Synthesis and an X-ray diffraction study of Rb<Subscript>2</Subscript>[(UO<Subscript>2</Subscript>)<Subscript>2</Subscript>(C<Subscript>2</Subscript>O<Subscript>4</Subscript>)<Subscript>3</Subscript>]

The synthesis and X-ray diffraction study of compound Rb₂[(UO₂)₂(C₂O₄)₃], which crystallizes in the monoclinic crystal system, are performed. The unit cell parameters are as follows: a = 7.9996(6) Å, b = 8.8259(8) Å, c = 11.3220(7) Å, β = 105.394(2)°, and V = 770.7(1) ų; space group P2₁/n, Z = 2, and R ₁ = 0.0271. [(UO₂)₂(C₂O₄)₃]^2? layers belonging to the AK _0.5 ⁰² T ¹¹ crystal chemical group of uranyl complexes (A = UO ₂ ²⁺ , K ⁰² = C₂O ₄ ^2? , and T ¹¹ = C₂O ₄ ^2? ) are uranium-containing structural units of the crystals. The layers are connected with outer-sphere rubidium cations by electrostatic interactions.     

Refinement of the crystal structure of rhombohedral KU<Subscript>2</Subscript>(PO<Subscript>4</Subscript>)<Subscript>3</Subscript> as a representative of orthophosphates with the NaZr<Subscript>2</Subscript>(PO<Subscript>4</Subscript>)<Subscript>3</Subscript> structure

The crystal structure of the high-temperature β modification of synthetic orthophosphate KU₂(PO₄)₃ was refined from powder X-ray diffraction data by the Rietveld method: sp. gr. \(R\bar 3c\), the unit-cell parameters a= 9.113(1) Å and c= 24.997(1) Å. The isotropic refinement converged to R _wp = 6.15, R _B = 2.14, R _F = 3.52, and S = 0.42. It was confirmed that β-KU₂(PO₄)₃ belongs to the structure type of sodium zirconium phosphate containing an actinide atom in a sixfold (octahedral) coordination formed by oxygen atoms, which is unusual for orthophosphates. The principal interatomic distances and bond angles in the structure are reported.     

Crystal structure of Rb<Subscript>2</Subscript>Mn<Subscript>3</Subscript>(H<Subscript>2</Subscript>O)<Subscript>2</Subscript>[P<Subscript>2</Subscript>O<Subscript>7</Subscript>]<Subscript>2</Subscript>, a new representative of the family of hydrated diphosphates

The crystal structure of Rb₂Mn₃(H₂O)₂[P₂O₇]₂, a new phase obtained in the form of single crystals under hydrothermal conditions in the MnCl₂–Rb₃PO₄–H₂O system, is determined by X-ray diffraction (Xcalibur-S-CCD diffractometer, R = 0.0270): a = 9.374(2), b = 8.367(2), c = 9.437(2) Å, ß = 99.12(2)°, space group P2₁/c, Z = 2, D_x = 3.27 g/cm³. A correlation between the unit-cell parameters and the size of cations forming the crystal structures of isostructural A₂M₃(H₂O)₂[P₂O₇]₂ diphosphates (A = K, NH₄, Rb, or Na; _M = Mn, Fe, Co, or Ni) is revealed. It is shown that, due to the topological similarity, the structures of diphosphates and orthophosphates of the farringtonite structural type can undergo mutual transformations.     

Crystal chemistry of KCuMn<Subscript>3</Subscript>(VO<Subscript>4</Subscript>)<Subscript>3</Subscript> in the context of detailed systematics of the alluaudite family

The crystal structure of new manganese potassium copper vanadate KCuMn₃(VO₄)₃, which was prepared by the hydrothermal synthesis in the K₂CO₃–CuO–MnCl₂–V₂O₅–H₂O system, was studied by X-ray diffraction (R = 0.0355): a = 12.396(1) Å, b = 12.944(1) Å, c = 6.9786(5) Å, β = 112.723(1)°, sp. gr. C2/c, Z = 4, ρ_calc = 3.938 g/cm³. A comparative analysis of the crystal-chemical features of the new representative of the alluaudite family and related structures of minerals and synthetic phosphates, arsenates, and vanadates of the general formula A(1)A(1)′A(1)″A(2)A(2)′M(1)M(2)₂(TO₄)₃ (where A are sites in the channels of the framework composed of MО₆ octahedra and TО₄ tetrahedra) was performed. A classification of these structures into subgroups according to the occupancy of A sites is suggested.     

