Thermodynamics of dehydration of MAsUO6·xH2O (M = Li,Na, K,Rb, Cs) Crystal Hydrates

The existence regions of crystal hydrates in the systems MAsUO₆-H₂O (M = Li, Na, K, Rb, Cs) in the coordinates water vapor pressure-temperature were studied by the isopiestic method and static tensimetry. All individual compounds formed in these systems were isolated and studied by reaction calorimetry. The enthalpies of their formation and dehydration were determined.     

MZr2（AsO4）3（M=Na,K,Rb,Cs）的水热合成与结构表征

用水热晶化法合成了MZr_2(ASO_4)_3(M=Na,K,Rb,Cs)系列化合物。研究了反应物浓度、配比及不同砷源等水热晶化条件对产物物相的影响。用XRD、IR和Raman光谱对产物进行了表征。4种晶体的振动光谱由钠到铯呈现出规律性变化。     

Thermodynamic Properties of the MZr2(PO4)3 (M=Na,K, Rb or Cs) Compounds

The enthalpies of the solution of MZr₂(PO₄)₃(M=Na, K, Rb or Cs) compounds have been measured by the help of a differential automatic isothermal Calvet calorimeter and the standard enthalpies of formation have been derived. The temperature dependencies of the standard heat capacity of the samples of crystalline NaZr₂(PO₄)₃ and CsZr₂(PO₄)₃ were studied between 7 and 340 K in an automatic adiabatic vacuum calorimeter. The main thermodynamic functions H ⁰(T)–H ⁰(0), S ⁰(T) andG ⁰(T)–H ⁰(0) have been determined. The Gibbs energies of formation of the NaZr₂(PO₄)₃and CsZr₂(PO₄)₃ at 298.15 K were calculated on the basis of these experimental data and the enthalpy of formation data. Qualitative explanations for the results observed were presented. This revised version was published online in July 2006 with corrections to the Cover Date.     

Phase formation in the Re-Se-Br-MBr systems (M = Li, Na, K, Rb, Cs)

Phase formation in the Re-Se-Br-MBr systems (M = K, Rb, Cs) was studied by NMR spectroscopy and powder X-ray diffraction. The reactions taking place in alkali metal halide melts were found to give, among the series of cluster anions [{Re₆Se_{8 − n} Br _n }Br₆]^{(4 − n)}− (0 ≤ n≤ 4), polymeric complexes Re₆Se₈Br ₂ and M₂Re₆Se₈Br₄ (M = Cs, Rb) and salts containing cluster anions [Re₆Se₆Br₈]²⁻ and [Re₆Se₇Br₇]³⁻ as the major products. The effect of the alkali metal cation on the product composition and ratio was established. Original Russian Text ? S.S. Yarovoi, Yu.V. Mironov, S.V. Tkachev, V.E. Fyodorov, 2009, published in Zhurnal Neorganicheskoi Khimii, 2009, Vol. 54, No. 2, pp. 344–349.     

Nuclear quadrupole resonance in MSbClF3 compounds (M=Na,K, Cs,NH4)

Conclusion A study of the temperature dependence of the¹²³Sb NQR parameters for MSbClF₃ complexes (M=K, Cs, NH₄) at from 77 to 390K shows temperature ranges with anomalous change in the electric field gradient asymmetry parameter for the antimony atoms.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 5, pp. 1136–1139, May, 1987.The authors express their gratitude to G. K. Semin for a useful discussion of this work.     

Continuous recovery of uranium oxides by electrolysis of M2MoO4-M2Mo2O7-UO2MoO4 melts (M = Li, Na, K, Cs)

Effect of the electrolyte composition and of the solvent-salt cation on the oxygen coefficient of the cathodic product (O/U atomic ratio) and basic characteristics of the potentiostatic electrodeposition of uranium dioxide in prolonged recovery of uranium oxides from electrolytes of the system M₂MoO₄-M₂Mo₂O₇-UO₂MoO₄ Melts (M = Li, Na, K, Cs) in air was analyzed. A decrease in the UO₂MoO₄ concentration and accumulation of M₂Mo₂O₇ in the electrolyte in the course of a prolonged electrolysis suppress the solvolysis of uranyl ions and make lower the oxygen coefficient of the cathodic product. Li₂MoO₄-based melts possessing pronounced oxygenacceptor properties exhibit an anomalous behavior in these experiments. The current efficiency, initial current density, and deposition rate of the product decrease as electrolytes are depleted of uranium. In discussions of numerical data, it is necessary to take into account the formation of lower valence forms of uranium due to the chemical corrosion of the cathodic product, and in the case of melts of the lithium system, the additional cathodic process in which the solvent is reduced.     

