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  • 101
    Digitale Medien
    Digitale Medien
    Springer
    Journal of chemical crystallography 28 (1998), S. 645-648 
    ISSN: 1572-8854
    Schlagwort(e): 2-Bromoleptoclinidinone ; marine alkaloid ; cytotoxic ; crystal structure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Geologie und Paläontologie , Physik
    Notizen: Abstract 2-Bromoleptoclinidinone methanol solvate, C18H8BrN3O·CH4O, crystallizes in the orthorhombic space group Pbca with a = 15.7013(2), b = 7.3308(1), and c = 26.9326(1) Å. The molecule is essentially planar, with the largest deviations occurring at bromine (−0.21 Å), carbonyl oxygen O(l) (+0.19 Å) and in ring-A (C(9) −0.15 Å, C(10) −0.15 Å). Methanol occupies the 1,10-phenanthroline-like metal binding site of the title compound.
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  • 102
    Digitale Medien
    Digitale Medien
    Springer
    Journal of chemical crystallography 28 (1998), S. 925-929 
    ISSN: 1572-8854
    Schlagwort(e): Quinoline ; chloroquine ; antimalarial ; crystal structure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Geologie und Paläontologie , Physik
    Notizen: Abstract The preparation of N12-(7-chloro-4-quinolinyl)-N 1,N 1-diethyl-1,12-diaminododecane, AQ-40, was accomplished by a five-step process in 80% overall yield from 12-aminododecanoic acid and 4,7-dichloroquinoline. AQ-40 crystallizes as a monohydrate from reagent grade chloroform/ diethyl ether mixtures in the triclinc space group P-1 with a = 8.667(2), b = 8.9425(10), c = 17.217(3) Å, α = 99.34(1), β = 99.89(2), γ = 91.56(1)°, V = 1295.0 Å3 and Z = 2. The l2-(N 1,N 1-diethylamino)dodecyl side chain is in the fully extended conformation and the water molecule forms hydrogen bonds to the two tertiary nitrogen atoms as well as with the secondary amino group. The nitrogen of the secondary amino group bound to the four-position of the quinoline moiety is virtually planar. This together with the rather short C–N distance of 1.347(3) Å to the quinoline moiety suggests involvement of the lone pair on this nitrogen with the π system of the ring.
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  • 103
    Digitale Medien
    Digitale Medien
    Springer
    Journal of chemical crystallography 28 (1998), S. 69-72 
    ISSN: 1572-8854
    Schlagwort(e): Co(III) complex ; crystal structure ; kinetics ; steric effects
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Geologie und Paläontologie , Physik
    Notizen: Abstract The title compound crystallizes in the orthorhombic space group Pnma, with a = 7.9209(5), b = 9.818(1), c = 16.867(2) Å, and Z = 4. The structure was solved employing 1864 independent x-ray reflections with I〉2σ(I) by Patterson and difference Fourier techniques and refined by full-matrix least-squares to R = 0.036. The trans-[CO(NH3)4(NH2CH3)Cl](ClO4)2 molecule is on a crystallographic mirror plane. The cobalt ion is in an elongated octahedral coordination with four equatorial ammonia ligands [average Co–N distance equal to 1.966(2) Å], an axial methylamine [Co–N=1.965(3)Å], and an axial chlorine ion [Co–Cl=2.2771(9)Å]. Kinetic steric effects of the complex are interpreted in terms of structural results.
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  • 104
    Digitale Medien
    Digitale Medien
    Springer
    Journal of chemical crystallography 28 (1998), S. 209-212 
    ISSN: 1572-8854
    Schlagwort(e): Bismuth ; crystal structure ; inorganic polymer
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Geologie und Paläontologie , Physik
    Notizen: Abstract The ethylenediammonium pentachlorobismuthate(III) dihydrate salt is monoclinic with the following unit cell dimensions: a = 10.902(8)Å, b = 7.926(6)Å, c = 15.199(6)Å, β = 96.40(1)°, space group P21/n with Z = 4. The structure shows a layer arrangement parallel to the $$\vec a$$ axis: planes of the [Bi2Cl10]4− bioctahedra alternate with planes of [NH3(CH2)2NH3]2+ dications. The [Bi2Cl10]4− bioctahedra are connected through O(W)–H··· Cl hydrogen bonds, so that infinite unidimensional chains of composition [Bi2Cl10(H2O)2] n 4n− are formed in the structure parallel to the $$\vec a$$ axis. These chains are themselves interconnected by means of the N–H···Cl bonds originating from the [NH3(CH2)2NH3]2+ entities, forming a three-dimensional network.
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  • 105
    Digitale Medien
    Digitale Medien
    Springer
    Journal of chemical crystallography 28 (1998), S. 221-226 
    ISSN: 1572-8854
    Schlagwort(e): Strontium ; triphenylsiloxy ; crystal structure ; ammonia
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Geologie und Paläontologie , Physik
    Notizen: Abstract The title complex [Sr2(OSiPh3)4(NH3)5]·0.5C7H8 was prepared by the reaction of strontium metal granules with triphenylsilanol in an ammoniacal-toluene solution at −40°C. It crystallizes in monoclinic space group P21/n with a = 14.465(3), b = 20.715 (6), c = 25.199(6) Å, β = 95.98(2)°, and Z = 4. The complex has a dimeric structure with one terminal and three bridging triphenylsiloxy ligands, the remaining coordination sites being occupied by five ammonia molecules. The central Sr2O4N5 moiety adopts a distorted M2X9 face-sharing bioctahedral arrangement.
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  • 106
    Digitale Medien
    Digitale Medien
    Springer
    Journal of chemical crystallography 28 (1998), S. 335-338 
    ISSN: 1572-8854
    Schlagwort(e): Mixed rubidium–ammonium acid sulfate ; crystal structure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Geologie und Paläontologie , Physik
    Notizen: Abstract The structure of Rb0.7(NH4)0.3HSO4 has been determined by X-ray analysis. The mixed compound crystallizes in the monoclinic space group P21/n with unit cell parameters a = 14.374(6) Å, b = 4.618(6) Å, c = 14.412(2) Å, β = 118.03(2)°, V = 844.4(4) Å3, and D cal = 1.536 g cm−3 for Z = 8. The mixed compound Rb0.7(NH4)0.3HSO4 is a chain-based structure. The Rb+ and NH4 + cations are intercalated between chains, formed of HSO4 - groups linked with OH⋯O hydrogen-bonding. Rb0.7(NH4)0.3HSO4 presents a new type of structural arrangement different from those of pure RbHSO4 and NH4HSO4.
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  • 107
    ISSN: 1572-8854
    Schlagwort(e): 2-[1,5-Dimethyl-4-hexenyl]-6-hydroxy-5-methyl-1,4-benzoquinone ; 2-[1,5-dimethyl-4-hexenyl]-6-amino-3-hydroxy-5-methyl-1,4-benzoquinone ; 2-[1,5-dimethyl-4-hexenyl]-3-amino-6-hydroxy-5-methyl-1,4-benzoquinone ; crystal structure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Geologie und Paläontologie , Physik
    Notizen: Abstract The crystal structures of isoperezone (1), aminoperezone (2), and isoaminoperezone (3) have been determined by single-crystal X-ray diffraction. Compound (1) yields orange crystals, orthorhombic space group P212121 with unit cell dimensions a = 6.271(6), b = 30.373(7), c = 7.257(1) Å, and Z = 4; compound (2) yields purple crystals, orthorhombic space group P212121 with unit cell dimensions a = 6.498(3), b = 7.500(1) c = 29.200(6) Å, and Z = 4; compound (3) yields purple crystals, monoclinic space group P21 with unit cell dimensions a = 7.354(1), b = 7.511(1), c = 13.283(1) Å, β = 102,07(1)°, and Z = 2. The side chains in (1)–(3) are oriented out of the plane of the quinone ring at an angle of 124, 144, and 97°, respectively. The molecules in the crystal are held together by hydrogen-bonding networks and van der Waals interactions.
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  • 108
    Digitale Medien
    Digitale Medien
    Springer
    Journal of chemical crystallography 28 (1998), S. 639-643 
    ISSN: 1572-8854
    Schlagwort(e): Tungsten(II) ; diiodo ; carbonyl ; trimethylphosphite ; crystal structure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Geologie und Paläontologie , Physik
    Notizen: Abstract [WI2(CO)3{P(OMe)3}2]crystallizes in the orthorhombic space group Pca21, with a = 26.924(5), b = 10.726(2), c = 14.136(3) Å, and Z = 8. There are two molecules in the asymmetric unit, the metal atoms in each case being seven-coordinate with a capped fac-(CO)3 octahedral geometry. The molecular dimensions in the two molecules are nearly identical. The W–P distance to the capping atom 2.397 Å (average) is significantly shorter than the other W–P distance, 2.525 Å (average).
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  • 109
    ISSN: 1572-8854
    Schlagwort(e): Pyrimidine ; carboxamide ; sulfonyl ; chiral ; crystal structure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Geologie und Paläontologie , Physik
    Notizen: Abstract Three novel dihydropyrimidine compounds N8,6-di(4-nitrophenyl)-(3R)-ethyl-(7R)-methyl-5-oxo-2,3,6,7-tetrahydrooxazolo[3,2,c] pyrimidine-8-carboxamide (2), N8,6-di((4-methylphenyl)-sulfonyl)-(3R)-ethyl-5-oxo-(7R)-phenyl-2,3,6,7-tetrahydrooxazolo [3,2,c]pyrimidine-8-carboxamide (3) and N8,6-di ((4-methylphenyl)sulfonyl)-(3R)-ethyl-(7R)-methyl-5-oxo-2,3,6,7-tetrahydrooxazolo[3,2,c] pyrimidine-8-carboxamide (4) have been prepared (from 2-amino-1-butanol of 64.4% e.e.) and structurally characterized by X-ray crystallography. All three compounds contain stereogenic centers, but the crystal of (2) chosen was found to be racemic whilst those of (3) and (4) were found to be homochiral. Compound (2) crystallizes in the monoclinic space group P21/c, with a = 17.958(4), b = 12.431(2), c = 9.653(2) Å, β = 96.20(3)°, U = 2142.3(7) Å3, Z = 4, and D c = 1.449 g cm−3. Compounds (3) and (4) both crystallize in the monoclinic space group P21, with a = 9.349(2), b = 5.824(5), c = 26.513(8) Å, β = 99.43(2)°, U = 1424.1(13) Å3, Z = 2 and D c = 1.389 g cm−3 for (3), and a = 5.9526(9), b = 16.3521(10), c = 13.2263(11) Å, β = 92.81(12)°, U = 1285.9(2) Å3, Z = 2 and D c = 1.378 g cm−3 for (4).
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  • 110
    ISSN: 1572-8854
    Schlagwort(e): Heterotrimetallic sulfido cluster ; linear ; synthesis ; crystal structure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Geologie und Paläontologie , Physik
    Notizen: Abstract The complex Cu(PPh3)3I reacts with [Et4N]2MoS4 and FeBr2 to give the heterotrimetallic complexes [Et4N][(Ph3P)2{CuS2MoS2Fe}Br2] (1). [Et4N][(Ph3P)2{CuS2MoS2Fe}Br2] (1) crystallizes in the triclinic space group P-1, a = 13.537(4), b = 15.316(4), c = 12.381(4) Å, α = 105.16(2), β = 93.27(3), γ = 101.18(2)°, and V = 2415.0(12) Å3 for Z = 2. The three metal atoms of the structure [Et4N][(Ph3P)2{CuS2MoS2Fe}Br2] (1) are nearly distributed along a line, where three metal atoms (Mo, Cu, Fe) are each in an approximate tetrahedral coordination, the lengths Mo-Fe and Mo-Cu distances are 2.772(2) and 2.798(2) Å, respectively.
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  • 111
    Digitale Medien
    Digitale Medien
    Springer
    Journal of chemical crystallography 28 (1998), S. 447-452 
    ISSN: 1572-8854
    Schlagwort(e): Bimetallic EDTA complex ; crystal structure ; antimony
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Geologie und Paläontologie , Physik
    Notizen: Abstract The synthesis and crystal structure of a new EDTA complex, [CaSb2(EDTA)2(H2O)8]n, are reported. This compound crystallizes in the monoclinic space group P21/n, with a = 7.132(1) Å, b = 21.893(3) Å, c = 10.891(2) Å, β = 91.15(2)°. Sb(EDTA) entities are connected through carboxylate bridges to the calcium atoms resulting in layers parallel to the (101) plane. These layers are linked through a weak Sb···O bond (3.171 Å). Pyrolysis of this complex under sulfur vapor, between 400 and 800°C, leads to a mixture of the monometallic sulfides. Pyrolysis in air above 700°C allows the easy preparation of the mixed oxide CaSb2O6.
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  • 112
    ISSN: 1572-8854
    Schlagwort(e): 1-1′-Diphosphaferrocene conformation ; P···P secondary bonding ; bis-[W(CO)5](l,l′-diphosphaferrocene system) ; crystal structure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Geologie und Paläontologie , Physik
    Notizen: Abstract The structures of (3,3′,4,4′-tetramethyl-1,1′-diphosphaferrocen-2-yl)carboxylic acid (1) and its bis-[W(CO)5] pentane solvate complex (2) have been determined by X-ray analysis. The compound 1 crystallizes in the monoclinic P21 /n space group with Z = 4; a = 7.8404(9), b = 14.9441(16), c = 11.7730(14) Å, β = 92.773(10)°, V = 1377.8(3) Å3, and Dcalc = 1.553 g cm−3. The compound 2 crystallizes in the triclinic $$P\bar 1$$ space group with two complex molecules and one pentane molecule in the unit cell. Cell parameters: a = 10.7070(2), b = 12.577(2), c = 13.239(3) Å, α = 84.00(2), β = 77.58(1), γ = 66.06(1)°, V = 1591.0(5) Å3, and Dcalc = 2.100 g cm−3 .The fully eclipsed conformation of the phospholyl rings with P···P secondary bonding of 3.353(1) Å is observed in 1 and a partially eclipsed conformation is found in 2. The 10 possible conformations of 1,1′-diphosphaferrocenes were described as the function of conformational parameter θ and observed geometry of the phospholyl rings.7 We suppose that the earlier conclusions concerning the destabilizing nature of 1,1′-diphosphaferrocene conformations with θ 〈 100° cannot be considered as general. The mode of W – P coordination, the structural changes of 1 by W(CO)5 coordination, the structural effect of phospholyl rings substitution by the –COOH group, and hydrogen bonds are analyzed.
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  • 113
    Digitale Medien
    Digitale Medien
    Springer
    Journal of chemical crystallography 28 (1998), S. 635-638 
    ISSN: 1572-8854
    Schlagwort(e): Cobalt(II) ; 2-aminobenzenethiol ; trimethylphosphite ; crystal structure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Geologie und Paläontologie , Physik
    Notizen: Abstract A cobalt-thiolato-phosphite complex [Co(o-SC6H4NH2){P(OMe)3}3]PF6 has been prepared and characterized by X-ray crystallography. The complex crystallizes in the triclinic space group $$P\bar 1$$ with a = 10.590(4), b = 11.122(3), c = 13.577(5) Å, α = 101.85(1), β = 108.50(1), γ = 101.75(1)°, V = 1420.6(8) Å3, and Z = 2. The structure comprises discrete [Co(o-SC6H4NH2){P(OMe)3}3]+ cations and PF 6 − anions where the metal atom is coordinated in a highly distorted square-pyramidal environment by one chelate o-SC6H4NH 2 − (abt) and two P(OMe)3 ligands in the basal positions, and a third P(OMe)3 in the axial site with Co–N,, 1.847(5), Co–S, 2.166(2), Co–P, 2.157(2), 2.147(2), and 2.125(2) Å.
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  • 114
    Digitale Medien
    Digitale Medien
    Springer
    Journal of cluster science 9 (1998), S. 547-554 
    ISSN: 1572-8862
    Schlagwort(e): Silver cluster ; crystal structure ; tetrameric cluster
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau , Physik
    Notizen: Abstract The sought-after member of the [(PDBP) n AgX] m (n, m=1,4; 2,2; 3,1; PDBP=5-Phenyldibenzophosphole, X=halides) series, the tetrameric [(PDBP)AgCl]4 cluster has been prepared and structurally characterized. The [P4Ag4Cl4] cluster core of [(PDBP)AgCl]4 bears striking similarity to that of [(Ph3P)AgCl]4.
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  • 115
    ISSN: 1572-9001
    Schlagwort(e): 1-Acetyl-indoline ; crystal structure ; electronic structure ; AM1 calculation ; CI calculation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract The crystal and molecular structures of the following molecules have been determined: 1-acetyl-indoline, 1-acetyl-5-nitro-indoline, l-acetyl-5-nitro-7-bromo-indoline, 1-acetyl-5-bromo-7-nitroindoline, and l-acetyl-5-bromo-7-nitro-indol. Molecular orbital calculations are performed for these compounds and two related species.
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  • 116
    ISSN: 1572-8951
    Schlagwort(e): hydrogen bond ; ferrocenyl carbonyl proanoic ; supermolecule ; crystal structure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract Selective recognition in the title compound, (C14H14FeO3)2 ċ (C10H8N2), between ferrocenyl carbonyl propanoic acid and 4,4'-bipyridine through strong O–-HċN intermolecular hydrogen bonds results in a novel supramolecular architecture. Its crystal structure has been solved by single-crystal X-ray diffraction methods while its characterization has been studied by IR and DSC.
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  • 117
    Digitale Medien
    Digitale Medien
    Springer
    Structural chemistry 9 (1998), S. 39-45 
    ISSN: 1572-9001
    Schlagwort(e): Enantioselective chromatographic technique ; chiral selector ; ergot alkaloid derivative ; crystal structure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract The structure of (+)1-(3-allylpropyl)-(5R,8S,10R)-N,N-diethyl-N′-[6-methylergolin-8-yl]urea, C22H33N4O (allyl-terguride), has been determined as part of a study on the chiral recognition mechanism of ergot alkaloids when they are used as the chiral stationary phase for the separation of racemic mixtures in liquid chromatographic methods. At the pH of the solution used for the crystallization, the molecules of allyl-terguride are protonated at N(6). All bond distances and angles are in the expected ranges. In the asymmetric unit one hydroxide ion is present. Hydrogen bonds join molecules of allyl-terguride in pairs along the b axis, connecting O(2) of the hydroxide ion to O(1) of one molecule and to N(2) and N(6) of another.
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  • 118
    Digitale Medien
    Digitale Medien
    Springer
    Journal of sol gel science and technology 13 (1998), S. 987-990 
    ISSN: 1573-4846
    Schlagwort(e): mullite ; MnO ; crystal structure ; electronic paramagnetic resonance (EPR) ; sol-gel chemistry
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract Gels were synthesized from solutions of tetraethylorthosilicate (TEOS) and aluminium nitrate (with and without manganese nitrate). The structural evolution of the gels as a function of manganese content and heat-treatment temperature was studied by visible spectrophotometry (VIS), electron paramagnetic resonance (EPR), X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results show that the presence of manganese can induce mullitization at lower temperatures. However, the effect of manganese depends on its content and how it enters into the mullite structure.
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  • 119
    ISSN: 1573-4943
    Schlagwort(e): Artificial neural network ; crystal structure ; statistics ; tetanus toxin ; botulinum neurotoxin
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract Earlier studies used Rost and Sander's artificial neural network [(1993a), J. Mol. Biol. 232, 584–599] to predict the secondary structures [Lebeda and Olson (1994), Proteins 20, 293–300] and residue solvent accessibilities [Lebeda and Olson (1997), J. Protein Chem. 16, 607–618] of the clostridial neurotoxins. Because the X-ray crystal structure of the 50-kDa C-terminal half of the heavy chain of tetanus toxin was recently determined, this report evaluates the accuracy of these network-derived predictions. For this predominantly β-strand-containing fragment, predictions, on a per-residue basis, for both secondary structure and solvent accessibility were about 70% accurate. A more flexible and realistic analysis based on overlapping segments yielded accuracies of over 80% for the three-state secondary structure and for the two-state accessibility predictions. Because the accuracies of these predictions are comparable to those made by Rost and Sander using a dataset of 126 nonhomologous globular proteins, our predictions provide a quantitative foundation for gauging the results when building by homology the structures of related proteins.
