Synthesis and crystal structure of Rb<Subscript>2</Subscript>[(UO<Subscript>2</Subscript>)<Subscript>2</Subscript>(C<Subscript>2</Subscript>O<Subscript>4</Subscript>)<Subscript>2</Subscript>(SeO<Subscript>4</Subscript>)] · 1.33H<Subscript>2</Subscript>O

The single crystals of Rb₂[(UO₂)₂(C₂O₄)₂(SeO₄)] · 1.33H₂O were synthesized and studied by X-ray diffraction. The crystals are monoclinic, space group P2₁/m, Z= 2, the unit cell parameters: a = 5.6537(8), b = 18.736(3), c = 9.4535(15) Å, β = 98.440(5)°, V = 990.6(3) ų, R ₁ = 0.0506. The main structural units of the crystal are infinite layers of [(UO₂)₂(C₂O₄)₂(SeO₄)]^2?, corresponding to the crystal chemical group A₂K ₂ ⁰² B² (A = UO ₂ ²⁺ , K⁰² = C₂O ₄ ^2? , B² = SeO ₄ ^2? ) of uranyl complexes. The uranium-containing layers are united into a three-dimensional framework through the electrostatic interactions with the outer-sphere rubidium ions and the hydrogen bonding system involving the outer-sphere water molecules.     

Crystal structure of Na<Subscript>3</Subscript>(NH<Subscript>4</Subscript>)<Subscript>2</Subscript>[Ir(SO<Subscript>3</Subscript>)<Subscript>2</Subscript>Cl<Subscript>4</Subscript>]·4H<Subscript>2</Subscript>O

The complex Na₃(NH₄)₂[Ir(SO₃)₂Cl₄]·4H₂O was examined with single crystal X-ray diffraction and IR spectroscopy. Crystal data: a = 7.3144(4) Å, b = 10.0698(5) Å, c = 12.3748(6) Å, β = 106.203(1)°, V = 875.26(8) ų, space group P2₁/c, Z = 2, d _calc = 2.547 g/cm³. In the complex anion two trans SO ₃ ^2? groups are coordinated to iridium through the S atom. The splitting of O-H bending vibrations of crystallization water molecules and N-H ones of the ammonium cation is considered in the context of different types of interactions with the closest neighbors in the structure.     

CsBr—Cs<Subscript>2</Subscript>ZnBr<Subscript>4</Subscript>—Cs<Subscript>2</Subscript>CdBr<Subscript>4</Subscript>—Cs<Subscript>2</Subscript>HgBr<Subscript>4</Subscript> Four-component system

Component interactions in the CsBr—Cs₂ZnBr₄—Cs₂CdBr₄—Cs₂HgBr₄ system were studied using differential thermal analysis (DTA) and powder X-ra y diffraction. The system is characterized by a continuous solid solution series. New compounds have not been found.     

Ternary Systems LiBr–LiVO<Subscript>3</Subscript>–Li<Subscript>2</Subscript>CrO<Subscript>4</Subscript> and KBr–KVO<Subscript>3</Subscript>–K<Subscript>2</Subscript>CrO<Subscript>4</Subscript>

The binary system KVO₃–K₂CrO₄ and two ternary systems, LiBr–LiVO₃–Li₂CrO₄ and KBr–KVO₃–K₂CrO₄, were studied. In the ternary systems, the compositions and melting points of eutectic alloys were determined by differential thermal analysis: (49.0 mol % LiBr, 5.0 mol % LiVO₃, 46.0 mol % Li₂CrO₄, 400°C) and (17.0 mol % KBr, 78.0 mol % KVO₃, 5.0 mol % K₂CrO₄, 458°C), respectively.     

