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51.
A. Manohar V. Venkatachalam K. Ramalingam S. Thirumaran G. Bocelli A. Cantoni 《Journal of chemical crystallography》1998,28(12):861-866
Synthesis, spectral, and single crystal X-ray structural studies on (2,2-bipyridyl)bis (dimethyldithiocarbamato)zinc(II) (1) and (l,10-phenanthroline)bis(dimethyldithiocarbamato)zinc(II) (2) complexes are reported in this paper. The complex (1) crystallizes in the orthorhombic lattice, space group Pcca, a = 18.456(3), b = 6.529(2), and c = 17.092(2) Å. The complex (2) crystallizes in the monoclinic space group C2/c, a = 13.372(2), b = 13.850(2), c = 24.680(3) Å, and = 102.71(4)°. IR spectra of the complexes (1) and (2) show the thioureide (C-N) bands at 1489 and 1510 cm–1, respectively, which are lower than the value observed for the parent bisdithiocarbamate. Reduction in the thioureide stretching frequency is due to the increase in coordination around the zinc ion and the resultant increase in electron density. Thermal studies indicate that the 1,10-phenanthroline adduct is marginally more stable than the other complex. X-ray crystal structures of the two adducts show them to be octahedrally coordinated and monomeric in nature. The Zn-S distances are longer than those observed in the parent bisdithiocarbamate. The thioureide C-N bond distances in (1) and in (2) indicate the partial double bond character. The most important structural changes as a result of the adduct formation are observed in the Zn-S bond distances and S-Zn-S bond angles, in terms of very significant increases in Zn-S bond distances and reductions in S-Zn-S angles, compared to the parent bisdithiocarbamate. The observed changes are indicative of a strong steric force in operation in the adducts rather than electronic effects. 相似文献
52.
N. I. Leonyuk E. L. Belokoneva G. Bocelli L. Righi E. V. Shvanskii R. V. Henrykhson N. V. Kulman D. E. Kozhbakhteeva 《Crystal Research and Technology》1999,34(9):1175-1182
The laser crystals of chromium doped yttrium oxyorthosilicate (YSO) were grown from the melt by Czochralski technique. The crystals of YSO, yttrium pyrosilicate and stillwellite-like lanthanum borosilicate were obtained from high temperature solutions. Lithium and potassium di- and trimolybdates were used as fluxes in the growth experiments on silicate crystals. In the case of borosilicate crystals, the choice of fluxes was based on the potassium trimolybdate with an excess of potassium fluoride. The composition of grown crystals was studied by electron microprobe analysis, and structural characteristics were determined for all the single crystals. 相似文献
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The structures of polytetramethylene terephthalate (PTMT) and selected model compounds are described for the solid state [X-ray, 13C-NMR (magic angle spinning, and cross polarization)] and in solution. Compounds representative of the unstressed (α) crystalline form of PTMT have isotropic chemical shifts different from those of the stressed (β) form. The chemical shifts are interpreted in terms of conformational differences in the tetramethylene segments. 相似文献
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Gabriele Bocelli Marie Florence Grenier-Loustalot 《Journal of chemical crystallography》1983,13(1):19-29
C26H38O4,Mr=414.6, is monoclinic,P21/c, witha=15.059(2),b=7.348(2),c=23.164(3) Å,β=90.35(16)°,V c =2563.13(85) Å3,D x =1.07(4) g cm?3,μ(CuKα)=5.28 cm?1. The structure was determined by direct methods and refined by full-matrix least squares toR=0.074 for 2479 observed reflections. The two cyclohexane rings both adopt a chair conformation. 相似文献
58.
Annamalai Subashini P. Thomas Muthiah Gabriele Bocelli Andrea Cantoni 《Journal of chemical crystallography》2007,37(9):597-600
The title compound, [C4H7N4O+, C7H5O6S? . H2O] contains one 2, 6-diamino-4-oxopyrimidinium cation, one sulfosalicylate anion and a water molecule. The crystal structure was determined by single crystal X-ray diffraction. This compound crystallized in the orthorhombic system; space group Pna21 with the unit cell parameters a = 13.402(3) Å, b = 16. 221(3) Å, c = 6.714(2) Å, V = 1459.6(6), Z = 4. The sulfonic acid group has protonated the aminopyrimidine moiety. The protonated N1 atom and N4 amino group are hydrogen bonded to the keto group (O1) of the neighbouring pyrimidine forming a six-membered ring with graph-set notation R2 1(6) and a supramolecular chain along the c-axis. This supramolecular chain is further strengthened by one of the sulfonate oxygen atoms (O3), bridging the pyrimidines via hydrogen bonded rings, R3 2(10) involving N(3)–H(3)···O(3) and N(2)–H(2B)···O(3) hydrogen bonds. The other two oxygen atoms of the sulfonate groups are bridged by water molecules via O-H···O hydrogen bonds constituting a supramolecular chain. The water molecule also acts as hydrogen bond acceptor with respect to the carboxyl group. 相似文献
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