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  • 120
    ISSN: 1573-5079
    Schlagwort(e): bacterial photosynthesis ; crystal structure ; electron transfer ; proton transfer
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Structural features that have important implications for the fundamental process of transmembrane proton transfer are examined in the recently published high resolution atomic structures of the reaction center (RC) from Rhodobacter sphaeroides in the dark adapted state (DQAQB) and the charged separated state (D+QAQB −); the latter is the active state for proton transfer to the semiquinone. The structures have been determined at 2.2 Å and 2.6 Å resolution, respectively, as reported by Stowell et al. (1997) [Science 276: 812–816]. Three possible proton transfer pathways (P1, P2, P3) consisting of water molecules and/or protonatable residues were identified which connect the QB binding region with the cytoplasmic exposed surface at Asp H224 & Asp M240 (P1), Tyr M3 (P2) and Asp M17 (P3). All three represent possible pathways for proton transfer into the RC. P1 contains an uninterrupted chain of water molecules. This path could, in addition, facilitate the exchange of quinone for quinol during the photocycle by allowing water to move into and out of the binding pocket. Located near these pathways is a cluster of electrostatically interacting acid residues (Asp-L213, Glu-H173, Asp-M17, Asp H124, Asp-L210 and Asp H170) each being within 4.5 Å of a neighboring carboxylic acid or a bridging water molecule. This cluster could serve as an internal ‘proton reservoir’ facilitating fast protonation of QB − that could occur at a rate greater than that attainable by proton uptake from solution.
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  • 121
    ISSN: 1573-6881
    Schlagwort(e): Terminal oxidase ; redox coupling ; electrochemical gradient ; electron transport ; energy transduction ; proton translocation ; crystal structure ; site-directed mutagenesis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie , Physik
    Notizen: Abstract One of the challenging features of energy-transducing terminal oxidases, like the aa 3 cytochrome c oxidase of Paracoccus denitrificans, is the translocation of protons across the cytoplasmic membrane, which is coupled to the transfer of electrons to oxygen. As a prerequisite for a more advanced examination of the enzymatic properties, several amino acid residues, selected on the basis of recent three-dimensional structure determinations, were exchanged in subunit I of the Paracoccus enzyme by site-directed mutagenesis. The properties of the mutated oxidases were analyzed by different methods to elucidate whether they are involved in the coupled and coordinated transfer of protons via two different pathways either to the site of oxygen reduction or through the enzyme from the cytoplasm to the periplasmic side.
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  • 122
    ISSN: 1572-9605
    Schlagwort(e): GdBa2Cu3O7−δ ; Ca substitution ; Mo substitution ; Hf substitution ; crystal structure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik , Physik
    Notizen: Abstract The structural and superconducting properties of (Gd1−x−y Ca y M x )Ba2Cu3O z with M = Mo, Hf are investigated using X-ray diffraction, electrical resistivity, and oxygen content measurements. The effect of increasing the Mo concentration in (Gd1−x Mo x )Ba2Cu3O z changes the structure from orthorhombic to tetragonal accompanied by a large increase in resistivity and a fast decrease in T c at the rate of 1.9 K per at.% of Mo, unlike that of Hf substitution in (Gd1−x Hf x )Ba2Cu3O z , which maintains the orthorhombic structure and decreases T c very slowly at the rate of 0.6 K per atm.% of Hf with nearly no change in resistivity. The suppression of T c by M = Mo, Hf can be counterbalanced by hole doping by Ca which increases T c with increasing Ca content showing maximum compensation for Mo. A comparative study of M = Mo, Hf doped samples in (Gd1−x−y Ca y M x )Ba2Cu3O z indicates that the valence of the dopant M = Mo4+,6+, Hf4+ and its ionic radius play an important role in controlling the structural and superconducting properties of the systems.
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  • 123
    ISSN: 0887-3585
    Schlagwort(e): protein modeling ; crystal structure ; conformation change ; prediction ; mechanism ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin
    Notizen: The occurrence of large domain motions associated with the mechanism of action of many proteins is well established. We present a general method of predicting domain closure applicable to proteins containing domains separated by an apparent hinge. The method attempts to allow for natural directional bias within the closing protein by repeatedly applying a weak pulling force over a short distance between pairs of atoms chosen at random in the two domains in question. Appropriate parameters governing the pulling function were determined empirically. The method was applied to the bi-lobal protein PGK and a closed-form activated ternary complex generated for Bacillus stearothermophilus PGK. This model was compared with the recently determined crystal structure of closed-form Trypanosoma brucei PGK. The model predicts the correct hinge regions, although the magnitude of movement at one hinge point was overestimated, and provides a reasonable representation of the closed-form ternary complex. Proteins 30:372-380, 1998. © 1998 Wiley-Liss, Inc.
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  • 124
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Proteins: Structure, Function, and Genetics 30 (1998), S. 232-243 
    ISSN: 0887-3585
    Schlagwort(e): turkey lysozyme ; human lysozyme ; crystal structure ; protein structure ; structure refinement ; protein crystal ; atomic resolution ; rigid-body motion ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin
    Notizen: Crystal structures of turkey egg lysozyme (TEL) and human lysozyme (HL) were refined by full-matrix least-squares method using anisotropic temperature factors. The refinement converged at the conventional R-values of 0.104 (TEL) and 0.115 (HL) for reflections with Fo 〉 0 to the resolution of 1.12 Å and 1.15 Å, respectively. The estimated r.m.s. coordinate errors for protein atoms were 0.031 Å (TEL) and 0.034 Å (HL). The introduction of anisotropic temperature factors markedly reduced the R-value but did not significantly affect the main chain coordinates. The degree of anisotropy of atomic thermal motion has strong positive correlation with the square of distance from the molecular centroid. The ratio of the radial component of thermal ellipsoid to the r.m.s. magnitude of three principal components has negative correlation with the distance from the molecular centroid, suggesting the domination of libration rather than breathing motion. The TLS model was applied to elucidate the characteristics of the rigid-body motion. The TLS tensors were determined by the least-squares fit to observed temperature factors. The profile of the magnitude of reproduced temperature factors by the TLS method well fitted to that of observed Beqv. However, considerable disagreement was observed in the shape and orientation of thermal ellipsoid for atoms with large temperature factors, indicating the large contribution of local motion. The upper estimate of the external motion, 67% (TEL) and 61% (HL) of Beqv, was deduced from the plot of the magnitude of TLS tensors determined for main chain atoms which were grouped into shells according to the distance from the center of libration. In the external motion, the translational portion is predominant and the contribution of libration and screw motion is relatively small. The internal motion, estimated by subtracting the upper estimate of the external motion from the observed temperature factor, is very similar between TEL and HL in spite of the difference in 54 of 130 amino acid residues and in crystal packing, being suggested to reflect the intrinsic internal motion of chicken-type lysozymes. Proteins 30:232-243, 1998. © 1998 Wiley-Liss, Inc.
    Zusätzliches Material: 11 Ill.
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  • 125
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Proteins: Structure, Function, and Genetics 32 (1998), S. 229-240 
    ISSN: 0887-3585
    Schlagwort(e): active-site geometry ; crystal structure ; enzyme action ; protein hydration ; protein mobility ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin
    Notizen: Earlier studies involving water-mediated transformations in lysozyme and ribonuclease A have shown that the overall movements in the protein molecule consequent to the reduction in the amount of surrounding water are similar to those that occur during enzyme action, thus highlighting the relationship among hydration, plasticity, and action of these enzymes. Monoclinic lysozyme retains its crystallinity even when the level of hydration is reduced further below that necessary for activity (about 0.2 gram of water per gram of protein). In order to gain insights into the role of water in the stability and the plasticity of the protein molecule and the geometrical basis for the loss of activity that accompanies dehydration, the crystal structures of monoclinic lysozyme with solvent contents of 17.6%, 16.9%, and 9.4% were determined and refined. A detailed comparison of these forms with the normally hydrated forms show that the C-terminal segment (residues 88-129) of domain I and the main loop (residues 65-73) in domain II exhibit large deviations in atomic positions when the solvent content is reduced, although the three-dimensional structure is essentially preserved. Many crucial water bridges between different regions of the molecule are conserved in spite of differences in detail, even when the level of hydration is reduced well below that required for activity. The loss of activity that accompany dehydration appears to be caused by the removal of functionally important water molecules from the active-site region and the reduction in the size of the substrate binding cleft. Proteins 32:229-240, 1998. © 1998 Wiley-Liss, Inc.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
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  • 126
    Digitale Medien
    Digitale Medien
    Springer
    Journal of inclusion phenomena and macrocyclic chemistry 31 (1998), S. 357-365 
    ISSN: 1573-1111
    Schlagwort(e): calixarenes ; crystal structure ; supramolecular assembly
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract p-Benzylcalix[5]arene.3py (py = pyridine) (1) crystallizes in the triclinic space group P1, a = 10.641(3), b = 13.975(3), c = 24.052(12) Å, α = 94.60(4), β = 91.51(4), γ = 111.46(2)°, V = 3312(4) Å3, Z = 2. Refinement led to a final conventional R value of 0.065 for 5457 reflections. The calixarene is in a distorted cone conformation. Two pyridine molecules are hydrogen bonded to phenolic oxygen atoms and one of them is included in the hydrophobic cavity of the neighboring calixarene molecule along the a axis.
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  • 127
    Digitale Medien
    Digitale Medien
    Springer
    Journal of inclusion phenomena and macrocyclic chemistry 30 (1998), S. 13-19 
    ISSN: 1573-1111
    Schlagwort(e): THF clathrate ; Schiff base macrocycle ; crystal structure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract A new clathrate inclusion compound of 2,3:11,12:20,21:29,30-tetrabenzo-1,13,16,19,31,34-hexaoxa-5,6,8,9,23,24,26,27- octaaza-7,25-dithioketone-2,3:4,5:9,10:11,12:22,23:27,28:29,30-cyclo-[36]ene([ 36]eneO6N8), which contains THF, has been prepared and crystallizes in the monoclinic space group P21/n with a = 9.829(5)Å, b = 24.23(1)Å, c = 10.181(9)Å, β = 92.93(5)-. Each unit cell contains two [36]ene-O6N8 molecules and four THF molecules. The [36]ene-O6N8 molecule lies on the crystallographic centre of symmetry and a pair of the THF molecules with half-chair conformation are located within rectangular channels formed by the macrocycle molecules.
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  • 128
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Biopolymers 45 (1998), S. 307-321 
    ISSN: 0006-3525
    Schlagwort(e): morphology ; crystal structure ; recombinant silk-like molecule ; silk I ; wide angle x-ray scattering ; electron diffraction ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Morphology and crystal structure of a recombinant silk-like molecule, SLP4, were studied. Wide angle x-ray scattering (WAXS) and electron diffraction revealed that SLP4 lyophilized powder and thin films were isomorphic with the silk I crystal structure. Transmission electron microscopy of SLP4 thin films demonstrated a morphology of flat, variable width, crystallites that may aggregate in an epitaxial manner. Theoretical diffraction patterns from silk I crystal structure models were critically compared with SLP4 WAXS data. The analysis concluded that while the crankshaft model is capable of describing details of the SLP4 structural data well, the out-of-register model does not explain the experimental results. In particular, the predicted intensities of the crystallographic reflections for the out-of-register model are inconsistent with the SLP4 WAXS data. © 1998 John Wiley & Sons, Inc. Biopoly 45: 307-321, 1998
    Zusätzliches Material: 12 Ill.
    Materialart: Digitale Medien
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  • 129
    ISSN: 1075-2617
    Schlagwort(e): Cα,α-disubstituted amino acids ; crystal structure ; molecular dynamics ; conformation ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The crystal structures of three fully protected tripeptides containing the Dφg residue (Cα,α-diphenylglycine) in the central position are reported, namely Z-Gly-Dφg-Gly-OMe (a), Z-Gly-Dφg-Aib-OMe (b) and Z-Aib-Dφg-Aib-OMe (c). The molecular conformations are quite unusual because the Dφg residue adopts a folded conformation in the 310-helical region when the following residue adopts a folded conformation of opposite handedness (peptidesbandc). In contrast, the Dφg residue adopts the more frequently observed fully extended conformation when the following residue adopts a semi-extended conformation (peptidea). These findings are in agreement with the theoretical calculations on Ac-Dφg-Aib-NHCH3 and Ac-Aib-Dφg-NHCH3 also reported in this work. © 1998 European Peptide Society and John Wiley & Sons, Ltd.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
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  • 130
    ISSN: 0894-3230
    Schlagwort(e): calixarenes ; complexes ; conformation ; crystal structure ; 1H NMR ; 13C NMR ; Chemistry ; Theoretical, Physical and Computational Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: The crystal structure of 25,27-dihydroxy-26,28-bis(diethoxyphosphoryloxy)-tert-butylcalix[4]arene (1) (hexane solvate, 1:1) was determined by x-ray crystallography. The crystal data are P21/n, a  =  12.652(1) Å, b  =  12.564(2) Å, c  =  18.781(4) Å, β  =  105.56(1)°, V  =  2876.0(8) Å3, Z  =  2. In this complex the molecule adopts a 1,2-alternate conformation. Both the calixarene and hexane molecules are centrosymmetric. The phenol units in the asymmetric part of the calix are inclined with respect to the main macrocyclic plane by 115.46(6)° and 128.01(7)° for the phosphorylated and the non-phosphorylated ring, respectively. Self-inclusion of the ethyl chains in the half-cavities is observed. One intramolecular O - H…O and several intermolecular C - H…O hydrogen bonds are present. In the 1H NMR spectrum one average AX spin system for methylene bridge protons can be interpreted as fast (on the NMR time-scale) interconversion of non-phosphorylated phenol fragments. © 1998 John Wiley & Sons, Ltd.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
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  • 131
    Digitale Medien
    Digitale Medien
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 11 (1998), S. 751-755 
    ISSN: 0894-3230
    Schlagwort(e): 2′,6′-dimethoxyflavone-2,6-dimethoxybenzoic acid complex ; crystal structure ; pKa values ; hydrogen bonds ; Chemistry ; Theoretical, Physical and Computational Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: The crystal structure of the 2′,6′-dimethoxyflavone-2,6-dimethoxybenzoic acid complex was determined. Owing steric hindrance of the methoxy groups, the two H-bonded molecules are twisted. Earlier results were used to establish a relationship between the pKa values of different acids and their hydrogen bond distances in complexes with 2′,6′-dimethoxyflavone. © 1998 John Wiley & Sons, Ltd.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
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  • 132
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Advanced Materials for Optics and Electronics 8 (1998), S. 263-267 
    ISSN: 1057-9257
    Schlagwort(e): semiconductors ; low-dimensional systems ; crystal structure ; optical properties ; photoluminescence ; Raman spectra ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik , Physik
    Notizen: The structural, optical and related properties (i.e. photoluminescence and resonance Raman spectra) of some synthetic (i.e. unconventional) low-dimensional semiconductor systems such as K2Cd3S4, [CH3SC(NH2)=NH2]3PbI5 and [H3N(CH2)6NH3]BiI5 are reported. They are compared with the properties of the corresponding higher-dimensionality systems. A blue shift of the excitonic bands and an enhancement of their binding energy and intensity were observed by decreasing the dimensionality or the size of the materials active part. The results are similar to those obtained from conventional semiconductors by decreasing the dimensionality or the size and are attributed to quantum confinement of excitons. © 1998 John Wiley & Sons, Ltd.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
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  • 133
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Peptide Science 4 (1998), S. 46-57 
    ISSN: 1075-2617
    Schlagwort(e): α-hydroxymethylserine peptides ; isopropylidene protecting group ; crystal structure ; peptide conformation ; peptide synthesis ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A synthetic methodology has been developed for peptide bond formation with α-hydroxmethylserine as the carboxyl or amino component and also for the preparation of homo-sequences. The key intermediate, O,O-protected α-hydroxymethylserine in the form of an isopropylidene derivative, is easily accessible and represents the first example of a heterocyclic Cα,α-disubstituted amino acid containing an 1,3-dioxane ring. The use of this intermediate facilitates protection of the sterically hindered amino and carboxyl groups and is advantageous for the coupling and deprotection steps. X-ray structure determination of Z-HmS(Ipr)-Ala-OMe revealed that the two crystallographically independent molecules present in the asymmetric unit adopt an S-shaped conformation. In the one molecule the achiral HmS(Ipr) residue has the torsion angle values (φ==61.4°,ψ=40.8°) in the left-handed helical region of the Ramachandran map, while in the second molecule the negative torsion angles (φ=-60.1°, ψ=-44.4°) are associated with the right-handed helix. © 1998 European Peptide Society and John Wiley & Sons, Ltd.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
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  • 134
    ISSN: 0268-2605
    Schlagwort(e): triarylantimony dichrysanthemate ; plant growth-regulating activity ; crystal structure ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A series of triarylantimony dichrysanthemate compounds of the type Ar3Sb(O2CR)2 [Ar=C6H5, 4-CH3C6H4, 3-CH3C6H4, -CH3C6H4, 4-ClC6H4; R=4-ClC6H4CH(i-Pr), cis-Cl2C:CH trans-Cl2C:CH] have been synthesized and characterized by elemental analysis, infrared spectra, 1H NMR spectra and mass spectra. Some activities of these compounds in plant growth regulation have been determined. Their results indicate that the derivatives of cis-dichlorochrysanthemic acid and trans-dichlorochrysanthemic acid significantly promote rooting of excised cucumber cotyledons at 10 ppm. An X ray structure determination has been carried out as follows for Ph3Sb(O2CCHCMe2CMe2)2: orthorhombic, space group Pbcn, Z=4, structure solution with 2385 independent reflections, R=0.035. Lattice dimensions at 26 °C: a=15.616(3) Å, b=10.275(2) Å, c=20.201(5) Å, V=3241(2) Å3, ρ=1.302 g cm-3. © 1998 John Wiley & Sons, Ltd.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
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  • 135
    Digitale Medien
    Digitale Medien
    Springer
    Journal of cluster science 8 (1997), S. 521-531 
    ISSN: 1572-8862
    Schlagwort(e): Zirconium clusters ; isocyanide ; synthesis ; crystal structure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau , Physik
    Notizen: Abstract The first isocyanide ligated hexanuclear zirconium halide cluster is reported. The unoxidized [(Zr6Be)Cl12(CNXyl)6] (CNXyl = 2,6-dimethylphenyl isocyanide) was obtained from the solid state precursor K3Zr6Cl15Be by dissolution in CH3CN in the presence of CNXyl. The CNXyl ligands occupy all the axial positions on the cluster. The compound was recrystallized from CH2Cl2 and Et2O. [(Zr6Be)Cl12(CNXyl)6].2CH2Cl2 crystallizes in the space group $${\text{P}}\overline {\text{1}} $$ (#2) with a = 12.092(5) Å, b=12.728(5) Å, c = 14.102(8) Å, α = 104.98(4)°, β =107.11°, γ = 100.94°, V = 1919(2) Å3, Z = l, R = 11.3% and R W = 27.0%. For the bound isocyanide ligands, v CN increases to 2140 cm−1.
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  • 136
    ISSN: 1572-8862
    Schlagwort(e): Rhenium ; dirhenium complexes ; rhenium–rhenium multiple bonds ; isocyanide ligands ; carbonyl ligand ; structural isomers ; crystal structure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau , Physik
    Notizen: Abstract The reaction of the unsymmetrical, coordinatively unsaturated dirhenium(II) complex [(XylNC)(OC)CIRe(μ-dppm)2ReCl2]O3SCF3 (dppm = Ph2PCH2PPh2) with one equivalent of XylNC in CH2Cl2 affords a fifth structural isomer of the [Re2Cl3(μ-dppm)2(CO)(CNXyl)2] + cation; this is believed to have a CO-bridged structure of the type [(XylNC)ClRe(μ-Cl)(μ-CO)(μ-dppm)2ReCl(CNXyl)]+. The latter complex reacts with a further equivalent of XylNC in the presence of Tl+ to form the [Re2Cl2(μ-dppm)2(CO)(CNXyl)3]2+ cation, which has been shown by IR spectroscopy, and by the X-ray crystallographic characterization of its neutral congener Re2Cl2(μ-dppm)2(CO)(CNXyl)3, to contain a very weak and unsymmetrical CO bridge.
