Synthesis and structure of a terephthalato-bridged nickel complex [Ni(tpt)(imi)<Subscript>3</Subscript>(H<Subscript>2</Subscript>O)]<Emphasis Type="Italic">n</Emphasis>

At room temperature, a new coordination polymer [Ni(tpt)(imi)₃(H₂O)]n was synthesized by the reaction of NiCl₂?6H₂O, terephthalic acid, and imidazole in aqueous solution. The structure was determined by X-ray crystallography. It crystallizes in monoclinicP2₁/n space group with the crystal cell parameters ofa = 9.8626(4) Å,b = 15.2498(3) Å, andc = 12.7681(3)Å, β = 90.309(2)^°,V = 1920.33(10) ų, andZ = 4. The crystal X-ray analysis shows that each nickel atom is coordinated by three imidazole ligands, two terephthalate ions, and one water molecule. Each terephthalate ion bridges two nickel atoms to form a zigzag chain. The chains are further linked together via hydrogen bonds to a three-dimensional network.     

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.     

Synthesis and crystal structure of the [Co<Subscript>2</Subscript>(Nicotinamide)<Subscript>4</Subscript>(C<Subscript>4</Subscript>H<Subscript>9</Subscript>COO)<Subscript>4</Subscript>(H<Subscript>2</Subscript>O)] complex

The [Co₂ L ₄(C₄H₉COO)₄(H₂O)] coordination compound of cobalt(II) valerate with nicotinamide (L) is synthesized and studied by IR spectroscopy. The crystal structure of the synthesized compound is determined. The crystals are triclinic, and the unit cell parameters are as follows: a = 10.2759(10) Å, b = 16.3858(10) Å, c = 16.4262(10) Å, α = 100.538(10)°, β = 101.199(10)°, γ = 90.813 (10)°, Z = 2, and space group P \(\bar 1\). The structural units of the crystal are dimeric molecular complexes in which pairs of cobalt atoms are linked by triple bridges formed by oxygen atoms of two bidentately coordinated valerate anions and a water molecule. The octahedral coordination of each cobalt atom is complemented by the pyridine nitrogen atoms of two nicotinamide ligands and the oxygen atom of the monodentate valerate group. The hydrocarbon chains of the valerate anions are disordered over two or three positions each.     

Crystal structure refinement of Sr<Subscript>3</Subscript>TaGa<Subscript>3</Subscript>Si<Subscript>2</Subscript>O<Subscript>14</Subscript>

An accurate X-ray diffraction study of Sr₃TaGa₃Si₂O₁₄ (STGS) crystal (a = 8.3023(10) Å, c = 5.0853(2) Å, sp. gr. P321, Z = 1, R/wR = 0.59/0.52%, 4004 independent reflections) is performed. The use of two independent data sets obtained on diffractometers with point and 2D detectors made it possible to determine the model structure characterized by the best reproducibility of parameters. The ordered distribution of atoms over crystallographic positions and the anharmonic character of displacements of all cations and one oxygen atom are established.     

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.     

Crystal structure of Ga<Subscript>0.5</Subscript>In<Subscript>1.5</Subscript>Se<Subscript>3</Subscript> solid solution

A solid solution of the GaIn₃Se₆ (2Ga_0.5In_1.5Se₃) composition with a hexagonal lattice (a = 7.051(3) Å, c = 19.148(2) Å, sp. gr. P6₁, z = 6, V = 824.4332(4) ų, ρ = 5.379(2) g/cm³) has been synthesized as a result of alloying Ga, In, and Se elements with a metal ratio of 1: 3. It was established that six out of nine In atoms in the lattice are located in a trigonal bipyramid, while the other three In atoms and three Ga atoms have a tetrahedral coordination.     

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.     

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.     

Accurate Refinement of the Crystal Structure of Ba<Subscript>3</Subscript>TaGa<Subscript>3</Subscript>Si<Subscript>2</Subscript>O<Subscript>14</Subscript> from Langasite Family and Analysis of Structural Transformations Due to Isomorphous Cation Substitutions

