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61.
The crystal structures of bis(2-thiobarbiturato-O)tetraaquamagnesium Mg(H2O)4(HTBA-O)2 I and catena-[(μ2-2-thiobarbiturato-O,O)(2-thiobarbiturato-O)bis(μ2-aqua)diaquastrontium] monohydrate catena-[Sr(μ2-H2O)2(H2O)2(μ2-HTBA-O,O)(HBTA-O)] n · nH2O (II), where H2TBA is 2-thiobarbituric acid C4H4N2O2S, have been determined. Crystal data for a=6.7598(2) Å, b = 7.6060(2) Å, c = 8.5797(2) Å, α = 79.822(2)°, β = 76.622(1)°, γ = 69.124(1)°, V = 398.82(2) Å3, space group P $\bar 1$ , Z = 1; for II: a = 20.8499(4) Å, b = 19.2649(5) Å, c = 4.14007(9) Å, β = 92.023(2)°, V = 1661.91(7) Å3, space group P21/n, Z = 4. The Mg2+ ion in I is bonded to six O atoms of two HTBA? ions and four water molecules that form a nearly regular octahedron. Each Sr2+ ion in II is coordinated to three oxygen atoms of three HTBA? ions and six water molecules that form an almost ideal tricapped trigonal prism. These polyhedra share edges to form infinite chains. Intermolecular hydrogen bonds create layered structures of I and II. 相似文献
62.
By powder X-ray diffraction the crystal structure of catena-(2-thiobarbiturato)dithallium(I) C4H2N2O2STl2 (C4H4N2O2S is 2-thiobarbituric acid, H2TBA), Tl2TBA, is determined. Crystallographic data for Tl2TBA are as follows: a = 15.1039(3) Å, b = 12.0818(2) Å, c = 3.86455(6) Å, β = 97.203(1)°, V = 741.34(2) Å3, space group P21/n, Z = 4. There are two non-equivalent thallium atoms in the structure. The Tl1 polyhedron is a distorted trigonal prism due to the shortened Tl-S contact (3.634 Å), and the Tl2 polyhedron is a distorted square antiprism. 相似文献
63.
Kartashev A. V. Bondarev V. S. Flerov I. N. Gorev M. V. Pogorel’tsev E. I. Shabanov A. V. Molokeev M. S. Guillemet-Fritsch S. Raevskii I. P. 《Physics of the Solid State》2019,61(6):1052-1061
Physics of the Solid State - The specific heat, thermal expansion, permittivity, and electrocaloric effect in bulk of BaTiO3 (BT) samples in the form of nano- (nBT-500 nm) and micro- (mBT-1200 nm)... 相似文献
64.
65.
Nikolay Golovnev Maxim Molokeev 《Acta Crystallographica. Section C, Structural Chemistry》2013,69(7):704-708
The structures of the LiI and NaI salts of 2‐thiobarbituric acid (2‐sulfanylidene‐1‐3‐diazinane‐4,6‐dione, H2TBA) have been studied. μ‐Aqua‐octaaquabis(μ‐2‐thiobarbiturato‐κ2O:O′)bis(2‐thiobarbiturato‐κO)tetralithium(I) dihydrate, [Li4(C4H3N2O2S)4(H2O)9]·2H2O, (I), crystallizes with four symmetry‐independent four‐coordinated LiI cations and four independent HTBA− anions. The structure contains two structurally non‐equivalent LiI cations and two non‐equivalent HTBA− anions (bridging and terminal). Eight of the coordinated water ligands are terminal and the ninth acts as a bridge between LiI cations. Discrete [Li4(HTBA)4(H2O)9]·2H2O complexes form two‐dimensional layers. Neighbouring layers are connected via hydrogen‐bonding interactions, resulting in a three‐dimensional network. Poly[μ2‐aqua‐tetraaqua(μ4‐2‐thiobarbiturato‐κ4O:O:S:S)(μ2‐thiobarbiturato‐κ2O:S)disodium(I)], [Na2(C4H3N2O2S)2(H2O)5]n, (II), crystallizes with six‐coordinated NaI cations. The octahedra are pairwise connected through edge‐sharing by a water O atom and an O atom from the μ4‐HTBA− ligand, and these pairs are further top‐shared by the S atoms to form continuous chains along the a direction. Two independent HTBA− ligands integrate the chains to give a three‐dimensional network. 相似文献
66.
