystal using 3 044 unique reflections (MoKα, λ = 0.71073 Å), R = 0.0463, Rw = 0.0465. The structure exhibits isolated tetrameric groups of octahedra encaged in a subnetwork of independent fluoride polyhedra and is related to that of Ba3Al2F12. A discussion about the existence and the structure of A3M2F12 compounds is given.
    Additional Material: 5 Ill.
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    URL: http://dx.doi.org/10.1002/zaac.19946200822
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    Ein Beitrag über Ba3Pt4HgO11: Das erste Erdkalimetall-Oxoplatinat(II,V)/Oxomercurat (1994)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 620 (1994), S. 1471-1475 
    Details
    ISSN: 0044-2313
    Keywords: Barium, mercury, platinum, oxide ; crystal structure ; high pressure ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: A Contribution on Ba3Pt4HgO11: The First Alkaline-Earth Oxoplatinate(II,V)/OxomercurateSingle crystals of Ba3Pt4HgO11 were prepared by oxygen high pressure technique (4 200-3 600 bar) and investigated by X-ray methods. It crystallizes with hexagonal symmetry, space group D3h4—P62c, a = 6.021, c = 17.374 Å, Z = 2. Ba3Pt4HgO11 represents a new structure type, showing structural relationships to Ba2Hg3Pd7O14 and to the precious metal 6L-perovskites. The Hg2+ ions show dumb-bell like coordination, Pt2+ a square-planar surrounding and Pt5+ face shared double octahedra.
    Notes: Ba3Pt4HgO11 wurde unter hohem Sauerstoffdruck (4 200-3 600 bar) einkristallin dargestllt und röntgenographisch untersucht. Die Verbindung kristallisiert hexagonal, Raumgruppe D3h4—P62c mit a = 6,021; c = 17,374 Å; Z = 2. Ba3Pt4HgO11 bildet einen neuen Strukturtyp, der kristallchemische Verwandtschaft zu Ba2Hg3Pd7O14 und den Edelmetall-6L-Perowskiten zeigt. Die Hg2+-Ionen weisen eine hantelförmige, Pt2+ eine quadratisch-planare Koordination auf. Pt5+ bildet mit O2- flächenverknüpfte Doppeloktaeder.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/zaac.19946200825
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  • 76
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    Die Kristallstruktur von Tris(N,N-diethyl-N′-benzoylselenoureato)cobalt(III) (1994)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 620 (1994), S. 1479-1482 
    Details
    ISSN: 0044-2313
    Keywords: Tris(N,N-diethyl-N′-benzoylselenoureato)cobalt(III) ; preparation ; crystal structure ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: The Crystal Structure of Tris(N,N-diethyl-N′-benzoylselenoureato)cobalt(III)Co(C12H15N2OSe)3 crystallizes in the trigonal space group P3. The cell parameters are a = 16.697(4), c = 8.557(8) Å, Z = 2. The structure was solved with Patterson and direct methods and was refined to a final R-value of 4.59%. CoIII is bidentally coordinated to three N,N-diethyl-N′-benzoylselenourea molecules to form a distorted octahedron with facial arrangement of the selenium and oxygen donor atoms. The Co—Se and Co—O bond lengths are 2.328(2) and 1.943(6) Å, respectively. The arrangement of the molecules within the unit cell leads to the formation of hexagonal channels parallel to the crystallographic c-axis. The wall of the channels is formed by carbon atoms of the phenyl group. The diameter of the channels is 8.148 Å.
    Notes: Co(C12H15N2OSe)3 kristallisiert in der trigonalen Raumgruppe P3 mit den Gitterkonstanten a = 16,697(4), c = 8,557(8) Å, Z = 2. Die Struktur wurde mit Patterson und Direkten Methoden gelöst und bis zu einem R-Wert von 4,59% verfeinert. CoIII bildet mit dem Liganden N,N-Diethyl-N′-benzoylselenoharnstoff einen oktaedrisch koordinierten Neutralkomplex, in dem drei Ligandmoleküle in facialer Anordnung bidental über Selen- und Sauerstoffatome an das Zentralatom gebunden sind. Der Co—Se-Abstand beträgt 2,328(2) Å, der Co—O-Abstand 1,943(6) Å. Die Anordnung der Komplexmoleküle in der Elementarzelle führt zur Ausbildung von hexagonalen Kanälen parallel zur kristallographischen c-Achse. Die Kanalwände werden von Kohlenstoffatomen der Phenylreste gebildet; der Durchmesser der Kanäle beträgt 8,148 Å.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/zaac.19946200827
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    Hydrate schwacher und starker Basen. XI. Die Kristallstrukturen von NaOH · 3,5H2O und NaOH · 7 H2O. Eine PräzisierungProfessor Horst Sabrowsky zum 60. Geburtstage gewidmet (1994)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 620 (1994), S. 1509-1513 
    Details
    ISSN: 0044-2313
    Keywords: Sodium hydroxide hydrates ; crystal structure ; hydrogen bonding ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Hydrates of Weak and Strong Bases. XI. The Crystal Structures of NaOH · 3,5H2O and NaOH · 7 H2O. A RefinementThe crystal structures of the hydrates NaOH · 3,5 H2O (space group P21/c, Z = 8 formula units per unit cell; lattice parameters: a = 6.481, b = 12.460, c = 11.681 Å, β = 104.12° at -100°C) and NaOH · 7 H2O (P21/c, Z = 4; a = 7.344, b = 16.356, c = 6.897 Å, β = 92.91° at -150°C) have been redetermined using MoKα diffractometer data. The obtained refinement of the structures, including the localization also of the H atoms for the first time, has led to new findings with respect to the H bonds. In particular, in both hydrates there is one such interaction of the rare type OH- … OH2, from an OH- ion to an H2O molecule, i. e. with the OH- ion as the proton donor.
    Notes: Die Kristallstrukturen der Hydrate NaOH · 3,5H2O (Raumgruppe P21/c, Z = 8 Formeleinheiten pro Elementarzelle; Gitterkonstanten a = 6,481, b = 12,460, c = 11,681 Å, β = 104,12° bei -100°C) und NaOH · 7 H2O (P21/c, Z = 4; a = 7,344, b = 16,356, c = 6,897 Å, β = 92,91° bei -150°C) wurden mit MoKα-Diffraktometerdaten einer Zweitbestimmung unterzogen. Die erreichte Präzisierung der Strukturen, einschließlich der erstmaligen Lokalisierung auch der H-Atome, führte zu neuen Erkenntnissen bezüglich der H-Brücken. Insbesondere gibt es in beiden Hydraten eine solche Wechselwirkung vom seltenen Typ OH- · OH2, von einem OH--Ion zu einem H2O-Molekül, also mit dem OH--Ion als Protondonor.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/zaac.19946200903
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    Neue Silicate mit „Stuffed Pyrgoms“: CsKNaLi9{Li[SiO4]}4, CsKNa2Li8{Li[SiO4]}4, RbNa3Li8{Li[SiO4]}4 [1] und RbNaLi4{Li[SiO4]}2 [2]Professor Horst Sabrowsky zum 60. Geburtstage gewidmet (1994)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 620 (1994), S. 1495-1508 
    Details
    ISSN: 0044-2313
    Keywords: New Lithosilicates ; preparation ; crystal structure ; MAPLE and CHARDI calculations ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: More Silicates with „Stuffed Pyrgoms“: CsKNaLi9{Li[SiO4]}4, CsKNa2Li8{Li[SiO4]}4, RbNa3Li8{Li[SiO4]}4 [1] and RbNaLi4{Li[SiO4]}2 [2]Single crystals of the new silicates CsKNaLi9{Li[SiO4]}4, CsKNa2Li8{Li[SiO4]}4, RbNa3Li8{Li[SiO4]}4 and RbNaLi4{Li[SiO4]}2 as well as powder (Rb-containing compounds only) were obtained for the first time. The samples were prepared by heating well ground mixtures of the binary oxides in Ni and Ag tubes, respectively. The structure determination was carried out by four-circle diffractometer data (MoKα radiation; Siemens AED 2):CsKNaLi9{Li[SiO4]}4: tetragonally prismatic crystals, light yellow; 726 I0(hkl), R = 4.4%, Rw = 2.8%; a = 1 102.0(6), c = 637.9(5) pm; Z = 2; space group I4/m; 2 CsO0.55 + Li4TlO4 + glas (560°C, 15 d).CsKNa2Li8{Li[SiO4]}4: tetragonally prismatic crystals, light yellow; 727 I0(hkl), R = 4.4%, Rw = 2.6%; a = 1 103.5(7), c = 637.7(4) pm; Z = 2; space group I4/m; 1.1 CsO0.61 + 1.1 KO0.55 + 1.4 NaO0.52 + 6.5 Li2O + 4 SiO2 (600°C, 60 d).RbNa3Li8{Li[SiO4]}4: tetragonally prismatic crystals, colourless; 600 I0(hkl), R = 2.3%, Rw = 2.0%; a = 1 092.08(6), c = 632.76(4) pm; Z = 2; space group I4/m; 4 RbO0.57 + 3 NaO0.52 + 6.5 Li2O + 4 SiO2 (650°C, 63 d).RbNaLi4{Li[SiO4]}2: monoclinic, ball-shaped, colourless; 1 224 I0(hkl), R = 3.1%, Rw = 3.1%; a = 1 573.10(13), b = 630.48(5), c = 781.25(8) pm, b = 90.566(8)°; Z = 4; space group C2/m; 1.1 RbO0.52 + 1.2 NaO0.45 + 5 Li2O + 4 SiO2 (700°C, 40 d).
