Thermal decomposition of organo-bielemental vanadium compounds Cp2V(ER3) (ER3 - GeEt3, SnEt3, CH2SiMe3 SeGeEt3)

The thermal decompositon of a number of organo-bielemental vanadium compounds with the general formula Cp₂V(ER₃) (ER₃ - GeEt₃, SnEt₃, CH₂SiMe₃, SeGeEt₃) has been investigated in solids and in solution. The main decomposition products of Cp₂V(SnEt₃) are vanadocene and hexaethyldistannane. Et₃GeH, Et₃GeCp, Cp₂V and CpV(C₅H₄GeEt₃) are formed from Cp₂V (GeET₃) decomposition. Isolated CpV(C₅H₄GeEt₃) is characterized by IR and mass spectra. The decomposition of Cp₂V(CH₂SiMe₃) is accompanied by Me₄Si, Cp₂V and CpV-(C₅H₄CH₂SiMe₃) formation, the latter is identified from the mass spectrum. Triethylgermane, vanadocene, and a diselenide of vanadium are isolated on decomposition of Cp₂V(SeGeEt₃). Based upon the experimental data, mechanisms for the decompositon are proposed.     

Sm2O3Ga2O3 and Gd2O3Ga2O3 phase diagrams

Four definite compounds exist in the Sm₂O₃Ga₂O₃ binary phase diagram, namely: Sm₃GaO₆, Sm₄Ga₂O₉, SmGaO₃, and Sm₃Ga₅O₁₂. The $\text{3}\text{1}$ compound is orthorhombic (space group Pnna - Z.4) with the cell parameters: a = 11.40₀Å, b = 5.51₅Å, c = 9.07Å and belongs to the oxysel family. Sm₃GaO₆ and SmGaO₃ melt incongruently at 1715 and 1565°C; Sm₄Ga₂O₉ and Sm₃Ga₅O₁₂ have a congruent melting point at 1710 and 1655°C. With regard to the Gd₂O₃Ga₂O₃ system three definite compounds have been identified: Gd₃GaO₆, Gd₄Ga₂O₉, and Gd₃Ga₅O₁₂. Only the garnet melts congruently at 1740°C with the following composition: Gd_3.12Ga_4.88O₁₂. Gd₃GaO₆, and Gd₄Ga₂O₉ melt incongruently at 1760 and 1700°C. GdGaO₃ is only obtained by melt overheating which may yield an equilibrium or a metastable phase diagram.     

Synthesis and characterisation of HRuRh3(CO)12. Crystal structures of HRuRh3(CO)12, HRuRh3(CO)10(PPh3)2 and HRuCo3(CO)10(PPh3)2

A new ruthenium-rhodium mixed-metal cluster HRuRh₃(CO)₁₂ and its derivatives HRuRh₃(CO)₁₀(PPh₃)₂ and HRuCo₃(CO)₁₀(PPh₃)₂ have been synthesized and characterized. The following crystal and molecular structures are reported: HRuRh₃(CO)₁₂: monoclinic, space group P2₁/c, a 9.230(4), b 11.790(5), c 17.124(9) Å, β 91.29(4)°, Z = 4; HRuRh₃(CO)₁₀(PPh₃)₂·C₆H₁₄: triclinic, space group P$\text{1}$, a 11.777(2), b 14.079(2), c 17.010(2) Å, α 86.99(1), β 76.91(1), γ 72.49(1)°, Z = 2; HRuCo₃(CO)₁₀(PPh₃)₂·CH₂Cl₂: triclinic, space group P$\text{1}$, a 11.577(7), b 13.729(7), c 16.777(10) Å, α 81.39(4), β 77.84(5), γ 65.56°, Z = 2. The reaction between Rh(CO)₄^? and (Ru(CO)₃Cl₂)₂ tetrahydrofuran followed by acid treatment yields HRuRh₃(CO)₁₂ in high yield. Its structural analysis was complicated by a 80–20% packing disorder. More detailed structural data were obtained from the fully ordered structure of HRuRh₃(CO)₁₀(PPh₃)₂, which is closely related to HRuCo₃(CO)₁₀(PPh₃)₂ and HFeCo₃(CO)₁₀(PPh₃)₂. The phosphines are axially coordinated.     

