Synthesis and Properties of Uranosilicates M[HSiUO6] · nH2O (M = NH4+, Li,Na, K,Rb, Cs)

A complete set of uranosilicates M[HSiUO₆] · nH₂O of alkali metals and ammonium was obtained under hydrothermal conditions. The functional and phase similarity of the compounds was proved by X-ray phase analysis and IR spectroscopy. The effect of water molecules on the structures of hydrated and anhydrous uranosilicates and the nature of water in these compounds were elucidated by studying hydration-dehydration processes. The dependence of the X-ray and thermal properties of the compounds on the nature of interlayer atoms was considered.     

Na,Rb‖F,Br three-component reciprocal system and analysis of the Na,M‖F,Br (M = K,Rb, and Cs) series

Solid-phase reactions were studied by differential thermal analysis and X-ray powder diffraction in a sample whose composition corresponds to the complete conversion point K of the Na,Rb‖F,Br three-component reciprocal system. A stable diagonal and a metastable diagonal were studied, and the parameters of two ternary eutectics were determined.     

Aqueous sol–gel synthesis,thermoanalytical study and luminescent properties of M0.05Eu0.05Ca0.9MoO4 (M=Li,Na, K,Rb, Cs) nanocrystallites

Nano-sized M_0.05Eu_0.05Ca_0.9MoO₄ (M=Li, Na, K, Rb, Cs) ceramics have been successfully synthesized by an aqueous sol–gel synthesis method using a tartaric acid as a ligand. In order to reveal the influence of the peculiarities of the nature of dopants effect into the crystallization of CaMoO₄ double oxide, the thermal analysis of the as-prepared gels was performed. In addition, infrared spectroscopy was used in order to identify the functional groups from the characteristic stretching vibrations in the M–Eu–Ca–Mo–O tartrate gel precursors. Besides, to confirm the dynamics of growing crystallites in the final ceramics and to reveal the morphological changes on the surface, the x-ray diffraction and scanning electron microscopy were applied. Finally, photoluminescence measurements were used to estimate the optical properties of europium oxide as a dopant in the samples according to the nature of alkali metal. Therefore, according to the obtained results, it was estimated that luminescence intensity of Eu³⁺ ions is mainly affected by the chemical reaction, which takes place at about 973 K of temperature. This effect was partly confirmed from the results of the thermal decomposition of M–Eu–Ca–Mo–O tartrate gel precursors with an endothermic behaviour in the DSC curve, which indicates the crystallization mechanism of the CaMoO₄ double oxide.

     

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。     

Solubility of AIVUO6·nH2O (AI = H,Na, K,Rb, Cs,Tl) Uranovanadates

The solubility of uranovanadates of the series A^IVUO₆·nH₂O (A^I = H, Na, K, Rb, Cs, Tl) in water and aqueous solutions of acids under various conditions were determined. On this basis standard Gibbs functions of formation were calculated, which made it possible to consider the state of these compounds under conditions not covered by the experiment.     

Preparation and photoluminescent properties of Eu(III) containing M-layered silicates (M = Li,Na, K,Rb, Cs)

Eu(III) containing M-layered silicates (M = Li, Na, K, Rb, Cs) were prepared using the layered silicates, such as ilerite, magadiite, and kenyaite, as a host matrix and the luminescence properties were investigated. The results from the luminescence measurements indicated that the luminescence properties in the EuM-layered silicate system depended strongly on the types of host matrices and alkali cations. Among the EuM-layered silicates, EuM-ilerite exhibited the strongest luminescence intensity for all alkali cations, whereas EuM-kenyaite exhibited relatively weak luminescence intensity. The luminescence intensity was significantly increased by heat treatment at high temperature, mainly due to the phase change of host matrices and the presence of alkali cations in the host matrices. Particularly, the luminescence intensity of EuM-layered silicate calcined at 1,000 °C increased with the increase of the ion size of alkali cations.     