Polymorphism of the borophosphate anion in K(Fe,Al)[BP<Subscript>2</Subscript>O<Subscript>8</Subscript>(OH)] and Rb(Al,Fe)[BP<Subscript>2</Subscript>O<Subscript>8</Subscript>(OH)] crystal structures

The crystal structure of two borophosphates, Rb(Al,Fe)[BP₂O₈(OH)] (a = 9.381(6), b = 8.398(5), c = 9.579(6) Å, β = 102.605(10)°, sp. gr. P2₁/c) and K(Fe,Al)[BP₂O₈(OH)] (a = 5.139(2), b = 8.065(4), c = 8.290(4)Å, α = 86.841(8)°, β = 80.346(8)°, γ = 86.622(8)°, sp. gr. P \(\bar 1\)), obtained by hydrothermal synthesis in the AlCl₃: FeCl₃: K₃PO₄(Rb₃PO₄): B₂O₃: H₂O system has been established using X-ray diffraction (Bruker Smart diffractometer, T = 100 K). Hydrogen atoms are located and their coordinates and thermal parameters are refined. It is shown that the polymorphism of the [BP₂O₈(OH)]^4? borophosphate anion has a morphotropic nature and is related to the substitutions both in the cationic part of the structure and in the octahedral position of the anionic mixed framework. The synthesis of new isotypic triclinic compounds under hydrothermal conditions is predicted.     

Crystal structure of the new radical cation salt (<Emphasis Type="Italic">DOET</Emphasis>)<Subscript>4</Subscript>[Fe(CN)<Subscript>5</Subscript>NO]<Subscript>1.25</Subscript>(C<Subscript>6</Subscript>H<Subscript>5</Subscript>Cl)<Subscript>0.75</Subscript>

A new radical cation salt based on 4,5-(1,4-dioxanediyl-2,3-dithio)-4′,5′-ethylenedithiotetrathiafulvalene (DOET) with the photochromic anion [Fe(CN)₅NO]^2?, namely, (DOET)₄[Fe(CN)₅ NO]_1.25(C₆H₅Cl)_0.75, is synthesized. Single crystals of this salt are studied using X-ray diffraction [a = 10.398(2) Å, b = 11.168(2) Å, c = 18.499(4) Å, α = 103.14(3)°, β = 92.80(3)°, γ = 106.02(3)°, V = 1996.3(7) ų, space group \(P\bar 1\), and Z = 1]. In the structure, radical cation layers alternate with anion layers along the c axis. The centrosymmetric dimers are formed by DOET radical cations in the donor layer with packing of the β type. Like the vast majority of DOET-based salts, the new salt possesses semiconductor properties.     

The Influence of Cation Substitution on the Kinetics of Phase Transitions in Crystals of (K,NH<Subscript>4</Subscript>)<Subscript>3</Subscript>H(SO<Subscript>4</Subscript>)<Subscript>2</Subscript> Solid Solutions

The structure of (K_0.967(NH₄)_0.033)₃H(SO₄)₂ crystals, belonging to the K₃H(SO₄)₂–(NH₄)₃H(SO₄)₂–H₂O salt system, has been investigated by X-ray structural analysis. The room-temperature characteristics of the atomic structure of these crystals are found to be as follows: sp. gr. C2/c, Z = 4, a = 14.7025(4) Å, b = 5.6859(2) Å, c = 9.7885(3) Å, and R/wR = 0.021/0.030%. The thermal and optical properties of (K,NH₄)₃H(SO₄)₂ and K₃H(SO₄)₂ single crystals have been investigated and compared in a temperature range of 295–500 K.     

Synthesis and structure of (Rb<Subscript>0.50</Subscript>Ba<Subscript>0.25</Subscript>)[UO<Subscript>2</Subscript>(CH<Subscript>3</Subscript>COO)<Subscript>3</Subscript>]

A new compound (Rb_0.50Ba_0.25)[UO₂(CH₃COO)₃] is synthesized and its crystal structure is studied by X-ray diffraction. The compound crystallizes in the form of yellow plates belonging to the cubic crystal system. The unit cell parameter a = 17.0367(1) Å, V = 4944.89(5) ų, space group I \(\bar 4\)3d, Z = 16, and R = 0.0182. The coordination polyhedron of the uranium atom is a hexagonal bipyramid with oxygen atoms of three acetate groups and the uranyl group in the vertices. The crystal chemical formula of the uranium-containing group is AB ₃ ⁰¹ (A = UO ₂ ²⁺ , B ⁰¹ = CH₃COO^?). The oxygen atoms of the acetate groups that enter the coordination polyhedron of uranium are bound to barium and rubidium atoms.     