    Notes: Einkristalle der neuen Silicate CsKNaLi9{Li[SiO4]}4, CsKNa2Li8{Li[SiO4]}4, RbNa3Li8{Li[SiO4]}4 und RbNaLi4{Li[SiO4]}2, sowie Pulver der Rb-haltigen Verbindungen wurden dargstellt. Die Proben entstanden durch Tempern inniger Gemenge binärer Oxide in geschlossenen Ni- bzw. Ag-Bömbchen. Die Strukturaufklärung erfolgte jeweils durch Vierkreisdiffraktometerdaten (MoKα-Strahlung; Siemens AED 2):CsKNaLi9{Li[SiO4]}4: tetragonale Prismen, hellgelb; 726 I0(hkl), R = 4,4%, Rw = 2,8%; a = 1 102,0(6), c = 637,9(5) pm; Z = 2; Raumgruppe I4/m; 2 CsO0,55 + LiTlO4 + Duran-Glas (560°C, 15 d).CsKNa2Li8{Li[SiO4]}4: tetragonale Prismen, hellgelb; 727 I0(hkl), R = 4,4%, Rw = 2,6%; a = 1 103,5(7), c = 637,7(4) pm; Z = 2; Raumgruppe I4/m; 1,1 CsO0,61 + 1,1 KO0,55 + 1,4 NaO0,52 + 6,5 Li2O + 4 SiO2 (600°C, 60 d).RbNa3Li8{Li[SiO4]}4: tetragonale Prismen, farblos; 600 I0(hkl), R = 2,3%, Rw = 2,0%; a = 1 092,08(6), c = 632,76(4) pm; Z = 2; Raumgruppe I4/m; 4 RbO0,57 + 3 NaO0,52 + 6,5 Li2O + 4 SiO2 (650°C, 63 d).RbNaLi4{Li[SiO4]}2: monoklin, kugelförmig, farblos; 1 224 I0(hkl), R = 3,1%, Rw = 3,1%; a = 1 573,10(13), b = 630,48(5), c = 781,25(8) pm, b = 90,566(8)°; Z = 4; Raumgruppe C2/m; 1,1 RbO0,52 + 1,2 NaO0,45 + 5 Li2O + 4 SiO2 (700°C, 40 d)
    Additional Material: 17 Ill.
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    URL: http://dx.doi.org/10.1002/zaac.19946200902
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    Cs[Er10(C2)2]I18 und [Er10(C2)2]Br18: zwei neue Beispiele für „reduzierte“ Halogenide der Lanthanide mit isolierten [M10(C2)2]-Clustern (1994)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 620 (1994), S. 1532-1536 
    Details
    ISSN: 0044-2313
    Keywords: Erbium Clusters, [Er10(C2)2] ; crystal structure ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Cs[Er10(C2)2]I18 and [Er10(C2)2]Br18: Two New Examples for Reduced Halides of the Lanthanides with Isolated [M10(C2)2] ClustersCs[Er10(C2)2]I18 is obtained from the reaction of ErI3 with caesium and carbon in sealed tantalum containers at 700°C and [Er10(C2)2]Br18 through the metallothermic reduction of ErBr3 with rubidium in the presence of carbon at 750°C in sealed niobium containers. The crystal structures {Cs[Er10(C2)2]I18: triclinic, P1; a = 1 105.2(8) pm, b = 1 112.0(7) pm; c = 1 122.9(8) pm; α = 66.91(3)°, β = 87.14(3)°; γ = 60.80(3)°; Z = 1; R = 0.049, Rw = 0.043; [Er10(C2)2]Br18: monoclinic, P21/n, a = 971.8(6) pm, b = 1 623.4(9) pm, c = 1 163.8(6) pm, β = 104.00(6)°; Z = 2; R = 0.077, Rw = 0.057} contain isolated dimeric [Er10(C2)2] clusters. Due to the inclusion of C2 units, the octahedra are elongated in the direction of the pseudo C4 axis. The connecting edges of the two octahedra are exceptionally short (316.7 pm and 314.8 pm respectively). The dimeric units are connected via Xi-a and Xa-i (X = Br, I) bridges according to [Er10(C2)2X10iX8/2i-a]X8/2a-i. Cs+ is surrounded by a cuboctahedron of iodide ions in Cs[Er10(C2)2]I18.
    Notes: Cs[Er10(C2)2]I18 entsteht bei der Umsetzung von Erl3 mit Caesium und Kohlenstoff in verschweißten Tantalampullen bei 700°C, [Er10(C2)2]Br18 bei der metallothermischen Reduktion von ErBr3 mit Rubidium in Gegenwart von Kohlenstoff bei 750°C in verschweißten Niobampullen. Die Kristallstrukturen {Cs[Er10(C2)2]I18: triklin, P1; a = 1 105,2(8) pm; b = 1 112,0(7) pm; c = 1 122,9(7) pm; α = 66,91(3)°; β = 87,14(3)°; γ = 60,80(3)°; Z = 1; R = 0,049, Rw = 0,043; [Er10(C2)2]Br18: monoklin, P21/n; a = 971,8(6); b = 1 623,4(9); c = 1 163,8(6); β = 104,00(6)°; Z = 2; R = 0,077, Rw = 0,057} beinhalten isolierte dimere [Er10(C2)2]-Cluster. Wegen des Einbaus der C2-Hantel sind die Oktaeder entlang ihrer pseudovierzähligen Achse gestreckt. Die verknüpfenden Oktaederkanten weisen einen besonders kurzen Metall-Metall-Abstand auf (316,7 bzw. 314,8 pm). Die dimeren Einheiten sind über Xi-a bzw. Xa-i-Brücken (X = Br, I) miteinander verknüpft, gemäß [Er10(C2)2X10iX8/2i-a]X8/2a-i. Cs+ ist in Cs[Er10(C2)2]I18 kuboktaederisch von Iodidionen umgeben.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/zaac.19946200907
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    Zur Oxydation intermetallischer Phasen: Die Oxoplumbate(II) K6[Pb2O5] [1] und K4[PbO3] [2] (1994)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 620 (1994), S. 1549-1558 
    Details
    ISSN: 0044-2313
    Keywords: Potassium plumbates ; preparation ; crystal structure ; MAPLE and CHARDI calculations ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: On the Oxidation of Intermetallic Phases: The Oxoplumbates(II) K6[Pb2O5] [1] and K4[PbO3] [2]Very pale yellow crystals of K6[Pb2O5] were obtained by heating a wellground mixture of LiPb und K2O2 (K2O2: LiPb = 2.5:1) in Ag-tubes (550°C; 40 d). The crystal structure, triclinic, space group P1, a = 1 326.7(6); b = 758.8(4); c = 637.0(3) pm; α = 92.17(3)°; β = 94.41(3)°; γ = 112.85(4)°; Z = 2 was determined (four-circle diffractometer data, Mo—Kα-, 3 270 Io(hkl), R = 8.0%, Rw = 3.5%, parameters see text). The pale yellow crystals of K4[PbO3] were received by heating KPb and K2O2 (K2O2: KPb = 3.3:2) in Ni-tubes (450°C; 17 d). The crystal structure (orthorhombic, space group Pbca with a = 658.2(1); b = 1 131.8(4); c = 1 872.2(6) pm; Z = 8) was refined (four-circle diffractometer data, Mo—Kα-, 2 003 Io(hkl), R = 4.9%, Rw = 2.8%).The Madelung Part of Lattice Energy (MAPLE), Effective Coordination Numbers (ECoN), the Mean Fictive Ionic Radii (MEFIR) and the Charge Distribution (CHARDI) are being calculated for both oxides.
