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11.
Dikarev EV Shpanchenko RV Andreini KW Block E Jin J Petrukhina MA 《Inorganic chemistry》2004,43(18):5558-5563
The crystal structure of a new hybrid product comprised of two rigid building blocks, namely dirhodium(II) tetraacetate, [Rh(2)(O(2)CCH(3))(4)] (1), and 2,6-diselenaspiro[3.3]heptane, Se(2)C(5)H(8) (2), has been solved ab initio using laboratory source X-ray powder diffraction (XRPD) data. The rigid body refinement approach has been applied to assist in finding an adequate model and to reduce the number of the refined parameters. Complex [Rh(2)(O(2)CCH(3))(4).mu(2)-Se(2)C(5)H(8)-Se,Se'] (3) conforms to the triclinic unit cell with lattice parameters of a = 8.1357(4), b = 8.7736(4), and c = 15.2183(8) A, alpha = 77.417(3), beta = 88.837(3), and gamma = 69.276(4) degrees, V = 989.66(8) A(3), and Z = 2. The centrosymmetric P space group was selected for calculations. The final values of the reduced wR(p), R(p), and chi(2) were calculated at 0.0579, 0.0433, and 5.95, respectively. The structure of 3 is a one-dimensional zigzag polymer built on axial Rh...Se interactions at 2.632(6) A. The 2,6-diselenaspiro[3.3]heptane ligand acts as a bidentate linker bridging dirhodium units via both selenium atoms. The geometrical parameters of individual groups for rigid body refinement have been obtained from X-ray powder data for dirhodium(II) tetraacetate (1) and from single-crystal X-ray diffraction for diselenium molecule 2. The crystal structures of 1 and 2 are reported here for the first time. For 1 indexing based on XRPD data has resulted in the triclinic unit cell P with lattice parameters of a = 8.3392(7), b = 5.2216(5), and c = 7.5264(6) A, alpha = 95.547(10), beta = 78.101(6), and gamma = 104.714(13) degrees, V = 309.51(5) A(3), and Z = 1. The final values were wR(p) = 0.0452, R(p) = 0.0340, and chi(2) = 1.99. The 1D polymeric motif built on axial Rh.O interactions of the centrosymmetric dirhodium units has been confirmed for the solid-state structure of 1. Compound 2,6-diselenaspiro[3.3]heptane (2) conforms to the monoclinic space group P2(1)/c with the unit cell parameters of a = 5.9123(4), b = 19.6400(13), and c = 5.8877(4) A, beta = 108.5500(10) degrees, V = 648.15(8) A(3), and Z = 4. 相似文献
12.
Roman V. Shpanchenko Evgeny V. Dikarev Svetlana N. Mudretsova 《Journal of solid state chemistry》2006,179(8):2681-2689
The crystal structures of new sodium vanadylphosphate, Na4.35VO(PO4)2 (, , , Z=8, S.G. Ibam), and new (γ-) modification of Na4VO(PO4)2 (, , , Z=8, S.G. Pbc21) have been investigated by X-ray single-crystal diffraction. Both structures contain isolated infinite chains of the corner-sharing VO6 octahedra. The octahedra within the chains are additionally linked to each other by the tetrahedral PO4 groups. Sodium atoms are situated in the positions between the chains. Depending on the conditions of synthesis, the number of sodium atoms in the unit cell of the Na4+xVO(PO4)2 compounds may vary resulting in a change of the oxidation state of vanadium atoms and a change of their coordination environment. In Na4.35VO(PO4)2 vanadium atoms have almost regular octahedral coordination with six close V-O separations and all chains in the structure are equivalent. The crystal structure of γ-Na4VO(PO4)2 contains two non-equivalent chain types: the first one is similar to that found in Na4.35VO(PO4)2 whereas the second one contains VO6 octahedra with the short vanadyl bonds. The charge re-distribution was supposed in the new γ-modification of Na4VO(PO4)2 where the V4+δ and V4−δ cations orderly occupy octahedral positions in different chains. The origin of this phenomena is discussed. 相似文献
13.
