Synthesis and Structure of Ba<Subscript>5</Subscript>(V<Subscript>2</Subscript>O<Subscript>7</Subscript>)<Subscript>2</Subscript>Cl<Subscript>2</Subscript>

Abstract  A new barium chlorovanadate, Ba₅(V₂O₇)₂Cl₂, was isolated by a high-temperature (850 °C) reaction employing a CsCl/RbCl flux. The structure was determined by single crystal X-ray diffraction methods. This compound crystallizes in an orthorhombic crystal system, Pmmn (No. 59), with a = 11.558(2) ?, b = 15.164(3) ?, c = 10.023(2) ?, Z = 4 and V = 1756.7(6) ?³. The structure of Ba₅(V₂O₇)₂Cl₂ was determined by full-matrix, least-squares methods with R ₁ = 0.0398, wR ₂ = 0.1069 and GOF = 1.048 for all data. This new structure can be described as a composite lattice made up of mixed covalent and ionic moities. The extended framework is orchestrated by stacked [Ba(V₂O₇)Cl]³⁻ slabs that are interconnected by Ba²⁺ cations through Ba–O bonds to the [V₂O₇] units. The Ba²⁺ and Cl^- ions form BN-type “[BaCl]” sheets with pseudo-hexagonal windows that are centered by [V₂O₇]⁴⁻ pyrovanadate units. Graphical Abstract  The structure of a new chlorovanadate, Ba₅(V₂O₇)₂Cl₂, exhibits an interesting BN-type salt lattice that consists of an extended [BaCl] sheet containing pseudo-hexagonal windows that are centered by [V₂O₇] pyrovanadate units.      

Low-temperature X-ray diffraction studies of [(CH<Subscript>3</Subscript>)<Subscript>2</Subscript>NH<Subscript>2</Subscript>]<Subscript>5</Subscript>Cd<Subscript>3</Subscript>Cl<Subscript>11</Subscript> crystals

[(CH₃)₂NH₂]₅Cd₃Cl₁₁ crystals are grown by the method of isothermal evaporation from saturated aqueous solutions containing dimethylamine and cadmium chlorides, [(CH₃)2NH₂]Cl and CdCl_2.5H₂O. The crystal grown are studied by the X-ray diffraction method. It is established that the crystals are orthorhombic with the unit-cell parameters at room temperature a = 18.115 ± 0.004 Å, b = 11.432 ± 0.002 Å, and c = 15.821 ± 0.003 Å. The unit-cell parameters a, b, and c of the [(CH₃)₂NH₂]₅Cd₃Cl₁₁ crystals are measured as functions of temperature in the temperature range 100–320 K. The data obtained were used to determine the thermal expansion coefficients along the main crystallographic axes. The temperature curves of the unit-cell parameters and thermal expansion coefficients showed pronounced anomalies in the vicinity of the temperatures T ₁ = 120, T ₂ = 150, and T ₃ = 180 K corresponding to the phase transitions in the [(CH₃)₂NH₂]₅Cd₃Cl₁₁ crystals. The crystals are also characterized by a pronounced anisotropy of thermal expansion.     

Domain Structure and Orientational Ordering of NO<Subscript>2</Subscript> Groups in K<Subscript>2</Subscript>Ba(NO<Subscript>2</Subscript>)<Subscript>4</Subscript> Crystals

Polarization-optical studies of the domain structure of K₂Ba(NO₂)₄ crystals and differentialscanning calorimetric measurements have been performed in the vicinity of the high-temperature phase transition. The orientational ordering of NO₂ atomic groups is analyzed and the temperature dependence of the birefringence coefficient is theoretically described.     

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.     

Crystal and Molecular Structure of Dichloro(ethylenediamine)gold(III) Nitrate: [Au(NH<Subscript>2</Subscript>CH<Subscript>2</Subscript>CH<Subscript>2</Subscript>NH<Subscript>2</Subscript>)Cl<Subscript>2</Subscript>]NO<Subscript>3</Subscript>

Abstract  The gold(III) atom in [Au(NH₂CH₂CH₂NH₂)Cl₂]NO₃ is chelated by the ethylenediamine (en) ligand and the approximately square planar geometry is completed by two chloride atoms. Weak Au···O and Au···Cl contacts are noted above and below the square plane leading to a tetragonally distorted octahedron for the gold(III) center. Extensive charge-assisted hydrogen bonding of the type N–H···O leads to the formation of a 2-D array and layers are consolidated into a 3-D network via C–H···O and C–H···Cl contacts. The compound crystallizes in the orthorhombic space group Pbca with a = 10.3380(11) ?, b = 8.2105(7) ?, c = 19.625(2) ?, and Z = 8. Index Abstract  Square planar complex cations form additional Au···O and Au···Cl interactions to form a tetragonally distorted octahedron for gold. The ionic components are connected into a 2-D array via charge-assisted N–H···O hydrogen bonding interactions.      