Crystal structure of Na<Subscript>4</Subscript>[Na<Subscript>2</Subscript>Cr<Subscript>2</Subscript>(C<Subscript>2</Subscript>O<Subscript>4</Subscript>)<Subscript>6</Subscript>] · 10H<Subscript>2</Subscript>O

Single crystals of the Na₄[Na₂Cr₂(C₂O₄)₆] · 10H₂O complex were synthesized for the first time. The structure of the complex was determined by X-ray diffraction analysis. The compound crystallizes in the monoclinic crystal system with the unit cell parameters a = 17.290(4) Å, b = 12.521(3) Å, c = 15.149(3) Å, β = 100.45(3)°, Z = 4, space group Cc. Anionic layers [NaCr(C₂O₄)₃] _2n ^4n? can be distinguished in the crystal structure of the complex. The Na⁺ cations and water molecules, involved in the formation of a hydrogen bond network, are located between the anionic layers.     

Multicomponent systems LiCl–LiBr–Li<Subscript>2</Subscript>SO<Subscript>4</Subscript> and LiCl–LiBr–Li<Subscript>2</Subscript>SO<Subscript>4</Subscript>–Li<Subscript>2</Subscript>MoO<Subscript>4</Subscript>

Phase equilibria in the LiCl–LiBr–Li₂SO₄ ternary system and the LiCl–LiBr–Li₂SO₄–Li₂MoO₄ quaternary system were studied by differential thermal analysis. The compositions and temperatures of minima in the ternary and quaternary systems were determined to be (31.2 mol % LiCl, 46.8 mol % LiBr, 22.0 mol % Li₂SO₄, 460°C) and (25.2 mol % LiCl, 30.2 mol % LiBr, 14.6 mol % Li₂SO₄, 30.0 mol % Li₂MoO₄, 411°C), respectively.     

Phase formation in the system Li<Subscript>2</Subscript>MoO<Subscript>4</Subscript>–MgMoO<Subscript>4</Subscript>–Sc<Subscript>2</Subscript>(MoO<Subscript>4</Subscript>)<Subscript>3</Subscript>

Phase formation in the system Li₂MoO₄–MgMoO₄–Sc₂(MoO₄)₃ was studied by X-ray powder diffraction analysis and differential thermal analysis. Ternary molybdate LiMgSc(MoO₄)₃ was synthesized, which crystallizes in the triclinic system (space group P\(\bar 1\)). In the Li₂Mg₂(MoO₄)₃–Li₃Sc(MoO₄)₃ section, a continuous solid solution in the rhombic system was found to form (space group Pnma).     

Crystal structure and thermal properties of [Au(en)<Subscript>2</Subscript>]<Subscript>2</Subscript>[Cu(C<Subscript>2</Subscript>O<Subscript>4</Subscript>)<Subscript>2</Subscript>]<Subscript>3</Subscript>·8H<Subscript>2</Subscript>O

The crystal structure of a double complex salt of the composition [Au(en)₂]₂[Cu(C₂O₄)₂]₃·8H₂O (en = ethylenediamine) at 150 K is determined by single crystal X-ray diffraction. The crystal data for C₂₀H₄₈Au₂Cu₃N₈O₃₂ are: a = 9.1761(3) Å, b = 16.9749(6) Å, c = 13.4475(5) Å, β = 104.333(1)°, V = 2029.43(12) ų, P2₁/c space group, Z = 2, d _x = 2.450 g/cm³. It is demonstrated that the thermal decomposition of the double complex salt in a helium or hydrogen atmosphere affords the solid solution Au_0.4Cu_0.6.     

Synthesis,Structure and Solid-Phase Transformations of Fe Nitrosyl Complex Na<Subscript>2</Subscript>[Fe<Subscript>2</Subscript>(S<Subscript>2</Subscript>O<Subscript>3</Subscript>)<Subscript>2</Subscript>(NO)<Subscript>4</Subscript>] · 4H<Subscript>2</Subscript>O