Syntheses, crystal structures, and properties of three new metal selenites Na2Co2(SeO3)3, Na2Co1.67Ni0.33(SeO3)3, and Na2Ni2(SeO3)3

Three new sodium cobalt (nickel) selenite compounds, namely, Na₂Co₂(SeO₃)₃, Na₂Co_1.67Ni_0.33(SeO₃)₃, and Na₂Ni₂(SeO₃)₃ have been hydro-/solvothermally synthesized in the mixed solvents of acetonitrile and water. Single-crystal X-ray diffraction analyses reveal that these isostructural compounds belong to the orthorhombic Cmcm space group and their structures feature three-dimensional open frameworks constructed by the two-dimensional layers of [MSeO₃] pillared by the [SeO₃]²⁻ groups. The two different types of Na⁺ ions reside in the intersecting two-dimensional channels parallel to the a- and c-axes, respectively. Their thermal properties have been investigated via TGA-DSC. The magnetic measurements indicate the existence of the antiferromagnetic interactions in these compounds.     

RbAuUSe3, CsAuUSe3, RbAuUTe3, and CsAuUTe3: Syntheses and structure; magnetic properties of RbAuUSe3

The compounds RbAuUSe₃, CsAuUSe₃, and RbAuUTe₃ were synthesized at 1073 K from the reactions of U, Au, Q, and A₂Q₃ (A=Rb or Cs; Q=Se or Te). The compound CsAuUTe₃ was synthesized at 1173 K from the reaction of U, Au, Te, and CsCl as a flux. These isostructural compounds crystallize in the KCuZrS₃ structure type in space group Cmcm of the orthorhombic system. The structure consists of layers that contain nearly regular UQ₆ octahedra and distorted AuQ₄ tetrahedra. The infinite layers are separated by bicapped trigonal prismatic A cations. The magnetic behavior of RbAuUSe₃ deviates significantly from Curie–Weiss behavior at low temperatures. For T>200 K, the values of the Curie constant C and the Weiss constant θ_p are 1.82(9) emu K mol⁻¹ and −3.5(2)×10² K, respectively. The effective magnetic moment μ_eff is 3.81(9) μ_B. Formal oxidation states of A/Au/U/Q may be assigned as +1/+1/+4/−2, respectively.     

Syntheses, structures, and properties of Ag4(Mo2O5)(SeO4)2(SeO3) and Ag2(MoO3)3SeO3

Ag₄(Mo₂O₅)(SeO₄)₂(SeO₃) has been synthesized by reacting AgNO₃, MoO₃, and selenic acid under mild hydrothermal conditions. The structure of this compound consists of cis-MoO₂²⁺ molybdenyl units that are bridged to neighboring molybdenyl moieties by selenate anions and by a bridging oxo anion. These dimeric units are joined by selenite anions to yield zigzag one-dimensional chains that extended down the c-axis. Individual chains are polar with the C₂ distortion of the Mo(VI) octahedra aligning on one side of each chain. However, the overall structure is centrosymmetric because neighboring chains have opposite alignment of the C₂ distortion. Upon heating Ag₄(Mo₂O₅)(SeO₄)₂(SeO₃) looses SeO₂ in two distinct steps to yield Ag₂MoO₄. Crystallographic data: (193 K; MoKα, λ=0.71073 Å): orthorhombic, space group Pbcm, a=5.6557(3), b=15.8904(7), c=15.7938(7) Å, V=1419.41(12), Z=4, R(F)=2.72% for 121 parameters with 1829 reflections with I>2σ(I). Ag₂(MoO₃)₃SeO₃ was synthesized by reacting AgNO₃ with MoO₃, SeO₂, and HF under hydrothermal conditions. The structure of Ag₂(MoO₃)₃SeO₃ consists of three crystallographically unique Mo(VI) centers that are in 2+2+2 coordination environments with two long, two intermediate, and two short bonds. These MoO₆ units are connected to form a molybdenyl ribbon that extends along the c-axis. These ribbons are further connected together through tridentate selenite anions to form two-dimensional layers in the [bc] plane. Crystallographic data: (193 K; MoKα, λ=0.71073 Å): monoclinic, space group P2₁/n, a=7.7034(5), b=11.1485(8), c=12.7500(9) Å, β=105.018(1) V=1002.7(2), Z=4, R(F)=3.45% for 164 parameters with 2454 reflections with I>2σ(I). Ag₂(MoO₃)₃SeO₃ decomposes to Ag₂Mo₃O₁₀ on heating above 550 °C.     