    Notes: Äußerst schwach hellgelbe Kristalle von K6[Pb2O5] entstanden beim Tempern inniger Gemenge von LiPb und K2O2 (K2O2: LiPb = 2,5:1) in Ag-Bömbchen (550°C; 40 d). Die Kristallstruktur, triklin, Raumgruppe P1 (I.T. No. 2), mit a = 1 326,7(6); b = 758,8(4); c = 637,0(3) pm; α = 92,17(3)°; β = 94,41(3)°; γ = 112,85(4)°; Z = 2 wurde aufgeklärt (Vierkreisdiffraktometerdaten, Mo—Kα-, 3 270 Io(hkl), R = 8,0%, Rw = 3,5%, Parameter siehe Text). Die blaß gelben Kristalle von K4[PbO3] entstanden beim Tempern von KPb mit K2O2 (K2O2: KPb = 3,3:2) in Ni-Bömbchen (450°C; 17 d). Die Kristallstruktur (orthorhombisch, Raumgruppe Pbca, a = 658,2(1); b = 1131,8(4); c = 1872,2(6) pm; Z = 8) wurde verfeinert (Vierkreisdiffraktometerdaten, Mo—Kα-, 2 003 Io(hkl), R = 4,9%, Rw = 2,8%).Für beide Oxide werden der Madelunganteil der Gitterenergie (MAPLE), Effektive Koordinationszahlen (ECoN), die Mittleren Fiktiven Ionenradien (MEFIR) sowie die Ladungsverteilung (CHARDI) berechnet.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19946200910
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  • 81
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    Ein weiteres Alkali-Erdalkalimetall-Oxoniccolat mit Perowskitstruktur: Sr12NaNi7O23 (1994)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 620 (1994), S. 1565-1568 
    Details
    ISSN: 0044-2313
    Keywords: Strontium, sodium, nickel, oxide ; crystal structure ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Another Alkaline Alkaline-Earth Oxoniccolate of Perovskite Type Structure: Sr12NaNi7O23Single Crystals of Sr12NaNi7O23 were prepared in closed system by Na2O2 flux reaction. X-ray single crystal work show hexagonal symmetry, space group D32-P321, a = 9.429, c = 7.896 Å, Z = 1. Sr12NaNi7O23 is strongly related to the stackered perovskites containing consequently face shared Ni2O9 double octahedra and Na+ inside a trigonal prismatic coordination by oxygen. One underoccupied oxygen point position decreases the coordination number of one Ni3+ of the Ni2O9 groups and a second surrounded by trigonal prisms to corner connected Ni2O7 double tetrahedra. The crystal chemistry will be discussed with respect to compounds of the same structure.
    Notes: Einkristalle von Sr12NaNi7O23 wurden im geschlossenen System mit Na2O2 als Schmelzmittel dargestellt. Röntgenographische Untersuchungen zeigen hexagonale Symmetrie, Raumgruppe D32-P321; a = 9,429; c = 7,896 Å, Z = 1. Sr12NaNi7O23 ist eng mit den Stapelvarianten der Perowskite verwandt und zeigt flächenverknüpfte Ni2O9-Oktaederdoppel sowie Na+ in einer trigonal prismatischen Koordination von Sauerstoff. Eine unterbesetzte Sauerstofflage erniedrigt die Koordinationszahl von einem Ni3+-Ion in den Ni2O9-Gruppen und von einem weiteren in trigonal prismatischer Koordination. Es entstehen eckenverknüpfte Ni2O7- Doppeltetraeder. Die Kristallchemie wird mit Blick auf Verbindungen vom gleichen Strukturtyp diskutiert.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/zaac.19946200912
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  • 82
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    Ein neues Kupferzinnboratoxid mit isolierten BO3-Baugruppen: Cu5Sn(BO3)2O4 (1994)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 620 (1994), S. 1578-1582 
    Details
    ISSN: 0044-2313
    Keywords: Copper, tin, borate, oxide ; synthesis ; crystal structure ; X-ray diffraction ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: On a New Copper Tin Borate Oxide with Isolated BO3 Units: Cu5Sn(BO3)2O4Single Crystals of the new compound Cu5Sn(BO3)2O4 were obtained by a B2O3 fluxtechnique. They crystallize in a monoclinic distorted variant of a Ludwigite structure with a partly ordered metal distribution. X-ray investigations on single crystals led to the space group C2h5-P21/c (No. 14); a = 6.3526(7); b = 9.502(1); c = 12.100(9) Å; β = 93.30(3)°; Z = 4. All metal-sites are distorted octahedraly coordinated by oxygen-ions. The structure contains BO3-units and oxygen which is not coordinated to boron.
    Notes: Aus einer B2O3-Schmelze gelang die Synthese von Einkristallen der Substanz Cu5Sn(BO3)2O4, die in einer monoklin verzerrten Strukturvariante eines Ludwigites mit weitgehend geordneter Metallverteilung kristallisiert. Röntgenographische Untersuchungen an Einkristallen ergeben die Raumgruppe C2h5-P21/c (Nr. 14); a = 6,3526(7); b = 9,502(1); c = 12,100(9) Å; β = 93,30(3)°; Z = 4. Die Metallkationen sind verzerrt oktaedrisch von Sauerstoffionen koordiniert. Die Struktur weist sowohl isolierte, planare BO3-Baugruppen als auch nicht an Bor gebundenen Sauerstoff auf.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19946200914
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  • 83
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    Synthese und Kristallstrukturen von (PPh4)2[In(S4)(S6)Cl] und (PPh4)2[In(S4)Cl3] (1994)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 620 (1994), S. 1607-1612 
    Details
    ISSN: 0044-2313
    Keywords: Indium polysulfido complexes ; preparation ; crystal structure ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthesis and Crystal Structures of (PPh4)2[In(S4)(S6)Cl] and (PPh4)2[In(S4)Cl3]InCl and PPh4Cl yield (PPh4)2[In2Cl6] in acetonitrile. This reacts with Na2S4 in presence of PPh4Cl, forming (PPh4)2[In(S4)(S6)Cl]. Its crystal structure was determined by X-ray diffraction (R = 0.075, 2 282 observed reflexions). It is isotypic with (PPh4)2[In(S4)(S6)Br] and contains anions with trigonal-bipyramidal coordination of In, Cl occupying an axial position, and the S4 and S6 groups being bonded in a chelate manner. The reaction of (PPh4)2[In2Cl6] and sulfur in acetonitrile yielded (PPh4)2[InCl5] and (PPh4)2[In(S4)Cl3]. The crystal structure analysis of the latter (R = 0.072, 4 080 reflexions) revealed an anion with distorted trigonal-bipyramidal coordination of In, the S4 group occupying one axial and one equatorial position; the S4 group shows positional disorder.