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  • 137
    Digitale Medien
    Digitale Medien
    Springer
    Journal of thermal analysis and calorimetry 50 (1997), S. 569-586 
    ISSN: 1572-8943
    Schlagwort(e): crystal structure ; metal(II) picolinate and quinaldinate ; thermal degradation of imidazole and pyrazole complexes
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract Complexes of the type M(Pa)2(HAz)2 and M(QA)2(HAz)2 (M=cobalt(II) and nickel(II); HPa=picolinic acid, HQa=quinaldic acid; HAz=azoles like imidazole (Him), pyrazole (HPz), benzimidazole (HBzIm) etc.) show a similar thermal behaviour. In the first step of decomposition the corresponding azolinium picolinates or quinaldinates (H2AzPa, H2AzQa) are split off with formation of polymeric mixed ligand complexes M(Pa)(Az) or M(Qa)(Az). X-ray analysis of Co(Qa)2(HBzIm)2 XIIIa illustrates a proton transfer and a subsequent thermal removal of benzimidazolinium quinaldinate (H2BzImQa): Hydrogen bridges from pyrrole nitrogen of the benzimidazole to the non-coordinated oxygen of the quinaldinate predetermine the thermal initiated proton transfer. The high volatility of the heterocyclic acids and the nitrogen coordination are responsible for the formation of the mixed ligand complex Co(Qa)(BzIm) XIVa. Exceptions are the complexes M(Pa)2(HPz)2 XIa-b and M(Qa)2(HIm)2 XVIIa-b. Pyrazole is eliminated from the complexes XIa-b with formation of the solvent-free inner complex M(Pa)2 XIIa-b. From compounds XVIIIa-b quinaldic acid or their decomposition products are split off and a high temperature modification of M(Im)2 XVIIIa-b is formed at elevated temperature. XVIIIa-b are decomposed to the cyanides M(CN)2 similarly to the thermal behaviour of Cu(Im). In the first step the thermal degradation of imidazole and pyrazole adducts of copper(II) picolinates and quinaldinates is characterized by the elimination of azoles. The reason for this thermal behaviour is the weaker coordination of the azole heterocycles in copper chelate compounds.
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  • 138
    ISSN: 1572-9001
    Schlagwort(e): Tautomerism ; anthraquinone ; crystal structure ; semiempirical computations
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract Substituted 1-hydroxy-9,10-anthraquinone-9-imines have been found to exhibit tautomeric interconversions between the 9,10- and 1,10-quinonoid forms in the solid state as well as in solution. Single-crystal X-ray crystallography was used to study the structures of 4-(N-acetyl-p-tolylamino)-9-amino-1,10-anthracenedione and 4-hydroxy-1-phenylamino-10-mesitylimino-9(10H)-anthracenone at ambient and low temperatures. The former compound gave crystals belonging to the monoclinic space group P2l/c and, at 295 K,a=9.684(2),b=16.371(3),c=12.097(2) å,Β=110.41(1)
    Materialart: Digitale Medien
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  • 139
    Digitale Medien
    Digitale Medien
    Springer
    Structural chemistry 8 (1997), S. 453-457 
    ISSN: 1572-9001
    Schlagwort(e): Benzopsoralen ; photochemotherapeutic agent ; crystal structure ; molecular mechanics ; AM1 theoretical calculations
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract 5-Methoxy-4-methyl-2H-benzofuro[3,2-g]benzo-1-pyran-2-one was synthesized and its crystal structure was determined and compared with the optimal conformation arrived at by MM and AM1 theoretical calculations. The latter indicated that the tetracyclic skeleton is planar with total length (C2–C8) 9.23 å, and that the line joining the conters of the terminal-benzene and furan rings makes an angle of 30.5
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  • 140
    Digitale Medien
    Digitale Medien
    Springer
    Glycoconjugate journal 14 (1997), S. 677-690 
    ISSN: 1573-4986
    Schlagwort(e): molecular dynamics ; crystal structure ; cellulose I and II
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract The paper describes molecular dynamics (MD) simulations on the crystal structures of the Iβ and II phases of cellulose. Structural proposals for each of these were made in the 1970s on the basis of X-ray diffraction data. However, due to the limited resolution of these data some controversies remained and details on hydrogen bonding could not be directly obtained. In contrast to structure factor amplitudes in X-ray diffraction, energies, as obtained from MD simulations, are very sensitive to the positions of the hydroxyl hydrogen atoms. Therefore the latter technique is very suitable for obtaining such structural details. MD simulations of the Iβ phase clearly shows preference for one of the two possible models in which the chains are packed in a parallel orientation. Only the parallel-down mode (in the definition of Gardner and Blackwell (1974) J Biopolym 13: 1975-2001) presents a stable structure. The hydrogen bonding consists of two intramolecular hydrogen bonds parallel to the glycosidic linkage for both chains, and two intralayer hydrogen bonds. The layers are packed hydrophobically. All hydroxymethyl group are positioned in the tg conformation. For the cellulose II form it was found that, in contrast to what seemed to emerge from the X-ray fibre diffraction data, both independent chains had the gt conformation. This idea already existed because of elastic moduli calculations and 13C-solid state NMR data. Recently, the structure of cellotetraose was determined. There appear to be a striking similarity between the structure obtained from the MD simulations and this cellotetraose structure in terms of packing of the two independent molecules, the hydrogen bonding network and the conformations of the hydroxymethyl group, which were also gt for both molecules. The structure forms a 3D hydrogen bonded network, and the contribution from electrostatics to the packing is more pronounced than in case of the Iβ structure. In contrast to what is expected, in view of the irreversible transition of the cellulose I to II form, the energies of the Iβ form is found to be lower than that of II by 1 kcal mol-1 per cellobiose.
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  • 141
    Digitale Medien
    Digitale Medien
    Springer
    Structural chemistry 8 (1997), S. 141-147 
    ISSN: 1572-9001
    Schlagwort(e): Dibenzanthracene ; trinitrobenzene complex ; trinitrobenzene complex ; π-complex ; crystal structure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract The crystal structure of the complex between the polycyclic aromatic hydrocarbon di-benz[a,c]anthracene and 1,3,5-trinitrobenzene is reported. The crystals are triclinic, space group P¯1 with unit cell dimensionsa=7.277(2) å,b=11.237(6) å, andc=13.902(5) å,α= 104.13(4)
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  • 142
    ISSN: 0887-3585
    Schlagwort(e): small-angle scattering ; x-rays ; allosteric enzymes ; crystal structure ; rigid body modeling ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin
    Notizen: Solution scattering curves evaluated from the crystal structures of the T and R states of the allosteric enzyme aspartate transcarbamylase from Escherichia coli were compared with the experimental x-ray scattering patterns. Whereas the scattering from the crystal structure of the T state agrees with the experiment, large deviations reflecting a significant difference between the quaternary structures in the crystal and in solution are observed for the R state. The experimental curve of the R state was fitted by rigid body movements of the subunits in the crystal R structure which displace the latter further away from the T structure along the reaction coordinates of the T→R transition observed in the crystals. Taking the crystal R structure as a reference, it was found that in solution the distance between the catalytic trimers along the threefold axis is 0.34 nm larger and the trimers are rotated by 11° in opposite directions around the same axis; each of the three regulatory dimers is rotated by 9° around the corresponding twofold axis and displaced by 0.14 nm away from the molecular center along this axis. Proteins 27:110-117 © 1997 Wiley-Liss, Inc.
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  • 143
    ISSN: 0887-3585
    Schlagwort(e): bactericidal antibody ; crystal structure ; Neisseria meningitidis ; peptide-fluorescein conjugate ; PorA outer membrane protein ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin
    Notizen: Class 1 outer membrane protein PorA of Neisseria meningitidis is a vaccine candidate against bacterial meningitis. Antibodies against PorA are able to induce complement-mediated bacterial killing and thereby play an important role in protection against meningococcal disease. Bactericidal antibodies are all directed against variable regions VR1 and VR2 of the PorA sequence, corresponding to loops 1 and 4 of a two-dimensional topology model of the porin with eight extracellular loops. We have determined the crystal structure to 2.6 Å resolution of the Fab fragment of bactericidal antibody MN12H2 against meningococcal PorA in complex with a linear fluorescein-conjugated peptide TKDTNNNL derived from the VR2 sequence of sero-subtype P1.7,16 (residues 180-187) from meningococcal strain H44/76. The peptide folds deeply into the binding cavity of the Fab molecule in a type I β-turn, with the minimal P1.16 epitope DTNNN virtually completely buried. The structure reveals H-bonds and van der Waals interactions with all minimal epitope residues and one essential salt bridge between Asp-182 of the peptide and His-31 of the MN12H2 light chain. The key components of the recognition of PorA epitope P1.16 by bactericidal antibody MN12H2 correspond well with available thermodynamic data from binding studies. Furthermore, they indicate the structural basis of an increased endemic incidence of infection by group B meningococci in England and Wales since 1981 associated with the occurrence of an Neisseria meningitidis escape mutant (strain MC58). The observed three-dimensional conformation of the peptide provides a rationale for the development of a synthetic peptide vaccine against meningococcal disease. Proteins 29:113-125, 1997. © 1997 Wiley-Liss, Inc.
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  • 144
    ISSN: 0887-3585
    Schlagwort(e): Brownian dynamics ; molecular recognition ; site-directed mutagenesis ; facilitated diffusion ; crystal structure ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin
    Notizen: Key charged residues in Cu,Zn superoxide dismutase (Cu,Zn SOD) promote electrostatic steering of the superoxide substrate to the active site Cu ion, resulting in dismutation of superoxide to oxygen and hydrogen peroxide. Lys-136, along with the adjacent residues Glu-132 and Glu-133, forms a proposed electrostatic triad contributing to substrate recognition. Human Cu,Zn SODs with single-site replacements of Lys-136 by Arg, Ala, Gln, or Glu or with a triple-site substitution (Glu-132 and Glu-133 to Gln and Lys-136 to Ala) were made to test hypotheses regarding contributions of these residues to Cu,Zn SOD activity. The structural effects of these mutations were modeled computationally and validated by the X-ray crystallographic structure determination of Cu,Zn SOD having the Lys-136-to-Glu replacement. Brownian dynamics simulations and multiple-site titration calculations predicted mutant reaction rates as well as ionic strength and pH effects measured by pulse-radiolytic experiments. Lys-136-to-Glu charge reversal decreased dismutation activity 50% from 2.2 × 109 to 1.2 × 109 M-1 s-1 due to repulsion of negatively charged superoxide, whereas charge-neutralizing substitutions (Lys-136 to Gln or Ala) had a less dramatic influence. In contrast, the triple-mutant Cu,Zn SOD (all three charges in the electrostatic triad neutralized) surprisingly doubled the reaction rate compared with wild-type enzyme but introduced phosphate inhibition. Computational and experimental reaction rates decreased with increasing ionic strength in all of the Lys-136 mutants, with charge reversal having a more pronounced effect than charge neutralization, implying that local electrostatic effects still govern the dismutation rates. Multiple-site titration analysis showed that deprotonation events throughout the enzyme are likely responsible for the gradual decrease in SOD activity above pH 9.5 and predicted a pKa value of 11.7 for Lys-136. Overall, Lys-136 and Glu-132 make comparable contributions to substrate recognition but are less critical to enzyme function than Arg-143, which is both mechanistically and electrostatically essential. Thus, the sequence-conserved residues of this electrostatic triad are evidently important solely for their electrostatic properties, which maintain the high catalytic rate and turnover of Cu,Zn SOD while simultaneously providing specificity by selecting against binding by other anions. Proteins 29:103-112, 1997. © 1997 Wiley-Liss, Inc.
    Zusätzliches Material: 8 Ill.
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  • 145
    Digitale Medien
    Digitale Medien
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 35 (1997), S. 1621-1625 
    ISSN: 0887-624X
    Schlagwort(e): 1,4-benzenedithiol ; 1,4-diethynylbenzene ; crystal structure ; solid-state polymerization ; layer structure ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The crystal structure of 1,4-benzenedithiol (BDT) was determined by the Rietveld method based on the calculation of the atomic coordinates of the BDT molecule using the Molecular Mechanics Program (MMP2). The refined crystal structure of BDT was monoclinic P21/c with dimensions, a = 7.795, b = 7.290, c = 5.955 Å, β = 92.16°, z = 2. The R factor of the refined structure was 0.038. Using above results, the mechanism of solid-state addition polymerization of BDT to 1,4-diethynylbenzene (DEB) was studied. Sublimed BDT piles up onto glass plate substrate and forms the layer structure along with the a axis. An inclination angle of the piled BDT column was 60° toward the substrate surface. DEB crystal structure was also monoclinic P21/c with a = 4.007, b = 6.018; c = 15.340 Å, β = 91.42°, z = 2. Sublimation of equimolar mixture of BDT and DEB gave a crystal having 1 : 1 composition, in which DEB column is situated between the columns of BDT. Relative arrangement of both monomers was suitable for the addition of —SH and —C=CH groups, since the distance between the two groups is 3.3 Å by CERIUS II calculation. Therefore, the addition polymerization of BDT to DEB easily proceeded by UV irradiation and the resulting polymer had a highly layer structure along with the a axis of BDT crystal. Tentatively estimated crystal structure of polymer obtained is monoclinic with a = 7.73, b = 7.30, c = 5.95 Å, β = 92.16°. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 1621-1625, 1997
    Zusätzliches Material: 8 Ill.
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  • 146
    Digitale Medien
    Digitale Medien
    Springer
    Journal of inclusion phenomena and macrocyclic chemistry 27 (1997), S. 169-178 
    ISSN: 1573-1111
    Schlagwort(e): Bridged calix[4]arene ; ditopic receptor ; crystal structure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract The crystal structures of a new solvate of the ditopic receptor 1,3-calix[4]-bis-crown-6, Bis-C6, and of 1,3-calix[4]-bis-(benzo-crown-6), Bis-benzoC6, are reported. Bis-C6.3 CH3CN (1) crystallizes in the monoclinic space group P21/n, a = 14.388(3), b = 26.947(8), c = 14.707(4) Å, β = 113.19(3)°, V = 5241(5) Å3, Z = 4. Refinement led to a final conventional R value of 0.092 for 2723 reflections. The structure of (1) differs from the previously reported structure of Bis-C6.4 CH3CN by the conformation of one crown either chain. Two acetonitrile molecules are in the close neighbourhood of the crown ether cavities. Bis-benzoC6.3 CH3CN (2) crystallizes in the monoclinic space group P21/c, a = 10.391(4), b = 17.264(11), c = 30.426(9) Å, β = 94.62(3)°, V = 5440(7) Å3, Z = 4. Refinement led to a final conventional R value of 0.106 for 2965 reflections. Two acetonitrile molecules are located near the crown ether cavities, as in (1). One of the crown ether conformations is the same as in the binuclear caesium complex of Bis-benzoC6, supporting the hypothesis of a preorganization of this ligand towards the complexation of this ion; the second crown ether chain is partially disordered.
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  • 147
    Digitale Medien
    Digitale Medien
    Springer
    Journal of inclusion phenomena and macrocyclic chemistry 28 (1997), S. 125-140 
    ISSN: 1573-1111
    Schlagwort(e): X-ray ; crystal structure ; Li-complex ; triamides ; 1H-NMR
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract The structure of the lithium complex with1,3,5-tris[oxymethylene(N,N-dicyclohexyl)carboxyamido]cyclohexanehas been determined by the X-ray method.The compound is triclinic, space group P¯1,a = 15.623(3), b = 19.279(4),c = 19.295(4)Å α = 102.32(3), β = 92.45(3),γ = 105.67(3)0, V = 5436(2)Å3, Z = 4. Itscomposition is represented by the formulaC48H82N3O6LiI 0.5H2O. The lithium cationis encapsulated in a polar pseudo-cavity of six oxygen atoms of the ligandmolecule and displays a distorted trigonal prism coordination. The conformationof the ligand in the solid state complex has been compared with the conformationof the complex in solution determined by 1H-NMR measurements. Supplementary data relevant to this publication have been deposited with the British Library, No. SUP 82224 (21 pages).
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  • 148
    Digitale Medien
    Digitale Medien
    Springer
    Journal of inclusion phenomena and macrocyclic chemistry 28 (1997), S. 17-32 
    ISSN: 1573-1111
    Schlagwort(e): Azocrown ether ; azoxycrown ether ; sodium complexes ; crystal structure ; X-ray analysis ; conformation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract Sodium iodide complexes of 13-membered azo-(I)and azoxycrown ethers (II) have been synthesized. Compound I[Na(L1 trans)2]⋅I⋅H2O is triclinic witha = 11.53(2), b = 15.74(2), c = 19.17(2) Å,α = 98.93(9), β = 105.51(9),γ = 89.20(9) deg.; Z = 4, space groupP1. Compound II [Na(L2)2]⋅I is orthorhombic witha = 12.451(2), b = 13.796(3), c = 18.667(4)Å; Z = 4, space group P212121. In bothcomplexes the cation is coordinated tochain oxygen atoms and to one nitrogen atom of the azoor azoxy unit. The ability of bothligands to form complexes in relation to thegeometry of the azo or azoxy subunit of themacrocycle is discussed.
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  • 149
    ISSN: 1573-1111
    Schlagwort(e): β-Dimorph ; crystal structure ; dianilinegossypol ethylacetate 1 : 1 clathrate ; packing motifs
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract Depending on crystallization conditions, dianilinegossypol and ethylacetate form low (ambient temperature, α-phase) and high temperature (t = 35°C, β-phase) clathrate modifications. The structure of the α-phase has been discussed earlier [1]. Crystals of the 1 : 1 β-phase complex, C42H40O6N2·C4O2H8, are monoclinic, space group P21/c, a = 11.362(6), b = 19.479(9), c = 19.085(9) Å, β = 103.21(4)°, V = 4112(3)Å3, Z = 4, R = 0.084 for 3210 observed reflections. In these complexes centrosymmetric dimers of dianilinegossypol molecules formed via O(5)—H···O(3) hydrogen bonds are associated into columns by a weak O(8)—H···O(7) H-bond. A difference in the structure of these two phases is in the packing mode of the columns. The angle formed by intersecting host columns is about 126° for the α-phase and 104° for the β-modification. Guest molecules are hydrogen bonded to the host molecules via an O(1)—H···O(10) bond and are accommodated in channels in α-phase complex and in cavities in β-phase complex.
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  • 150
    Digitale Medien
    Digitale Medien
    Springer
    Journal of inclusion phenomena and macrocyclic chemistry 27 (1997), S. 13-20 
    ISSN: 1573-1111
    Schlagwort(e): Uranyl complexes ; calixarenes ; crystal structure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract The synthesis and crystal structure of the inclusion complex between uranyl and p-tert-butylcalix[5]arene are reported. [UO2 (p-tert-butylcalix[5]arene-4H]2- · $${\text{2HNE}}_{{\text{t}}_{\text{3}} }^{\text{ + }} $$ &·2MeOH(1) crystallizes in the monoclinic space group C2/c, a = 30.06(2), b = 18.20(3), c = 31.35(2) Å, β = 128.51(6)°, V = 13423(40) Å3, Z = 8. Refinement led to a final conventional R value of 0.043 for 4155 reflections. The uranyl ion is bonded, in its equatorial plane, to the five oxygen atoms of the calixarene, four of which are deprotonated. A protonated triethylamine molecule is located inside the calixarene cavity and hydrogen bonded to a uranyl oxygen atom, and another one outside and hydrogen bonded to a calixarene oxygen atom. The calixarene conformation is the usual cone one.