Non-centrosymmetric Ba3Ti3O6(BO3)2

The compound previously reported as Ba₂Ti₂B₂O₉ has been reformulated as Ba₃Ti₃B₂O₁₂, or Ba₃Ti₃O₆(BO₃)₂, a new barium titanium oxoborate. Small single crystals have been recovered from a melt with a composition of BaTiO₃:BaTiB₂O₆ (molar ratio) cooled between 1100°C and 850°C. The crystal structure has been determined by X-ray diffraction: hexagonal system, non-centrosymmetric space group, a=8.7377(11) Å, c=3.9147(8) Å, Z=1, wR(F²)=0.039 for 504 unique reflections. Ba₃Ti₃O₆(BO₃)₂ is isostructural with K₃Ta₃O₆(BO₃)₂. Preliminary measurements of nonlinear optical properties on microcrystalline samples show that the second harmonic generation efficiency of Ba₃Ti₃O₆(BO₃)₂ is equal to 95% of that of LiNbO₃.     

Interactions of Cr2S3 with GeS2 and Cu2GeS3

The interactions in the GeS₂-Cr₂S₃ and Cu₂GeS₃-Cr₂S₃ sections were studied by differential thermal analysis and X-ray powder diffraction. The GeS₂-Cr₂S₃ section was shown to be quasi-binary, with a degenerate eutectic; no ternary compound was formed. In the Cu₂GeS₃-Cr₂S₃ section, a quaternary phase of variable composition having a homogeneity range of 69–75 mol % Cr₂S₃ crystallized in the cubic system. The samples of this composition are spin glasses with freezing temperatures of 20–25 K.     

Conductivities of the Ternary Systems Y(NO3)3+La(NO3)3+H2O, La(NO3)3+Ce(NO3)3+H2O, La(NO3)3+Nd(NO3)3+H2O and Their Binary Subsystems at Different Temperatures

Electrical conductivities were measured for the ternary systems Y(NO₃)₃+La(NO₃)₃+H₂O, La(NO₃)₃+Ce(NO₃)₃+H₂O, La(NO₃)₃+Nd(NO₃)₃+H₂O, and their binary subsystems Y(NO₃)₃+H₂O, La(NO₃)₃+H₂O, Ce(NO₃)₃+H₂O, and Nd(NO₃)₃+H₂O at (293.15, 298.15 and 308.15) K. The measured conductivities were used to test the generalized Young’s rule and the semi-ideal solution theory. The comparison results show that the generalized Young’s rule and the semi-ideal solution theory can yield good predictions for the conductivities of the ternary electrolyte solutions, implying that the conductivities of aqueous solutions of (1:3 + 1:3) electrolyte mixtures can be well predicted from those of their constituent binary solutions by the simple equations.     

Synthesis and crystal structure of the palladium oxides NaPd3O4, Na2PdO3 and K3Pd2O4

NaPd₃O₄, Na₂PdO₃ and K₃Pd₂O₄ have been prepared by solid-state reaction of Na₂O₂ or KO₂ and PdO in sealed silica tubes. Crystal structures of the synthesized phases were refined by the Rietveld method from X-ray powder diffraction data. NaPd₃O₄ (space group Pm3¯n, a=5.64979(6) Å, Z=2) is isostructural to NaPt₃O₄. It consists of NaO₈ cubes and PdO₄ squares, corner linked into a three-dimensional framework where the planes of neighboring PdO₄ squares are perpendicular to each other. Na₂PdO₃ (space group C2/c, a=5.3857(1) Å, b=9.3297(1) Å, c=10.8136(2) Å, β=99.437(2)°, Z=8) belongs to the Li₂RuO₃-structure type, being the layered variant of the NaCl structure, where the layers of octahedral interstices filled with Na⁺ and Pd⁴⁺ cations alternate with Na₃ layers along the c-axis. Na₂PdO₃ exhibits a stacking disorder, detected by electron diffraction and Rietveld refinement. K₃Pd₂O₄, prepared for the first time, crystallizes in the orthorhombic space group Cmcm (a=6.1751(6) Å, b=9.1772(12) Å, c=11.3402(12) Å, Z=4). Its structure is composed of planar PdO₄ units connected via common edges to form parallel staggered PdO₂ strips, where potassium atoms are located between them. Magnetic susceptibility measurements of K₃Pd₂O₄ reveal a Curie-Weiss behavior in the temperature range above 80 K.     