I. N. Flerov M. S. Molokeev N. M. Laptash A. A. Udovenko E. I. Pogoreltsev S. V. Mel'nikova S. V. Misyul 《ChemInform》2015,46(49):no-no
Single crystals of (NH4)3SnF7 are obtained from aqueous solutions of (NH4)2SnF6 and excess NH4F during solvent evaporation. 相似文献
67.
The structure of the low-temperature triclinic phase of the (NH4)3WO3F3 crystal has been determined and the structure of the cubic phase of this crystal has been refined from data of an X-ray diffraction
experiment performed for a powder sample. The profile and structural parameters have been refined according to the procedure
implemented in the DDM program. The results obtained have been discussed with invoking the group-theoretical analysis of the
complete order parameter condensate, which takes into account the critical and noncritical atomic orderings and allows one
to interpret the obtained experimental data. It has been found that the symmetry transformation in the crystal can be schematically
represented in the following form: Fm[`3]m(Z = 4) ? P[`1](Z = 1) ? P[`1](Z = 6)Fm\bar 3m(Z = 4) \to P\bar 1(Z = 1) \to P\bar 1(Z = 6). This transformation is accompanied by the complete ordering of WO3F3 polyhedra and the displacement of NH4 ions. 相似文献
68.
L. V. Udod S. S. Aplesnin M. N. Sitnikov M. S. Molokeev 《Physics of the Solid State》2014,56(7):1315-1319
The Bi2Sn2O7 compound existing simultaneously in two polymorphic modifications, namely, orthorhombic and cubic, has been synthesized for the first time by solid-phase synthesis. The dielectric and electrical properties of the compound have been studied in the temperature range 100 K < T < 500 K. Anomalies in the temperature dependences of the electrical resistivity and the permittivity (imaginary and real parts) have been found at both low and high temperatures. These features are explained in terms of the model of martensitic phase transitions. 相似文献
69.
I. N. Flerov V. D. Fokina A. F. Bovina E. V. Bogdanov M. S. Molokeev A. G. Kocharova E. I. Pogorel’tsev N. M. Laptash 《Physics of the Solid State》2008,50(3):515-524
The temperature dependences of the heat capacity, the unit cell parameter, and the permittivity for the (NH4)3MoO3F3 cryolite (space group Fm $ \overline 3 The temperature dependences of the heat capacity, the unit cell parameter, and the permittivity for the (NH4)3MoO3F3 cryolite (space group Fm
m) are investigated. It is revealed that the compound undergoes ferroelectric and ferroelastic structural phase transitions
at temperatures of 297 and 205 K, respectively. The mechanism of structural distortions is discussed in terms of the entropy
parameters, pressure-temperature phase diagrams, and electron density maps for critical atoms. An analysis is made of the
influence of the cation size and shape on the phase transitions in oxyfluorides of the general formula A
2
A′MO3 (A,A′ = NH4, K; M = Mo, W).
Original Russian Text ? I.N. Flerov, V.D. Fokina, A.F. Bovina, E.V. Bogdanov, M.S. Molokeev, A.G. Kocharova, E.I. Pogorel’tsev,
N.M. Laptash, 2008, published in Fizika Tverdogo Tela, 2008, Vol. 50, No. 3, pp. 497–506. 相似文献
70.
K.?S.?Aleksandrov V.?N.?Voronov A.?N.?Vtyurin A.?S.?Krylov M.?S.?Molokeev M.?S.?Pavlovski? S.?V.?Gorya?nov A.?Yu.?Likhacheva A.?I.?Ancharov 《Physics of the Solid State》2009,51(4):810-816
Pressure-induced phase transitions in the ScF3 crystal were studied using synchrotron radiation diffraction, polarization microscopy, and Raman spectroscopy. The phase existing in the range 0.6–3.0 GPa is optically anisotropic; its structure is described by space group R 3 c (Z = 2), and the transition is due to rotation of ScF6 octahedra around a threefold axis. The pressure dependence of the structural parameters and angle of rotation are determined. The number of Raman spectral lines corresponds to that expected for this structure; above the phase transition point, a recovery of soft modes takes place. At a pressure of 3.0 GPa, a transition occurs to a new phase, which remains metastable as the pressure decreases. The results are interpreted using an ab initio method based on the Gordon-Kim approach. 相似文献