    Notes: Aus InCl und PPh4Cl entsteht in Acetonitril (PPh4)2[In2Cl6]. Aus diesem wurde mit Na2S4 im Beisein von PPh4Cl (PPh4)2[In(S4)(S6)Cl] erhalten. Seine Kristallstruktur wurde mittels Röntgenbeugung bestimmt (R = 7,5%, 2 282 beobachtete Reflexe). Es kristallisiert isotyp zum (PPh4)2[In(S4)(S6)Br] und enthält Anionen mit trigonal-bipyramidaler Koordination des In; das Cl-Atom nimmt eine axiale Position ein und die S4- und S6-Gruppe ist jeweils chelatartig gebunden. Aus (PPh4)2[In2Cl6], PPh4Cl und Schwefel entstanden in Acetonitril (PPh4)2[InCl5] und (PPh4)2[In(S4)Cl3]. Nach der Kristallstruktur des letzteren (R = 7,2%, 4 080 Reflexe) ist im [In(S4)Cl3]2--Ion das In-Atom verzerrt trigonal-bipyramidal koordiniert, wobei die S4-Gruppe an eine axiale und eine equatoriale Position gebunden ist; die S4-Gruppe ist fehlgeordnet.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19946200919
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  • 84
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    Verfeinerung der Kristallstruktur von SrO2 (1994)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 620 (1994), S. 879-881 
    Details
    ISSN: 0044-2313
    Keywords: Strontium peroxide ; crystal structure ; composition ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Refinement of the Crystal Structure of SrO2Single crystals of SrO2 have been obtained after high pressure/high temperature reaction of a SrO/KClO3 mixture at 20 kbar, 1 400°C. The crystal structure was refined using 154 unique diffractometer data (I4/mmm; a = 3.5626(3), c = 6.6159(6) Å; Z = 2; R = 0.033, Rw = 0.022, S = 0.932). The O—O distance (1.493(4) Å) is significantly longer than the one previously assumed. From a refinement of the site occupation factor for oxygen a composition SrO1.95(2) has been found for the crystal investigated.
    Notes: Einkristalle von SrO2 wurden durch Hochdruck-Hochtemperatur-Reaktion eines SrO—KClO3-Gemisches bei 20 kbar, 1 400°C erhalten. Die Kristallstruktur wurde auf der Basis von Vierkreisdiffraktometerdaten (154 unabhängige Strukturfaktoren) verfeinert (I4/mmm; a = 3,5626(3), c = 6,6159(6) Å; Z = 2; R = 0,033, Rw = 0,022, S = 0,932). Der gefundene O—O-Abstand ist mit 1,493(4) Å deutlich größer als bisher angenommen. Eine Verfeinerung des Besetzungsfaktors von Sauerstoff ergab für den untersuchten Kristall eine Zusammensetzung SrO1,95(2).
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19946200521
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  • 85
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    Darstellung und Kristallstruktur von K6[Al2O6] und Rb6[Al2O6]Professor Heinz Dieter Lutz zum 60. Geburtstage gewidmet (1994)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 620 (1994), S. 882-887 
    Details
    ISSN: 0044-2313
    Keywords: K6[Al2O6], Rb6[Al2O6] ; preparation ; crystal structure ; MAPLE ; CHARDI ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Preparation of Crystal Structure of K6[Al2O6] and Rb6[Al2O6]Colourless single crystals of K6[Al2O6] have been prepared from intimate mixtures of KAlO2 and K2O (550°C, 90 d). The structure determination from four-circle diffractometer data (MoKα, 742 Io(hkl), R = 2.2%, Rw = 2.1%) confirms the space group C2/m with Z = 2; a = 698.25 pm, b = 1 103.54 pm, c = 646.49 pm, β = 102.49°.Colourless single crystals of hitherto unknown Rb6[Al2O6] have been prepared from intimate mixtures of RbAlO2 and Rb2O (520°C, 120 d). The structure determination from four-circle diffractometer data (MoKα, 1 240 Io(hkl)) results in the residual values R = 7.2%, Rw = 4.9%; space group C2/m; a = 725.92 pm, b = 1 143.33 pm, c = 678.06 pm, β = 104.05°; Z = 2.K6[Al2O6] and Rb6[Al2O6] are isostructural with K6[Fe2O6]. A characteristic structure unit is the anion [Al2O6]6- consisting of two edge-sharing [AlO4] tetrahedra.Effective Coordination Numbers (ECoN), Mean Fictive Ionic Radii (MEFIR), the Madelung Part of Lattice Energy (MAPLE) and the Charge Distribution (CHARDI) are calculated and discussed.
    Notes: Farblose Einkristalle von K6[Al2O6] wurden aus innigen Gemengen von KAlO2 und K2O erhalten (550°C, 90 d). Die Strukturaufklärung (Vierkreisdiffraktometer, MoKα, 742 Io(hkl), R = 2,2%, Rw = 2,1%) bestätigt die Raumgruppe C2/m mit Z = 2; a = 698,25 pm, b = 1 103,54 pm, c = 646,49 pm, β = 102,49°.Analog erhielten wir erstmals Rb6[Al2O6] aus RbAlO2 und Rb2O in Form farbloser Einkristalle (520°C, 120 d). Die Strukturaufklärung (Vierkreisdiffraktometer, MoKα, 1 240 Io(hkl)) ergab in C2/m die Residualwerte R = 7,2%, Rw = 4,9%; a = 725,92 pm, b = 1 143,33 pm, c = 678,06 pm, β = 104,05°.K6[Al2O6] und Rb6[Al2O6] sind mit K6[Fe2O6] isotyp; charakteristische Strukturelemente sind die Anionen [Al2O6]6-, die aus zwei kantenverknüpften [AlO4]-Tetraedern bestehen.Effektive Koordinationszahlen (ECoN), Mittlere Fiktive Ionenradien (MEFIR), der Madelunganteil der Gitterenergie (MAPLE) sowie die Ladungsverteilung (CHARDI) werden berechnet und diskutiert.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19946200522
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  • 86
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    Die Kristallstruktur von Bis(N,N-diethyl-N′ -benzoylselenoureato)nickel(II)Professor Hans Bock zum 65. Geburtstage gewidmet (1994)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 620 (1994), S. 177-182 
    Details
    ISSN: 0044-2313
    Keywords: Bis(N,N-diethyl-N′-benzoylselenoureato)nickel(II) ; crystal structure ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: The Crystal Structure of Bis(N,N-diethyl-N′ -benzoylselenoureato)nickel(II)Ni(C12H15N2OSe)2 crystallizes in the monoclinic space group P21/c. The cell parameters are a = 11.399(3), b = 16.016(4), c = 14.910(6) Å, β = 104.64(3)° and Z = 4. The structure was solved with Patterson and direct methods and was refined to a final R-value of 5.43%. Nickel is coordinated to two N,N-diethyl-N′ -benzoylselenourea molecules to form a bidentally coordinated chelate complex with cis arrangement of the donor atoms. Coordinaton around the nickel atom is planar while the chelate rings diverge from planarity. The ethyl groups of one diethylamino group are disordered. The Ni—Se bond lengths are 2.244(1) and 2.264(1) Å, the Ni—O bond lengths are 1.871(4) and 1.883(4) Å, respectively.