Calorimetric investigations of the MBr−NdBr3 melts (M=Li,Na, K,Cs)

Present work is a part of thermodynamic research program on the MX?LnX₃ system (M=alkali metal,X=Cl, Br andLn=lanthanide). Molar enthalpies of mixing in the LiBr?NdBr₃, NaBr?NdBr₃ and KBr?NdBr₃ liquid binary systems have been determined at temperature 1063 K by direct calorimetry in the whole range of composition. Investigated systems are generally characterized by negative enthalpies of mixing with minimum atX _NdBr3≈0.3–0.4. These enthalpies decrease with decrease of ionic radii of alkali metals. Molar enthalpies of solid-solid and solid-liquid phase transitions of K₃NdBr₆ and Cs₃NdBr₆ have been also determined by differential scanning calorimetry (DSC). K₃NdBr₆ is formed at 689 K from KBr and K₂NdBr₅ with enthalpy of 44.0 kJ·mol^?1 whereas Cs₃NdBr₆ is stable at ambient temperature and undergoes phase transition in the solid state at 731 K with enthalpy of 8.8 kJ·mol^?1. Enthalpies of melting have been also determined.     

Rhenium octahedral clusters: the systems Re-S-Br and M-Re-S-Br (M = Na, K, RB, Cs)

The quaternary systems M-Re-S-Br (M = Na, K, Rb, Cs) have been investigated in the domains of composition which are expected to lead to the formation of Re₆ octahedral cluster based compounds. A number of compounds have been obtained. They include the ternaries Re₆S_4+xBr_10−2x (integer x = 0–4) among them crystal data are reported for Re₆S₄Br₁₀ and Re₆S₅Br₈. Various quaternaries are also presented. Most of them are built from the ¦Re₆S_4+nBr_10−n¦ⁿ⁻ anionic units (n = 1–4) stacked in various compounds and solid solutions, the structure of which strongly depends on the number and size of counter cations.     

Enhanced water splitting activity of M-doped Ta(3)N(5) (M = Na, K, Rb, Cs)

We use a highly aligned Ta(2)O(5) nanochannel structure to fabricate alkali metal ion (Na, K, Rb or Cs) doped Ta(3)N(5)via solution seeding and thermal conversion in NH(3). Under optimized conditions the resulting doped structures show a strongly enhanced visible light water splitting performance in comparison to undoped Ta(3)N(5).     

Interrelation between the physicochemical properties of MnCl2-MCl (M = Li, Na, K, Rb, and Cs) melts

Our own experimental studies of vapor pressure and surface tension were used to analyze isotherms of various types of the properties under consideration. The data obtained were processed using a mathematical model to calculate the molar surface and excess molar Gibbs energy, which clearly indicated that the surface properties obeyed the general rules that governed changes in these properties of solutions according to the position of alkali metals in the periodic table of the elements. The data on various physicochemical properties of the cesium chloride-manganese chloride system are evidence of the presence of singular extremum points on concentration dependence isotherms.     

Über Hexafluoroindate(III): A2TllnF6 (A=Rb,Cs), (RbTI)BlnF6 (B= Na,Ag, K) und A2AglnF6 (A=Rb,TI,Cs)

On Hexafluoroindates(II1): A₂TlInF₆ (A = Rb, Cs), (RbTI)BInF₆ (B = Na, Ag, K), and A₂AgInF₆ (A = Rb, TI, Cs) By heating the binary components in a closed system are new prepared the compounds Rb₂AgInF₆, Rb₂CsInF₆, (RbTl)NaInF₆ (RbTI)AgInF₆, (RbTI)KInF₆, Tl₂AgInF₆, Cs₂AgInF₆ and Cs₂TlInF₆, all cubic, colourless Elpasolithes, as well as Rb₂TlInF₆, according to powder photographs tetragonal. The Madelung Part of Lattice Energy, MAPLE, is calculated and discussed.     

溴代类卡宾H2CMBr(M=Na,K)的结构与稳定性

本文用RHF/3-21G^*解析梯度方法研究了溴代类卡宾H2CMBr(M=Na,K)势能面的主要特征, 得到了它们各自的三种平衡构型及两种异构化的过渡态构型, 并用二级微扰方法进行了能量的相关能校正, 计算了振动频率, 以确证平衡构型和过渡态。计算结果表明, 溴代类卡宾H2CMBr(M=N,K))的三元环构型是最稳定的几何构型, 其它的两种构型σ-配合物和p-配合物, 也是势能面上的极值点, 但能量相对较高, 不稳定。本文分析了各构型的特点, 对其化学反应特性进行了评估。     

Phase formation in the systems TiOCl2-H3PO4-MF(HF)-H2O (M = K, Rb, Cs)

From solutions containing 2–17 wt % TiO₂ at the molar ratios M/Ti = 1–4, F/Ti = 2–4, and PO ₄ ^3? /Ti = 0.5–10 under mild conditions, fluoro- and oxo(hydroxo) fluorophosphate titanates were isolated: crystalline M₂TiF₆ (M = K, Rb, Cs) and K₂Ti₂O_2.5F₂PO₄ · 2H₂O, and amorphous K₃Ti₄O(OH)F₇(PO₄)₃ · 5H₂O, Cs₂Ti₃O₂F₇PO₄ · 6H₂O, and CsTi₃O₃F₄PO₄ · 3H₂O. In a mixture with M₂TiF₆ and KCl, phosphate-ion-containing crystalline phases of unidentified composition were detected. The phases were studied by elemental, crystal-optical, X-ray powder diffraction, thermal, IR spectroscopic, and electron microscopic analyses. Annealing fluorophosphate titanates gives a mixture of MTiOPO₄ and TiO₂. All the mentioned alkali metal fluorophosphates contain the tetrahedral ion PO ₄ ^3? and titanium polyhedra with bonds Ti-F and Ti-O; some of them also contain bridging oxygen connecting titanium atoms: Ti-O-Ti; i.e., these substances are polymeric.     