Crystal structure of (Al,V)<Subscript>4</Subscript>(P<Subscript>4</Subscript>O<Subscript>12</Subscript>)<Subscript>3</Subscript>, archetype of double cubic ring tetraphosphate

The crystal structure of the (Al,V)₄(P₄O₁₂)₃ solid solution, obtained in the single-crystal form by hydrothermal synthesis in the Al(OH)₃-VO₂-NaCl-H₃PO₄-H₂O system, has been solved by X-ray diffraction analysis (Xcalibur-S-CCD diffractometer, R = 0.0257): a = 13.7477(2) Å, sp. gr. I \(\bar 4\)3d, Z = 4, and ρ_calcd = 2.736 g/cm³. It is shown that the crystal structure of the parent cubic Al₄(P₄O₁₂)₃ modification can formally be considered an archetype for the formation of double isosymmetric tetraphosphates on its basis.     

Synthesis and structure of new framework phosphates Li<Subscript>1/4</Subscript><Subscript>M</Subscript><Subscript>7/4</Subscript>(PO<Subscript>4</Subscript>)<Subscript>3</Subscript>(<Emphasis Type="Italic">M</Emphasis> = Nb,Ta)

New lithium-niobium and lithium-tantalum phosphates Li_1/4 M _7/4(PO₄)₃(M = Nb, Ta) are synthesized by the solid-phase method. The compounds prepared are characterized using electron microprobe analysis, X-ray powder diffraction, and IR spectroscopy. The crystal structure of the Li_1/4Ta_7/4(PO₄)₃ phosphate is determined from the X-ray powder diffraction data (the Rietveld method) and belongs to the framework type. The framework of the structure consists of TaO₆ and LiO₆ vertex-shared octahedra and PO₄ tetrahedra. The isostructural phosphates Li_1/4 M _7/4(PO₄)₃ crystallize in the trigonal crystal system (space group R \(\bar 3\) c, Z = 6) and belong to the NaZr₂(PO₄)₃ structure type.     

Molecular structure of [(C<Subscript>5</Subscript>H<Subscript>5</Subscript>)<Subscript>2</Subscript>(C<Subscript>5</Subscript>H<Subscript>4</Subscript>CH<Subscript>3</Subscript>)(C<Subscript>4</Subscript>H<Subscript>8</Subscript>O)Sm]

The mixed tris-cyclopentadienyl tetrahydrofuranato samarium complex bis-(cyclopentadienyl) methylcyclopentadienyl tetrahydrofuranato samarium (I) was synthesized by reaction of (C₅H₅)₂SmCl with methyl cyclopentadienyl sodium in THF. [(C₅H₅)₂(C₅H₄CH₃)(C₄H₈O)Sm] (I) was characterized by elemental analyses—IR spectra and MS spectra. The structure of [(C₅H₅)₂(C₅H₄CH₃)(C₄H₈O)Sm] (I), which has two slightly different independent molecules per asymmetric unit, has been elucidated through complete X-ray analysis. The crystals are monoclinic, with a = 12.791(3) Å, b = 10.467(2) Å, c = 26.108(5) Å, β = 98.22(2)°, and space group Cc, R = 0.0381 for 2103 observed-reflection with I ≥ 3σ(I).     

Growth and crystal structure of binary molybdate CsFe(MoO<Subscript>4</Subscript>)<Subscript>2</Subscript>

CsFe(MoO₄)₂ single crystals have been grown by solution-melt crystallization with a charge-to-solvent ratio of 1: 3 (with Cs₂Mo₃O₁₀ used as a solvent). The crystal structure of this compound has been refined by X-ray diffraction (X8 APEX automatic diffractometer, MoK _α radiation, 356 F(hkl), R = 0.0178). The trigonal unit cell has the following parameters: a = b = 5.6051(2) Å, c = 8.0118(4) Å, V = 217.985(15) ų, Z = 1, ρ_calc = 3.875 g/cm³, and sp. gr. P \(\bar 3\) m1. The structure is composed of alternating layers of FeO₆ octahedra (with MoO₄ tetrahedra attached by sharing vertices) and CsO₁₂ icosahedra.     