    Notes: Ni(C12H15N2OSe)2 kristallisiert in der monoklinen Raumgruppe P21/c mit den Gitterkonstanten a = 11,399(3), b = 16,016(4), c = 14,910(6) Å, β = 104,64(3)°, Z = 4. Die Struktur wurde mit Patterson und Direkten Methoden gelöst und bis zu einem R-Wert von 5,43% verfeinert. Nickel bildet mit dem Liganden N,N-Diethyl-N′-benzoylselenoharnstoff einen bidental koordinierten Chelatkomplex, in dem zwei Ligandmoleküle über Selen- und Sauerstoffatome in cis-Anordnung an das Zentralatom koordiniert sind. Die Koordinationssphäre um das Nickelatom ist planar, die Chelatringe weichen dagegen deutlich von der Planarität ab. Die Ethylgruppen einer Diethylaminogruppe sind fehlgeordnet. Die Ni—Se-Abstände betragen 2,244(1) und 2,264(1) Å, die Ni—O-Abstände 1,871(4) und 1,883(4) Å.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19946200129
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  • 87
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    CdHgO2: Ein Oxomercurat mit Verwandtschaft zur Crednerit-StrukturProfessor Wilhelm Preetz zum 60. Geburtstage gewidmet (1994)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 620 (1994), S. 1137-1141 
    Details
    ISSN: 0044-2313
    Keywords: Cadmium ; mercury ; oxide ; high pressure ; crystal structure ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: CdHgO2: An Oxomercurate related to the Crednerite StructureSingle crystals of CdHgO2 were prepared by oxygen high pressure technique (600°C, 3900 bar) and investigated by X-ray technique. It crystallizes with monoclinic symmetry, space group C2h3-C2/m; a = 5.933, b = 3.452, c = 5.875 Å, β = 91.26°; Z = 2. The Hg2+ ions show dumb-bell like coordination, Cd2+ an octahedral one. CdHgO2 shows strong relationship to the Crednerite structure. The orientation of the O—Hg—O dump-bells to the CdO6 octahedra layers is discussed with respect to related oxomercurates.
    Notes: CdHgO2 wurde mit Sauerstoff-Hochdrucktechnik (600°C, 3900 bar) einkristallin dargestellt und röntgenographisch untersucht. Es kristallisiert monoklin, Raumgruppe C2h3-C2/m mit a = 5,933, b = 3,452, c = 5,875 Å, β = 91,26° und Z = 2. Die Hg2+-Ionen zeigen eine hantelförmige, Cd2+ eine oktaedrische Koordination. CdHgO2 zeigt große Ähnlichkeit zur Crednerit-Struktur. Die Anordnung der O—Hg—O-Hanteln zu den CdO6-Oktaederschichten wird unter Bezug auf verwandte Oxomercurate diskutiert.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19946200702
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  • 88
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    Cu3SbS3: Zur Kristallstruktur und PolymorphieProfessor Heinz Dieter Lutz zum 60. Geburtstag gewidmet (1994)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 620 (1994), S. 1992-1997 
    Details
    ISSN: 0044-2313
    Keywords: Copper antimony sulfide ; sulfo salts ; crystal structure ; phase transitions ; Extended Hückel calculations ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Cu3SbS3: Crystal Structure and PolymorphismThe hitherto unknown crystal structure of β-Cu3SbS3 at room temperature could be determined from a twinned crystal. The compound crystallizes in the monoclinic system, space group P21/c (No. 14), with a = 7.808(1), b = 10.233(2) and c = 13.268(2) Å, β = 90.31(1)°, V = 1 060.1(2) Å3, Z = 8. An Extended-Hückel-Calculation shows weak bonding interactions between copper atoms which are coordinated trigonal planar. At -9°C a first order phase transition occurs and the crystals disintegrate. The low-temperature modification (γ) crystallizes in the orthorhombic system with a = 7.884(2), b = 10.219(2) and c = 6.623(2) Å, V = 533.6(2) Å3 (-100°C). At 121°C a phase transition of higher order is observed. The high-temperature polymorph (α) of Cu3SbS3 is orthorhombic again. From high-temperature precession photographs the space groups Pnma (No. 62) or Pna21 (No. 33) can be derived. The lattice constants at 200°C are a = 7.828(3), b = 10.276(4) and c = 6.604(3) Å, V = 531.2(2) Å3.
    Notes: Die bisher unbekannte Kristallstruktur von β-Cu3SbS3 bei Zimmertemperatur wurde anhand eines verzwillingten Kristalls ermittelt. Die Verbindung kristallisiert monoklin, RG P21/c (Nr. 14) mit a = 7,808(1), b = 10,233(2) und c = 13,268(2) Å, β = 90,31(1)°, V = 1 060,1(2) Å3, Z = 8. Eine Extended-Hückel-Rechnung ergibt schwach bindende Wechselwirkungen zwischen den trigonal-planar koordinierten Kupferatomen. Bei -9°C erfolgt eine reversible Phasenumwandlung 1. Ordnung, bei der die Kristalle zerfallen. Die Tieftemperaturmodifikation (γ) kristallisiert orthorhombisch mit a = 7,884(2), b = 10,219(2) und c = 6,623(2) Å, V = 533,6(2) Å3 (-100°C). Beim Aufheizen beobachtet man bei 121°C eine Phasenumwandlung höherer Ordnung. Die Hochtemperaturmodifikation (α) von Cu3SbS3 kristallisiert ebenfalls orthorhombisch. Aus Hochtemperatur-Präzessionsaufnahmen ergibt sich Pnma (Nr. 62) oder Pna21 (Nr. 33) als mögliche Raumgruppe. Die Gitterkonstanten bei 200°C sind nach Guinier-Aufnahmen a = 7,828(3), b = 10,276(4) und c = 6,604(3) Å, V = 531,2(2) Å3.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19946201126
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  • 89
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    Li10Si2PbIIO10 = Li20[(SiO4)4(OPbO2PbO)]  -  Das erste „gemischte“ Silicat-Plumbat(II)Professor Kurt Issleib in memoriam (1994)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 620 (1994), S. 2026-2032 
    Details
    ISSN: 0044-2313
    Keywords: Lithium silicate plumbate ; preparation ; crystal structure ; MAPLE and CHARDI calculations ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Li10Si2PbIIO10 = Li20[(SiO4)4(OPbO2PbO)]  -  The first „mixed“ Silicate-Plumbate(II)Colourless crystals of Li10Si2PbO10 were obtained by heating a well-ground mixture of LiPb, Li2O2 and „SiO2“ (deriving from Duran glas) in Ag-tubes (650°C; 60 d). The crystal structure was determined (four-circle diffractometer data, Mo—Kα-, 1 474 Io(hkl), R = 4.2%, Rw = 2.8%, parameters see text). The silicate-plumbate crystallizes monoclinic (space group C2/m; I. T. No. 12) with a = 2985.1(4); b = 610.6(6); c = 512.8(1) pm, β = 99.70(9)° (four-circle data), Z = 4.Further the Madelung Part of Lattice Energy (MAPLE), Effective Coordination Numbers (ECoN), the Mean Fictive Ionic Radii (MEFIR) and the Charge Distribution (CHARDI) are being calculated.
    Notes: Farblose Kristalle von Li10Si2PbO10 entstanden beim Tempern inniger Gemenge von LiPb, Li2O2 und „SiO2“ (aus Duranglas) in Ag-Bömbchen (650°C; 60 d). Die Kristallstruktur wurde aufgeklärt (Vierkreisdiffraktometerdaten, Mo—Kα-, 1 474 Io(hkl), R = 4,2%, Rw = 2,8%, Parameter siehe Text). Das Silicat-Plumbat kristallisiert monoklin (Raumgruppe C2/m; I. T. No. 12) mit a = 2 985,1(4); b = 610,6(1); c = 512,8(1) pm; β = 99,70(9) (Vierkreisdaten), Z = 4.Ferner werden der Madelunganteil der Gitterenergie (MAPLE), Effektive Koordinationszahlen (ECoN), die Mittleren Fiktiven Ionenradien (MEFIR) sowie die Ladungsverteilung (CHARDI) berechnet.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19946201203
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  • 90
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    Electronic Resource
    Neue Rheniumkomplexe mit Trichalkogenido- und Tetrachalkogenido-Chelatliganden (1994)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 620 (1994), S. 299-303 
    Details
    ISSN: 0044-2313
    Keywords: Rhenium complexes ; rhenium trichalcogenido, -tetrachalcogenido complexes ; preparation ; crystal structure ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: New Rhenium Complexes Containing Trichalcogenido and Tetrachalcogenido Chelate LigandsThe reactions of Cp*ReCl4 with polychalcogenide salts such as Na2S4 or (NEt4)2Se6 lead initially to the violet trichalcogenido chelate complexes Cp*ReCl2(E3) (E = S (3a), Se (3b)) which, due to their functional chloro ligands, can be used as intermediates for further reactions. Upon hydrolysis in moist solvents or aminolysis with tert. butylamine 3a, b are converted into the tetrachalcogenido chelate complexes Cp*Re(O)(E4) (E = S (4a), Se (4b)) and Cp*Re(NtBu)(E4) (E = S (5a), Se (5b)), respectively. X-Ray structure analyses were carried out for the three mononuclear cyclo-oligoselenido compounds 3b-5b. It appears that the size of the Se2-n chelate ring (n = 3 or 4) essentially depends on steric factors within the coordination sphere of rhenium.