A New Family of Binary Layered Compounds of Platinum with Alkali Metals (A = K,Rb, Cs)

By reacting platinum with alkali metals (A = K, Rb, Cs) a new family of binary alkali metal platinides has been synthesized and characterized by chemical analysis, X‐ray powder diffraction, thermal analysis (DTA and DSC), and magnetic measurements. All three compounds exhibit similar XRD‐patterns with strong reflections that can be indexed on the basis of a rhombohedral crystal system (K_xPt: a = 2.6462(1), c = 17.123(1); Rb_xPt: a = 2.6415(1) Å, c = 17.871(1) Å; Cs_xPt: a = 2.6505(1) Å, c = 18.536(1) Å; x < ½. The a lattice constant is independent on the alkali metal used and of value close to the Pt–Pt distance in NaPt₂ (2.645Å). The c parameter increases monotonically with the growing atomic radius of the alkali metal. The average structure of the alloys consists of cubic close packed layers of platinum atoms with layers of disordered alkali metals in between. For all compounds besides the strong reflections small satellites are observed which cannot be indexed together with the rhombohedral peaks in any rational 3‐dimensional lattice. However, these satellites can be indexed as incommensurate modulations within the ab plane (found propagation vectors k = (0.1011, 0.2506, 0) for Cs_xPt, and k = (0.0168, 0.2785, 0) for Rb_xPt).     

Synthesis, structure, and multi-NMR studies of (Me4N)[A(M(SC(O)Ph)3)2] (A = Na, M = Hg; A = K, M = Cd or Hg)

The compounds (Me4N)[A(M(SC(O)Ph)3)2] (A = K, M = Cd (2); A = Na, M = Hg (3); and A = K, M = Hg (4)) were synthesized by reacting the appropriate metal chloride with A+PhC(O)S- and Me4NCl in the ratios 1:3:1 and 2:6:1. The structures of these compounds were determined by single-crystal X-ray diffraction methods. All the compounds are isomorphous, isostructural, and crystallized in the space group P1 with Z = 1. Single-crystal data for 2: a = 106670(2) A, b = 111522(2) A, c = 119294(2) A, alpha = 71782(1) degrees, beta = 85208(1) degrees, gamma = 69418(1) degrees, V = 126140(4) A3, Dcalc = 1528 g cm-3. Single-crystal data for 3: a = 10840(2) A, b = 10946(4) A, c = 12006(3) A, alpha = 7218(2) degrees, beta = 8675(2) degrees, gamma = 6743(2) degrees, V = 12493(6) A3, Dcalc = 1756 g cm-3. Single-crystal data for 4: a = 104780(1) A, b = 112563(2) A, c = 119827(2) A, alpha = 71574(1) degrees, beta = 85084(1) degrees, gamma = 70705(1) degrees, V = 126523(3) A3, Dcalc = 1755 g cm-3. In the [A(M(SC(O)Ph)3)2]- anions, each M(II) atom is bonded to three thiobenzoate ligands through sulfur atoms, giving a trigonal planar MS3 geometry. The carbonyl oxygen atoms from the two [M(SC(O)Ph)3]- anions are bonded to the alkali metal atom, providing an octahedral environment. Solution metal NMR studies showed the concentration-dependent dissociation of the alkali metal ions in the trinuclear anions.     

298.15和308.15 K时1,2-丙二醇+MCl (M=Na,K, Rb,Cs)+H2O三元体系的溶解度、密度和折光率

系统研究了1,2-丙二醇+MCl (M=Na, K, Rb, Cs)+H₂O三元体系在298.15 和308.15 K时的等温相平衡. 采用硝酸汞滴定法测定了体系中无机盐的含量, 采用安东帕RXA170 折光率仪及DMA4500 密度计测定了所有体系的折光率和密度数值. 报道了1,2-丙二醇质量分数从0增加到0.9过程中饱和及不饱和三元溶液体系的等温溶解度、密度和折光率数据. 实验结果发现, 随着1,2-丙二醇的不断加入, 饱和溶液的溶解度和密度均呈现出减小的趋势, 而折光率的变化则呈现出相反的趋势. 采用经验方程关联了不同醇水比条件下不饱和溶液的密度和折光率实验数据, 获得了较为理想的拟合结果. 本研究的开展充实了碱金属盐在混合溶剂中的热力学数据, 为相关溶液化学研究奠定了基础.