Na(H<Subscript>2</Subscript>O)[Mn(H<Subscript>2</Subscript>O)<Subscript>2</Subscript>(BP<Subscript>2</Subscript>O<Subscript>8</Subscript>)]: Crystal structure refinement

The crystal structure of synthetic manganese sodium borophosphate hydrate Na(H₂O)[Mn(H₂O)₂(BP₂O₈)] was refined based on X-ray diffraction data. The compound was prepared by soft hydrothermal synthesis in the MnCl₂-Na₃PO₄-B₂O₃-H₂O system. The unit-cell parameters are a= 9.602(1) Å, c= 16.037(3) Å, sp. gr. P6₅22, Z= 6, D _x = 2.57 g/cm³. The water molecules were found to be statistically distributed in the channels of the mixed anionic paraframework consisting of (BO₄) and (PO₄) tetrahedra and [MnO₄(H₂O)₂] octahedra. The hydrogen atoms of the water molecules coordinated to the Mn²⁺ cations were located and their positional and thermal parameters were refined. The crystal-chemical features of borophosphates of the general formula A _x M(H₂O)₂(BP₂O₈)(H₂O) are considered.     

Synthesis and crystal chemical characteristics of the structure of <Emphasis Type="Italic">M</Emphasis><Subscript>0.5</Subscript>Zr<Subscript>2</Subscript>(PO<Subscript>4</Subscript>)<Subscript>3</Subscript> phosphates

Double phosphates of zirconium and metals with an oxidation degree of +2 of the composition M_0.5Zr₂(PO₄)₃ (M = Mg, Ca, Mn, Co, Ni, Cu, Zn, Sr, Cd, and Ba) are synthesized and characterized by X-ray diffraction methods and IR spectroscopy. The crystal structures of all the compounds are based on three-dimensional frameworks of corner-sharing PO₄-tetrahedra and ZrO₆-octahedra. Phosphates with large Cd²⁺, Ca²⁺, Sr²⁺, and Ba²⁺ cations octahedrally coordinated with oxygen atoms form rhombohedral structures (space group R3), whereas phosphates with small tetrahedrally coordinated Mg²⁺, Ni²⁺, Cu²⁺, Co²⁺, Zn ²⁺, and Mn²⁺-cations are monoclinic (space group P2₁/n). The effect of various structure-forming factors on the M_0.5Zr₂(PO₄)₃ compounds with a common structural motif but different symmetries are discussed.     

Structure and some properties of [UO<Subscript>2</Subscript>(C<Subscript>5</Subscript>H<Subscript>12</Subscript>N<Subscript>2</Subscript>O)<Subscript>5</Subscript>](ClO<Subscript>4</Subscript>)<Subscript>2</Subscript>

Compound [UO₂(C₅H₁₂N₂O)₅](ClO₄)₂ is synthesized and characterized by thermogravimetry, IR spectroscopy, and X-ray diffraction. The compound crystallizes in the monoclinic crystal system; a = 15.2985(9) Å, b = 26.9676(15) Å, c = 20.6962(11) Å, β = 100.697(1)°, space group P2₁/c, Z = 8, and R = 0.0445. Discrete [UO₂(C₅H₁₂N₂O)₅]²⁺ groups belonging to the AM ₅ ¹ crystal chemical group of uranyl complexes (A = UO ₂ ²⁺ and M ¹=C₅H₁₂N₂O) are uranium-containing structural units of the crystals.     