Complex salts (DienH3)[IrCl6](NO3), (DienH3)[PtCl6](NO3), and (DienH3)[IrCl6]0.5[PtCl6]0.5(NO3): Synthesis, structure, and thermal properties

The complex salts ((DienH₃)[IrCl₆](NO₃) (I), (DienH₃)[PtCl₆](NO₃) (II), and (DienH₃)[IrCl₆]_0.5[PtCl₆]_0.5(NO₃) (III) (where Dien is NH₂(CH₂)₂NH(CH₂)₂NH₂) were synthesized and characterized by elemental, X-ray diffraction, and thermal analyses and by electronic and IR spectroscopies. Solid solution of the composition Ir_0.35Pt_0.65 was obtained by decomposition of compound III in the atmosphere of hydrogen. Original Russian Text ? E.V. Makotchenko, I.A. Baidina, P.E. Plusnin, L.A. Sheludyakova, Yu.V. Shubin, S.V. Korenev, 2007, published in Koordinatsionnaya Khimiya, 2007, Vol. 33, No. 1, pp. 47–54.     

Vibrational spectra of the peroxotantalates (NH4)3[Ta(O2)4], K3[Ta(O2)4], Rb3[Ta(O2)4] and Cs3[Ta(O2)4] and the crystal structure of Rb3[Ta(O2)4]

The compounds (NH₄)₃[Ta(O₂)₄], K₃[Ta(O₂)₄], Rb₃[Ta(O₂)₄] and Cs₃[Ta(O₂)₄] have been prepared and investigated by X-ray powder methods as well as Raman- and IR-spectroscopy. In the case of Rb₃[Ta(O₂)₄] the structure has been solved from single crystal data. It is shown that all these compounds are isotypic and crystallize in the K₃[Cr(O₂)₄] type (SG , No. 121). The infrared- and Raman spectra (recorded on powdered samples) are discussed with respect to the internal vibrations of the peroxo-group and the dodecahedral [Ta(O₂)₄]³⁻ ion. Symmetry coordinates for the [Ta(O₂)₄]³⁻ ion are given from which the vibrational modes of the O-O stretching vibrations of the O₂²⁻ groups, the Ta-O stretching vibrations and the Ta-O bending vibrations are deduced.     

Synthesis, crystal structures and photoluminescence properties of new oxyborates, Mg5NbO3(BO3)3 and Mg5TaO3(BO3)3, with novel warwickite-type superstructures

Single crystals of new oxyborates, Mg₅NbO₃(BO₃)₃ and Mg₅TaO₃(BO₃)₃, were prepared at 1370 °C in air using B₂O₃ as a flux. They were colorless and transparent with block shapes. X-ray diffraction analysis of the single crystals revealed Mg₅NbO₃(BO₃)₃ and Mg₅TaO₃(BO₃)₃ to be isostructural. The X-ray diffraction reflections were indexed to the orthorhombic Pnma (No. 62) system with a=9.3682(3) Å, b=9.4344(2) Å, c=9.3379(3) Å and Z=4 for Mg₅NbO₃(BO₃)₃ and a=9.3702(3) Å, b=9.4415(3) Å, c=9.3301(2) Å and Z=4 for Mg₅TaO₃(BO₃)₃. The crystal structures of Mg₅NbO₃(BO₃)₃ and Mg₅TaO₃(BO₃)₃ are novel warwickite-type superstructures having ordered arrangements of Mg and Nb/Ta atoms. Polycrystals of Mg₅NbO₃(BO₃)₃ prepared by solid state reaction at 1200 °C in air showed broad blue-to-green emission with a peak wavelength of 470 nm under 270 nm ultraviolet excitation at room temperature.     

The support and characterization of C60 and MoO3 on Al2O3

A new type of catalyst from supporting C₆₀ on MoO₃ and Al₂O₃ has been prepared. The effect of different order of impregnation and calcination atmosphere on catalyst are investigated by the solution test in toluene, UV-VIS spectroscopy and temperature programmed reduction (TPR). The results show that when the catalyst was prepared by supporting MoO₃ on C₆₀/Al₂O₃ and calcined in N₂, there is a stronger interaction between C₆₀, MoO₃ and Al₂O₃, but when supporting C₆₀ on MoO₃/Al₂O₃, the interaction is relatively weak. We consider that in the former method a new complex, Mo–C₆₀–O–Al, is formed.     

Laser-induced fluorescence of high-temperature vapor complexes of ErCl3 with AlCl3, GaCl3 and InCl3

Laser excitation of equilibrium vapor mixtures ErCl₃(s)-ACl₃(g) (A = Al, Ga, In) at 475–1100 K gives rise both to resonance fluorescence from the f → f Er³⁺ transitions of the Er-Cl-A vapor complexes, and to Raman scattering due to the vibrational modes of the ACl₃ vapor. The laser-induced fluorescence from the ⁴F_{$\text{9}\text{2}$}, ⁴S_{$\text{3}\text{2}$} and ²H_{$\text{11}\text{2}$} states has been investigated at different temperatures and excitation.     