Anodic Dissolution of Aluminum in Liquid Electrolytes MF· 2AlEt3 (M = Na,K, Rb)

The kinetics of anodic dissolution of aluminum films electrodeposited on platinum via direct aluminum electrooxidation without preliminary discharge of electrolyte components is studied. The process probably involves adatoms and clusters Al* on the electrode surfaces, with limiting stage Al* – e (A1⁺)_ads.     

Optimization and Calculation of the EuCl<Subscript>3</Subscript>–MCl (M = Na,K, Rb,Cs) Phase Diagrams

By using the CALPHAD technique, an optimization of the binary EuCl₃–MCl (M = Na, K, Rb, Cs) systems has been carried out. To describe the Gibbs energies of liquid phases in these systems the new modified quasi-chemical model was used in the pair-approximation for short-range ordering. From the measured phase equilibrium data and the experimental thermo-chemical properties, the EuCl₃–MCl phase diagrams were optimized and calculated. A set of thermodynamic functions has been optimized based on an interactive computer-assisted analysis. The calculated phase diagrams and thermodynamic data are self-consistent.     

CH_2=CH(XM)(X=S,Se,Te;M=H,Li,Na,K,Rb,Cs,-)的从头算研究

应用相对论有效势在ＭＰ２水平上对ＣＨ２ＣＨ（ＸＭ）（Ｘ＝Ｓ，Ｓｅ，Ｔｅ；Ｍ＝Ｈ，Ｌｉ，Ｎａ，Ｋ，Ｒｂ，Ｃｓ，－）进行了从头计算研究．结果表明，所研究的化合物都有平面式和非平面桥式两种构型．分析了碱金属离子对两可亲核底物ＣＨ２ＣＨＸ－（Ｘ＝Ｓ，Ｓｅ，Ｔｅ）离域化的影响，并用自然布局分析方法（ＮＰＡ）研究了电荷分布的变化，得出了有价值的结论．     

Study of reactions of some halides, cyclopentadienyl dichlorides, and bis(cyclopentadienyl) chlorides of lanthanides withtrans-stilbene adducts with alkali metals [PhCHCHPh]·−M+ (M=Li, Na)

Reaction of Sml₂(THF)₂ with metallic lithium andtrans-stilbene in 1:2:2 ratio in DME gives the stilbene complex of divalent samarium (PhCHCHPh)Sm(DME)₂. This complex reacts with hydrogen in THF to give SmH₂(THF)₂ and 1,2-diphenylethane. The reaction with (Me₃Si)₂NH gives the amide [(Me₃Si)₂N]₂Sm(DME)₂ and the reaction with triphenylgermane yields Ph₃GeGePh₃. Reaction of CpLuCl₂(THF)₂ with 2 equivalents of [PhCHCHPh]·⁻Na⁺ in DME results in the dimerization of stilbene fragments to give anate-complex {Cp₂Lu[μ-CH (Ph)CH(Ph)CH(Ph)CH(Ph)]}Na(DME)₃. In the reaction of Cp₂GdCl with [PhCHCHPh]·⁻Na⁺, the known complex Cp₃Gd(THF) was isolated as the only lanthanidecontaining product. Published inIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1442–1446, August, 2000.     

XPS study of nanorods of doped vanadium oxide MxV2O5 · nH2O (M = Na, K, Rb, Cs)

Nanorods of vanadium oxide doped with alkali metal ions M _x V₂O₅ · nH₂O (M = Na, K, Rb, Cs, x = 0.31–0.44) have been obtained under hydrothermal conditions. The particles are 30–80 nm in diameter and a few micrometers in length. The chemical state of atoms and their concentration ratios have been studied by XPS. It has been shown that vanadium atoms are in two oxidation states V⁵⁺ and V⁴⁺ and the concentration of vanadium(IV) ions directly depends on the alkali metal. The X-ray photoelectron spectra of the valence bands of M _x V₂O₅ · nH₂O (M = Na, K, Rb, Cs) nanorods have been measured and interpreted.     

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.     