The scattering of incident plane elastic waves by a varietyof different defects that lie upon a fluid-solid interface isconsidered here using matched asymptotic expansions. The expansionscheme is developed in terms of a parameter , the ratio of typicaldefect length scale to a typical wavelength of the incidentfield, taken to be small. Three different canonical situations occur and these are illustratedvia three specific examples treated here: a rigid strut, anedge crack, and a rigid strip. In each case the leading-ordermatching is performed to identify the leading-order contributionof the defect to the acoustic field in the far field. In particular,each defect is identified with a source of dipole response ininterfacial stress of displacement. It is shown in the limit as s<<s1 that in the inner problemsthe fluid and solid pieces uncouple in a particularly convenientmanner allowing analytical solutions to be deduced. These arethen matched with appropriate outer solutions. 相似文献
14.
Bulychev BM Shpanchenko RV Antipov EV Sheptyakov DV Bushmeleva SN Balagurov AM 《Inorganic chemistry》2004,43(20):6371-6376
Single-phase ternary deuteride Li(2)BeD(4) was synthesized by a high-pressure high-temperature technique from LiD and BeD(2). The crystal structure of Li(2)BeD(4) was solved from X-ray and neutron powder diffraction data. The compound crystallizes in the monoclinic space group P2(1)/c with lattice parameters a = 7.06228(9) A, b = 8.3378(1) A, c = 8.3465(1) A, beta =93.577(1) degrees, and Z = 8. Its structure contains isolated BeD(4) tetrahedra and Li atoms that are located in the structure interstices. Li(2)BeD(4) does not undergo any structural phase transitions at temperatures down to 8 K. 相似文献
15.
Roman V. Shpanchenko Rodion V. Panin Catherine Bougerol Evgeny V. Antipov 《Journal of solid state chemistry》2005,178(12):3715-3721
Lead vanadium phosphate Pb3V(PO4)3 was synthesized by solid state reaction and characterized by X-ray single crystal and powder diffraction, electron microscopy, and magnetic susceptibility measurements. The crystal structure model of Pb3V(PO4)3 was refined using X-ray single crystal data (a=10.127(1)Å, S.G. Z=4). The compound has an eulytite-like structure and its average structure model may be presented as a three-dimensional network formed by strongly distorted mixed (Pb/VIII) metal-oxygen octahedra connected by edge sharing and forming corrugated chains. The octahedra are additionally linked by tetrahedral phosphate groups via corner sharing. Lead and vanadium atoms randomly occupy two close positions in the octahedra. The electron microscopy study revealed the presence of a rhombohedral superstructure with and indicating ordering in the structure. The same type of superstructure was found by us for two another lead-containing eulytite Pb3Fe(PO4)3 where Fe+3 has an ionic radius close to that of V+3. Magnetic susceptibility measurements revealed Curie-Weiss behavior for the Pb3V(PO4)3 compound. 相似文献
16.
Roman V. Shpanchenko Alexander S. Mitiaev Evgeny V. Antipov Eiji Takayama-Muromachi 《Journal of solid state chemistry》2005,178(10):3014-3019
The first tin vanadium phosphate SnVPO5 was synthesized by a solid-state reaction and characterized by X-ray single crystal diffraction and magnetic susceptibility measurements. The crystal structure of SnVPO5 (, , , α=113.283(11)°, β=108.037(9)°, γ=94.603(9)°, S.G. P-1, Z=2) is a three-dimensional framework constructed by V2O10 units fasten together by tetrahedral phosphate groups. Tin atoms are situated in structure interstices. They have five-fold coordination arrangement due to a presence of sterically active lone pair which position was visualized by ELF calculations. The magnetic susceptibility shows a broad maximum at 22 K which is probably due to low-dimensional spin correlations. We propose that the magnetism of the compound can be understood by interacting spin-dimers on a distorted square lattice. Strong quantum fluctuations were suggested by unusual field dependence of the transition temperature and unexpectedly low Curie constant. 相似文献
17.
