共查询到20条相似文献,搜索用时 15 毫秒
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Jan-Olov Willerström Bertil Carlsson Stig Rundqvist 《Journal of solid state chemistry》1980,31(2):227-232
Hf3As has a monoclinic unit cell of dimensions a = 15.3898(14) Å, b = 5.3795(5) Å, c = 15.330(14) Å, β = 90.291(6)°. A structure proposal based on space group (No. 15) has been refined by the least-squares method using a Rietveld-type fullprofile analysis of Guinier-Hägg X-ray powder film intensity data. The Hf3As structure is an intermediate between the Fe3P and the Ti3P types. The atomic coordination follows rules formulated earlier for representatives of the Fe3PTi3PV3S family of structures. 相似文献
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The crystal structure of Pd2B has been investigated by X-ray powder diffraction and single-crystal diffractometry. There are strong indications that Pd2B crystallizes with the anti-CaCl2 type structure (C 35), space group Pnnm (No. 58), a = 4.6918(4) Å, b = 5.1271(4) Å, and c = 3.1096(3) Å, but the extent to which the boron atoms assume ordered positions cannot be determined precisely with X-ray diffraction methods alone. 相似文献
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Koji Kuroda Nobuo Ishizawa Nobuyasu Mizutani Masanori Kato 《Journal of solid state chemistry》1981,38(3):297-299
α-SrMnO3 crystallizes in the hexagonal system with unit-cell dimensions a = 5.454(1) Å, c = 9.092(2)Å, space group . The structure was solved by the heavy-atom method; of 404 unique reflections measured by counter method, 203 that obeyed the condition |F0| ≥ 3σ (|F0|) were used in the refinement to a conventional R value of 0.043. The structure consists of four close-packed SrO3 layers in an ABAC stacking sequence along the hexagonal c axis. Oxygen octahedra containing Mn4+ are grouped into face-sharing pairs linked by corner sharing within the cubically stacked “A” layer. 相似文献
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The crystal structure of α-copper vanadate has been determined and refined by full-matrix least-squares procedures using automatic diffractometer data to a residual R = 0.050 (Rw = 0.059). The space group is rhombohedral, , with hexagonal unit cell a = 12.857(3) and c = 7.161(2) Å (aR = 7.797(2) Å and α = 111.06(1)°). On the basis of the detailed structural analysis the contents Cu7?xV6O19?x with x = 0.22 are proposed for the rhombohedral cell. Copper is in the divalent and vanadium in the quadrivalent state. The structure is based on a cubic close-packed array of oxygen ions with the vanadium ion occupying an octahedral site, one copper in a partially occupied octahedral site and the other copper in a tetrahedral site. The latter is one of the few examples of tetrahedrally coordinated copper. 相似文献
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Harold J. Whitfield 《Journal of solid state chemistry》1981,39(2):209-214
The crystal structure of synthetic copper arsenic selenide CuAsSe, has been determined by a three-dimensional single-crystal X-ray examination using film data. The crystals, of orthorhombic space group Pbcn, have Z = 24 in a unit cell of dimensions a = 11.75 ± 0.02, b = 6.79 ± 0.01, and c = 19.21 ± 0.03 Å. The structure was solved by Patterson projection and electron density methods and isotropically refined to R = 0.125 for 300 observed reflections. The structure of CuAsSe is related to the B6 structure of 6H ZnS as CuAsS is to the B3 structure of zincblende. Alternately in Jagodzinski nomenclature CuAsSe has hcc packing rather than ccc packing of CuAsS. 相似文献
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The crystal structure of nonactin 总被引:1,自引:0,他引:1
M Dobler 《Helvetica chimica acta》1972,55(5):1371-1384
An X-ray crystal structure investigation of the macrotetrolide antibiotic nonactin is reported. The shape of the molecule is discussed with special reference to the conformational changes involved in passing from free nonactin to the K+-complex. 相似文献
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《Journal of Inorganic and Nuclear Chemistry》1981,43(10):2419-2423
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S. M. Nasirov V. G. Andrianov Yu. T. Struchkov T. Kh. Khasanov A. I. Saidkhodzhaev G. K. Nikonov 《Chemistry of Natural Compounds》1976,10(5):589-590
Summary The reaction of 3,3,5,7-tetraacetylquercetin with tetraacetylglucopyranosyl bromide has given quercetin 4-O--D-glucopyranoside, and the substance has been characterized.Khar'kov Scientific-Research Institute of Pharmaceutical Chemistry. Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 577–578, September–October, 1974. 相似文献
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Paolo Ganis Donatella Furlani Daniele Marton Giuseppe Tagliavini Giovanni Valle 《Journal of organometallic chemistry》1985,293(2):207-212
The crystal structure of (C6H5)3SnCH2CHCH2 has been determined. The asymmetric unit consists of two molecules of triphenylallyltin having virtually the same conformation. Their geometrical parameters exclude pπ-dπ bonding between the metal and the allyl double bond, and seem to be in a better agreement with a σ-π conjugation effect. 相似文献