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  • 151
    ISSN: 1573-1111
    Schlagwort(e): Calix[4]arene ; polyether ; crystal structure ; alkali metal ion binding
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract The ligand 5,11,17,23-tetra-t-butyl-25,27-di(phenylmethoxy)-26,28-di(2-methoxy-ethoxy)calix[4]arene,designed as an analogue of some calixcrown speciesin order to evaluate possible origins of their selectivity in alkali metal ion binding, has been synthesised and structurally characterised by X-ray crystallography. The crystals are monoclinic, P21/n, a = 15.940(6), b = 19.388(5), c = 20.020(5) Å,β = 109.10(2) deg., Z = 4, conventional R on |F| being 0.073 for 3454 independent, ’observed‘ (I 〉 3σ(I)) reflections. 1H-NMR studies in 1:1 CD3CN/CDCl3solvent have shown that the ligand exerts a strong preference for the lighteralkali metal ions (Li+ and Na+) contrary to the binding behaviour of knowncalixcrowns. This may reflect interactions restricted to the lower rim donor atoms without concomitant interaction with the calixarene π-electrons, perhaps because the latter interactions are substituted by those with the benzyl group π-electrons.
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  • 152
    ISSN: 1573-1111
    Schlagwort(e): Dianilinegossypol ; crystal structure ; host–guest complexes ; H-bond ; α- and β-dimorphs
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract Dianilinegossypol forms a 1 : 2 host-guest complex with DMSO:monoclinic, space group P21/n, a = 8.522(3), b = 18.034(4), c= 28.462(6) Å, β = 94.14(2)°, V = 4362Å3, Z = 4, D x = 1.26 g cm-3, T = 295 K.Final R value is 0.102 for 1793 observed reflections. A 1 : 1 : 1 adduct ofdianilinegossypol with 1,4-dioxane and 1,2-dichloroethane is found to beisostructural with the dianilinegossypol complex with DMSO: monoclinic,space group P21/n, a = 8.281(2), b = 19.245(3), c = 27.970(7)Å, β = 95.18°, V = 4439 Å3, Z = 4, D x =1.28 g cm-3, T = 295 K. Final R value is 0.114 for 2458observed reflections.The host molecules are associated by O(4)—H ...O(3) H-bonds toinfinite chains running in the direction of the c-axis The chains areincorporated into layers through 1,4-dioxane or DMSO molecules havingH-bonds with dianilinegossypol molecules. Another DMSO or 1,2-dichloroethanemolecule is included as a guest in the channels formed between the layers.At 60 °C a cryptate-type inclusion complex of dianilinegossypol isformed with DMSO or 1,4-dioxane. It is isostructural with the acetonecomplex reported in Part IV of the present series.
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  • 153
    Digitale Medien
    Digitale Medien
    Springer
    Journal of inclusion phenomena and macrocyclic chemistry 29 (1997), S. 175-185 
    ISSN: 1573-1111
    Schlagwort(e): p-tert-Butylcalix[5]arene ; synthesis ; complexation ; crystal structure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract The formation of p-tert-butylcalix[5]arene by the opening ofp-tert-butyldihomooxacalix [4]arene and the addition of a monomer has beenstudied. Various facets, including the effects of bases and the nature ofthe monomer added to the p-tert-butyldihomooxacalix[4]arene, have beeninvestigated. p-tert-Butylcalix[5]arene can be prepared in yields up to30%. The structure of its 1 : 2 complex with DMF has been determinedby X-ray crystallography. Crystals are triclinic, space group P¯1, a =1428.2(3) pm, b = 1837.3(3) pm, c = 1276.1(2) pm, α = 108.98(1)°,β = 105.02(2)°, γ = 95.21(1)°, Z = 2, D c = 1.059 kg m-3,final R value = 0.087. The macrocycle adopts a cone conformation, one guestenclosed inside the cavity, the other one outside.
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  • 154
    Digitale Medien
    Digitale Medien
    Springer
    Journal of inclusion phenomena and macrocyclic chemistry 29 (1997), S. 335-346 
    ISSN: 1573-1111
    Schlagwort(e): Glycophane ; macrocycle ; carbohydrate ; crystal structure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract Preparation of two new glycophanes is reported. These compounds arecomprised of two glucose molecules linked by hydrocarbon units at the 1,1′ and 3, 3′ or 3, 3′ and 6, 6′ positions. Thecrystal structure of one of the glycophanes is also described.
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  • 155
    ISSN: 0006-3525
    Schlagwort(e): chemotaxis ; conformation ; crystal structure ; Cα-tetrasubstituted amino acids ; formylpeptides ; 2-[2′-(methylthio)ethyl]methionine ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The new Cα-tetrasubstituted α-amino acid residue 2-[2′-(methylthio) ethyl]methionine (Dmt) has been introduced into the reference chemotactic tripeptide HCO-Met-Leu-Phe-OMe (fMLP-OMe) in place of the leucine or methionine, respectively. The biological activity of the new analogues [Dmt2] fMLP-OMe (2) and [Dmt1] fMLP-OMe (3) has been determined; whereas 2 is active toward human neutrophils, stimulating directed migration, superoxide anion generation, and lysozyme release, 3 results practically inactive in all tested assays. A conformational analysis on 2 and 3 has been performed in solution by using ir absorption and 1H-nmr. The conformation of 2 was also examined in the crystal by x-ray diffraction methods. Both 2 and 3 adopt fully extended conformation in correspondence with the Dmt residue. Biological and conformational results are discussed and compared with related previously studied models. © 1997 John Wiley & Sons, Inc. Biopoly 42: 415-426, 1997
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
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  • 156
    ISSN: 0006-3525
    Schlagwort(e): x-ray diffraction ; crystal structure ; dehydrophenylalanine ; constrained peptides ; 310-helix ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: An Nα-protected model pentapeptide containing two consecutive ΔPhe residues, Boc-Leu-ΔPhe-ΔPhe-Ala-Phe-NHMe, has been synthesized by solution methods and fully characterized. 1H-nmr studies provided evidence for the occurrence of a significant population of a conformer having three consecutive, intramolecularly H-bonded β-bends in solution. The solid state structure has been determined by x-ray diffraction methods. The crystals grown from aqueous methanol are orthorhombic, space group P212121, a = 11.503(2), b = 16.554(2), c = 22.107(3) Å, V = 4209(1) Å,3 and Z = 4. The x-ray data were collected on a CAD4 diffractometer using CuKa radiation (λ = 1.5418 Å). The structure was determined using direct methods and refined by full-matrix least-squares procedure. The R factor is 5.3%. The molecule is characterized by a right handed 310-helical conformation (〈φ〉 = -68.2°, 〈ψ〉 = -26.3°), which is made up of two consecutive type III β-bends and one type I β-bend. In the solid state the helical molecules are aligned head-to-tail, thus forming long rod like structures. A comparison with other peptide structures containing consecutive ΔPhe residues is also provided. The present study confirms that the -ΔPhe-ΔPhe-sequence can be accommodated in helical structures. © 1997 John Wiley & Sons, Inc. Biopoly 42: 373-382, 1997
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    Materialart: Digitale Medien
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  • 157
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Biopolymers 44 (1997), S. 3-21 
    ISSN: 0006-3525
    Schlagwort(e): RNA ; x-ray crystallography ; crystal structure ; transfer RNA ; ribozyme ; catalytic RNA ; internal loop ; review ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The current state of three-dimensional structure analysis of RNA by x-ray crystallograpy is summarized. The methods of sample preparation, crystallization, data collection, and structure solution are discussed, followed by a review of the RNA structures that have been determined and of common structural features, and finally, an appraisal of future prospects for x-ray crystal structure analysis of RNA. © 1997 John Wiley & Sons, Inc. Biopoly 44: 3-21, 1997
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
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  • 158
    Digitale Medien
    Digitale Medien
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 35 (1997), S. 1533-1543 
    ISSN: 0887-6266
    Schlagwort(e): polysilane ; lamellar microstructure ; crystal structure ; crystallization kinetics ; Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: The thermal behavior and physical structure of atactic poly(methyl-n-propylsilane) (PMPrS) have been investigated by complementary techniques. Temperature-dependent wide-angle X-ray scattering as well as thermal analysis clearly indicate that atactic PMPrS crystallizes below 40°C in a monoclinic lattice with PMPrS adopting an all-trans planar zigzag conformation. Above 40°C, the polymer is in the isotropic amorphous state. A restricted analysis of the structure factors of PMPrS has been performed, indicating that the zigzag planes most probably lie in (110) planes. The chains pack with little interpenetration, and the crystals may be considered as bundles of long, closely packed prisms. The restricted interlocking of neighboring chains results, in turn, in a poor register of the chains along the c-axis. Moreover, transmission electron microscopy reveals that the crystallized polymer adopts a lamellar microstructure, with parallel lamellae tending to form tight bundles. Both electron microscopy and small-angle X-ray scattering indicate crystal thicknesses of about 60 Å. Finally, PMPrS was found to crystallize with a nucleation-controlled type of kinetics. Avrami exponents were calculated as n ≈ 1, suggesting a fibrillar growth geometry compatible with the absence of spherulitic superstructure. A double-melting behavior is also observed for PMPrS. © 1997 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 35: 1533-1543, 1997
    Zusätzliches Material: 11 Ill.
    Materialart: Digitale Medien
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  • 159
    Digitale Medien
    Digitale Medien
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 35 (1997), S. 1575-1588 
    ISSN: 0887-6266
    Schlagwort(e): poly(naphthalic anhydride) ; crystal structure ; electron diffraction ; confined thin film melt polymerization ; Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: Single crystals of poly(naphthalic anhydride) (PNA) have been grown using our confined thin film melt polymerization technique. Lamellae, 70-100 Å thick, are found for the crystals polymerized at 180°C with thinner lamellae for a 200°C polymerization temperature. In addition, irregular lath-shaped crystals are found for both polymerization temperatures, apparently formed by a solid-state polymerization process within the original needle-like monomer crystals. The crystal structure of PNA has been studied by electron diffraction (ED) and computer modeling based on seven different zonal ED patterns. It is found that, in most cases, two or three different zonal patterns are superimposed with a common plane, suggesting variable chain tilting even in individual lamellae. Shearing of the material shortly after the initiation of polymerization, permitted obtaining an additional [010] zone ED pattern. A monoclinic unit cell with one chain, two repeat units is proposed based on measurements of 21 independent reflections; the space group is Pc11; a = 6.26 Å, b = 4.33 Å, c = 18.60 Å, and α = 122.5°. The computer-simulated (Cerius2) molecular conformation and chain packing are described with the corresponding simulated electron diffraction patterns being in good agreement with the observed ones. © 1997 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 35: 1575-1588, 1997
    Zusätzliches Material: 10 Ill.
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  • 160
    ISSN: 0947-6539
    Schlagwort(e): crystal structure ; cyclobutenes ; nickel ; radialenes ; radical reactions ; Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The reaction of hexakis(dibromomethyl)benzene with [(Bu3P)2-Ni(COD)] (COD = 1,5-cyclooctadiene) in DMF at 65-70°C yielded a mixture of the title compounds. The mixture was separated by column chromatography to yield hexabromotricyclobutabenzene (3 a) and hexabromohexaradialene (4) in 24 and 16% yields, respectively. 1H and 13C NMR spectroscopy suggest that 3 is obtained as the syn-all-trans isomer 3 a, and the symmetric anti-all-trans isomer 3 b is not obtained at all. The X-ray structures of 3 a and 4 are reported. The hexaradialene 4 has a chair conformation, and deviates from planarity by 43.6°. Heat or radical impurities cause the clean transformation of 3 a to 4.
    Zusätzliches Material: 2 Ill.
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  • 161
    ISSN: 0947-6539
    Schlagwort(e): cadmium ; crystal structure ; hydrothermal synthesis ; hydroxyphosphate ; molybdenum ; Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Two new molybdenum(v) hydroxyphosphates have been synthesized hydrothermally, Na2Cd3(Mo2O4OH)6-(PO4)2(PO3OH)6[N(CH3)4]4·10H20 (1) and Cd9(Mo2O4OH)12(PO4)6(PO3OH)10-[N(CH3)4]8·15H2O (2). Their structures have been determined from single-crystal X-ray diffraction. The water molecules and hydroxyl groups have been deduced from valence calculations. Both compounds crystallize in the triclinic space group P1, with the cell parameters for 1 a = 12.340(2), b = 12.596(1), c = 14.717(2) Å, α = 107.24(1)°, β = 89.83(1)°, γ = 114.31(1)°, V = 1972.3(4) Å3, and for 2 a = 11.942(1), b = 13.339(2), c = 26.765(3) Å, α = 85.33(1)°, β = 86.87(1)°, γ = 64.08(1)°, V = 3821.3(9) Å3. The two frameworks can be described on the basis of similar [Mo6P4X31]n- (X = O, OH) anionic clusters, but 1 is a tridimensional structure, whereas 2 exhibits a monodimensional structure.
    Zusätzliches Material: 5 Ill.
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  • 162
    Digitale Medien
    Digitale Medien
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 35 (1997), S. 1807-1820 
    ISSN: 0887-6266
    Schlagwort(e): poly(p-oxybenzoate) ; confined thin film melt polymerization ; epitaxy ; mica substrate ; morphology ; crystal structure ; Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: Polymerization of p-acetoxybenzoic acid between mica sheets, from both the melt and dilute solution, in a wide range of polymerization temperatures (180-400°C) yields an epitaxial-like overgrowth of PpOBA on the mica cleavage surface. The PpOBA overgrowth forms long rows by lateral aggregation of ribbon crystals situated in three substrate directions rotated by 60°. The c-axes of the PpOBA phase I and II lattices are parallel to the 001 plane of the mica, coinciding with the a-axes of the mica hexagonal structure. The aI- and bII-axes lie predominantly on the mica surface. The surface-orienting effect is tentatively attributed to surface steps and or/polar effects; lattice matching does not occur. The recrystallization of bulk polymer samples previously prepared also leads to ordering between mica like that in melt or solution polymerization. © 1997 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 35: 1807-1820, 1997
    Zusätzliches Material: 12 Ill.
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  • 163
    Digitale Medien
    Digitale Medien
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 35 (1997), S. 623-630 
    ISSN: 0887-6266
    Schlagwort(e): ultra-high modulus and molecular weight polyethylene fibers (UHM-WPE) ; high-temperature wide-angle x-ray diffraction (HTWAXD) ; crystal structure ; orthorhombic/monoclinic/pseudohexagonal transformation ; annealing and thermal behavior ; Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: Wide-angle x-ray diffraction (WAXD) of the ultra-high modulus and molecular weight polyethylene (UHMWPE) fibers at room temperature shows a predominantly orthorhombic structure with trace amount of nonorthorhombic crystals and very low amorphous contents. The calculated unit cell dimensions a and b of the orthorhombic crystals are 7.36 (±0.04) Å, and 4.89 (±0.04) Å, respectively. The apparent crystallite sizes perpendicular to the orthorhombic 110 and 200 reflection planes are 169.8 and 143.4 Å, respectively. The crystallite size perpendicular to the nonorthorhombic 010 reflection is 149.4 Å. The crystal density is calculated to be 1.02 g/cc. With increasing temperature, the thermal expansion coefficient in the a direction is much higher than that in the b direction which explains the structural transformation from the orthorhombic crystals to a pseudohexagonal form. Tension along the fiber axis while being heated during the high-temperature x-ray diffraction (HTWAXD) scanning has shown enhanced structural transformation from the orthorhombic form to the monoclinic form. Structural transformation from the orthorhombic form to the pseudohexagonal phase is not observed on the UHMWPE fibers under axial tension or annealing conditions in HTWAXD. © 1997 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys, 35: 623-630, 1997
    Zusätzliches Material: 7 Ill.
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  • 164
    Digitale Medien
    Digitale Medien
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 35 (1997), S. 2511-2521 
    ISSN: 0887-6266
    Schlagwort(e): isotactic poly(propylenes) ; unit-cell density ; crystal structure ; unit-cell parameters ; Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: The lattice parameters of a series of monoclinic metallocene poly(propylenes) of constant molecular weight are measured as a function of defect content, that vary between 0.3 and 2.35 total defects per 100 monomeric units. The parameters are also measured as a function of molecular weight for a fixed defect content and as a function of the crystallization temperature. The b axis is found to increase with decreasing isothermal crystallization temperature whereas only small changes are found for samples rapidly crystallized. The a and c axis showed basically no variation with crystallization temperature. The parameters of the unit cell were essentially constant with varying defect content in the poly(propylene) chain. Lack of observed effect on the dilation of the unit cell by increasing defects is a consequence of the rapid crystallization required to ensure formation of monoclinic crystals. The unit cell parameters increased as a mild function of the molecular weight. © 1997 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 35: 2511-2521, 1997
    Zusätzliches Material: 3 Ill.
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  • 165
    ISSN: 0952-3499
    Schlagwort(e): bovine α-chymotrypsin ; bovine basic pancreatic trypsin inhibitor (Kunitz-type inhibitor) ; serine proteinase:Kunitz inhibitor complex ; crystal structure ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin
    Notizen: The crystal structure of bovine α-chymotrypsin (α-CHT) in complex with the bovine basic pancreatic trypsin inhibitor (BPTI) has been solved and refined at 2.8 Å resolution (R-factor=0.18). The proteinase:inhibitor complex forms a compact dimer (two α-CHT and two BPTI molecules), which may be stabilized by surface-bound sulphate ions, in the crystalline state. Each BPTI molecule, at opposite ends, is contacting both proteinase molecules in the dimer, through the reactive site loop and through residues next to the inhibitor's C-terminal region. Specific recognition between α-CHT and BPTI occurs at the (re)active site interface according to structural rules inferred from the analysis of homologous serine proteinase:inhibitor complexes. Lys15, the P1 residue of BPTI, however, does not occupy the α-CHT S1 specificity pocket, being hydrogen bonded to backbone atoms of the enzyme surface residues Gly216 and Ser217. © 1997 John Wiley & Sons, Ltd.
    Zusätzliches Material: 5 Ill.
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  • 166
    ISSN: 0947-6539
    Schlagwort(e): crystal structure ; electrophilic aromatic substitutions ; magnesium ; regioselectivity ; template synthesis ; Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The crystal structures of the bromomagnesium phenolate 5 and its complex 7 with para-isopropylbenzaldehyde are reported; for the first time it has been possible to demonstrate that the reactive complex 7, responsible for the complete ortho-regioselective control in the alkylation of phenoxymagnesium bromides with aldehydes, is not obtained by simple replacement of the ethereal ligand but by expansion of the metal coordination sphere from 4 (usual tetrahedral configuration) to 5. We infer from 1H NMR studies that the magnesium coordination of complex 7 in solution is analogous to that shown in the solid state, with a complexed ethereal molecule.
    Zusätzliches Material: 1 Ill.
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  • 167
    ISSN: 0947-6539
    Schlagwort(e): crystal structure ; cyclophanes ; electrochemistry ; porphyrazines ; tetrathiafulvalenes ; Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The pyrazinoporphyrazine system 13 (metal-free, zinc and copper derivatives) has been synthesised by tetramerisation of 2,3-dicyanopyrazine monomer unit 10. The structure of 13a-c has been established by 1H NMR spectroscopy, UV/Vis spectrophotometry, MALDI-TOF mass spectrometry, cyclic voltammetry and differential pulse voltammetry. The electrochemical redox behaviour of 13a-c is strongly solvent dependent. The expected two-stage oxidation of the tetrathiafulvalene (TTF) units of 13a-c was observed in a range of solvents; in addition, oxidation and reduction of the pyrazinoporphyrazine core of the metal-free derivative 13a was detected in benzonitrile. On excitation of 13 in the Q-band region no fluorescence was observed, which is presumably the consequence of intramolecular charge transfer between the TTF moieties and the excited state of the central porphyrazine. Molecular modelling studies on 13a and 13c are reported. During the course of this work, the novel TTF macrocycles 11 and 20 were synthesised; their X-ray crystal structures reveal severely bent TTF units, the conformations of which are discussed in detail. The X-ray crystal structures of the bis(1,3-dithiole) systems 15 and 18 have also been determined.