    Notes: Die Reaktionen von Cp*ReCl4 mit Polychalkogenid-Salzen wie Na2S4 oder (NEt4)2Se6 führen zunächst zu den violetten Trichalkogenido-Chelatkomplexen Cp*ReCl2(E3) (E = S (3a), Se (3a), die aufgrund der funktionellen Chloroliganden als Zwischenstufen bei weiteren Reaktionen verwendet werden können. Bei Hydrolyse in feuchten Solvenzien oder Aminolyse mit tert. Butylamin werden 3a, b in die Tetrachalkogenido-Chelatkomplexe Cp*Re(O)(E4) (E = S (4a), Se (4b) bzw. Cp*Re(NtBu)(E4) (E = S (5a), Se (5b) umgewandelt. Für die drei einkernigen cyclo-Oligoselenido-Verbindungen 3b-5b wurden Röntgenstrukturanalysen durchgeführt. Es scheint, daß die Größe des Se2-n-Chelatrings (n = 3 oder 4) im wesentlichen von sterischen Faktoren innerhalb der Koordinationssphäre des Rheniums abhängt.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/zaac.19946200214
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  • 91
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    Crystal Structure of a New Acentric Oxide Fluoride of VIV: BaVOF4 (1994)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 620 (1994), S. 309-312 
    Details
    ISSN: 0044-2313
    Keywords: Barium vanadium oxide fluoride ; synthesis ; crystal structure ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Kristallstruktur eines neuen azentrischen Oxidfluorids des VIV: BaVOF4Die Struktur von BaVOF4, erhalten durch hydrothermale Synthese, wurde röntgendiffraktometrisch aus Einkristalldaten bestimmt: Raumgruppe Fdd2 (azentrisch), Z = 16, a = 7,920(1), b = 27,608(2), c = 7,375(1) Å mit R = 0,0262, Rw = 0,0273 für 1 508 unabhängige Reflexe und 64 Parameter. Das Gitter wird von cis-verknüpften VOF5-Oktaedern aus gewinkelten unendlichen Ketten entlang [101] und [101] gebildet, die über Barium-Kationen verbunden sind. Die Lage der O2- und F- wird mittels Valenzband-Rechnungen diskutiert. Wie für BaTiOF4 und einige Verbindungen aus der Reihe AIIMIIIF5 (A = Ba, Sr und M = Ga, Al, Mn) kann die Struktur durch quasi-hexagonal dichteste Ebenen aus Stapeln von Ba2+, O2-- und F--Ionen beschrieben werden.
    Notes: The structure of BaVOF4 has been determined by X-ray diffraction data from a single crystal obtained by hydrothermal synthesis: S.G. Fdd2 (acentric), Z = 16, a = 7.920(1), b = 27.608(2) and c = 7.375(1) Å with R = 0.0262 and Rw = 0.0273 for 1 508 independent reflections and 64 parameters. The network is built up from cis-linked VOF5 octahedra forming infinite kinked chains running along the [101] and [101] directions, connected by barium cations. The location of O2- and F- ions is discussed using bond valence calculations. As for BaTiOF4 and some compounds in the series AIIMIIIF5 (A = Ba, Sr and M = Ga, Al, Mn), the structure can be described in terms of a quasi hexagonal compact planes stacking of Ba2+, O2- and F- ions.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/zaac.19946200216
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  • 92
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    Synthese und Kristallstruktur von Ba25Cu142+Cu43+Zn4O49 (1994)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 620 (1994), S. 313-318 
    Details
    ISSN: 0044-2313
    Keywords: Barium, copper, zinc, oxide ; crystal structure ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthesis and Crystal Structure of Ba25Cu142+Cu43+Zn4O49Single crystals of Ba25Cu142+Cu43+Zn4O49 were prepared with solid state and flux reactions. X-ray investigations show tetragonal symmetry, space group D74th-P4/nmm, a = 18.2146, c = 9.3230 Å, Z = 2. The hitherto unknown structure type shows copper in square pyramids and planar polygones, connected to six member rings or Cu5O20 groups. Slightly bent Cu5O12 groups produced by edge connection of five CuO4 polygones are connected with ZnO4 tetrahedra forming Cu5Zn4O20 units. The complicated structure is shown step by step.
    Notes: Einkristalle von Ba25Cu142+Cu43+Zn4O49 wurden mit einer Kombination von Feststoff- und Schmelzmittel-reaktionen dargestellt. Diese Substanz kristallisiert tetragonal, Raumgruppe D74th-P4/nmm mit a = 18,2146, c = 9,3230 Å, Z = 2. Der bisher unbekannte Strukturtyp zeigt Kupfer in tetragonal pyramidaler und planarer Koordination. Diese Polygone sind zu Sechsringen oder Cu5O20-Baugruppen verknüpft. Schwach gebogene Cu5O12-Baugruppen, die durch Kantenverknüpfung von fünf planaren CuO4-Polygonen gebildet werden, sind mit ZnO4-Tetraedern verknüpft und bilden Cu5Zn4O20-Baueinheiten aus. Die komplizierte Kristallstruktur wird schrittweise aufgebaut.
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/zaac.19946200217
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  • 93
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    Ein Beitrag über ein cobaltreiches Oxoarsenat/-vanadat: Co5AsVO10 (1994)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 620 (1994), S. 319-322 
    Details
    ISSN: 0044-2313
    Keywords: Cobalt, arsenic, nickel, oxide ; crystal structure ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: A Contribution about a New Cobalt-rich Oxoarsenate/-vanadate: Co5AsVO10Single crystals of Co5AsVO10 were prepared by solid state reactions and investigated by X-ray structure determination. It crystallizes with monoclinic symmetry, space group C2h3-C2/m, a = 19.134, b = 6.095, c = 17.482 Å, β = 133.37°; Z = 8. The new structure type is characterized by layers of CoO6- and AsO6-octahedra with partly alternating occupation. The layers are connected by Co2+ within tetrahedral oxygen coordination and tetrahedra around statistically occupied point positions of V5+ /As5+.
    Notes: Einkristalle von Co5AsVO10 wurden durch Feststoffreaktionen erhalten und röntgenographisch untersucht. Diese Verbindung kristallisiert mit monokliner Symmetrie, Raumgruppe C2h3-C2/m; a = 19,134; b = 6,095; c = 17,482 Å; β = 133,37°; Z = 8. Der neue Strukturtyp ist durch CoO6- und AsO6-Oktaederschichten ausgezeichnet, die teilweise alternierend mit Co2+ und As5+ besetzt sind. Die Oktaederschichten werden durch Co2+ in tetraedrischer Koordination und statistisch mit V5+ und As5+ besetzte Punktlagen verknüpft.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/zaac.19946200218
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  • 94
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    On the Crystal Structure of LaCaCuGaO5 (1994)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 620 (1994), S. 326-328 
    Details
    ISSN: 0044-2313
    Keywords: Lanthanum calcium copper gallate ; crystal structure ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zur Kristallstruktur von LaCaCuGaO5Die Kristallstruktur von LaCaCuGaO5 wurde röntgenographisch an Einkristallen untersucht. Es kristallisiert orthorhombisch in der Raumgruppe C2v22-Ima2 mit a = 15,8467, b = 5,5077, c = 5,3188 Å, Z = 4. LaCaCuGaO5 gehört zum Brownmillerit-Typ und zeigt somit Schichten von eckenverknüpften CuO6-Oktaedern, die über GaO4-Tetraeder vernetzt sind. Die La3+- bzw. Ca2+-Ionen besetzen eine Punktlage statistisch.