Enthalpies of Phase Transitions and Heat Capacity of TbCl3 and Compounds Formed in TbCl3–MCl Systems (M=K, Rb, Cs)

The molar enthalpies of the solid–solid and solid–liquid phase transitions were determined by differential scanning calorimetry for pure TbCl₃ and KTb₂Cl₇, RbTb₂Cl₇, CsTb₂Cl₇, K₃TbCl₆, Rb₃TbCl₆ and Cs₃TbCl₆ compounds. Both types of compounds, i.e. M₃TbCl₆ and MTb₂Cl₇ (M=K, Rb, Cs) melt congruently and show additionally a solid–solid phase transition with a corresponding enthalpy Δ_trs H ⁰ of 6.1, 7.6 and 7.0 kJ mol^–1 for potassium, rubidium and caesium M₃TbCl₆ compounds andΔ_trs H ⁰ of 17.1 (rubidium) and of 12.1 and 10.9 kJ mol^–1 (caesium) for MTb₂Cl₇ compounds, respectively. The enthalpies of fusion were measured for all the above compounds with the exception of Rb₃TbCl₆ and Cs₃TbCl₆. The heat capacities of the solid and liquid compounds have been determined by differential scanning calorimetry (DSC) in the temperature range 300–1100 K. The experimental heat capacity strongly increases in the vicinity of a phase transition, but varies smoothly in the temperature ranges excluding these transformations. C _p data were fitted by an equation, which provided a satisfactory representation up to the temperatures of C _p discontinuity. The measured heat capacities were checked for consistency by calculating the enthalpy of formation of the liquid phase, which had been previously measured. The results obtained agreed satisfactorily with these experimental data. This revised version was published online in August 2006 with corrections to the Cover Date.     

The structures of X2[(Mo6Cl8)Cl6]·nH2O,X=NH4, K,Rb, Cs

The title compounds were synthesized from MoCl₂ and the appropriate commercial chlorides and their structures were solved by a combination of single crystal X-ray diffraction analysis and theoretical methods. The NH₄, K and Rb compounds are essentially isostructural, and crystallize in space group Ia (No. 9) with the cell parameters (in Å) a=9.173(1), b=14.986(2), c=17.505(3), β=92.94(2)° (NH₄); a=9.140(4), b=14.852(5), c=17.445(11), β=93.48(6)° (K); a=9.215(1), b=14.941(3), c=17.532(2), β=92.70(1)° (Rb); while the Cs compound crystallizes in space group P2₁/n (No. 14) with the cell dimensions a=9.771(3), b=12.984(4), c=21.535(4), β=90.81(3)°.     

Opening the paddlewheel: unusual coordination of [Mo2] dumbbells in the chain structures of A[Mo2(CF3SO3)5]·2CF3SO3H (A = Na, Rb, Cs)

The reaction of Mo(II)acetate, concentrated triflic acid and the alkaline metal triflates A(CF(3)SO(3)) (A = Na, Rb, Cs) in sealed glass ampoules at 110 °C yielded red single crystals of A[Mo(2)(CF(3)SO(3))(5)]·2CF(3)SO(3)H (A = Na: triclinic, P-1, Z = 4, a = 13.714(1) ?, b = 14.339(1) ?, c = 21.340(2) ?, α = 81.78(1)°, β = 75.21(1)°, γ = 62.65(1)°; A = Rb/Cs: monoclinic, P2(1)/m, Z = 2, a = 11.561(1)/11.584(1) ?, b = 14.817(1)/14.9472(8) ?, c = 11.6208(1)/11.744(1) ?, β = 112.38(1)/113.48(1)°). The crystal structures contain dumbbell shaped [Mo(2)] moieties surrounded by three chelating and four monodentate triflate anions leading to an opening of the typical paddlewheel fragment at one of its edges. The monodentate triflate anions are connected to further [Mo(2)] dumbbells leading to infinite anionic chains according to (∞)(1)[Mo(2)(CF(3)SO(3))(3/1)(CF(3)SO(3))(4/2)](-). The charge balance is achieved by the alkaline metal ions that are additionally coordinated by triflic acid molecules. Theoretical investigations were preformed on the open paddlewheel fragment and are in good agreement with the experimental findings. According to DTA/TG measurements and the XRD investigations the decomposition of the compounds occurs in multiple steps and leads to MoO(2) and A(2)MoO(4).     