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  • 168
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Chemistry - A European Journal 3 (1997), S. 121-126 
    ISSN: 0947-6539
    Schlagwort(e): crystal structure ; NMR spectroscopy ; proton transfer ; pyrazoles ; tautomerism ; Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The crystal structure of the title compound was determined by X-ray analysis at 200 K. Three independent molecules form a trimer joined by strong and linear N-H … N hydrogen bonds. There is another centrosymmetrically related trimer in the unit cell. Both tautomers (1H and 2H) are present in each trimer. Disorder of the NH protons involved in the N-H … N hydrogen bonds has been observed. Solid-state 13C CPMAS NMR was used to establish the dynamic nature of the NH-proton disorder, the title compound being the first example of proton transfer in a tautomeric mixture of pyrazoles with an equilibrium constant other than 1.
    Zusätzliches Material: 5 Ill.
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  • 169
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 623 (1997), S. 1201-1202 
    ISSN: 0044-2313
    Schlagwort(e): Cobalt(II) complex ; 1,2-dimethyl-5-nitro-imidazole ligand ; crystal structure ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Synthesis and Crystal Structure of Bis(1,2-dimetyl-5-nitro-imidazole)dichlorocobalt(II)Bis(1,2-dimethyl-5-nitro-imidazol)dichlorocobalt(II) was obtained by reaction of CoCl2 · 6 H2O with 1,2-dimethyl-5-nitro-imidazole in methanol. The compound forms blue crystals which were characterized by IR and UV-vis spectroscopy and by an X-ray crystal structure determination. Co(C5H7N3O2)2Cl2: tetragonal, space group I42d, Z = 8, a = 1142.1(1) pm, c = 2577.3(2) pm. R = 0.036 for 670 independent reflexions. The Co atom is tetrahedrally surrounded by two chlorine and two N atoms at distances of 222.8(2) and 203.5(4) pm.
    Zusätzliches Material: 1 Ill.
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  • 170
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 623 (1997), S. 1503-1505 
    ISSN: 0044-2313
    Schlagwort(e): Ditetraammine lithium tetraphenyldistannide ; synthesis ; single-crystals ; crystal structure ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Tetraammine Lithium Cations Stabilizing Phenylsubstituted Zintl-Anions: The Compound [Li(NH3)4]2[Sn2Ph4]Ruby-red, brittle single crystals of [Li(NH3)4]2[Sn2Ph4] were synthesized by the reaction of diphenyltin dichloride and metallic lithium in liquid ammonia at -35°C. The structure was determined from X-ray singlecrystal diffractometer data: Space group, P1, Z = 1, a = 9.462(2) Å, b = 9.727(2) Å, c = 11.232(2) Å, α = 66.22(3)°, β = 85.78(3)°, γ = 61.83(3)°, R1 (F02 ≥ 4σF02) = 5.13%, wR2 (F02 ≥ 4σF02) = 10.5%, N(F02 ≥ 4σF02) = 779, N(Var.) = 163.The compound contains to Sb2Ph4 isosteric centres [Sn2Ph4]2- as anions which are connected to rods by lithium cations in distorted tetrahedral coordination by ammonia. These rods are arranged parallel to one another in the b,c-plane, but stacked along [100].
    Zusätzliches Material: 2 Ill.
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  • 171
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 623 (1997), S. 1535-1541 
    ISSN: 0044-2313
    Schlagwort(e): Bismuth platinum iodide ; subhalide ; crystal structure ; pseudo-symmetry ; stacking faults ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Beschreibung / Inhaltsverzeichnis: Bi13Pt3I7: A Subiodide with a Pseudo-Symmetric Layer StructureThe reaction of PtI2 with Bi and BiI at 630 K yields black, lustrous, air insensitive crystals of the subiodide Bi13Pt3I7. The layered crystal structure (triclinic, C1, a = 1581.0(2) pm, b = 912.6(1) pm, c = 2149.6(6) pm, α = 90.03(2)°, β = 96.96(2)°, γ = 90.11(1)°, V = 3078.6 · 106 pm3) contains edge-sharing [PtBi8/2] cubes, which form nets of Kagomé type. Iodine atoms fill the hexagonal-prismatic voids therein. These ∞2[(PtBi8/2)3I] layers are alternately separated by layers of iodine atoms or ∞1[BiI4-] zigzag-chains. The marked pseudo-symmetry of the structure favours stacking faults, which cause streaks of diffuse scattering in the diffraction pattern.
    Notizen: Aus der Reaktion von PtI2 mit Bi und BiI bei 630 K erhält man schwarze, metallisch glänzende und luftbeständige Kristalle des Subiodids Bi13Pt3I7. In der schichtartig aufgebauten Kristallstruktur (triklin, C1, a = 1581,0(2) pm, b = 912,6(1) pm, c = 2149,6(6) pm, α = 90,03(2)°, β = 96,96(2)°, γ = 90,11(1)°, V = 3078,6 · 106 pm3) liegen Kagomé-Netze aus kantenverknüpften [PtBi8/2]-Würfeln vor, deren hexagonal-prismatische Lücken mit Iodatomen gefüllt sind. Diese ∞2[(PtBi8/2)3I]-Schichten sind abwechselnd durch eine Lage von Iodatomen oder eine Schicht aus parallel angeordneten ∞1[BiI4-]-Zickzackketten getrennt. Die in der Struktur stark ausgeprägte Pseudosymmetrie begünstigt Stapelfehler, welche sich auch in diffusen Streifen im Beugungsbild äußern.
    Zusätzliches Material: 6 Ill.
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  • 172
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 623 (1997), S. 1287-1289 
    ISSN: 0044-2313
    Schlagwort(e): Calcium hexahydroxodizincate dihydrate ; synthesis ; crystal structure ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Beschreibung / Inhaltsverzeichnis: Crystal Structure of CaZn2(OH)6 · 2 H2OThe electrochemical oxidation of zinc in a zinc/iron-pair leads in an aqueous NH3 solution of calciumhydroxide at room temperature to colourless crystals of CaZn2(OH)6 · 2 H2O. The X-ray structure determination was now successful including all hydrogen positions.P21/c, Z = 2, a = 6.372(1) Å, b = 10.940(2) Å, c = 5.749(2) Å, β = 101.94(2)° N(F2o ≥ 3σF2o) = 809, N(Var.) = 69, R/RW = 0.011/0.012The compound CaZn2(OH)6 · 2H2O contains Zn2+ in tetrahedral coordination by OH- and Ca2+ in octahedral coordination by four OH- and two H2O. The tetrahedra around Zn2+ form corner sharing chains, three-dimensionally linked by isolated polyhedra around Ca2+. Weak hydrogen bridge bonds result between H2O as donor and OH-.
    Notizen: Die elektrochemische Oxidation von Zink in einem Zink/Eisen-Paar führt in einer wäßrigen NH3-Lösung von Calciumhydroxid bei Raumtemperatur zu farblosen Kristallen von CaZn2(OH)6 · 2 H2O. An ihnen wurde röntgenographisch die Struktur jetzt einschließlich aller H-Lagen bestimmt.P21/c, Z = 2, a = 6,372(1) Å, b = 10,940(2) Å, c = 5,749(2) Å, β = 101,94(2)° Z(F2o ≥ 3σF2o) = 809, Z(Var.) = 69, R/RW = 0,011/0,012In CaZn2(OH)6 · 2 H2O ist Zn2+ tetraedrisch von OH- und Ca2+ oktaedrisch von vier OH- und zwei H2O umgeben. Die Tetraeder um Zn2+ bilden Ketten über gemeinsame Ecken, die durch voneinander isolierten Oktaedern um Ca2+ dreidimensional verknüpft werden. Es liegen schwache H-Brückenbindungen von H2O als Donator zu OH- vor.
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  • 173
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 623 (1997), S. 1299-1305 
    ISSN: 0044-2313
    Schlagwort(e): Pseudoelement compounds ; cyanamidonitrate ; copper(I) ; silver(I) ; platinum(II) ; crystal structure ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Beschreibung / Inhaltsverzeichnis: Pseudoelement Compounds. XI. [1] Investigations on the Coordination Behaviour of Cyanamidonitrate [NO2NCN]-With the ionic, potentially ambidentate ligand cyanamidonitrate complexes of the types [MX(PPh3)3], [MX(PPh3)2]2 (M=CuI, AgI) and trans-[Pt(H)X(PPh3)2] (X-=[NO2NCN]-) are introduced. The new compounds are characterized by 1H NMR, 31P NMR, and IR spectroscopy. The crystal structures of [Cu(NO2NCN)(PPh3)2]2 and [Ag(NO2NCN)(PPh3)2]2 are reported. In the complexes [MX(PPh3)3] and trans-[Pt(H)X(PPh3)2] cyanamidonitrate is unidentately coordinated through the nitrile group end-on. In the dimeric complexes [MX(PPh3)2]2 the anion acts bidentately as a bridging ligand. Surprisingly, both coordinative bonds are formed through nitrogen atoms of the NCN group.
    Notizen: Es werden mit dem ionischen, potentiell ambidenten Liganden Cyanamidonitrat Komplexe der Typen [MX(PPh3)3], [MX(PPh3)2]2 (M=CuI, AgI) sowie trans-[Pt(H)X(PPh3)2] (X-=[NO2NCN]-) vorgestellt. Die Verbindungen wurden 1H-NMR-, 31P-NMR- und IR-spektroskopisch charakterisiert. Für [Cu(NO2NCN)(PPh3)2]2 und [Ag(NO2NCN)(PPh3)2]2 liegen Kristallstrukturanalysen vor.Cyanamidonitrat wird in den Komplexen [MX(PPh3)3] und trans-[Pt(H)X(PPh3)2] einzähnig über das endständige N-Atom der Nitrilgruppe koordiniert. In den dimeren Komplexen [MX(PPh3)2]2 liegt das Anion als zweizähniger Brükkenligand vor. Überraschend werden beide koordinativen Bindungen über die Stickstoffatome der NCN-Gruppe ausgebildet.
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  • 174
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 623 (1997), S. 1657-1660 
    ISSN: 0044-2313
    Schlagwort(e): Ruthenium ; chalcogenide ; chemical transport ; crystal structure ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Beschreibung / Inhaltsverzeichnis: Crystal Structure of the Low Temperature Modification of RuTe2Black shining, platelet like single crystals of α-RuTe2 were obtained by chemical transport reaction with Cl2/AlCl3 (crystal dimensions up to 1 mm). The crystal structure of this low temperature modification of α-RuTe2 hitherto only known from powder measurements, was redetermined at room temperature by single crystal X-ray diffraction on a four-circle diffractometer. α-RuTe2 crystallizes in the marcasit structure typ in the orthorhombic spacegroup Pnnm (No. 58) with the lattice constants a = 528.12(13), b = 639.43(19), c = 400.85(13) pm.
    Notizen: Durch chemischen Transport mit dem Transportmittel Cl2/AlCl3 konnten schwarzglänzende, plattenartige Einkristalle von α-RuTe2 erhalten werden (Kantenlänge bis zu 1 mm). Die Kristallstruktur dieser bisher nur aus Pulverdaten bekannten Tieftemperaturmodifikation von RuTe2 wurde röntgenographisch an einem Einkristall auf einem Vierkreisdiffraktometer bei Raumtemperatur neu bestimmt. α-RuTe2 kristallisiert im Markasit-Strukturtyp in der orthorhombischen Raumgruppe Pnnm (Nr. 58) mit den Gitterkonstanten a = 528,12(13), b = 639,43(19), c = 400,85(13) pm.
    Zusätzliches Material: 1 Ill.
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  • 175
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 623 (1997), S. 1661-1664 
    ISSN: 0044-2313
    Schlagwort(e): Organo molybdenum compounds ; oxo complexes ; crystal structure ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Beschreibung / Inhaltsverzeichnis: Mesityl Oxo Molybdenum and Tungsten Compounds. I. Structure of LiMoO2Me2Mes(OEt2)2LiMoO2Me2Mes(OEt2)2 2 is prepared by literature method [2] from MoO2Mes2 1 and LiMe. Its x-ray structure and NMR-spectral data are presented. 2 adopts a dimer structure in which two [MoO2Me2Mes]- anions are linked via two bridging [Li(OEt2)2]+ cations bonded to the oxo ligands. The resulting [‥OMoOLi‥]2 ring is planar.
    Notizen: Die Struktur der bekannten, aus MoO2Mes2 1 und LiMe dargestellten Verbindung LiMoO2Me2Mes(OEt2)2 2 [2] sowie ihre NMR-spektroskopischen Daten werden mitgeteilt. 2 bildet ein in der Raumgruppe P1 kristallisierendes Dimer durch Verknüpfung zweier [MoO2Me2Mes]--Anionen über Oxo-Liganden durch zwei Kationen [Li(OEt2)2]+. Der gebildete [‥OMoOLi‥]2- Achtring ist eben.
    Zusätzliches Material: 1 Ill.
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  • 176
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 623 (1997), S. 1679-1683 
    ISSN: 0044-2313
    Schlagwort(e): Organoindium compounds ; chelate complexes ; crystal structure ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Beschreibung / Inhaltsverzeichnis: The 3-(N,N-Dimethylamino)prop-1-enyl Group as a Chelate Ligand in Indium OrganylsInBr3 reacts with Me2NCH2CH=CHMgCl (molar ratio 1 : 2) to form (Me2NCH2CH=CH)2InBr (1) as the first indium alkenyl compound with amino-functionalized alkenyl groups. The X-ray structure determination shows the formation of a chelate complex. 1 crystallizes in the orthorhombic space group Fddd with the unit cell parameters a = 14.904(2) Å, b = 17.140(1) Å and c = 21.035(2) Å. By reaction of Me2InBr with Me2NCH2CH=CHMgCl (molar ratio 1 : 1) (Me2NCH2CH=CH)InMe2 (2) is formed as a colorless, at room temperature liquid, monomeric compound. The n.m.r. and mass spectra are discussed.
    Notizen: InBr3 reagiert mit Me2NCH2CH=CHMgCl (Molverhältnis 1 : 2) in Diethylether als Lösungsmittel zu (Me2NCH2CH=CH)2InBr (1), der ersten Indium-Alkenylverbindung mit aminofunktionalisierten Alkenylresten. Die Röntgenkristallstrukturanalyse zeigt das Vorliegen eines Chelatkomplexes an. 1 kristallisiert orthorhombisch in der Raumgruppe Fddd mit Z = 16, a = 14,904(2) Å, b = 17,1405(14) Å und c = 21,035(2) Å. Aus Me2InBr und Me2NCH2CH=CHMgCl (Molverhältnis 1 : 1) wurde (Me2NCH2CH=CH)InMe2 (2) als farblose, bei Raumtemperatur flüssige, monomere Verbindung erhalten. Die 1H- und 13C-NMR-Spektren sowie Massenspektren werden mitgeteilt.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
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  • 177
    ISSN: 0044-2313
    Schlagwort(e): Chromium(II)-orthophosphate ; crystal growth ; crystal structure ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Beschreibung / Inhaltsverzeichnis: Beiträge zum thermischen Verhalten und zur Kristallchemie von wasserfreien Phosphaten. XIX. Tri-chrom(II)-bis-phosphat Cr3(PO4)2 (≙ Cr6(PO4)4) - Ein Übergangsmetall(II)- Orthophosphat mit neuem StrukturtypIntensiv blau-violette Kristalle des bislang unbekannten Tri-chrom(II)-bis-phosphats, Cr3(PO4)2, entstehen bei der Reduktion von CrPO4 mit Chrom oberhalb von 1050°C (evakuierte Quarzglasampullen, wenige mg NH4I oder I2 als Mineralisator). Die Kristallstruktur von Cr3(PO4)2 enthält sechs kristallographisch unabhängige Cr2+ in der Elementarzelle (P212121, Z = 8, a = 8,4849(10) Å, b = 10,3317(10) Å, c = 14,206(3) Å). Davon sind fünf in der ersten Koordinationssphäre von vier Sauerstoffatomen leicht verzerrt quadratisch-planar umgeben (1,96 Å ≤ d(Cr—O) ≤ 2.15 Å). Deren Koordination wird vervollständigt durch zwei bzw. drei weiter entfernte Sauerstoffatome (2,32 Å ≤ d(Cr—O) ≤ 3,21 Å). Das sechste Cr2+-Ion ist stark verzerrt oktaedrisch koordiniert (d(Cr—O): 1,97, 2,04, 2,15, 2,28, 2,29, 2,53 Å).Die vier kristallographisch unterschiedlichen [PO4]-Gruppen zeigen nur geringe Abweichungen von der Geometric eines idealen Tetraeders (1,51 Å ≤ d(P—O) ≤ 1,57 Å; 104,3° ≤ ∠(O—P—O) ≤ 114,4°).Für die Cr2+ wurde mit μexp = 4,28(2) μB (θP = -54,8(5) K) ein ungewöhnlich niedriges mittleres magnetische Moment gefunden.
    Notizen: Deep blue-violet single crystals of hitherto unknown chromous orthophosphate have been obtained reducing CrPO4 by elemental Cr at temperatures above 1050°C in evacuated silica ampoules (NH4I or I2 as mineraliser). The complex structure of Cr3(PO4)2 (P212121, Z = 8, a = 8.4849(10) Å, b = 10.3317(10) Å, c = 14.206(2) Å) contains six crystallographically independent Cr2+ per unit cell. Five of them are coordinated by four oxygen atoms which form a distorted (roof shaped) square plane as first coordination sphere at interatomic distances 1.96 Å ≤ d(Cr—O) ≤ 2.15 Å. Their coordination is completed by additional oxygen atoms (2 or 3) at distances 2.32 Å ≤ d(Cr—O) ≤ 3.21 Å. The sixth Cr2+ shows six-fold octahedral coordination with strong radial distortion (d(Cr—O): 1.97, 2.04, 2.15, 2.28, 2.29, 2.53 Å).The four different [PO4] groups exhibit only minor deviations from ideal tetrahedral geometry (1.51 Å ≤ d(P—O) ≤ 1.57 Å, 104.3° ≤ ∠(O—P—O) ≤ 114.4°).An unusually low magnetic moment μexp = 4.28(2) μB (θP = -54.8(5) K) has been observed for Cr2+.
    Zusätzliches Material: 5 Ill.
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  • 178
    ISSN: 0044-2313
    Schlagwort(e): Ternary Rhodium phosphides ; crystal structure ; phase transition ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Beschreibung / Inhaltsverzeichnis: About the Effect of Temperature, Pressure, and Substitution on the Crystal Structure of ARh2P2 (A = Ca, Sr, Eu, Ba)Four compounds ARh2P2 (A = Ca, Sr, Eu, Ba) were prepared by heating mixtures of the elements and investigated by means of single crystal X-ray methods. They crystallize in the ThCr2Si2 type structure (I4/mmm; Z = 2) with P—P distances along [001] reaching from 2.26 Å (CaRh2P2) to 3.74 Å (BaRh2P2). With increasing temperature (EuRh2P2) or increasing pressure (SrRh2P2) a first order phase transition occurs with strong changes of the P—P distances. Substitution of the atoms changes the bond lengths of the compounds too.
    Notizen: Vier Verbindungen ARh2P2 (A = Ca, Sr, Eu, Ba) wurden durch Erhitzen entsprechender Elementgemenge dargestellt und hinsichtlich ihrer Kristallstruktur mit Hilfe von Einkristallmethoden charakterisiert. Sie kristallisieren in der tetragonalen ThCr2Si2-Struktur (I4/mmm; Z = 2) und unterscheiden sich im wesentlichen durch ihre P—P-Abstände längs [001]. Diese reichen von 2,26 Å bei CaRh2P2 bis 3,74 Å bei BaRh2P2 und verändern sich drastisch im Zuge von Phasenumwandlungen 1. Ordnung durch Temperaturerhöhung bei EuRh2P2 sowie unter erhöhtem Druck bei SrRh2P2. Substitution übt ebenfalls einen großen Einfluß auf den Strukturfeinbau der Verbindungen aus.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
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  • 179
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 623 (1997), S. 1744-1746 
    ISSN: 0044-2313
    Schlagwort(e): Terbium sesquiselenide ; chemical transport ; crystal structure ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Beschreibung / Inhaltsverzeichnis: Crystal Structure of Tb2Se3Single crystals of Tb2Se3 could be prepared by chemical transport reaction with AlCl3. By starting from TbSe1.9 and terbium metal black needles of Tb2Se3 in the U2S3 type structure with the space group Pnma and a = 1113,0(1) pm, b = 402,4(1) pm and c = 1095,1(3) pm were obtained.