    Notes: The crystal structure of LaCaCuGaO5 has been investigated by single crystal X-ray analysis. It crystallizes with orthorhombic symmetry, space group C2v22-Ima2, a = 15.8467, b = 5,5077, c = 5.3188 Å, Z = 4. LaCaCuGaO5 belongs to the mineral Brownmillerite showing layers of corner connected CuO6 octahedra linked by GaO4 tetrahedra. The La3+ and Ca2+ ions are distributed statistically over one crystallographic point position.
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/zaac.19946200220
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  • 95
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    Einkristall-Röntgenstrukturanalyse von Sr3TiGa10O20 (1994)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 620 (1994), S. 323-325 
    Details
    ISSN: 0044-2313
    Keywords: Strontium, titanium, gallium, oxide ; crystal structure ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Single Crystal X-Ray Analysis of Sr3TiGa10O20Single crystals of Sr3TiGa10O20 were prepared by recrystallisation of a molten oxide mixture and investigated by X-Ray technique. It crystallizes with monoclinic symmetry, space group C2h3-C2/m, a = 15.451, b = 11.579, c = 5.051 Å, β = 108.57°, Z = 2. Sr3TiGa10O20 belongs to the Pb3GeAl10O20 type, showing Ga3+ in tetrahedral and octahedral coordination. The octahedral coordinated point positions are occupied by Ga3+ and Ti4+ statistically.
    Notes: Einkristalle von Sr3TiGa10O20 wurden durch Rekristallisation aus Schmelzen erhalten und röntgenographisch untersucht. Diese Verbindung kristallisiert mit monokliner Symmetrie, Raumgruppe C2h3-C2/m, a = 15,451; b = 11,579; c = 5,051 Å; β = 108,57°; Z = 2. Sr3TiGa10O20 gehört zum Pb3GeAl10O20-Typ und zeigt Ga3+ in tetraedrischer und oktaedrischer Koordination. Die oktaedrisch koordinierten Punktlagen sind mit Ga3+ und Ti4+ statistisch besetzt.
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/zaac.19946200219
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  • 96
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    Zur Existenz des Tetrahydrogenorthoperiodations Die Kristallstruktur von LiH4IO6 · H2O (1994)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 620 (1994), S. 805-808 
    Details
    ISSN: 0044-2313
    Keywords: Lithiumtetrahydrogenorthoperiodate monohydrate ; crystal structure ; tetrahydrogenorthoperiodate Ion ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: On the Existence of the Tetrahydrogenorthoperiodate Ion. The Crystal Structure of LiH4IO6 · H2OThe crystal structure of LiH4IO6 · H2O has been determined (P1; a = 564.74(12), b = 574.41(13), c = 970.4(6) pm, α = 101.37(2), β = 96.37(2), γ = 114.72(2)°; Z = 2; 5 731 independent reflections; R = 0.038). All hydrogen-atoms were localized from difference fourier map and refined without applying constraints. Thus the existence of the tetrahydrogenorthoperiodate-ion in the solid state is proved, unambigously. The crystal structure is discussed and compared to other alkaliorthoperiodates.
    Notes: Die Kristallstruktur von LiH4IO6 · H2O wurde bestimmt (P1; a = 564,74(12), b = 574,41(13), c = 970,4(6) pm, α = 101,37(2), β = 96,37(2), γ = 114,72(2)°; Z = 2; 5 731 unabhängige Reflexe, R = 0,038). Alle Wasserstofflagen konnten aufgefunden und frei verfeinert werden und beweisen erstmals die Existenz des Tetrahydrogenorthoperiodations im Festkörper. Die Kristallstruktur wird diskutiert und mit denjenigen anderer Alkaliorthoperiodate verglichen.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/zaac.19946200508
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  • 97
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    Synthesis of cis-Tetrabromobispyridinemolybdates(III) and the crystal structure of cis-(NH4)[MoBr4py2] · ⅓3 H2O (py = pyridine) (1994)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 620 (1994), S. 950-954 
    Details
    ISSN: 0044-2313
    Keywords: Tetrabromobispyridinemolybdates ; preparation ; isomerisation ; crystal structure ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Darstellung von cis-tetrabromobispyridinemolybdaten(III) und die Kristallstruktur von cis-(NH4)[MoBr4py2] · ⅓ H2O (py = Pyridin)(NH4)2[MoBr5 · H2O] reagiert mit Pyridin im Acetonitril (CH3CN) bei Zimmertemperatur. Das Produkt ist ein Gemenge von cis- und trans-(pyH)[MoBr4py2], das auf Grund der Löslichkeitsunterschiede aufgetrennt werden kann. cis-M[MoBr4py2] · ⅓ H2O (M = NH4+, Rb+, Cs+), cis-(bipyH)[MoBr4py2] (bipy = 2,2′-Bipyridyl) und cis-(PPh4)[MoBr4py2] wurden aus cis-(pyH)[MoBr4py2] dargestellt.In siedendem Acetonitril (82°C) erfolgt irreversible cis-trans-Isomerisierung. Brom oxidiert das cis-Diastereoisomere zu trans-MoBr4py2.Die Verbindungen wurden durch chemische Analyse, Infrarot-, UV-VIS-Spektroskopie, Konduktometrie und Röntgen-Pulveraufnahmen charakterisiert.Die Kristallstruktur von cis-(NH4)[MoBr4py2] · ⅓ H2O wurde bestimmt: rhomboedrisch, R3c, (No. 161), a = 15,809(3) Å, β = 112,79(2)°, Z = 6, Dröntg. = 2,29, Dgemess. = 2,27(3) g/cm3, V = 2 601(1) Å3, R1 = 0,046, Rw = 0,068. Die mittleren Mo—Br und Mo—N(Pyridin)-Abstände sind 2,58(2) bzw. 2,20(2) Å. cis-Rb[MoBr4py2] · ⅓ H2O und cis-Cs[MoBr4py2] · ⅓ H2O sind isostrukturell mit cis-(NH4)[MoBr4py2] · ⅓ H2O.
    Notes: The reaction between (NH4)[MoBr5 · H2O] and pyridine in acetonitrile (CH3CN) at room temperature results in the mixture of cis- and trans-(pyH)[MoBr4py2] which can be separated on the basis of solubility. cis-M[MoBr4py2] · ⅓ H2O (M = NH4+, Rb+, Cs+), cis-(bipyH)[MoBr4py2] (bipy = 2,2′-bipyridil) and cis-(PPh4)[MoBr4py2], were prepared from cis-(pyH)[MoBr4py2].At the temperature of boiling acetonitrile irreversible cis to trans isomerisation takes place. Bromine oxydizes cis isomers at room temperature to trans-MoBr4py2.The compounds were characterised by chemical analysis, infrared, UV-VIS spectroscopy, conductivity measurements and powder diffraction.The crystal structure of cis-(NH4)[MoBr4py2] · ⅓ H2O has been determined: rhombohedral, R3c, (No. 161), a = 15.809(3) Å, β = 112.79(2)°, Z = 6, DC = 2.29, DO = 2.27(3) g/cm3, V = 2 601(1) Å3, R1 = 0.046, Rw = 0.068. Average Mo—Br and Mo—N(pyridine) distances within the anion are 2.58(2) and 2.20(2) Å. cis-Rb[MoBr4py2] · ⅓ H2O and cis-Cs[MoBr4py2] · ⅓ H2O are isostructural with cis-(NH4)[MoBr4py2] · ⅓ H2O.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/zaac.19946200534
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  • 98
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    Synthesis, crystal structure, magnetism, and absorption spectra of A2UX5 Type Halides (A = K, Rb; X = Cl, Br, I)Dedicated to Professor Hugo F. Franzen on his 60th Birthday (1994)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 620 (1994), S. 1339-1345 
    Details
    ISSN: 0044-2313
    Keywords: Alkali uranium halides, A2UX5 (A = K, Rb; X = Cl, Br, I) ; preparation ; crystal structure ; magnetic susceptibility ; UV-Vis spectra ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthese, Kristallstruktur, Magnetismus und Absorptionsspektren von Halogeniden des Typs A2UX5 (A = K, Rb; X = Cl, Br, I)Die ternären Uran(III)-halogenide A2UX5 (A = K, Rb; X = Cl, Br, I) wurden aus den binären Komponenten AX und UX3 in verschweißten Tantalampullen gewonnen. Nach Guinier-Aufnahmen (Raumtemperatur) kristallisieren sie sämtlich im K2PrCl5/Y2HfS5-Typ. Einkristall-Strukturverfeinerungen wurden für K2UI5 und Rb2UCl5 unternommen. Magnetische Suszeptibilitätsmessungen erfolgten mit einem SQUID-Magnetometer von Raumtemperatur bis zur Temperatur des flüssigen Heliums: Eindimensionale (innerhalb einer Kette) und dreidimensionale antiferromagnetische Ordnung wird bei tiefen Temperaturen, abhängig vom Abstand U3+—U3+, beobachtet. Absorptionsspektren wurden zwischen 4000 und 28000 cm-1 aufgenommen. Sie zeigen die für U3+ charakteristischen Übergänge und, abhängig vom Halogenid, sehr starke f - d Übergänge oberhalb 14000 bzw. 15000 cm-1.