<Emphasis Type="Italic">Trans-</Emphasis>dichlorodioxobis(triphenylphosphate)molybdenum(VI), MoO<Subscript>2</Subscript>Cl<Subscript>2</Subscript>[OP(OPh)<Subscript>3</Subscript>]<Subscript>2</Subscript>

Abstract  The molecular structure of trans-dichlorodioxobis(triphenylphosphate) molybdenum(VI), MoO₂Cl₂[OP(OPh)₃]₂ has been determined. Crystal data: Monoclinic, Pn, a = 11.767(2), b = 10.341(2), c = 15.682(3) ?, β = 92.27(3)°, V = 1906.8(7) ?⁻³, Z = 2. Trans-dichlorodioxobis(triphenylphosphate)molybdenum(VI) was obtained by the reaction of molybdenum oxide, HCl and triphenylphosphate and was characterized by elemental analysis, IR, and ¹H-NMR spectroscopy. Index Abstract   Trans-dichlorodioxobis(triphenylphosphate)molybdenum(VI), MoO₂Cl₂[OP(OPh)₃]₂ V. Huch¹, R. Kumar², S. Mathur¹, R. Ratnani² The immediate environment around Mo is distorted octahedral with two cis-oxygen atoms and two trans-chlorine atoms along with two triphenylphosphate moieties.      

X-Ray Structure Investigation of Sr<Subscript>3</Subscript>NbGa<Subscript>3</Subscript>Si<Subscript>2</Subscript>O<Subscript>14</Subscript> Langasite Family Crystal

An accurate structure analysis of Sr₃NbGa₃Si₂O₁₄ single crystals, belonging to the langasite family, has been performed. Two datasets are obtained on an Xcalibur S diffractometer equipped with a CCD detector. The structure is been refined using an averaged dataset: sp. gr. P 321, Z = 1, 295 K, sin θ/λ ≤ 1.35 Å^–1, a = 8.2797(3) Å, c = 5.0774(5) Å; the agreement factors between the model and experiment are found to be R/wR = 0.76/0.64% and Δρ_min/Δρ_max =–0.21/0.17 e/ų for 3820 independent ref lections. The Sr₃NbGa₃Si₂O₁₄ and Sr₃NbFe₃Si₂O₁₄ structures are compared, and the role of magnetic ions in the predicted P321 → P3 phase transition is analyzed.     

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.     

Phase transitions in compounds with the Ca<Subscript>3</Subscript>Ga<Subscript>2</Subscript>Ge<Subscript>4</Subscript>O<Subscript>14</Subscript> structure

Possible structural changes described by the group-subgroup relationships in the Ca₃Ga₂Ge₄O₁₄-type structure (sp. gr. P321) are considered. The most probable phase transitions seem to be those accompanied by lowering of the symmetry to the maximal non-isomorphic subgroups P3 and C2. It is shown that only destructive phase transitions accompanied by symmetry rise up to the minimal non-isomorphic supergroups for the given structure type can take place. The change of the trigonal symmetry to monoclinic is revealed in La₃SbZn₃Ge₂O₁₄, whose crystal structure is refined as a derivative structure of the Ca₃Ga₂Ge₄O₁₄ structure type within the sp. gr. A2 (C2). At ～250°C, La₃SbZn₃Ge₂O₁₄ undergoes a reversible phase transition accompanied by symmetry rise, A2 ? P321. Similar phase transitions, P321 ? A2, are also observed in La₃Nb_0.5Ga_5.5O₁₄ and La₃Ta_0.5Ga_5.5O₁₄ under the hydrostatic pressures 12.4(3) and 11.7(3) GPa, respectively. The mechanisms of compression and phase transition are based on the anisotropic compressibility of a layer structure. With the attainment of the critical stress level in the structure, the elevated compressibility in the (ab) plane gives rise to a phase transition accompanied by the loss of the threefold axis. Attempts to reveal low-temperature phase transitions in a number of representatives of the langasite family have failed.     

Synthesis and crystal structure of Pb<Subscript>3</Subscript>[IO<Subscript>3</Subscript>]<Subscript>2</Subscript>Cl<Subscript>4</Subscript>, a representative of a new iodate-chloride class of compounds

Compound Pb₃[IO₃]₂Cl₄ (space group C12/c1), representing a new iodate-chloride class of compounds, is synthesized under hydrothermal conditions. Only two minerals, schwartzembergite Pb₃[IO₃]Cl₂O(OH) and seeligerite Pb₃[IO₃]Cl₃O, the structures of which are unknown, are close in composition to this compound. In the iodate-chloride studied, the pentavalent iodine atom has an umbrella-like coordination, which is typical of iodates and consists of three O atoms at short distances and the fourth O atom at a longer distance. [IO₄]³⁻ tetrahedra share edges to form pairs. Lead ions form layers parallel to the ab plane. Along the c axis, these layers alternate with layers of iodate groups. Pb atoms are coordinated by O atoms of iodate groups and Cl atoms. The coordination sphere of the Pb(1) atom contains a free sector which is directed to more distant halogen atoms and possibly accommodates the lone electron pair.     