Binuclear iron nitrosyl complex Na₂[Fe₂(S₂O₃)₂(NO)₄] · 4H₂O (I) was synthesized by the reaction of iron(II) sulfate with sodium thiosulfate in the flow of NO gas. According to X-ray diffraction data, the [Fe₂(S₂O₃)₂(NO)₄]^2– anion has binuclear centrosymmetric structure with Fe atoms bonded by the µ-S atoms of thiosulfate groups. The isomeric shift for complex I =0.168(1) mm/s and quadrupole splitting E _Q =1.288 mm/s at T=80 K. When heated, complex I transforms to Na₂[Fe₂(S₂O₃)₂(NO)₄] (II), whose unit cell parameters found by X-ray diffraction method differ from those of complex I. The process of transformation of I to II was studied by calorimetric method. Complex I transforms to complex II without chemical decomposition, which was confirmed by IR and mass spectroscopy data.__________Translated from Koordinatsionnaya Khimiya, Vol. 31, No. 5, 2005, pp. 323–328.Original Russian Text Copyright © 2005 by Sanina, Aldoshin, Rudneva, Golovina, Shilov, Shulga, Martynenko, Ovanesyan.     

Crystal structure of Ba<Subscript>3</Subscript>[UO<Subscript>2</Subscript>(C<Subscript>2</Subscript>O<Subscript>4</Subscript>)<Subscript>2</Subscript>(NCS)]<Subscript>2</Subscript> · 9H<Subscript>2</Subscript>O

Single crystals of Ba₃[UO₂(C₂O₄)₂(NCS)]₂ · 9H₂O are synthesized and studied by X-ray diffraction. The crystals are orthorhombic, space group Fddd, Z = 16, and the unit cell parameters are a = 16.253(3) Å, b = 22.245(3) Å, c = 39.031(6) Å. The main crystal structural units are mononuclear complex groups [UO₂(C₂O₄)₂NCS]^3? of the crystal-chemical family (AB ₂ ⁰¹ M¹ (A = UO ₂ ²⁺ , B⁰¹ = C₂O ₄ ^2? , M¹ = NCS^?) of the uranyl complexes linked into a three-dimensional framework by electrostatic interactions and hydrogen bonds involving oxalate ions and water molecules.     

Crystal structure of Cs[(UO<Subscript>2</Subscript>)<Subscript>2</Subscript>(C<Subscript>2</Subscript>O<Subscript>4</Subscript>)<Subscript>2</Subscript>(OH)] · H<Subscript>2</Subscript>O

Single crystals of Cs[(UO₂)₂(C₂O₄)₂(OH)] · H₂O were synthesized and structurally studied using X-ray diffraction. The compound crystallizes in monoclinic space group P2₁/m, Z = 2, with the unit cell parameters a = 5.5032(4) Å, b = 13.5577(8) Å, c = 9.5859(8) Å, β = 97.012(3)°, V = 709.86(9) ų, R = 0.0444. The main building units of crystals are [(UO₂)₂(C₂O₄)₂(OH)]^? layers of the A₂K ₂ ⁰² M² (A = UO ₂ ²⁺ , K⁰² = C₂O ₄ ^2? , and M² = OH^?) crystal-chemical family. Uranium-containing layers are linked into a three-dimensional framework via electrostatic interactions with outer-sphere cations and hydrogen bonds with water molecules.     

Synthesis and Structure of [Co(NH<Subscript>3</Subscript>)<Subscript>6</Subscript>]<Subscript>2</Subscript>[W<Subscript>4</Subscript>Se<Subscript>4</Subscript>(CN)<Subscript>12</Subscript>]·8.5H<Subscript>2</Subscript>O

The compound [Co(NH₃)₆]₂[W₄Se₄(CN)₁₂]·8.5H₂O was obtained by evaporating an aqueous ammonia solution of K₆[W₄Se₄(CN)₁₂]·6H₂O and CoCl₂·6H₂O complexes. The starting Co(II) of CoCl₂·6H₂O transforms into [Co(NH₃)₆]³⁺ when exposed to air in a water-ammonia medium. Crystal data: triclinic crystal system, a = 10.7750(8) Å, b = 12.2843(9) Å, c = 19.6539(14) Å; α = 90.213(2)°, β = 99.910(2)°, γ = 114.737(1)°, V = 2319.1(3) ų, space group , Z = 2, D _x = 2.633 g/cm³.Original Russian Text Copyright © 2004 by I. V. Kalinina, Z. A. Starikova, F. M. Dolgushin, D. G. Samsonenko, and V. P. Fedin__________Translated from Zhurnal Strukturnoi Khimii, Vol. 45, No. 5, pp. 905–908, September–October, 2004.     