    Notes: The ternary uranium(III) halides A2UX5 (A = K, Rb; X = Cl, Br, I) have been prepared from the binary components AX and UX3 in sealed tantalum containers. According to their Guinier X-ray powder patterns, they all crystallize with the K2PrCl5/Y2HfS5 type of structure. Lattice constants for ambient temperature are reported. Single-crystal structure refinemens were undertaken for K2UI5 and Rb2UCl5. Magnetic susceptibility data were recorded with a SQUID magnetometer from liquid helium to room temperature. One-dimensional (intrachain) and three-dimensional antiferromagnetic ordering occur at low temperatures dependent upon the U3+—U3+ distance. Absorption spectra were recorded between 4 000 and 28 000 cm-1. They show f - f transitions typical for U3+ and, depending on the halide, very strong f - d transitions above 14 000 to 15 000 cm-1, respectively.
    Additional Material: 8 Ill.
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    URL: http://dx.doi.org/10.1002/zaac.19946200802
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  • 99
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    Na4[PbO4]  -  Darstellung neuer Plumbate(IV) durch Oxydation intermetallischer PhasenProfessor Hugo F. Franzen zum 60. Geburtstage gewidmet (1994)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 620 (1994), S. 1346-1350 
    Details
    ISSN: 0044-2313
    Keywords: Sodium orthoplumbate ; preparation ; crystal structure ; MAPLE and CHARDI calculations ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Na4[PbO4]  -  Preparation of new Plumbates(IV) by Oxidizing Intermetallic PhasesBy oxidizing NaPb with Na2O2 (molar ratio Na2O2:NaPb = 2.04:1; Ag-tubes; 600°C/50d) we obtained for the first time small orange coloured single crystals of Na4[PbO4]: Na4[SiO4]-type [2], P—1 (I.T. No. 2) with a = 898.5(3); b = 675.6(3); c = 592.2(2) pm; α = 124.75(1)°; β = 96.75(1)°; γ = 100.18(2)°; Z = 2; (four circle diffractometer data (MoKα-; 3 251 Io(hkl); R = 3.4%; Rw = 3.0%), parameters see text. Furthermore the Madelung part of lattice energy (MAPLE), effective coordination numbers (ECoN), mean fictive ionic radii (MEFIR) and the charge distribution (CHARDI) are being calculated.
    Notes: Durch Oxydation von NaPb mit Na2O2 (mol. Verhältnis Na2O2:NaPb = 2,04:1; Ag-Bömbchen; 600°C/50d) wurden erstmals orangefarbene, gedrungene Einkristalle von Na4[PbO4] erhalten: Na4[SiO4]-Typ [2], P—1 (I.T. No. 2) mit a = 898,5(3); b = 675,6(3); c = 592,2(2) pm; α = 124,75(1)°; β = 96,75(1)°; γ = 100,18(2)°; Z = 2; (Vierkreisdiffraktometerdaten; MoKα-; 3 251 Iohkl); R = 3,4%; Rw = 3,0%), Parameter siehe Text. Ferner werden der Madelunganteil der Gitterenergie (MAPLE), Effektive Koordinationszahlen (ECoN), Mittlere Fiktive Ionenradien (MEFIR) und die Ladungsverteilung (CHARDI) berechnet.
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    URL: http://dx.doi.org/10.1002/zaac.19946200803
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  • 100
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    Synthese und Charakterisierung von Fluorenylgallaten und Fluorenylindaten (1994)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 620 (1994), S. 2088-2098 
    Details
    ISSN: 0044-2313
    Keywords: Fluorenyl gallates ; Fluorenyl indates ; synthesis ; crystal structure ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthesis and Characterization of Fluorenyl Gallates and Fluorenyl IndatesGaCl3 reacts with Fluorenyllithium (LiFl) in the ratio 1:4 in Et2O to [Li(THF)4][GaFl4] (1). The addition of DME (1,2-dimethoxyethane) to solutions of 1 in THF leads to [Li(DME)3][GaFl4] (2) under replacement of THF molecules by DME molecules in the coordination sphere of the Li+ ions.Treatment of InCl with LiFl in Et2O and recrystallization from THF gives [Li(THF)4][ClInFl3] (3), which is formed by an disproportionation reaction. 3 can also be obtained by the reaction of InCl with FlZnCl/LiCl in Et2O and recrystallization from THF.1 and 2 crystallize from THF and THF/DME as [Li(THF)4][GaFl4] · THF (1 · THF) and [Li(DME)3][GaFl4] · THF (2 · THF), respectively. Crystalline 3 is isolated from the reaction of InCl and FlZnCl/LiCl, while the reaction mixture of InCl and LiFl gives after recrystallization in THF 3 · 1,5 THF. The gallate ions in 1 and 2 differ mainly in the position of the fluorenyl ligands. The unit cells of 3 and 3 · 1,5 THF contain two crystallographic unique ion pairs of [Li(THF)4][ClInFl3].
    Notes: GaCl3 reagiert mit Fluorenyllithium (LiFl)Fl = Fluorenyl im Molverhältnis 1:4 in THF zu [Li(THF)4][GaFl4] (1). Durch Zugabe von DME (1,2-Dimethoxyethan) zu Lösungen von 1 in THF werden die THF-Moleküle aus der Koordinationssphäre der Li+-Ionen verdrängt, was zu [Li(DME)3][GaFl4] (2) führt.Bei Einwirkung von LiFl auf InCl in Et2O wird nach einer Disproportionierungsreaktion und Umkristallisieren in THF [Li(THF)4][ClInFl3] (3) gebildet. 3 kann ebenfalls durch die Umsetzung von InCl mit FlZnCl/LiCl in Et2O und Umkristallisieren aus THF erhalten werden.1 kristallisiert aus THF in Form von [Li(THF)4][GaCl4] · THF (1 · THF) und 2 aus THF/DME in Form von [Li(DME)3][GaFl4] · THF (2 · THF). Kristallines 3 wird aus der Reaktion von InCl und FlZnCl/LiCl isoliert, während die Reaktionsmischung von InCl und LiFl nach Umkristallisieren aus THF 3 · 1,5 THF liefert. Die Anionen in 1 · THF und 2 · THF unterscheiden sich nach den Ergebnissen der Röntgenstrukturanalysen hauptsächlich durch die Stellung der Fl-Liganden in den Gallat-Ionen. 3 und 3 · 1,5 THF enthalten zwei kristallographisch unabhängige Ionenpaare [Li(THF)4] · [ClInFl3] in der Elementarzelle.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19946201211
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