    Notizen: Einkristalle von Tb2Se3 konnten durch chemischen Transport mit AlCl3 dargestellt werden. Ausgehend von pulverförmigem TbSe1,9 und Terbiummetall wurden schwarze, nadelförmige Einkristalle von Tb2Se3 im U2S3-Strukturtyp mit der Raumgruppe Pnma und a = 1113,0(1) pm, b = 402,4(1) pm und c = 1095,1(3) pm erhalten.
    Zusätzliches Material: 5 Tab.
    Materialart: Digitale Medien
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  • 180
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 623 (1997), S. 1747-1752 
    ISSN: 0044-2313
    Schlagwort(e): Lanthanides ; nitride sulfide chlorides ; Pr5N3S2Cl2 ; synthesis ; crystal structure ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Beschreibung / Inhaltsverzeichnis: Nitride Sulfide Chlorides of the Lanthanides. III. Synthesis and Crystal Structure of Pr5N3S2Cl2By reacting praseodymium with sulfur, sodium azide and praseodymium trichloride in sealed, evacuated silica tubes (850°C, 7 d), the nitride sulfide chloride Pr5N3S2Cl2 is obtained in case of a 4:2:1:1 molar ratio of the reactants (Pr:S:NaN3:PrCl3). A slight excess of trichloride or the addition of NaCl as a flux supports the yield of brownish red, rod-shaped transparent crystals which prove to be stable against hydrolysis. The crystal structure (monoclinic, C2/m (no. 12), a = 1540.2(1), b = 400.92(3), c = 1656.3(1) pm, β = 101.24(1)°, Z = 4, R = 0.039, Rw = 0.028) was determined by means of X-ray single crystal data. Thus five crystallographically different cations (Pr3+) are present which with three distinct kinds of nitride anions (N3-) build up two types of translationally commensurate chains from interconnected [NPr4] tetrahedra. With an additional edge per “chain-link” in chain I, two single chains ∞1[NPr3/3ePr1/1t]3+ (≡∞1[NPr2]3+) of cis-edge connected [NPr4] tetrahedra (known from the Sm4N2S3-type structure) are condensed into the double chain ∞1[(N1){(Pr1)(2+2)/(2+2)e,e(Pr2)(2+1)/(2+1)e,v}(N2)(Pr3)1/1t]3+ (≡∞1[N2Pr3]3+). Chain II consists of two single chains ∞1[NPr2/2vPr2/1t] 6+ (≡∞1[NPr3]6+) of vertex-connected [NPr4] tetrahedra (known from the Sm3NS3-type structure), which are condensed to the double chain ∞1[(N3)(Pr4)2/2e(Pr5)2/2v]3+ (≡∞1[NPr2]3+) via an additional edge per “chain-link” too. Both types of chains are bundled along [010] like a closest packing of rods. Four crystallographically different but by X-ray diffraction indistinguishable anions S2- and Cl- hold both cationic double chains together and also adjust the charge balance in a molar ratio of 1 : 1.
    Notizen: Durch Umsetzung von Praseodym mit Schwefel, Natriumazid und Praseodymtrichlorid in evakuierten Quarzglasampullen (850°C, 7 d) wird bei molaren Verhältnissen der Edukte (Pr:S:NaN3:PrCl3) von 4:2:1:1 das Nitridsulfidchlorid Pr5N3S2Cl2 erhalten. Ein geringer Überschuß an Trichlorid oder der Zusatz von NaCl als Flußmittel fördert die Bildung von braunroten, stäbchenförmigen, transparenten Kristallen, die sich als unempfindlich gegenüber Hydrolyse erweisen. Die Kristallstruktur (monoklin, C2/m (Nr. 12); a = 1540,2(1); b = 400,92(3); c = 1656,3(1) pm; β = 101,24(1)°, Z = 4; R = 0,039; Rw = 0,028) wurde röntgenographisch anhand von Einkristalldaten bestimmt. Danach liegen fünf kristallographisch unterschiedliche Kationen. (Pr3+) vor, die mit drei verschiedenen Sorten von Nitridionen (N3-) zwei Typen translationskommensurabler Stränge aus verknüpften [NPr4]-Tetraedern bilden. In Strang I werden zwei Einfachketten ∞1[NPr3/3kPr1/1t]3+ (≡∞1[NPr2]3+) cis-kantenverknüpfter [NPr4]-Tetraeder (bekannt aus der Sm4N2S3-Struktur) über eine zusätzliche Kante pro „Kettenglied“ zur Doppelkette ∞1[(N1){(Pr1)(2+2)/(2+2)k,k(Pr2)(2+1)/(2+1)k,e}(N2)(Pr3)1/1t]3+ (≡∞1[N2Pr3]3+) verknüpft. Strang II besteht aus zwei Einfachketten ∞1[NPr2/2ePr2/1t]6+ (≡∞1[NPr3]6+) eckenverknüpfter [NPr4]-Tetraeder (bekannt aus der Sm3NS3-Struktur), die über eine zusätzliche Kante pro „Kettenglied“ zur Doppelkette ∞1[(N3)(Pr4)2/2k(Pr5)2/2e]3+ (≡∞1[NPr2]3+) kondensiert sind. Beide Strangsorten ordnen sich längs [010] nach dem Motiv einer dichtesten Stabpackung an. Vier kristallographisch unterschiedliche, röntgenographisch jedoch nicht unterscheidbare Anionen S2- und Cl- sorgen für den Zusammenhalt der kationischen Doppelketten und regeln im molaren Verhältnis von 1 : 1 auch den Ladungsausgleich.
    Zusätzliches Material: 5 Ill.
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  • 181
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 623 (1997), S. 1786-1790 
    ISSN: 0044-2313
    Schlagwort(e): Ammonium diamido dioxo phosphate(V) ; synthesis ; crystal structure ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Beschreibung / Inhaltsverzeichnis: Synthesis and Structure of an Ammonium Diamidodioxophosphate(V), NH4PO2(NH2)2The ammonolysis of P3N5 under ammonothermal conditions (T = 400°C, p(NH3) = 6 kbar, 14 d in autoclaves) in the presence of small definite amounts of water leads to the formation of NH4PO2(NH2)2. The structure was solved by single crystal X-ray methods.NH4PO2(NH2)2: P21/c (Nr. 14), a = 6.886(1) Å, b = 8.366(2) Å, c = 9.151(2) Å, β = 111.78(3)°, Z = 4, R1/wR2 = 0.026/0.072, Z(Fo2 〉 2σ(Fo2)) = 1183, N(variables) = 87. In NH4PO2(NH2)2 the anions [PO2(NH2)2]- are linked to chains by N—H … N and N—H … O bridge bonds. The ammonium ions are located between these chains and are donors for N—H … O bridge bonds which connect the chains three-dimensionally.
    Notizen: Bei Ammonolysen von P3N5 unter ammonothermalen Bedingungen (T = 400°C und p(NH3) = 6 kbar 14 d in Autoklaven) führt eine geringe, definierte Menge Wasser zur Bildung von NH4PO2(NH2)2. Die Struktur wurde röntgenographisch am Einkristall bestimmt.NH4PO2(NH2)2: P21/c (Nr. 14), a = 6,886(1) Å, b = 8,366(2) Å, c = 9,151(2) Å, β = 111,78(3)°, Z = 4, R1/wR2 = 0,026/0,072, Z(Fo2 〉 2σ(Fo2)) = 1183, Z(Variable) = 87. In NH4PO2(NH2)2 sind Anionen [PO2(NH2)2]-, über N—H … N und N—H … O Brückenbindungen zu unendlichen Ketten verknüpft. Die Ammoniumionen liegen zwischen den Ketten und wirken als Donatoren für N—H … O Brückenbindungen, die die Ketten dreidimensional verknüpfen.
    Zusätzliches Material: 7 Ill.
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  • 182
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 623 (1997), S. 1781-1785 
    ISSN: 0044-2313
    Schlagwort(e): Copper ; aluminium ; gallium ; oxide arsenate ; crystal structure ; oxidation of alloys ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Beschreibung / Inhaltsverzeichnis: The Crystal Structure of (Al0,5Ga0,5)CuOAsO4 - Copper Intermediate between Planar and Closed CoordinationSingle crystals of the new oxide arsenate (Al0.5Ga0.5)CuOAsO4 (monoclinic, P21/c, a = 734.3(2) pm, b = 1024.79(9) pm, c = 563.4(2) pm, β = 99.93(1)°, Z = 4) were obtained by reaction of Al/As/Cu/Ga-alloys with oxygen. The crystal structure was determined from four-circle diffractometer data (w2R = 0.039 for 1211 F2 values and 76 parameters). The structure contains [Cu2O6] double squares arranged in slabs perpendicular to the a axis such that a [4 + 1]-coordination of the copper atoms by oxygen atoms results which is intermediate between square-planar and square-pyramidal. Along [100] layers of corner sharing (Al/Ga)O4 and AsO4 tetrahedra are alternating with buckled Cu layers.
    Notizen: Einkristalle des neuen Oxidarsenats (Al0,5Ga0,5)CuOAsO4 (monoklin, P21/c, a = 734,3(2) pm, b = 1024,79(9) pm, c = 563,4(2) pm, β = 99,93(1)°, Z = 4) wurden durch Oxidation von Al/As/Cu/Ga-Legierungen im Sauerstoffstrom erhalten. Die Kristallstruktur wurde aus Vierkreisdiffraktometer-Daten bestimmt (w2R = 0,039 für 1211 F2-Werte und 76 Parameter). [Cu2O6]-Doppelquadrate sind in Schichten senkrecht zur a-Achse so angeordnet, daß für Kupfer eine [4 + 1]-Koordination durch Sauerstoffatome resultiert, die als Übergang von quadratisch-planarer zu quadratisch-pyramidaler Koordination interpretiert werden kann. In [100]-Richtung wechseln Schichten aus eckenverknüpften (Al/Ga)O4- und AsO4-Tetraedern mit gewellten Cu-Schichten ab.
    Zusätzliches Material: 4 Ill.
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  • 183
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 623 (1997), S. 1621-1624 
    ISSN: 0044-2313
    Schlagwort(e): Sodium auride thallide ; gold chains ; thallium dumb-bells, synthesis ; crystal structure ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Beschreibung / Inhaltsverzeichnis: Na4AuTl, the First Ternary Compound in the System Sodium/Gold/ThalliumSilver coloured, brittle single crystals of Na4AuTl were obtained by the reaction of NaN3, gold sponge and TlN3 at 773 K. The structure was determined from X-ray single-crystal diffractometry data: \documentclass{article}\pagestyle{empty}\begin{document}$$ {\rm space}\,{\rm group}\,{\rm Fmmm,}\,{\rm Z = 8,}\,{\rm a = 5}{\rm .453(1)}\mathop {\rm A}\limits^ \circ,\,{\rm b = 10}{\rm .006(2)}\,\,\mathop {\rm A}\limits^ \circ,\,{\rm c = 23}{\rm .387(5)}\,\mathop {\rm A}\limits^ \circ $$\end{document} Na4AuTl crystallizes in a new structure type with separated gold and thallium partial structures. These consist of linear ∞1[Au2/2] chains and [Tl2] dumb-bells. Structural relationships between Na2Au and the Na Au partial structure of Na4AuTl are discussed.
    Notizen: Silberfarbene, spröde Einkristalle eines bislang unbekannten Na4AuTl wurden durch Umsetzung von NaN3, Goldschwamm und TlN3 bei 773 K erhalten. Die Struktur wurde aus Röntgen-Einkristall-Diffraktometerdaten bestimmt: \documentclass{article}\pagestyle{empty}\begin{document}$$ {\rm Raumgruppe}\,{\rm Fmmm,}\,{\rm Z = 8,}\,{\rm a = 5,453(1)}\mathop {\rm A}\limits^ \circ,\,{\rm b = 10,006(2)}\,\,\mathop {\rm A}\limits^ \circ,\,{\rm c = 23,387(5)}\,\mathop {\rm A}\limits^ \circ $$\end{document} Na4AuTl kristallisiert in einem neuen Strukturtyp mit voneinander separierten Gold- und Thallium-Teilstrukturen, die aus linearen ∞1[Au2/2]-Ketten und [Tl2]-Hanteln aufgebaut sind. Strukturbeziehungen zwischen Na2Au und der Na—Au-Teilstruktur von Na4AuTl werden diskutiert.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
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  • 184
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 623 (1997), S. 1625-1632 
    ISSN: 0044-2313
    Schlagwort(e): Sodium trifluormethanesulfonate ; monohydrate ; crystal structure ; phase transition ; sodium ionic conduction ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Beschreibung / Inhaltsverzeichnis: Studies on Sodium Trifluormethanesulfonate - Crystal Structure and Phase Transition of Sodium Trifluormethanesulfonate Monohydrate and Sodium Ion Conductivity of Anhydrous Sodium TrifluormethanesulfonateAccording to the results of temperature dependent powder diffractometry (Guinier-Simon-technique) sodium trifluormethanesulfonate monohydrate is dimorphous. The phase transition occurs at -35°C. The room-temperature modification crystallizes monoclinic in space group P21/c with the lattice parameters a = 941.6(5) pm, b = 654.3(2) pm, c = 1062.4(5) pm and β = 107.73(2)°. The crystal structure consists of double layers of trifluormethanesulfonate anions, the lipophilic CF3-groups pointing at each other. Sodium is coordinated by four oxygen atoms from four different anions and by two molecules of crystal water. The resulting polyhedron may be addressed as a distorted octahedron. The low-temperature modification crystallizes orthorhombic in space group Pnma with the lattice parameters a = 645.31(9) pm, b = 538.03(9) pm, c = 1745.3(3) pm. The loss of crystal water occurs at 136°C. Anhydrous sodium trifluormethanesulfonate shows a phase transition at 252°C. The high-temperature modification is a good sodium ionic conductor (σ = 4.1 · 10-1 Ω-1 cm-1 at 250°C).
    Notizen: Nach Kühl-Guinier-Simon-Untersuchungen ist Natriumtrifluormethylsulfonatmonohydrat dimorph. Die Phasenumwandlung erfolgt bei -35°C. Die Raumtemperaturmodifikation kristallisiert monoklin in der Raumgruppe P21/c mit den Gitterkonstanten a = 941,6(5) pm, b = 654,3(2) pm, c = 1062,4(5) pm und β = 107,73(2)°. In der Kristallstruktur liegen Doppelschichten aus Trifluormethylsulfonatanionen vor, in denen die unpolaren CF3-Gruppen einander zugewandt sind. Natrium wird von jeweils einem Sauerstoffatom aus vier verschiedenen Anionen sowie von zwei Kristallwassermolekülen koordiniert und erreicht eine verzerrt oktaedrische Koordination. Die Tieftemperaturmodifikation kristallisiert orthorhombisch in der Raumgruppe Pnma mit den Gitterkonstanten a = 645,31(9) pm, b = 538,03(9) pm, c = 1745,3(3) pm. Die Abgabe von einem Mol Kristallwasser erfolgt bei 136°C. Wasserfreies Natriumtrifluormethylsulfonat zeigt eine Phasenumwandlung in eine Hochtemperaturmodifikation bei 252°C, die eine gute Natriumionenleitfähigkeit zeigt (σ = 4,1 · 10-1 Ω-1 cm-1 bei 250°C).
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
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  • 185
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 623 (1997), S. 654-658 
    ISSN: 0044-2313
    Schlagwort(e): Titanium ; vinylidcne complexes ; cycloaddition reaction ; oxatitanacyclobnlanes ; crystal structure ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Beschreibung / Inhaltsverzeichnis: Preparation and Crystal Structure of Bis(π-pentamethylcyclopentadienyl) (2-methylene)(3-diphenylmethylene)oxatitanacyclobutane Cp*2 The title complex 5 was synthesized by a [2 + 2]-cycloaddition reaction of diphenytkelene and the titanaallene fragment [Cp2*Ti=C=CH2] (3). Complex 5 was characterized using 1H and 13C NMR spectra and by X-ray structure analysis, respectively.
    Notizen: Der Titelkomplex 5 wurde durch [2 + 2]-Cycloaddition von Diphenylketen mit dem Titanaallenfragment [Cp2*Ti=C=CH2] (3) erhalten. Verbindung 5 wurde 1H- und 13C-NMR-spektroskopisch, sowie durch eine Einkristallstrukturanalyse charakterisiert.
    Zusätzliches Material: 1 Ill.
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  • 186
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 623 (1997), S. 554-560 
    ISSN: 0044-2313
    Schlagwort(e): Magnesium ; aluminium ; 2-iminoimidazoline complexes ; imidazole derivatives ; crystal structure ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Beschreibung / Inhaltsverzeichnis: Imidazole Derivatives. XXIII. 2-Iminoimidazoline Derivatives of Magnesium and Aluminum1,3-dimethyl-2-iminoimidazoline (7, ImNH) forms with MgI2 the complex [(ImNH)4Mg]I2 (8). Whose X-ray structure analysis implies the presence of NHN bridges in the cation. With MeMgI and n-Bu2Mg the polymeric coordination compounds [(ImN)MgI]n (9) and [(ImN)2Mg]n (10) are formed. 7 and it's trimethylsilyl derivative 12 react with AlMe2Cl to give the ionic complexes [(ImNR)2AlMe2]Cl (11, 13, R = H, SiMe3) which are stable with respect to the formation of imidazol-2-imino complexes. The adduct ImNSiMe3 · AlCl3 (14) accessible from the reaction of 12 and AlCl3 eliminates chlorotrimethylsilane on heating to give the trimeric imino complex [(ImN)AlCl2]3 (15); the X-ray structure of 15 confirms the high π-donor properties of the imino substituent.
    Notizen: 1,3-Dimethyl-2-iminoirnidazolin (7, ImNH) bildet mit MgI2 den Komplex [(ImNH)4Mg]I2 (8), dessen Kristallstrukturanalyse das Vorliegen von NHN-Brücken innerhalb des Kations glaubhaft macht. Mit MeMgI und n-Bu2Mg werden die Koordinationspolymeren [(ImN)Mgl]n (9) und [(ImN)2Mg]n (10) gebildet. 7 und dessen Trimethylsilyl-Derivat ImNSiMe3 (12) reagieren mit AlMe2Cl zu den ionischen Komplexen [(ImNR)2AlMe2]Cl (11, 13; R = H, SiMe3), die sich als thermisch stabil bezüglich der Bildung von Imidazol-2-imino-Komplexen erweisen. Das aus 12 und AlCl3 zugängliche Addukt ImNSiMe3 · AlCl3, (14) eliminiert bei thermischer Belastung Chlortrimethylsilan: die strukturanalytische Charakterisierung des trimeren Imino-Komplexes [(ImN)AlCl2]3 (15) belegt die hohe π-Donorkapazität des Imino-Substituenten.
    Zusätzliches Material: 2 Ill.
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  • 187
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 623 (1997), S. 561-564 
    ISSN: 0044-2313
    Schlagwort(e): Tripotassium triantimonidostannate(II) ; anionic chains of six-membered rings ; crystal structure ; Zintl phase ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Beschreibung / Inhaltsverzeichnis: K3[SnSb3], a Zintl Phase with ∞1[SnSb3]3- ChainsThe metallic lustrous air sensitive compound K3[SnSb3] was prepared from melts of mixtures of the elements. K3[SnSb3] crystallizes in the monoclinic system, group C2/m (No 12), Z = 2, with lattice constants a = 1768.6(2) pm, b = 428.1(1) pm. c = 604.5(1) pm, β = 95.72(5)°. In the anionic partial structure six-membered rings [Sn2Sb4] with chair conformation are connected via common edges to infinite chains ∞1[SnSb3]3-. The potassium cations separate the chains from each other.