Synthesis and study of uranyl arsenate (UO<Subscript>2</Subscript>)<Subscript>3</Subscript>(AsO<Subscript>4</Subscript>)<Subscript>2</Subscript> · 12H<Subscript>2</Subscript>O

A method for producing synthetic troegerite of composition(UO₂)₃(AsO₄)₂ · 12H₂. Owas developed. X-ray diffraction, IR spectrometry, X-ray fluorescence analysis, and scanning calorimetry were used to study its dehydration and thermal decomposition, to solve the structgure, and to determine X-ray diffraction and IR spectroscopic characteristics.     

Synthesis and structure of the [Co(NioxH)<Subscript>2</Subscript>(Thio)<Subscript>2</Subscript>]<Subscript>2</Subscript>SO<Subscript>4</Subscript>·2H<Subscript>2</Subscript>O complex compound

A new Co(III) complex of 1,2-cyclohexanedionedioxime and thiocarbamide with an SO ₄ ^2? anion and solvation water molecules in the outer sphere has been synthesized and its structure has been defined. Orthorhombic crystals, a = 11.659(2) Å, b = 26.448(5) Å, c = 30.142(6) Å, V = 9295(3) Å ³, Z = 8, d_calc = 1.599 g/cm³, space group Pbca; final R index is 0.0578 for 8221 reflections with I > 2σ(I). In the octahedral Co(III) complex, two 1,2-cyclohexanedionedioxime residues lie in the equatorial plane, while two thiocarbamide molecules are in the axial plane. Intramolecular bonds: N-H…O and O-H…O type hydrogen bonds and π-π interactions that stabilize the complex cations. In crystal, the components are linked by N-H…O and O-H…O hydrogen bonds into a 3D framework.     

Na<Subscript>2</Subscript>MoO<Subscript>4</Subscript>-K<Subscript>2</Subscript>MoO<Subscript>4</Subscript>-H<Subscript>2</Subscript>O system at 25°C

Phase formation in the Na₂MoO₄-K₂MoO₄-H₂O system was studied at 25°C. Two incongruently saturating complex phases are formed in this system: Na₃K(MoO₄)₂ · 9H₂O and NaK₃(MoO₄)₂. The densities, refractive indices, and dynamic viscosities of saturated solutions of the system were determined; molar volume and ionic strength isotherms were calculated. A correlation relation was found between solubility and solution properties in the system. The indicated double salts were recovered and characterized using chemical analysis, powder X-ray diffraction, complex thermal analysis, and IR spectroscopy.     

Dissociation enthalpies and phase equilibrium for TBAB semi-clathrate hydrates of N<Subscript>2</Subscript>, CO<Subscript>2</Subscript>, N<Subscript>2</Subscript> + CO<Subscript>2</Subscript> and CH<Subscript>4</Subscript> + CO<Subscript>2</Subscript>

Tetra-n-butyl ammonium bromide (TBAB) semi-clathrate (sc) hydrates of gas are of prime importance in the secondary refrigeration domain and in the separation of gas molecules by molecular size. However, there is a scarcity of dissociation enthalpies under pressure of pure gases and gases mixtures for such systems. In addition, the phase equilibrium of TBAB sc hydrates of several pure gases is not well defined yet as a function of the TBAB concentration and as a function of the pressure. In this paper, dissociation enthalpies and the phase equilibrium of TBAB sc hydrates of gas have been investigated by differential scanning calorimetry (DSC) under pressure. Pure gases such as N₂ and CO₂ and gases mixtures such as N₂ +  CO₂ and CH₄ +  CO₂ were studied. To our knowledge, we present the first phase diagram of TBAB sc hydrates of N₂ for different pressures of gas in the TBAB concentration range from 0.170 to 0.350 wt. Enthalpies of dissociation of TBAB sc hydrates of pure gases and gases mixtures were determined as a function of the presssure for a compound with a congruent melting point whose hydration number corresponds to 26.     