A nonisothermal adsorption experiment using a controlled flow of cyclopentane in the 333-313 K range is used to simultaneously estimate the specific surface area and micropore volume of a hybrid (organic/inorganic) alcogel. For reference, the method is also applied to an all-inorganic material with a more rigid structure, namely, a high surface area SiO(2)-Al(2)O(3). The proposed data analysis provides guidelines to determine whether adsorption data on a certain adsorbate/adsorbent system can be modeled effectively as a convolution of BET (meso- and macropore) and Dubinin-Radushkevitch (DR, micropore) contributions. Copyright 2000 Academic Press. 相似文献
18.
E.M. Kopnin A.A. Belik R.V. Shpanchenko F. Izumi J. Hadermann 《Journal of solid state chemistry》2004,177(10):3499-3504
A new hexagonal perovskite-type oxide Ba8Ta4Ru8/3Co2/3O24 was synthesized by the solid-state method at 1573 K and characterized by electron diffraction (ED), time-of-flight (TOF) neutron powder diffraction, and magnetic susceptibility. Structure parameters of Ba8Ta4Ru8/3Co2/3O24 were refined by the Rietveld method from the TOF neutron powder diffraction data on the basis of space group P63/mcm and lattice parameters a=10.0075(1) Å and c=18.9248(2) Å as obtained from the ED data (Z=3). The crystal structure of Ba8Ta4Ru8/3Co2/3O24 consists of 8-layered (cchc)2 close-packed stacking of BaO3 layers along the c-axis. Corner-shared octahedra are filled by Ta only and face-shared octahedra are statistically occupied by Ru, Co, and vacancies. Similar compounds Ba8Ta4Ru8/3M2/3O24 with M=Ni and Zn were also prepared. Magnetic susceptibility measurements showed no magnetic ordering down to 5 K. 相似文献
19.
Alexander A. Tsirlin Evgeny V. Dikarev Evgeny V. Antipov Roman V. Shpanchenko 《Acta Crystallographica. Section C, Structural Chemistry》2006,62(2):i13-i15
Single crystals of a new complex phosphate, calcium sodium vanadium phosphate, Ca8.42Na1.16V(PO4)7, have been grown from a melt under an inert atmosphere. The crystal structure has rhombohedral (R3c) symmetry and belongs to the whitlockite structure type. Vanadium(III) ions occupy nearly regular octahedral sites (M5 with 3 point symmetry), which share corners with six PO4 tetrahedra to form isolated units. The calcium ions occupy eight‐ and nine‐coordinated sites. The sodium ions partially occupy one octahedral position and share one nine‐coordinated position with a Ca atom. 相似文献
20.
R.V Shpanchenko V.V Chernaya J Hadermann C Geibel 《Journal of solid state chemistry》2003,173(1):244-250
The new complex oxide Na2SrV3O9 was synthesized and investigated by means of X-ray diffraction, electron microscopy and magnetic susceptibility measurements. This oxide has a monoclinic unit cell with parameters a=5.416(1) Å, b=15.040(3) Å, c=10.051(2) Å, β=97.03(3)°, space group P21/c and Z=4. The crystal structure of Na2SrV3O9, as determined from X-ray single-crystal data, is built up from isolated chains formed by square V4+O5 pyramids. Neighboring pyramids are linked by two bridging V5+O4 tetrahedra sharing a corner with each pyramid. The Na and Sr atoms are situated between the chains. Electron diffraction and HREM investigations confirmed the crystal structure. The temperature dependence of the susceptibility indicates low-dimensional magnetic behavior with a sizeable strength of the magnetic intra-chain exchange J of the order of 80 K, which is very likely due to superexchange through the two VO4 tetrahedra linking the magnetic V4+ cations. 相似文献