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  • Artikel  (410)
  • crystal structure  (263)
  • Ecology  (147)
  • Geologie und Paläontologie  (410)
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  • 1
    Digitale Medien
    Digitale Medien
    Springer
    Journal of chemical crystallography 24 (1994), S. 759-762 
    ISSN: 1572-8854
    Schlagwort(e): Sulfonamide ; methanesulfonanilide ; crystal structure ; molecular structure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Geologie und Paläontologie , Physik
    Notizen: Abstract The title compound, crystallizes in the triclinic space group $$P\bar 1$$ witha=8.232(4),b=9.159(2),c=10.230(3)Å. α=74.07(3)°, β=72.50(4)°, γ=63.65(3)° andZ=2. The structure was solved by direct methods and refined by full matrix least squares methods toR=0.054 for 1817 observed reflections. The plane containing the nitrogen and sulfur atoms is perpendicular to the aromatic plane. One of the S−O bonds in each methanesulfonyl group is in nearly eclipsed conformation with the N−C bond.
    Materialart: Digitale Medien
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  • 2
    Digitale Medien
    Digitale Medien
    Springer
    Journal of chemical crystallography 24 (1994), S. 437-440 
    ISSN: 1572-8854
    Schlagwort(e): Ca(C4H4O4)·H2O ; pentagonal pyramid ; calcium succinate ; crystal structure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Geologie und Paläontologie , Physik
    Notizen: Abstract The crystal structure of calcium succinate monohydrate, Ca(C4H4O4)·H2O, has been determined by single crystal X-ray diffraction. The crystals are monoclinic witha=11.952(2),b=9.691(2),c=11.606(2)Å, β=108.81(1)°, space group C2/c,Z=8,V=1272.49 Å3,d m =1.80, andd c =1.818 Mg m−3. The structure was refined by full-matrix least-squares techniques toR=0.027,R w =0.040, for 829 reflections with1≥3δ(I). Ca is coordinated to seven oxygen atoms, and the coordination polyhedron is best described as a pentagonal bipyramid. One carboxylate group in the succinate ion is bonded to three different Ca ions, forming a four-membered chelate ring with one Ca ion is bonded to three different Ca ions, forming a four-membered chelate ring with one Ca ion and unidentate bridge bonds to two other Ca ions. The other carboxylate group is bonded to two Ca ions through unidentate bonds. The structure is highly polymeric. The general structural features are nearly identical to those of calcium adipate monohydrate.
    Materialart: Digitale Medien
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  • 3
    ISSN: 1572-8854
    Schlagwort(e): Tautomerism ; hydrogen bonding ; crystal structure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Geologie und Paläontologie , Physik
    Notizen: Abstract Crystals consisting of two distinct chemical entities, tautomers of each other, in exact 1∶1 ratio, have been obtained and their structure determined by X-ray analysis. The crystals of C9H11N3·C9H11N3 are monoclinic,P21/c,a=15.674(3),b=17.085(3),c=13.758(3)Å, β=90.78(2)°,Z=8. There are two hydroxylamine and two aminonitrone molecules in the asymmetric unit. Hydrogen bonds connect those molecules into chiral layers. Layers of opposite chirality alternate andthe crystal is centrosymmetric as a whole. Within those layers chains of tautomers joined by very strong O−H... O and strong N−H... N bonds can be recognized. Proton transfer along those chains with simultaneous rearrangement of π-bonds within the molecules would result in interconversion of tautomers and would affect chirality of the layer.
    Materialart: Digitale Medien
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  • 4
    Digitale Medien
    Digitale Medien
    Springer
    Journal of chemical crystallography 25 (1995), S. 57-62 
    ISSN: 1572-8854
    Schlagwort(e): phase diagram ; buffered chloroaluminate ; crystal structure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Geologie und Paläontologie , Physik
    Notizen: Abstract The phase diagram of the buffered neutral aluminum chloride + 1-ethyl-3-methyl-1H-imidazolium chloride + sodium chloride (AlCl3-EMIC-NaCl) ternary melt system can be represented by a binary phase diagram composed of (EMI)AlCl4 and NaAlCl4. In the binary phase diagram, the salts are liquid at, or near, room temperature for a wide range of compositions. At the 1∶1 composition, the congruently melting compound (EMI)(Na)(AlCl4)2 with m.p.=36.7°C is formed. Crystals of this mixed organic-inorganic salt were grown for single crystal x-ray diffraction analysis. The compound crystalizes in the space group $$P\bar 1$$ with lattice parametersa=10.321(1) Å,b=10.895(3) Å,c=9.284(4) Å, α=98.31(2)°, β=100.83(4)°, γ=101.95(3)°. Data collected at −120°C gave final residuals ofR=0.037 andR w=0.045 using 2713 observed reflections. The packing diagram reveals Na+ ion zig-zag chains running along thea-axis with each Na+ surrounded by four AlCl 4 − units, reminiscent of NaAlCl4. The AlCl 4 − ions form a distorted square planar coordination sphere around Na+ at an average Na−Al distance of 3.76(4) Å. Using a sodium ionic radius of 1.16 Å, a new AlCl 4 − ionic radius of 2.60 Å is calculated. This radius is 0.21 Å shorter than the reported thermodynamic radius.