Neutron diffraction study of Rb<Subscript>2</Subscript>UO<Subscript>2</Subscript>(SeO<Subscript>4</Subscript>)<Subscript>2</Subscript> · 2D<Subscript>2</Subscript>O

A powder of deuterated rubidium diselenatouranylate dihydrate Rb₂UO₂(SeO₄)₂ · 2D₂O has been studied by neutron diffraction. The compound is orthorhombic, space group Pna2₁, with the following unit cell parameters: a = 13.654(2) Å, b = 11.863(2) Å, c = 7.625(1) Å, Z = 4, R _F = 3.77, R _I = 6.12, and χ² = 2.21. Basic structure units are [UO₂(SeO₄)₂ · D₂O]^2? layers belonging to the AB ₂ ² M¹ crystal-chemical group (A = UO ₂ ²⁺ , B² = SeO ₄ ^2? , M¹ = D₂O) of uranyl complexes. The hydrogen atoms if the water molecules involved in the layer form intralayer hydrogen bonds with the terminal oxygen atoms of selenate ions. The outer-sphere water molecules are coordinated to the rubidium ions and are involved in hydrogen bonding with oxygen atoms of neighboring [UO₂(SeO₄)₂ · D₂O]^2? layers.     

Structure and thermal decomposition of Cs<Subscript>2</Subscript>HPO<Subscript>4</Subscript> · 2H<Subscript>2</Subscript>O

The thermal transformations of disubstituted cesium orthophosphate crystal hydrate under heating in air up to 400°C have been studied. The dehydration process occurs in two stages with the loss of 0.6 water molecules at 60?100°C and 1.4 water molecules at 100?160°C. Anhydrous Cs₂HPO₄ is stable up to 300°C and is completely converted into cesium pyrophosphate Cs₄P₂O₇ at 330°C. The structure of Cs₂HPO₄ · 2H₂O has been determined. The compound crystallizes in monoclinic space group P2₁/c and has the unit cell parameters a = 7.4761(5) Å, b = 14.2125(8) Å, c = 7.9603(6) Å, β = 116.914(5)°, V = 754.20(9) ų, and Z = 4 at?123°C. An earlier unknown polymorph of Cs₄P₂O₇ has been found. According to X-ray powder diffraction data, hexagonal space group Р6₃ has been proposed for the formed pyrophosphate.     

Thermogravimetric analysis of wheatleyite Na<Subscript>2</Subscript>Cu<Superscript>2+</Superscript>(C<Subscript>2</Subscript>O<Subscript>4</Subscript>)<Subscript>2</Subscript>·2H<Subscript>2</Subscript>O

Evidence for the existence of primitive life forms such as lichens and fungi can be based upon the formation of oxalates. These oxalates form as a film like deposit on rocks and other host matrices. The anhydrous oxalate mineral moolooite CuC₂O₄ as the natural copper(II) oxalate mineral is a classic example. Another example of a natural oxalate is the mineral wheatleyite Na₂Cu²⁺(C₂O₄)₂·2H₂O. High resolution thermogravimetry coupled to evolved gas mass spectrometry shows decomposition of wheatleyite at 255°C. Two higher temperature mass losses are observed at 324 and 349°C. Higher temperature mass losses are observed at 819, 833 and 857°C. These mass losses as confirmed by mass spectrometry are attributed to the decomposition of tennerite CuO. In comparison the thermal decomposition of moolooite takes place at 260°C. Evolved gas mass spectrometry for moolooite shows the gas lost at this temperature is carbon dioxide. No water evolution was observed, thus indicating the moolooite is the anhydrous copper(II) oxalate as compared to the synthetic compound which is the dihydrate.