121,123Sb NQR study of solid phases formed in systems (MF)1−x −(M′F) x −SbF3−H2O (M, M′=Na, K, Rb, Cs, and NH4)

Crystalline substances formed in the (MF)_1−x −(M′F) _x −SbF₃−H₂O systems (M, M′=Na, K, Rb, Cs, and NH₄;x=0 to 1) were investigated by^121,123Sb NQR spectroscopy at 77 K. The formation of individual Sb^III complexes NaCs₃Sb₄F₁₆·H₂O and NaKSbF₅·1.5H₂O, and statistically disordered mixed crystals M_1−x −M′ _x −SbF₄ (M, M′=K, Rb, Cs, and NH₄) was established. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 109–112, January, 1999.     

Reactivity of metal-bound peroxides; alkali triperoxovanadate(V) trihydrates,A[V(O2)3]·3H2O (A = Na or K), as oxidants resembling alkali—H2O2 reagent for some organic substrates

The efficacy of the triperoxovanadium(V) complexes, A[V(O₂)₃]·3H₂O (A = Na or K), as potential oxidants with respect to certain organic substrates has been investigated. Aqueous solutions of the complexes are basic (pH ca. 11) in nature. The complexes efficiently oxidise an α,β-unsaturated ketone to the corresponding epoxide and benzonitrile to benzamide. Such reactions are usually accomplished using alkaline-H₂O₂ reagent. The complexes are also capable of bringing about Bayer-Villiger-type oxidation and oxidise benzil to benzoic acid. The peroxo-depleted vanadium product, isolated after the oxidations, has been identified as a diperoxovanadate(V) complex, [VO(O₂)₂(H₂O)]⁻.     

Isolation of the Metalated Ylides [Ph3P−C−CN]M (M=Li,Na, K): Influence of the Metal Ion on the Structure and Bonding Situation

The isolation and structural characterization of the cyanido-substituted metalated ylides [Ph₃P−C−CN]M ( 1-M ; M=Li, Na, K) are reported with lithium, sodium, and potassium as metal cations. In the solid-state, most different aggregates could be determined depending on the metal and additional Lewis bases. The crown-ether complexes of sodium ( 1-Na ) and potassium ( 1-K ) exhibited different structures, with sodium preferring coordination to the nitrogen end, whereas potassium binds in an unusual η²-coordination mode to the two central carbon atoms. The formation of the yldiide was accompanied by structural changes leading to shorter C−C and longer C−N bonds. This could be attributed to the delocalization of the free electron pairs at the carbon atom into the antibonding orbitals of the CN moiety, which was confirmed by IR spectroscopy and computational studies. Detailed density functional theory calculations show that the changes in the structure and the bonding situation were most pronounced in the lithium compounds due to the higher covalency.     

Structures of MAu16 (-) (M=Ag, Li, Na, and K): how far is the endohedral doping?

The structural and electronic properties of MAu16 (-) (M=Ag, Li, Na, and K) have been studied by the scalar relativistic all-electron density-functional calculations, in which particular attention is paid to the stability of the endohedral Au16 (-) cage doped by different dopant atoms. It is found that only the smaller atoms, such as Cu, Li, and Na, can be stably encapsulated in the Au16 (-) cage, while the addition of the larger Ag or K atom prefers to locate in the surface or outside of the cage, which is inconsistent with the previous hypothesis that the Au16 (-) cage could act as a container to hold an arbitrary heterometal atom. The stable endohedral Li@Au16 (-) and Na@Au16 (-) have a large energy gap between the highest occupied molecular orbital and the lowest unoccupied molecular orbital gap, indicating that they are chemically stable and may be used as potential building blocks for designing cluster-assembled materials.