An accurate structure analysis of a Ba₃TaGa₃Si₂O₁₄ single crystal from langasite family was performed using four X-ray diffraction data sets collected on a diffractometer equipped with a CCD area detector (sp. gr. P321, Z = 1, sinθ/λ ≤ 1.35 Å^–1; at 295 K a = 8.516(1) Å, c = 5.1910(6) Å, R/wR = 0.58/0.56%, Δρ_min/Δρ_max =–0.73/0.42 e/ų, 4414 independent reflections; at 106 K a = 8.5109(9) Å, c = 5.1861(9) Å, R/wR = 0.75/0.86%, Δρ_min/Δρ_max =–0.81/1.06 e/ų, 4382 reflections). The distinguishing feature of the Ba₃TaGa₃Si₂O₁₄ structure is a strong disorder of the Ga atom at the 3f site. Structural transformations in the series of Сa₃TaGa₃Si₂O₁₄–Sr₃TaGa₃Si₂O₁₄–Ba₃TaGa₃Si₂O₁₄–Ba₃TaFe₃Si₂O₁₄ crystals were analyzed.     

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.     

Synthesis and structure of oxovanadium(IV) complexes [VO(<Emphasis Type="Italic">Acac</Emphasis>)<Subscript>2</Subscript>] and [VO(<Emphasis Type="Italic">Sal</Emphasis>: <Emphasis Type="Italic">L</Emphasis>-alanine)(H<Subscript>2</Subscript>O)]

Bis(acetylacetonato)oxovanadium C₁₀H₁₄O₅V (I) and (S)-[2-(N-salicylidene)aminopropionate]oxovanadium monohydrate C₁₀H₉NO₅V (II) are synthesized. The crystal structures of compounds I and II are determined using single-crystal X-ray diffraction. Crystals of compound I are triclinic, a = 7.4997(19) Å, b = 8.2015(15) Å, c = 11.339(3) Å, α = 91.37(2)°, β = 110.36(2)°, γ = 113.33(2)°, Z = 2, and space group \(P\bar 1\). Crystals of compound II are monoclinic, a = 8.5106(16) Å, b = 7.373(2) Å, c = 9.1941(16) Å, β = 101.88(1)°, Z = 2, and space group P2₁. The structures of compounds I and II are solved by direct methods and refined to R₁ = 0.0382 and 0.0386, respectively. The oxovanadium complexes synthesized are investigated by vibrational spectroscopy.     

Accurate structural study of langasite-family Ca<Subscript>3</Subscript>TaGa<Subscript>3</Subscript>Si<Subscript>2</Subscript>O<Subscript>14</Subscript> crystal

An accurate X-ray diffraction study of Ca₃TaGa₃Si₂O₁₄ single crystal has been performed using two datasets obtained on a diffractometer equipped with a CCD area detector (a = 8.1056(2) Å, c = 4.9800(1) Å, sp. gr. P321, Z = 1, R/wR = 0.486/0.488%). A model structure is determined which is characterized by a high degree of reproducibility of structural parameters. Each site in Ca₃TaGa₃Si₂O₁₄ is occupied by atoms of only one type. Nevertheless, its structural feature is asymmetric disordering of sites of Ca, Ta, Ga, and two out of three oxygen atoms occupying special and general sites. A transition of some part of Ca atoms (~3%) from 3e sites on the twofold symmetry axis to general 6g sites is revealed.     

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.     

Absolute structure of La<Subscript>3</Subscript>Ga<Subscript>5</Subscript>SiO<Subscript>14</Subscript> langasite crystals

The absolute structure of La₃Ga₅SiO₁₄ piezoelectric crystals (a = 8.1746(6) Å, c = 5.1022(4) Å, space group P321, Z = 1) with the positive sense of rotation of the plane of polarization is refined using X-ray diffraction analysis (R = 1.37%, R _w = 1.71%, 2413 unique reflections, max sinθ/λ = 1.15 Å^?1). The contributions from the anharmonicity of thermal vibrations of lanthanum atoms are calculated with the use of the components of the third-and fourth-rank tensors. It is demonstrated that these contributions can have a significant effect.     

Multicell model of La<Subscript>3</Subscript>Ga<Subscript>5</Subscript>GeO<Subscript>14</Subscript> crystal: A new approach to the description of the short-range order of atoms

The multicell model alternative to the model of mixed atomic sites used now is proposed for a single crystal of La₃Ga₅GeO₁₄ belonging to the langasite family. The multicell consists of four unit cells. In three identical cells of the structure, atoms adapt to the Ge atom occupying one of the two 2d positions on the threefold symmetry axis. In the fourth cell, atoms surround the Ge atom located at the 1a position. The multicell model allows one to study the short-range order of atoms by the methods of classical structure analysis based on Bragg scattering. Four high-resolution data sets measured at 295 and 111.5 K are used in the study. The results are obtained with high relative precision (space group P321, Z = 1; at 295 K a = 8.2020(6) Å and c = 5.1065(6) Å, R/wR = 0.81/0.73% for 3829 unique ref lections; at 111.5 K a = 8.1939(1) Å and c = 5.1022(4) Å, R/wR = 0.85/0.76% for 3880 reflections).     

