Synthesis and physicochemical investigation of LiMTif6

Mixed alkali hexafluorotitanates of the composition LiMTiF₆ are synthesized, which crystallize with the orthorhombic symmetry. The lattice parameters of these materials are determined. It is shown that substitution of the Li⁺ cation in Li₂TiF₆ by Na⁺, K⁺, Rb⁺, and Cs⁺ leads to various degrees of distortion of the hexafluoroion. It is determined (¹⁹F NMR data) that the change in the dynamic state of the octahedral [TiF₆]^2– ions is related to their transition from the hindered-rotational to the isotropic state.Institute of Chemistry, Far-Eastern Branch, Russian Academy of Sciences, 690022 Vladivostok. Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 11, pp. 2483–2490, November, 1992.     

Structure and properties of oxofluoroniobate glasses based on MnNbOF5

The MnNbOF₅-BaF₂ and MnNbOF₅-PbF₂ systems have a wider glass region than the binary system NbO₂F-BaF₂. According to thermogravimetric analysis data, the glasses in these systems are characterized by lower glass transition temperatures than the similar binary glass 50NbO₂F·50BaF₂. The thermal stability range and the degree of thermal stability of the glasses depend on the modifying cation. As demonstrated by IR and Raman spectroscopy, the glass structure is built from Nb(O,F)6 polyhedra linked into a glass network by oxygen and fluoride bridges. This is explained by the fact that the starting component MnNbOF₅·4H₂O decomposes to NbO₂F upon melting. The manganese cations form their own polyhedra, which are incorporated into the glass network. The modifying cations exert a considerable effect on the glass network structure and on short-and medium-range order domains.     

Crystal Structures of LiCsTiF6 and Cs2TiF6 and Internal Mobility of Complex Anions

Single crystals of LiCsTiF₆(I) and Cs₂TiF₆(II) are characterized by X-ray diffraction analysis (DAR-UMBk and SMART 1000 CCD diffractometers, MoK radiation, graphite monochromator; anisotropic least squares refinement to R = 0.038 and R _w = 0.046 (I) and R ₁ = 0.017 and wR ₂ = 0.046 (II)). Packing modes of structural units in the crystals are considered. Types of internal motions of complex TiF₆ ^2– ions are established, and their activation energies in the crystals of LiCsTiF₆ and Cs₂TiF₆ are estimated in the temperature range 200–500 K.     

Glasses in the CuNbOF<Subscript>5</Subscript>-BaF<Subscript>2</Subscript> and CuNbOF<Subscript>5</Subscript>-PbF<Subscript>2</Subscript> systems

Nonhygroscopic, colored glasses have been synthesized in the CuNbOF₅-BaF₂ and CuNbOF₅-PbF₂ systems proceeding from crystals of the complex compound CuNbOF₅ · 4H₂O. The glasses have been studied structurally and thermally. The crystallization resistance of the glasses has been studied as a function of glass composition. Lead difluoride glasses are more stable than barium difluoride glasses of the same composition. These glasses have lower glass-transition temperatures than the binary glasses formed in the NbO₂F-BaF₂ system. The glass structure is built of Nb(O,F)₆ polyhedra, which are linked in glass networks through oxygen bridges. Modifier cations influence both the structure of glass networks and the linkage of polyhedra.     

Reaction of methyl 3-phenyl-3-chloro-2-oxopropionate with thiosemicarbazones

The reaction of methyl 3-phenyl-3-chloro-2-oxopropionate with thiosemicarbazones proceeds via the intermediate formation of methyl [S-(1-alkylideneisothiosemicarbazidyl)]-3-phenyl-2-oxopropionate hydrochlorides, which then cyclize to novel 4-methoxycarbonyl-5-phenyl-2-substituted thiazoles. Hydrolysis of the intermediate products and the thiazoles obtained therefrom with simultaneous distillation of the carbonyl compound affords 2-hydrazino-4-methoxy-carbonyl-5-phenylthiazole.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 6, pp. 1422–1426, June, 1991.     

Ion Mobility and Conduction in the (NH4)6LiHf2Zr2F23 Compound

Russian Journal of Electrochemistry - The ion mobility and conduction in the (NH4)6LiHf2Zr2F23 compound are studied by 1H, 19F NMR and impedance spectroscopy methods. The types of ion motion in...     

Synthesis and characterization of bismuth-containing oxyfluoroniobate glasses

New glasses are prepared in the MnNbOF₅-BaF₂-BiF₃ system. The thermal parameters of these glasses are analyzed as influenced by bismuth trifluoride. IR and Raman spectroscopy shows that the glass structures are built of Nb(O, F)₆ polyhedra, which are linked by oxygen bridges to form glass nets via. A medium-order order region in the glass includes fluoroniobate polyhedra not linked directly to bismuth trifluoride polyhedra. A Ba_0.55Bi_0.45F_2.45 crystalline phase is discovered at 320°C in a glass of composition 20MnNbOF₅-40BaF₂-40BiF₃.     

Synthesis and physicochemical study of hexafluorocomplexes of tin with mixed alkali metal cations

Conclusions Hexafluorocomplexes of tin with mixed cations of alkali metals with the composition NaMSnF₆ (M=K, Rb, Cs) and crystallizing in the orthorhombic system have been synthesized for the first time from aqueous solutions. The parameters of the unit cells of these substances have been determined.The compounds synthesized are optically positive biaxial crystals; their optical and x-ray diffraction constants are given.In the IR spectra of all the fluorocomplexes synthesized a splitting is observed in the frequency of the stretching vibration (₃) for the octahedral anion SnF₆ ^2–.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 9, pp. 1927–1931, September, 1987.