    Notizen: Die metallisch glänzende, sehr hydrolyseempfindliche Verbindung K3[SnSb3] wurde aus Schmelzreaktionen, ausgehend von Gemengen der Elemente erhalten. K3[SnSb3] kristallisiert monoklin in der Raumgruppe C2/m (Nr, 12), Z = 2, mit den Gitterkonstanten a = 1768,6(2) pm, b = 428,1(1) pm, c = 694,5(1) pm, β = 95,72(5)°. In der Anionenteilstruktur sind [Sn2Sb4]-Sechsringe in Sesselkonformation über zwei gegenüberliegende Kanten zu eindimensional unendlichen ∞1[SnSb3]3--Bändern verknüpft. Die Kaliumkationen separieren die Bänder voneinander.
    Zusätzliches Material: 3 Ill.
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  • 188
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 623 (1997), S. 780-784 
    ISSN: 0044-2313
    Schlagwort(e): Heptadecaselenium(2+) ; Hexachloroniobate(-) ; Hexabromotantalate(-) ; solvothermal reactions ; crystal structure ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Beschreibung / Inhaltsverzeichnis: Se17[NbCl6]2 and Se17[TaBr6]2 - Two New Compounds in the Structure Type Sel7[MX6]2The reaction of Se, SeCl4 and NbCl5 in SnCl4 in a sealed glass ampoule at 150°C yields Se17[NbCl6]2 and from Se, SeBr4 and TaBr5 in SiBr4 under the same conditions Se17[TaBr6]2 is formed. Both compounds crystallize triclinic in form of black moisture sensitive crystals, space group P1, Z = 2 (Se17[NbCl6]2: a = 1322.3(5) pm, b = 1309.0(6) pm, c = 1144.9(4) pm, α = 99.18(3)°, β = 99.55(3)°, γ = 112.17(3)°; Se17[TaBr6]2; 1354.5(7) pm, b = 1346.0(9) pm c = 1179.5(6) pm, α = 99.26(5)°, β = 97.81(4)°, γ = 112.52(5)°). Both are isotypic to the previously reported Se17[WCl6]2. The structures are built of octahedral [NbCl6] and [TaBr6] ions, respectively, and of (Se17)2+ ions The cations consist of two Se7 rings which are connected by a Se3 chain, and thus contain two three-coordinate Se atoms which carry formally the positive charge.
    Notizen: Durch solvothermale Reaktion von Se, SeCl4 und NbCl5 in SnCl4 in einer geschlossenen Ampulle bei 150°C entsteht Se17[NbCl6]2 und aus Se, SeBr4 und TaBr5 in SiBr4 unter analogen Bedingungen Se17[TaBr6]2. Beide Verbindungen kristallisieren triklin in Form schwarzer, hydrolyseempfindlicher Kristalle, Raumgruppe P1, Z = 2 (Se17[NbCl6]2: a = 1322,3(5) pm, b = 1309,0(6) pm, c = 1144,9(4) pm, α = 99,18(3)°, β = 99,55(3)°, γ = 112,17(3)°; Se17[TaBr6]2: 1354,5(7) pm, b = 1346,0(9) pm, c = 1179,5(6) pm, α = 99,26(5)° β = 97,81(4)°, γ = 112,52(5)°) und sind isotyp zu Se17[WCl6]2 Die Strukturen sind aus oktaedrischen [NbCl6]- - bzw. [TaBr6]-- und aus (Se17)2+-Ionen aufgebaut, die aus jeweils zwei Se7-Ringen bestehen, die über eine Se3-Brücke verknüpft sind. Jedes Ion enthält zwei dreibindige Se-Atome, die formal die positive Ladung tragen.
    Zusätzliches Material: 2 Ill.
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  • 189
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 623 (1997), S. 805-809 
    ISSN: 0044-2313
    Schlagwort(e): Diammoniuni heptachloropentaoxotriniobate(V) ; niobiumoxochlorides ; crystal structure ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Beschreibung / Inhaltsverzeichnis: Preparation and Crystal Structure of Diammoniuni Heptachloropentaoxotriniobate(V) (NH4)2[Nb3O5Cl7]Colourless sometimes pale blue crystals of (NH4)2[Nb3O5Cl7] are prepared in silica tubes from a mixture of NbCI5, NH4CI and As2O3 at 1050 K. (NH4)2[Nb3O5Cl7] crystallizes in space group C2/c with Z = 4. The lattice constants at 293 K are a = 1680.6(8) pm, b = 886.6(1) pm, c = 1104.3(5) pm and β = 111.35(2)°. The structure consists of layers of [(Nb3O5Cl7)2-]∞2. Within a layer the niobium centered octahedra are corner sharing. The structure of the anion shows a new kind of octahedral connectivity for a layered MX4-structure. The ammonium ions are located in between the polyanionic layers.
    Notizen: Man erhält (NH4)2[Nb3O5Cl7] in kristalliner Form in Quarzglasampullen aus NbCl5, NH4Cl und As2O3 bei 1050 K. Die Kristalle sind farblos manchmal blaßblau. (NH4)2[Nb3O5Cl7] kristallisiert bei 293 K monoklin in der Raumgruppe C2/c mit Z = 4 und den Gitterkonstanten a = 1680,6(8) pm, b = 886,6(1) pm, c = 1104,3(5) pm und β = 111,35(2)° Die Struktur besteht aus [(Nb3O5Cl7)2-]∞2-Schichten in denen die Oktaederbasisflächen über Ecken verknüpft sind. Die Struktur des Polyanions zeigt eine neuartige Oktaederverknüpfung für eine MX4-Schichtstruktur. Zwischen diesen Schichten befinden sich die Ammoniumionen.
    Zusätzliches Material: 4 Ill.
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  • 190
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 623 (1997), S. 832-836 
    ISSN: 0044-2313
    Schlagwort(e): Cesiumbismuthate(III) ; synthesis ; crystal structure ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Beschreibung / Inhaltsverzeichnis: On the Crystal Structures of CsBiO2 and Cs3BiO3CsBiO2 (pale yellow) and Cs3BiO3 (yellow) were obtained by solid state reactions of the binary components Cs2O und Bi2O3 at temperatures of 700°C and 550°C, respectively, The crystal structure of CsBiO2 (C2/c, a = 827.4(2), b = 920.4(2), c = 597.87(9) pm, β = 122.51(1)°, Z = 4, 975 diffractometer data, R1 = 0.058, wR2 = 0.077) contains infinite ∞1[BiO2/2O′2/2] chains. The structure determination of Cs3BiO3 (P213, a = 920,86(8), Z = 4, 289 diffractometer data, R1 = 0,048, wR2 = 0.081) reveals ‘isolated’ BiO33- groups. In this structure the cation arrangement is the same as that of the atoms in the intermetallic phase Cs3Bi.
    Notizen: CsBiO2 (hellgelb) und Cs3BiO3 (gelb) wurden durch Festkörperreaktion aus den binären Komponenten Cs2O und Bi2O3 bei Temperaturen von 700°C bzw. 550°C dargestellt. In CsBiO2 liegen nach der Einkristallröntgenstrukturanalyse (C2/c; a = 827,4(2); b = 920,4(2); c = 597,87(9) pm; β = 122,51(1)°; Z = 4; 975 Diffraktometerdaten; R1 = 0,058; wR2 = 0,077) unendlich ausgedehnte ∞1[BiO2/2O′2/2]-Ketten vor. Die Kristallstruktur von Cs3BiO3 (P213; a = 920,86(8) pm; Z = 4; 289 Diffraktometerdaten; R1 = 0,048; wR2 = 0,081) enthält ‚isolierte‘ pyramidale BiO33--Anionen. Die Kationenanordnung in Cs3BiO3 entspricht der Atom-anordnung in der intermetallischen Phase Cs3Bi.
    Zusätzliches Material: 3 Ill.
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  • 191
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 623 (1997), S. 362-368 
    ISSN: 0044-2313
    Schlagwort(e): Aluminium/platinum alloys ; crystal structure ; phase transitions ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Beschreibung / Inhaltsverzeichnis: The Structure of Platinum-rich Aluminium/Platinum AlloysPlatinum-rich aluminium/platinum alloys have been synthesised via a coupled reaction between aluminium oxide and platinum in a stream of hydrogen at temperatures in the region of 1200°C. The phase richest in aluminium that was prepared was the alloy Al1.16Pt2.84 which crystallises in the AuCu3 structure type. In accordance with the composition, the platinum sites are statistically occupied to a slight extent by aluminium atoms. In a phase somewhat poorer in aluminium (Al1.05Pt2.95), the edge-sharing octahedra consisting almost exclusively of platinum atoms are twisted with respect to each other. The severity of the limited tetragonal distortion which results increases with further decrease in the aluminium content in the phase. A two phase region exists between the limiting composition of this phase and that of the aluminium-poor Pt/Al mixed crystal possessing a statistical atom distribution.By heating the alloys with the slight tetragonal distortion, a second order phase transition into the cubic phase occurs whilst the alloys with a stronger tetragonal distortion undergo a corresponding phase transition which is first order. This result conforms with the idea that, in the former case, the distortion of the platinum octahedra is progressively relieved while in the second case this event results discontinously. Consequently, both the tetragonal and the cubic phase are observed simultaneously in a distinct temperature region.
    Notizen: Über eine gekoppelte Reaktion konnten aus Aluminiumoxid und Platin im Wasserstoffstrom bei Temperaturen um 1200°C platinreiche Aluminium-Platin-Legierungen synthetisiert werden.Als aluminiumreichste Phase wurde die im AuCu3-Typ kristallisierende Legierung- Al1,16Pt2,84 erhalten. Entsprechend der Zusammensetzung sind Platinatomlagen zu einem geringen Anteil statistisch durch Aluminiumatome belegt. In einer etwas aluminiumärmeren Phase (Al1,05Pt2,95) sind die fast ausschließlich durch Platinatome gebildeten eckenverknüpften Oktaeder gegeneinander verdreht. Die dadurch be dingte tetragonale Verzerrung nimmt mit weiter sinkendem Aluminiumgehali zu. Zwischen der Grenzzusammensetzung dieser Phase und einem aluminiumarmen Pt-Al-Mischkristall mit statistischer Atomverteilung liegt ein Zweiphasen gebiet.Beim Aufheizen gehen Legierungen mit geringer tetragonaler Verzerrung in einem Reaktionsablauf zweiter Ordnung in die kubische Phase über, bei Legierungen mit stärkerer tetragonaler Verzerrung verläuft eine entsprechende Phasenumwandlung nach der ersten Ordnung ab. Dieses Verhalten entspricht der Vorstellung, daß im ersten Fall die Verdrehung der Platinoktaeder kontinuierlich mit steigender Temperatur aufgehoben wird, wogegen im zweiten Fall dieser Vorgang diskontinuierlich erfolgt und deshalb in einem gewissen Temperaturbereich die tetragonale und die kubische Phase nebeneinander beobachtet werden.
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  • 192
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 623 (1997), S. 379-383 
    ISSN: 0044-2313
    Schlagwort(e): Bromine oxygen compounds ; crystal structure ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Beschreibung / Inhaltsverzeichnis: Strukturen von Brom-Sauerstoff VerbindungenDie Kristallstrukturen von Br2O, BrO2F und O2Br—OTeF5 werden beschrieben. Br2O wurde nach einer neuen Methode aus BrOTeF5 und H2O als gelbbrau ner, kristalliner Feststoff erhalten. In der Kristallstruktur (a = 390.4(l), b = 686.2(1), c = 1062.2(2) pm, Raumgruppe Pc21n (Nr. 33), Z = 4) erscheinen gewinkelte (114.2(2)°) Moleküle, die im festen Zustand starke Br … Br Wechsel wirkungen haben, so daß sich eine Kettenstruktur ergibt. BrO2F wurde in bekannter Weise aus KBrO3 und BrF5 her gestellt. Es ist extrem empfindlich gegen. Reduktion. Durch Sublimation erzeugte Einkristalle ergaben eine sechsfache Fehlordnung, die die Sauerstoff- und Fluoratome ununterscheidbar macht (a - ()51.1(2) pm, (α = 47.05(2)°, Raum gruppe R3c, Z = 2). Das BrC2F-Molekül ist pyramidal aufgebaut mit einem durchschnittlichen Bindungswinkel von 103.8(5)°. O2Br-OTeF5 wurde durch Ozonisierung von BrO TeF5 hergestellt und ist ein farbloser Feststoff unterhalb sei ner Schmelz- und Zersetzungstemperatur von -20°C. Es wurde durch Schwingungs- und Kernresonanzspektroskopie und einer Einkristallstrukturanalyse vollständig charakterisiert (a = 517.40(1), b = 614.00(1), c = 1950.70(1) pm, β = 90.61(1)°, Raumgruppe P21/c, Z = 4). Das Molekül hat die erwartete pyramidale Molekülgestalt der BrO3-Gruppe.
    Notizen: The crystal structures of Br2O, BrO2F, and O2Br—OTeF5 are reported. Br2O is prepared in a novel manner from BrOTeF5 and H2O, and obtained pure as a yellow brown crystalline solid. The single crystal structure determination a = 390.4(1), b = 686.2(1), c = 1062.2(2) pm, space group Pc21n (No. 33), Z = 4) reveals bent 114.2(2)° Br—O—Br molecules that have strong Br … Br interactions in the solid state resulting in a chain. BrO2F is prepared in the known manner from KBrO3 and BrF5. It is extremely sensitive towards reduction. Crystals obtained by sublimation are rhomboedric with a sixfold disorder making oxygen and fluorine atoms undistinguishable (a = 051.1(2) pm, α = 47.05(2)°, space group R3c, Z = 2). The BrO2F molecular shape is pyramidal with an averaged bond angle of 103.8(3)°. O2Br—O—TeF5 is prepared by ozonisation of Br—O—TeF5 as a colorless solid, mp -20°C. It is fully characterized by vibrational and nmr spetroscopy and a single crystal structure determination (a = 517.40(1), b = 614.00(1), c = 1950.70(1) pm, β= 90.6(1)°, space group P21/c, Z = 4). The molecule has the expected pyramidal geometry at the BrO3 group.
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  • 193
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 623 (1997), S. 369-378 
    ISSN: 0044-2313
    Schlagwort(e): Iridium compound ; phthalocyaninatc complex ; electrochemistry ; optical spectra ; vibrational spectra ; crystal structure ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Beschreibung / Inhaltsverzeichnis: Dimeric IrII Phthalocyaninates with an Ir—Ir Bond;Crystal Structure of Di(pyridinephthalocyaninato(2-)-iridium(II))Blue, diamagnetic di(iridiumphthalocyaninate(2-)), [(Irpc2-)2] is prepared by controlled thermal decomposition of di(acido)phthalocyaninatoiridates in an inert, high-boiling solvent like 1-chloronaphthalene or under reduced pressure (T 〈 350°C). It is soluble in pyridine (py) yielding the blue violet, diamagnetic py adduct [{lr(py)pc2-}2]. This crystallizes in the orthorhombic space group P212121 (no, 19) with Z = 4. The short Ir—Ir distance (2.707(1) Å) indicates a strong Ir—Ir single bond. Due to the axial coordination of the py ligands the Ir atoms are virtually bond in the centre (Ct) of the pc ligands (d(Ir—Ct) = 0.06(1) Å). The pc ligands are staggered (α(N—Ir—Ir′—N′) = 43(1)°). In spite of the short interplanar distance (d(Ct—Ct) = 2.827(7) Å) the pc ligands are only slightly distorted (one wagging, one doming). One py ligand is disordered. Ir—Npy distances are 2.35(2) and 2.291(1) Å. Due the labilizing trans influence of the Ir—Ir bond these distances are rather long. The (Npy-Ir1—Ir2—N′py) skeleton is almost linear 177.2(4)°). The Ir—Niso distance is 1.99(2) A. Four quasi-reversible one electron transfer processes at -1.34, -0.82, 0.55 and 0.82 V are observed in the differential pulse voltammogram of [{Ir(py)pc2-)2]. The process at 0.55 V is assigned to the redox couple [{Ir(py2-}2]/[{(py)pc-Ir-;Irpc2-(py)}]+, according to the VIS spectrum of the product obtained by oxidation with iodine. In the UV-VIS-NIR spectrum of the dimer dissolved in pyridine the B region is split into two bands at 14970 (B-) and 17300 cm-1 (B+) of equal intensity due to strong excitonic coupling. The excitonic coupling/structure relationship of different mono- and dinuclear diphthalocyaninates is discussed. The Ir—Ir stretching vibration at 135 cm-1 is selectively enhanced in the FT-Raman spectrum.
    Notizen: Blaues, diamagnetisches Di(iridiumphthalo cyaninat(2—), [(Irpc2-)2] wird durch kontrollierten thermischen Abbau von Di(acido)phthalocyaninatoiridaten in einem inerten, hochsiedenden Lösungsmittel wie 1-Chlor-naphthalin oder unter vermindertem Druck (T 〈 350°C) dar gestellt. Es ist in Pyridin (py) unter Adduktbildung als blau violettes, diamagnetisches [{Ir(py)pc2-}22] löslich. Letzteres kristallisiert orthorhombisch -in der Raumgruppe P212121 (Nr. 19) mit Z = 4. Der sehr kurze (Ir—Ir)-Abstand (2,707(1) Å weist auf eine starke (Ir—Ir)-Einfachbindung. In folge der Koordination der py-Liganden in axialer Position befinden sich die Ir-Atome praktisch im Zentrum (Ct) der pc2--Liganden (d(Ir—Ct) = 0,06(1) Å). Die beiden pc2--Liganden sind gestaffelt angeordnet (α(N—Ir—Ir′—N′) = 43(1)°). Trotz des kurzen Interplanar-Abstandes (d(Ct-Ct) = 2,827(7) Å) ist der eine pc2--Ligand kaum propellerartig, der andere kaum konkav verzerrt. Ein py-Ligand ist fehlgeordnet. Die (Ir—Npy)-Bindungslängen betragen 2,35(2) und 2,291(1) Å. Sie sind u.a. wegen des labilisierenden trans-Einflusses der (Ir—Ir)-Bindung ungewöhnlich lang. Das (Npy—Ir1—Ir2—N′py)-Gerüst ist fast linear (177,2(4)°). Der (Ir—Niso)-Abstand beträgt 1,99(2) Å. Im differentiellen Pulsvoltammogramm von [{Ir(py)pc2-}2] beobachtet man vier quasi-reversible Einelektronen-Transfer-Prozesse bei -1,34, -0,82, 0,55 und 0,82V. In Übereinstimmung mit dem VIS-Spektrum des mit lod erhaltenen Oxydationsproduktes wird der Prozeß bei 0,55 V dem Redoxpaar [{Ir(py)pc2-)2]/ [{(py)pc-Ir-Irpc2-(py)}]+ zugeordnet. Im UV-VIS-NIR-Spektrum ist der B-Bereich des in Pyridin gelosten Dimeren auf-grund der starken excitonischen Wechselwirkung in zwei etwa gleich intensive Banden bei 14970 (B-) und 17300cm-1 (B+) aufgespalten. Die Abhängigkeit der Excitonen-Kopplung von der Struktur verschiedener ein- und zweikerniger Diphthalocyaninate wird diskutiert. Im FT-Raman-Spektrum wird die Ir—Ir-Valenzschwingung bei 135cm-1 selektiv angeregt.
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  • 194
    ISSN: 0044-2313
    Schlagwort(e): Dichloro(2,4,6-trimethylphenyl)bismuthane ; dibromo(2,4,6-trimethylphenyl)bismuthane ; crystal structure ; Bi—Br‥Bi bridges ; η6-arene‥Bi contacts ; ir and Raman data ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Beschreibung / Inhaltsverzeichnis: Element-Element Bonds. VIII. Synthesis, Molecular and Crystal Structure of Dibromo(2,4,6-trimethylphenyl)bismuthaneDichloro- (1) und dibromo(2,4,6-trimethylphenyl)bismuthane (2) are obtained in relatively high yields from metathesis reactions of the corresponding bismuth(III) halides with tris(2,4,6-trimethylphenyl)bismuthane. An X-ray structure determination of the dibromo derivative 2 (monoclinic, P21/c; a = 896.2(2); b = 1531.9(3); c = 1713.3(3) pm; β = 94.31(3)° at -100±3°C; Z = 8 molecules; R = 0.059) shows two crystallographically independent molecules to build up a zigzag chain via strong Bi—Br‥Bi bridges (Bi—Br 282 and 281; Br‥Bi 302 and 302 pm) and relatively weak η6-arene‥Bi interactions (mean values Bi‥C 348 and 359 pm); for sterical reasons one bromo substituent of each molecule is not involved in coordinative bonding (Bi—Br 262 and 261 pm). To allow a better comparison of Bi—Cipso bond lengths and arene‥Bi contacts, relevant values of a greater number of related compounds have been compiled; for some of these examples arene‥Bi interactions had not been reported before. Ir and Raman bands below 350 cm-1 are assigned to stretching frequencies of the BiCl2 (1) and BiBr2 (2) fragments, respectively.