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.     

Novel Polyoxovanadate K<Subscript>2</Subscript>ZnV<Subscript>5</Subscript>O<Subscript>14</Subscript>: Crystal Structure and Peculiarities of Crystal Chemistry

A novel structure type has been established as a result of studying a non-merohedral microtwin of polyoxovanadate (K₂ZnV₅O₁₄) by X-ray diffractometry (R = 0.0595). The new compound, synthesized under hydrothermal conditions in the ZnCl₂–K₂CO₃–V₂O₅–H₂O system, is characterized as follows: a = 8.066(5) Å, b = 8.117(5) Å, c = 9.236(5) Å, β = 105.287(5)°, sp. P2₁/m, Z = 2, ρ_calcd = 3.54 g/cm³. Edge-shared five-core “clusters” consisting of vanadium octahedra, between which ZnO₄ tetrahedra (sharing vertices with octahedra) are located, form two-dimensional two-layer anion packets of the (ZnV₅O₁₄)^2– composition, alternating along the c axis with layers of potassium atoms. Structural peculiarities determine the morphology and color of new-phase crystals.     

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.     

Crystal structure of a new synthetic Ca,Li pentaborate: CaLi<Subscript>4</Subscript>[B<Subscript>5</Subscript>O<Subscript>8</Subscript>(OH)<Subscript>2</Subscript>]<Subscript>2</Subscript>

When studying the phase formation in the CaO-Li₂O-B₂O₃-H₂O system, a new Ca,Li pentaborate was synthesized under hydrothermal conditions. The structure of a new compound with the crystallochemical formula CaLi₄[B₅O₈(OH)₂]₂ (sp. gr. Pb2n, a = 8.807(7), b = 9.372(7), c = 8.265(6) Å, V = 682.2(9) ų, Z = 2, d_calcd = 2.43 g/cm³, automated SYNTEX-\(P\bar 1\) diffractometer, 2690 reflections, 2θ/θ scan, λMo) is refined up to R_hkl = 0.0557 in the anisotropic approximation of atomic thermal vibrations with allowance for the localized H atoms. The structure of the Ca,Li pentaborate is formed by (010) open boron—oxygen layers formed by two independent [B₅O₈(OH)₂]^3? pentagroups, with each of them being formed by three B tetrahedra and two B triangles. The structure framework consists of the above boron—oxygen layers bound by isolated Li tetrahedra. The Ca cations are localized in the centers of eight-vertex polyhedra located in the [001] channels of the Li,B,O framework. Comparative crystallochemical analysis of the new Ca,Li pentaborate and Li pentaborate of the composition Li₃[B₅O₈(OH)₂]-II showed that the anionic matrices of both compounds are completely identical, whereas some of the cationic positions are different.     

New multicell model for describing the atomic structure of La<Subscript>3</Subscript>Ga<Subscript>5</Subscript>SiO<Subscript>14</Subscript> piezoelectric crystal: Unit cells of different compositions in the same single crystal

Accurate X-ray diffraction study of langasite (La₃Ga₅SiO₁₄) single crystal has been performed using the data obtained on a diffractometer equipped with a CCD area detector at 295 and 90.5 K. Within the known La₃Ga₅SiO₁₄ model, Ga and Si cations jointly occupy the 2d site. A new model of a “multicell” consisting of two different unit cells is proposed. Gallium atoms occupy the 2d site in one of these cells, and silicon atoms occupy this site in the other cell; all other atoms correspondingly coordinate these cations. This structure implements various physical properties exhibited by langasite family crystals. The conclusions are based on processing four data sets obtained with a high resolution (sin θ/λ ≤ 1.35 Å^–1), the results reproduced in repeated experiments, and the high relative precision of the study (sp. gr. P321, Z = 1; at 295 K, a = 8.1652(6) Å, c = 5.0958(5) Å, R/wR = 0.68/0.68%, 3927 independent reflections; at 90.5 K, a = 8.1559(4) Å, c = 5.0913(6) Å, R/wR = 0.92/0.93%, 3928 reflections).