Ti/Zr isomorphism in wadeite: The crystal structure of the titanium-dominant K<Subscript>2</Subscript>(Ti<Subscript>0.55</Subscript>Zr<Subscript>0.45</Subscript>)Si<Subscript>3</Subscript>O<Subscript>9</Subscript> member of the series

The crystal structure of the titanium-rich mineral wadeite K₂(Ti_0.55Zr_0.45)Si₃O₉ from rischorrites of the Khibiny Alkaline Massif (Kola Peninsula, Russia) is studied by X-ray diffraction (XCalibur-S diffractometer, R = 0.0459): a = 6.8611(6) Å and c = 10.0611(9) Å; space group P6₃/m, Z = 6, D _x = 3.03 g/cm³. It is shown that the unit-cell parameters and volume of the mineral of mixed (Ti/Zr) composition are naturally intermediate between those of the terminal members of the isomorphous wadeite-based K₂ZrSi₃O₉–K₂(Ti_0.55Zr_0.45)Si₃O₉–K₂TiSi₃O₉ series. The expected correlation is due to the ionic radii of Zr⁴⁺ and Ti⁴⁺ which determine the lengths of Zr/Ti–O bonds in octahedra. The data of field observations and microscopic studies show that the Ti-dominant wadeite is formed on the basis of primary zirconium mineral in the course of a late imposed process under unique geochemical conditions.     

Proton-Conducting Composites Based on the Cs<Subscript>4</Subscript>(HSO<Subscript>4</Subscript>)<Subscript>3</Subscript>(H<Subscript>2</Subscript>PO<Subscript>4</Subscript>) Compound

Proton-conducting composites xCs₄(HSO₄)₃(H₂PO₄) + (1–x)AlPO₄ in the composition range x = 0.9–0.5 have been obtained. Their transport properties are studied by impedance spectroscopy. The dependences of the phase composition of the materials on the component ratio are investigated by X-ray diffraction analysis. The spatial phase distribution in the materials is analyzed using scanning electron microscopy.     

X-Ray Crystal Structure of <Emphasis Type="Italic">trans</Emphasis>-PdCl<Subscript>2</Subscript>(PPh<Subscript>2</Subscript>C<Subscript>12</Subscript>H<Subscript>7</Subscript>S<Subscript>3</Subscript>)<Subscript>2</Subscript>, a New Morphology

Herein we report the crystal structure of trans-PdCl₂(PPh₂C₁₂H₇S₃)₂, 1, in a different morphology than has previously been reported [Stott et al. (Dalton Trans (4):652–653, 2005]. This structure crystallizes in a P-1 space group with a = 9.4249(19) Å, b = 11.540(2) Å, c = 12.559(3) Å, α = 79.07(3)°, β = 78.04(3)°, γ = 69.44(3)°, Z = 1. The earlier structure possessed a P2₁/n space group. Additionally the terthienyl moieties of 1 demonstrate the anti orientation exclusively while the P2₁/n space group structure has some syn and even syn/anti mixed geometries included.     

Crystal structure and microtwinning of monoclinic La<Subscript>3</Subscript>SbZn<Subscript>3</Subscript>Ge<Subscript>2</Subscript>O<Subscript>14</Subscript> crystals of the langasite family

The crystal structure of monoclinic La₃SbZn₃Ge₂O₁₄ crystals from the langasite family is determined by X-ray diffraction analysis [a = 5.202(1) Å, b = 8.312(1) Å, c = 14.394(2) Å, β = 90.02(1)°, sp. gr. A2, Z = 2, and R/R _w = (5.2/4.6)%]. The structure is a derivative of the Ca₃Ga₂Ge₄O₁₄-type structure (a = 8.069 Å, c = 4.967 Å, sp. gr. P321, Z = 1). The crystal studied is a polysynthetic twin with the twin index n = 2, whose monoclinic components are related by pseudomerohedry by a threefold rotation axis of the supergroup P321.     

X-ray and neutron diffraction studies of Rb<Subscript>4</Subscript>LiH<Subscript>3</Subscript>(XO<Subscript>4</Subscript>)<Subscript>4</Subscript><Emphasis Type="Italic">(X</Emphasis> = S,Se) single crystals

Rb₄LiH₃(SeO₄)₄ single crystals (1) are studied by the X-ray diffraction method at 180 K and Rb₄LiH₃(SO₄)₄ single crystals (2a–2c) are studied by the neutron diffraction method at 298 K (2a and (2b) and 480 K (2c). It is established that isostructural single crystals 1 and 2 (sp. gr. P4₁) have analogous systems of hydrogen bonds: chains of four XO₄ tetrahedra linked by three H bonds with the central bond (2.49 Å) being somewhat shorter than the terminal ones (2.52–2.54 Å). In the high-temperature 2c phase, the amplitudes of atomic thermal vibrations and the degree of proton disorder in the central hydrogen bond have somewhat elevated values.