    Materialart: Digitale Medien
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  • 5
    Digitale Medien
    Digitale Medien
    Springer
    Journal of chemical crystallography 25 (1995), S. 223-226 
    ISSN: 1572-8854
    Schlagwort(e): Antifungal alkaloids ; 3-methylsampangine ; crystal structure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Geologie und Paläontologie , Physik
    Notizen: Abstract 3-Methylsampangine, C16H10N2O, crystallizes in the monoclinic space group P21/c witha=7.260(3),b=10.697(5),c=15.342(6) Å, and β=102.69(4). All nonhydrogen atoms of this potent antifungal agent are planar to within 0.082 Å. The title compound exhibits potentin vitro antifungal activity againstC. neoformans, C. albicans andA. fumigatus.
    Materialart: Digitale Medien
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  • 6
    Digitale Medien
    Digitale Medien
    Springer
    Journal of chemical crystallography 25 (1995), S. 219-222 
    ISSN: 1572-8854
    Schlagwort(e): Calcium phosphate ; calcium pyrophosphate ; calcium potassium pyrophosphate ; crystal structure ; layer-type structure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Geologie und Paläontologie , Physik
    Notizen: Abstract The crystal structure of Ca10K4(P2O7)6·9H2O has been determined by single crystal X-ray diffraction. Crystals are hexagonal, space group P63cm witha=11.761(1),c=9.770(1) Å, andZ=1. The structure was refined toR=0.028 andR w=0.037 for 468 reflections withI≥3σ(I). The structure consists of a compact assembly of Ca and P2O7 ions arranged in layers perpendicular to thec-axis in a hexagonal array with relatively large open channels along thec-axis. The K ions and the water molecules are located in these open channels and are disordered.
    Materialart: Digitale Medien
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  • 7
    Digitale Medien
    Digitale Medien
    Springer
    Journal of chemical crystallography 25 (1995), S. 295-298 
    ISSN: 1572-8854
    Schlagwort(e): Cage-diol ; crystal structure ; photooxidation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Geologie und Paläontologie , Physik
    Notizen: Abstract An unusual photooxidation was noted upon photolytic cage closure of a substituted tricyclo[6.2.1.02.7]undecane-exo, exo-diol. The resultant compound, which may be regarded as a mono-reduced pentacyclo[5.4.0.02,6.03,10.05,9]undecane-8,11-dione, was characterizedvia X-ray crystallography. This species could be reduced to the tricyclo[6.2.1.02,7]undecane-endo, exo-diol under conditions previously shown to be inert for the parent dione.
    Materialart: Digitale Medien
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  • 8
    Digitale Medien
    Digitale Medien
    Springer
    Journal of chemical crystallography 25 (1995), S. 379-382 
    ISSN: 1572-8854
    Schlagwort(e): Benzonaphthodioxosuberane ; crystal structure ; radermachol
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Geologie und Paläontologie , Physik
    Notizen: Abstract The crystal and molecular structure of the title compound (2) C21H16O4 has been determined by an X-ray analysis, by direct methods from diffractometer data and refined by full-matrix least squares. The compound (2) crystallizes in the space group P21/a, with cell parameters:a=36.432(5),b=5.512(3),c=8.269(5) Å, β=108.0(3)°,z=4,D c =1.397 g/cm−3,R=7.8 for 1136 observed reflections. The conformation of the tetracyclic ring system shows a folding of two planar parts of the carbon skeleton about an axis passing thorough C8 and C16 of the seven membered ring C.
    Materialart: Digitale Medien
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  • 9
    Digitale Medien
    Digitale Medien
    Springer
    Journal of chemical crystallography 26 (1996), S. 677-681 
    ISSN: 1572-8854
    Schlagwort(e): Anthraquinone ; crystal structure ; intramolecular hindrance
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Geologie und Paläontologie , Physik
    Notizen: Abstract The title compound crystallizes in the monoclinic space group, P21/c;a=12.938(1),b=11.041(1),c=19.285(2) Å, β=104.314(8)°,Z=4. Refinement based on 1660 unique observed reflections converged toR=0.054. The anthraquinone moiety is distorted due to intramolecular steric hindrance from the tosylate groups.
    Materialart: Digitale Medien
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  • 10
    ISSN: 1572-8854
    Schlagwort(e): Organoiron complex ; dinuclear complex ; crystal structure ; phosphonium ylid
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Geologie und Paläontologie , Physik
    Notizen: Abstract The title compound crystallizes in the centrosymmetric monoclinic space group P21/n withZ=4. The cation consists of two (η5-C5h5)Fe(CO) units which are linked via a metal-metal bond (Fe(1)−Fe(2)=2.530(1) Å), a bridging carbonyl ligand (Fe(1)−C(4)=1.912(8) Å. Fe(2)−C(4)=1.940(9) Å) and a bridging phosphonium ylid ligand (Fe(1)−C(1)=1.991(6) Å, Fe(2)−C(1)=1.985(6) Å and C(1)−P(1)=1.781(6) Å).
    Materialart: Digitale Medien
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