    Notizen: Dichlor- (1) und Dibrom(2,4,6-trimethylphenyl)bismutan (2) erhält man in guter Ausbeute über eine Metathese des entsprechenden Bismut(III)-halogenids mit Tris(2,4,6-trimethylphenyl)bismutan. Nach den Ergebnissen einer Röntgenstrukturanalyse am Dibrom-Derivat 2 (monoklin, P21/c; a = 896,2(2); b = 1531,9(3); c = 1713,3(3) pm; β = 94,31(3)° bei -100±3°C; Z = 8 Moleküle; R = 0,059) assoziieren die beiden kristallographisch unabhängigen Moleküle über starke Bi—Br‥Bi-Brücken (Bi—Br 282 und 281; Br—Bi 302 und 302 pm) und verhältnismäßig schwache η6-Aren‥Bi-Wechselwirkungen (Mittelwerte Bi‥C 348 und 359 pm) zu Zickzack-Ketten; aus sterischen Gründen bleibt jeweils ein Brom-Substituent ohne eine weitere koordinative Bindung (Bi—Br 262 und 261 pm). Zur besseren Einordnung sind die Bi-Cipso-Abstände und die Aren‥Bi-Kontakte entsprechenden Werten aus einer größeren Zahl verwandter Verbindungen gegenübergestellt; bei einigen Beispielen wird erstmals auf bestehende Aren‥Bi-Wechselwirkungen hingewiesen. IR- und Raman-Banden unterhalb 350 cm-1 lassen sich den Valenzschwingungen des BiCl2- (1) bzw. BiBr2- Fragments (2) zuordnen.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
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  • 195
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 623 (1997), S. 967-972 
    ISSN: 0044-2313
    Schlagwort(e): Phthalocyaninates(2-) ; ruthenium compounds ; iron compounds ; vibrational spectra ; crystal structure ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Beschreibung / Inhaltsverzeichnis: Synthesis, Properties, and Crystal Structure μ-Carbidodi(pyridinephthalocyaninato(2-)iron(IV)) and -ruthenium(IV))Soluble μ-carbidodi(pyridinephthalocyaninato-(2-)iron(IV)) and -ruthenium(IV) is prepared as a pyridine solvate, [{M(py)pc2-)2(μ-C)] · py (M = Fe, Ru) by the reaction of μ-carbidodi(phthalocyaninato(2-)iron(IV)) and -ruthenium(IV)) with pyridine. The isotypic complexes crystallize in the orthorhombic space group P212121 (No. 19) with lattice parameters (in Å): a = 12.692(3)713.002(3) (Fe/Ru); b = 22.186(2)722.635(6); c = 23,653(2)/23.901(6). The M atoms are virtually in the centre (Ct) of the (Np)4 plane (d(M-Ct) = 0.039(6)70.054(8) Å; Np: pyrrole-N atom). The averaged (M-Npy) distance (py: pyridine) is 1.94(1)/2.010(8) Å. The M-(μ-C)-M core is almost linear. The (M-(μ-C)) distance is 1.69(2)71.77(1) Å. The pc2- ligands are in a hitherto unknown convex staggered conformation. The asymmetric (M-(μ-C)-M) stretching vibration is observed in the IR spectrum at 9117974 cm-1, while the corresponding symmetric one is selectively enhanced only in the RR spectrum at 477 cm-1 of the iron complex.
    Notizen: Lösliches μ-Carbidodi(pyridinphthalocyaninato(2-)eisen(IV) und -ruthenium(IV) wird durch die Umsetzung von μ-Carbidodi(phthalocyaninato(2-)eisen(IV) und -ruthenium(IV) mit Pyridin als Pyridin-Solvat, [{M(py)pc2-}2(μ-C)] · py (M = Fe, Ru) isoliert. Die isotypen isotypen Komplexe kristallisieren orthorombisch in der Raumgruppe P212121 (Nr. 19) mit den Gitterkonstanten (in Å): a = 12,692(3)/13,002(3) (Fe/Ru); b = 22,186(2)/22,635(6); c = 23,653(2)/23,901(6). Die M-Atom befinden sich fast im Zentrum (Ct) der (Np)4-Ebene (Np: Pyrrol-N-Atom): d(M-Ct) = 0,039(6)/0,054(8) Å. Der mittlere (M-Np)-Abstand beträgt 1,94(1)/2,010(8) Å. Die (M-(μ-C)-Abstand beträgt 1,69(2)/1,77(1) Å. Die pc2--Liganden sind in einer bislang unbekannten komplexen Staffel-Konformation einander zugeneigt. Die asymmetrische (M-(μ-C)-M)-Valenzschwingung liegt im IR-Spektrum bei 911/974 cm-1, die symmetrische beobachtet man dagegen nur im RR-Spektrum des Eisen-Komplexes bei 477 cm-1.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
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  • 196
    ISSN: 0044-2313
    Schlagwort(e): Phthalocyaninates ; indium compounds ; optical spectra ; vibrational spectra ; crystal structure ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Beschreibung / Inhaltsverzeichnis: Preparation and Properties of Phthalocyaninato(2-)indates(III) with Bidentate Oxo Ligands; Crystal Structure of Tetra(n-butyl)ammonium Carbonato(O,O′)phthalocyaninato(2-)indate(III)Tetra(n-butyl)ammonium acidophthalocyaninato(2-)indate(III) of selected bidentate dioxo ligands (oxalate, catecholate, sulfate and carbonate) are obtained by the reaction of tetra(n-butyl)ammonium cis-dihydroxophthalocyaninato(2-)indate(III) with oxalic acid, catechol, hydrogensulfate and ammonium carbaminate. The carbonato complex crystallizes monoclinic in the space group P21/c (No. 14). InIII is hexa-coordinated by four isoindole nitrogen atoms (Niso) and two oxygen atoms of the carbonate in a cis arrangement. InIII is directed out of the centre (Ct) of the (Niso)4 plane towards the carbonate ligand (d(In-Ct)) = 0.903(1) Å. The averaged (In-Niso) and (In-O) distance is 2.1865(4) and 2.1585(5) Å, the (O-In-O′) angle 60.1(2)°. The phthalocyaninate(2-) ligand (pc2-) is in a concave distortion. The optical spectra show the typical π-π* transition of the pc2- ligand at 14600 (B region), 28000 (Q), 35000 (N) und 40500 cm-1 (L). In the IR spectra, the internal vibrations of the oxalate, sulfate and carbonate ligand and the asymmetric (In-O) stretching vibrations are well separated from the internal vibrations of the pc2- skeleton. Spectra-structure correlations are discussed.
    Notizen: Tetra(n-butyl)ammoniumacidophthalocyaninato(2-)indate(III) ausgewählter zweizähniger Dioxo-Acidoliganden wie Oxalat, Katecholat, Sulfat und Carbonat werden durch die Reaktion von Tetra(n-butyl)ammoniumcis-dihydroxophthalocyaninato(2-)indat(III) mit Oxalsäure, Brenzkatechin, Hydrogensulfat und Ammoniumcarbaminat dargestellt. Der Carbonat-Komplex kristallisiert monoklin in der Raumgruppe P21/c (Nr. 14). Hexakoordiniertes InIII ist von den vier Isoindol-Stickstoffatomen (Niso) und zwei Sauerstoffatomen des Carbonats in cis-Anordnung umgeben. InIII ist aus dem Zentrum (Ct) der Ebene der vier Niso- Atome in Richtung des Carbonat-Liganden verschoben (d(In-Ct)) = 0,903(1) Å. Die mittleren (In-Niso)- und (In-O)-Abstände betragen 2,1865(4) und 2,1585(5) Å, der (O-In-O′)-Winkel 60,1(2)°. Der Phthalocyaninat(2-)-Ligand (pc2-) ist konkav verzerrt. Die optischen Spektren zeigen nur die typischen, vom Axialliganden unabhängigen π-π*-Übergänge des pc2- -Liganden bei 14600 (B-Bereich), 28000 (Q), 35000 (N) und 40500 cm-1 (L). In den IR-Spektren absorbieren die internen Schwingungen des Oxalat-, Sulfat- und Carbonat-Liganden sowie die asymmetrische (In-O)-Valenzschwingung weitgehend separiert von den pc2--Gerüstschwingungen. Die Spektren-Struktur-Korrelation wird diskutiert.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
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  • 197
    ISSN: 0044-2313
    Schlagwort(e): Technetium ; nitrido complexes ; crystal structure ; sulfur ligands ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Beschreibung / Inhaltsverzeichnis: Synthese und Charakterisierung von Bis(tetrabutylammonium) bis(isotrithiodithiolat-S,S′)nitridotechnetat(V), (Bu4N)2[TcN(dmit)2](Bu4N)2[TcN(dmit)2] (dmit2- = isotrithiodithiolat) wurde aus Na2dmit, (Bu4N)[TcNCl4] und (Bu4N)Cl in Acetonitril hergestellt. Die Verbindung kristallisiert monoklin, Raumgruppe C2/c mit a = 23,143(5), b = 8,342(2), c = 26,382(5) Å, β = 95,12(3), Z = 4. Die Bindungslänge Tc≡N beträgt 1,615(6) Å. Tc und N(l) befinden sich auf einer zweizähligen kristallographischen Achse. Der Komplex hat quadratisch-pyramidale Geometrie. Die vier Schwefelatome bilden die Grundfläche der Pyramide, deren Spitze vom Nitrido-Stickstoff eingenommen wird. Das Technetiumatom befindet sich um 0,62 Å über der Grundfläche.
    Notizen: (Bu4N)2[TcN(dmit)2] (dmit2- = isotrithionedithiolate) was prepared from Na2dmit, (Bu4N)[TcNCl4] and (Bu4N)Cl in acetonitrile. The compound crystallises in the monoclinic space group C2/c with a unit cell of the dimensions a = 23.143(5), b = 8.342(2), c = 26.382(5) Å, β = 95.12(3), Z = 4. The Tc≡N bond distance is comparatively short at 1.615(6) Å. Tc and N(1) are situated on a two-fold crystallographic axis. The general coordination geometry is a square pyramid with the four sulfur atoms forming the basal plane and the nitrido nitrogen at the apex. The technetium is located 0.62 Å above the plane defined by the four sulphurs.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
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  • 198
    ISSN: 0044-2313
    Schlagwort(e): Gold(III) ; complexes ; dichloro-2-(N,N-dimethylaminomethyl)phenylgoId(III) ; crystal structure ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Beschreibung / Inhaltsverzeichnis: Gold(III) Complexes with 2-(N,N-dimethylaminomethyl)phenyl (damp-). Syntheses and Structures of [Au(damp-C,N)Cl2], [Au(damp-C,N)(OOCCH3)2] and [Au(damp-C,N)(mnt)] (mnt2- = 1.2-dicyanoethene-1.2-dithiolate)Dichloro-2-(N,N-dimethylaminomethyl)phenylgold(III), [Au(damp-C,N)Cl2], was prepared by the reaction of [Hg(damp)Cl] with Na[AuCl4] and crystallizes monoclinic, space group P21/c a = 7.896(3), b = 9.487(2), c = 15.107(6) Å, β = 100.22(3)°, Z = 4. The crystal structure consists of monomeric [Au(damp-C,N)Cl2] units with square-planar coordinated gold atoms. The shortest Au-Au distances are 4.977 Å. [Au(damp-C,N)(OOCCH3)2] can be synthesized by the reaction of [Au(damp-C,N)Cl2] and AgOOCCH3 in CH2Cl2. Single crystals of the composition [Au(damp-C,N)(OOCCH3)2]. 0.5 H2O were obtained from moist CH2Cl2: monoclinic, space group C2/c, a = 16.626(8), b = 10.640(1), c = 16.271(7) Å, β = 91.90(2)°, Z = 8. The gold atom is square-planar coordinated. The acetato ligands are bound monodentately. The solvent water forms strong hydrogen bridges to the complex molecules in the solid state structure.The chloro ligands in [Au(damp-C,N)Cl2] can easily be replaced by dianionic chelate ligands. The reaction with Na2mnt (mnt2- = 1.2-dicyanoethene-l.2-dithiolate) gives in almost quantitative yield the neutral complex [Au(damp-C,N)(mnt)], which crystallizes orthorhombic, space group Pna21 with a = 7.651(1), b = 14.476(1), c = 13.353(1 ) Å, Z = 4. The gold atom is square-planar coordinated. The Au-S distances are 2.363(2) Å and 2.270(2) Å, respectively.
    Notizen: Dichloro-2-(N,N-dimethylaminomethyl)-phenylgold(III), [Au(damp-C,N)Cl2], hergestellt durch Umsetzung von [Hg(damp)Cl] mit Na[AuCl4], kristallisiert monoklin, Raumgruppe P21/c mit a = 7,896(3); b = 9,487(2); c = 15,107(6) Å; β = 100,22(3)°, Z = 4. Die Kristallstruktur besteht aus monomeren [Au(damp-CN)Cl2]-Einheiten mit quadratisch-planar koordinierten Goldatomen. Die kleinsten Gold-Gold-Abstände betragen 4,977 Å.[Au(damp-C,N)(OOCCH3)2] wird durch Reaktion von [Au(damp-C,N)Cl2] mit AgOOCCH3 in CH2Cl2 hergestellt und aus feuchtem CH2C12 als [Au(damp-C,N)(OOCCH3)2] · 0,5 H2O kristallisiert: monoklin, Raumgruppe C2/c a = 16,626(8); b = 10,640(1); c = 16,271(7) Å; β = 91,90(2)°, Z = 8. Das Goldatom ist quadratisch-planar koordiniert. Die Acetatoliganden binden jeweils einzähnig. Das in das Kristallgitter eingebaute Lösungsmittel ist durch Wasserstoffbrücken in die Festkörperstruktur eingebunden.Die Chloroliganden von [Au(damp-C,N)Cl2] können leicht durch zweifach negativ geladene Chelatliganden ausgetauscht werden. Die Reaktion mit Na2mnt in Aceton er gibt in nahczu quantitativer Ausbeute den Neutralkomplex [Au(damp-C,N)(mnt)], der in der orthorhombischen Raumgruppe Pna21 kristallisiert (a = 7,651(1); b = 14,476(1); c = 13,353(1) Å, Z = 4). Das Goldatom befindet sich in einer quadratisch-planaren Koordinationsumgebung. Die Au-S-Abstände betragen 2,363(2) bzw. 2,270(2) Å.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
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  • 199
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 623 (1997), S. 908-912 
    ISSN: 0044-2313
    Schlagwort(e): In[Nb6Cl15] ; Tl[Nb6Cl15] ; preparation ; crystal structure ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Beschreibung / Inhaltsverzeichnis: Synthese und Kristallstruktur von M[Nb6Cl15] (M = In, Tl): Neue ternäre Niobhalogenide mit verbrückten [Nb6Cl18]4- -ClusternDie neuen ternären Niobchloride M[Nb6Cl15] (M = In, Tl) wurden durch Festkörperreaktionen stöchiometrischer Gemische von NbCl5, Niobmetall und MCl3 bei 720°C dargestellt. Die Kristallstruktur von In[Nb6Cl15] wurde aus Einkristall-Röntgendaten bestimmt und in der orthorhombischen Symmetrie (Raumgruppe Pmma, Z = 4) mit a = 1786.6(1) pm, b = 1345,52(9) pm, c = 929,34(8) pm, R = 0,028, Rw = 0,037, GooF = 1,06 für alle symmetrieunabhängigen 1552 Reflexe verfeinert. Die Gitter-parameter der isotypen Verbindung Tl[Nb6Cl15] wurden aus Röntgen-Pulverdiffraktometerdaten verfeinert: a = 1785,9(2) pm, b = 1347,2(2) pm, c = 930,2(1) pm. Die Struktur besteht aus [Nb6Cl18]4--Clustern, die über terminale Chlorid-Liganden miteinander verbunden sind und zwei Sorten senkrecht zueinander stehender Ketten bilden, Diese Ketten sind über weitere terminale Liganden zu einem dreidimensionalen Netzwerk verbunden. Die In+- und Tl+-Ionen sind zehnfach koordiniert (in Form eines verzerrten zweifach bekappten Würfels), mit acht inneren und zwei äußeren Chlorid-Liganden.
    Notizen: New ternary niobium chlorides corresponding to the formula M[Nb6Cl15] (M = In, T1) were synthesized from solid state reactions of NbCl5, niobium metal, and MCl3 at 720°C. The crystal structure of In[Nb6Cl15] was determined from single crystal X-ray diffraction studies. The structure was refined in the orthorhombic symmetry (space group Pmma, Z = 4) with a = 1786.6(1) pm, b = 1345.52(8) pm, c = 929.34(8) pm, RF = 0.028 and Rw = 0.037, GooF = 1.06 for all 1552 unique reflections. The lattice parameters of the isotypic Tl[Nb6Cl15] compound were refined from X-ray powder diffraction data: a = 1785.9(2) pm, b = 1347.2(2) pm, c = 930.2(1) pm. The structure of In[Nb6Cl15] is made up of [Nb6Cl18]4- clusters linked to each other through terminal chloride ligands to form two sets of chains perpendicular to each other. The chains are linked through other terminal ligands to yield a three-dimensional network. The In+ or Tl+ ions are located in a ten coordination site (distorted bicapped cubic geometry) made up of eight inner and two outer chloride ligands.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
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  • 200
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 623 (1997), S. 1259-1263 
    ISSN: 0044-2313
    Schlagwort(e): Ammonium fluoromanganates ; redox behavior ; di(ammonium) hexafluoromanganate(IV) ; crystal structure ; tri(ammonium) hexafluoromanganate(III) ; high temperature modification ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Beschreibung / Inhaltsverzeichnis: About the Structure and Reactivity of Diammonium Hexafluoromanganate(IV)Electrolytic oxidation of an aqueous suspension of MnF2 containing NH4F, and subsequent crystallization in 40% HF yields yellow crystals of (NH4)2MnF6. It crystallizes in the hexagonal K2MnF6 type structure with the space group P63mc and a = 5.903; c = 9.565 Å; Z = 2. With in situ powder diffraction studies it is shown, that (NH4)2MnF6 is gradually reduced in a NH3 atmosphere between 30 and 230 °C to afford (NH4)3MnF6, (NH4)2MnF5, and finally NH4MnF3. (NH4)3MnF6, thereby, forms a hitherto unknown cubic (a = 9.082 Å) high temperature modification with the cryolite type structure. Under N2 the thermal decomposition of (NH4)2MnF6 proceeds via NH4MnF4 to yield MnF2.
    Notizen: Durch elektrolytische Oxidation einer NH4F-haltigen, wäßrigen MnF2-Suspension und anschließendes Umkristallisieren in 40%iger HF wird (NH4)2MnF6 in Form von gelben Kristallen erhalten. Es kristallisiert hexagonal im K2MnF6-Typ mit der Raumgruppe P63mc und a = 5,903; c = 9,565 Å; Z = 2. Mithilfe der in situ-Pulverdiffraktometrie wird gezeigt, daß (NH4)2MnF6 in einer NH3- Atmosphäre zwischen 30 und 230 °C über die Stufen (NH4)3MnF6 und (NH4)2MnF5 schrittweise zu NH4MnF3 reduziert wird. (NH4)3MnF6 entsteht dabei in einer bisher unbekannten, kubischen (a = 9,082 Å) Hochtemperaturmodifikation mit der Kryolith-Struktur. Unter N2 verläuft der thermische Abbau von (NH4)2MnF6 über NH4MnF4 zu MnF2.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
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