Thermoanalytical study of the systems PbCO3SrCO3 and PbCO3CaCO3

This study concerns the coprecipitation of the PbCO₃SrCO₃ and PbCO₃CaCO₃ systems in different molar relationships carried out under the same experimental conditions as the PbCO₃BaCO₃ system studied previously. The precipitates obtained were studied by chemical analysis, thermogravimetry, differential thermal analysis and X-ray powder diffraction. It has been established that, for the PbCO₃SrCO₃ system, solid solutions are obtained under all the different experimental conditions and for the PbCO₃CaCO₃ system the precipitates obtained are always mixtures of PbCO₃ and CaCO₃.     

Electrochemistry of solid-phase reactions: Phase formation in the In2O3-WO3 system. Processes at the WO3|In2O3 and WO3|In6WO12 interfaces

Reactions of interactions at the WO₃|In₂O₃ and WO₃|In₆WO₁₂ heterophase reaction interfaces, whose main product is In₂(WO₄)₃, are studied by electrochemical methods for the first time ever. Due to a far greater n type conductance inherent in the initial substances, the reactions are a model object for the development of methodology of the electrochemical approach. Both reactions are discovered to proceed at the expense of the transport of components of WO₃ and no evidence is discovered for the contribution of In³⁺ into diffusion and migration. Consisted data are obtained between the polarity of a spontaneously generated reaction difference of potentials and the direction of the field that accelerates the reaction: the current that is passed through electrochemical cells accelerates the reactions exclusively at the (−)-potential of a brick of WO₃. A difference is discovered between the charge and mass transport paths—spontaneous and field-induced mass transport of WO₃ or its components occurs via heterophase interfaces and adjacent areas and does not touch upon the In₂(WO₄)₃ grains. Shown is the antibatic character of the behavior exhibited by dependences of identical properties of cells (potential drop across a cell) following a change in the dc polarity. A possible role of a reactionless electrosurface transport of WO₃ in the mechanism of reaction and evolution of electrochemical properties of model electrochemical cells is demonstrated. The obtained data may or may not testify in favor of a hypothesis that presumes a prevailing role of the {WO₄}²⁻ mobility in the In₂(WO₄)₃ structure. Original Russian Text ? A.Ya. Neiman, T.E. Kulikova, 2007, published in Elektrokhimiya, 2007, Vol. 43, No. 6, pp. 714–726. Based on the report delivered at the 8th International Meeting on Fundamental Problems of Solid-State Ionics, Chernogolovka (Russia), 2006.     

A study of the formation of LiNbO3 in the system Li2CO3Nb2O5

The formation process of LiNbO₃ in the system Li₂CO₃Nb₂O₅ was discussed from the results of non-isothermal or isothermal TG experiments and X-ray analysis. The mixture Li₂CO₃ and Nb₂O₅ in mole ratios of 1:3, 1:1 or 3:1 was heated at a rate of 5°C min^?1 or at various temperatures fixed in the range 475 to 677°C. If the system has a composition of Li₂CO₃ + 3Nb₂O₅ or 3Li₂CO₃ + Nb₂O₅, the reaction between Li₂CO₃ and Nb₂O₅ proceeds with CO₂ evolution to form LiNbO₃ at ca. 300–600°C, but Nb₂O₅ or Li₂CO₃ remains unreacted. A composition of Li₂CO₃ + Nb₂O₅ gives LiNbO₃ at 300–700°C. The diffusion of Li₂O through the layer of LiNbO₃ is rate-controlling with an activation energy of 51 kcal mol^?1. The reaction between LiNbO₃ and Nb₂O₅ gives LiNb₃O₈ at 600–700°C. At 700–800°C, a slight formation of Li₃NbO₄ occurs by the reaction between LiNbO₃ and Li₂O at the outer surface of LiNbO₃ and the Li₂O component of Li₃NbO₄ diffuses toward the boundary of the LiNb₃O₈ layer through the LiNbO₃ layer. The single phase of LiNbO₃ is formed above 850°C.     

EPR study of the NO2+3 radical in irradiated K(UO2)(NO3)3 and K2(UO2)(NO3)4 single crystals

A new radical observed at low temperature in γ-irradiated K₂(UO₂)(NO₃)₄ single crystals has been tentatively assigned to a hitherto unknown oxyanion radical, NO²⁺₃. The assignment and the lack of ¹⁴N hyperfine structure, together with the g factors which are lower than the free-spin value, are discussed in terms of an orbital level scheme.