Structural Characterization of Na<Subscript>0.96</Subscript>Ho<Subscript>9.04</Subscript>(SiO<Subscript>4</Subscript>)<Subscript>6</Subscript>Cl<Subscript>0.02</Subscript>O<Subscript>1.98</Subscript> Apatite Prepared by Mechanical Milling

Abstract  

In this paper we report the synthesis and structural characterization of Na_0.96Ho_9.04(SiO₄)₆Cl_0.02O_1.98 apatite prepared by mechanical milling at room temperature, in which well crystallized sample was obtained after heating the sample at 1123 K. The crystal structure study was carried out by synchrotron radiation diffraction. This apatite crystallizes in the hexagonal space group P6 ₃ /m (No. 176) with cell parameters a = 9.3444(1) ?, c = 6.7611(1) ?, unit cell volume of 511.27(1) ?³ and Z = 1. As in other rare-earth orthosilicate apatites, it was found that sodium cations are mixed with holmium occupying the 4f position at the center of tricapped trigonal prisms; while holmium fully occupies the 6h position at the center of a seven-coordinated polyhedron. No vacancies are present in the two crystallographic sites available for holmium atoms. The chemical composition was established by wavelength dispersive spectroscopy.     

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 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.     

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.     

Crystallization of Ba<Subscript>3</Subscript>Fe<Subscript>2</Subscript>Ge<Subscript>4</Subscript>O<Subscript>14</Subscript> and Ba<Subscript>2</Subscript>Fe<Subscript>2</Subscript>GeO<Subscript>7</Subscript> in oxide-fluoride fluxes

Crystallization of trigonal Ba₃Fe₂Ge₄O₁₄ and tetragonal Ba₂Fe₂GeO₇ barium ferrogermanates is investigated in their own fluxes diluted by B₂O₃-BaF₂ and B₂O₃-PbF₂ mixtures, respectively. The ratios of the components at which the properties of the fluxes satisfy the requirements for controlled crystallization of these incongruently melting compounds are determined. Single crystals of Ba₂Fe₂GeO₇ barium ferrogermanate are grown for the first time.     

Reaction of (<Emphasis Type="Italic">n</Emphasis>-Bu<Subscript>4</Subscript>N)<Subscript>2</Subscript>[Re<Subscript>2</Subscript>Cl<Subscript>8</Subscript>] with a 2-Oxocarboxylic Acid: Crystallographic Characterization of a New Dirhenate(III) Complex

Abstract  

The reaction of tetra-n-butylammonium-octachloridodirhenate(III), (Bu₄N)₂[Re₂Cl₈], with molten 2-oxobutanoic acid Et(CO)CO₂H at 75 °C afforded pale-green tetra-n-butylammonium-hexachlorido-(2-oxobutanoato)-dirhenate(III), (Bu₄N)[Re₂(O₂C(CO)Et)Cl₆]. Slow evaporation of a solution in CHCl₃ yielded shiny, mint-green crystals of the dirhenate complex. The X-ray crystal structure determination (monoclinic, P2₁/n, a = 11.6557(3) ?, b = 20.5382(5) ?, c = 13.9281(3) ?, β = 112.508(1)°, Z = 4) revealed the presence of [Re₂(O₂C(CO)Et)Cl₆]⁻ anions and tetra-n-butylammonium cations. The central [Re₂]⁶⁺ core with a Re≣Re quadruple bond of 2.2263(3) ? length is μ₂-bridged by one 2-oxobutanoato ligand and additionally coordinated by six chlorido ligands. Each dirhenate unit is linked via two Re···Cl contacts to dimeric, centrosymmetric entities of the constitution {[Re₂(O₂C(CO)Et)Cl₆]₂}²⁻. In the crystal, these dimers of dinuclear complexes are separated from each other by the bulky tetra-n-butylammonium cations.     

Structural Analysis of the Phase Transitions of (NH<Subscript>4</Subscript>)<Subscript>4</Subscript>HgBr<Subscript>6</Subscript>

Abstract Single crystal diffraction and differential scanning calorimetry DSC techniques have been used to investigate the different phases of (NH₄)₄HgBr₆, tetrammonium mercury hexabromide, from room temperature to 120 K. Two anomalies in thermal behaviour were detected for this compound at 190 and 268 K, by DSC experiment. X-ray diffraction measurements confirm these anomalies. At room temperature the structure is tetragonal P4/mnc (No. 128) with lattice parameters a = b = 9.25560(8) ?; c = 8.8657(11) ?; V = 759.49(9) ?³ and Z = 2. At T = 250 K the structure is orthorhombic Pnnm with lattice parameters a = 8.8436(8) ?; b = 9.2191(8) ?; c = 9.2232(7) ?; V = 751.97(11) ?³ and Z = 2. Below approximately 200 K the structure is monoclinic P2₁/n (No. 14) with: a = 8.8080(9) ?; b = 9.1608(8) ?; c = 9.1498(8) ?; β = 90.230(7)°; V = 738.28(12) ?³ and Z = 2 (T = 120 K). The structure of (NH₄)₄HgBr₆ consists of isolated HgBr₆-octahedra in the whole temperature range which are slightly compressed in c-direction. The ammonium groups are located between the octahedra ensuring the stability of the structure by hydrogen bonding contacts: N–H···Br. The structural phase transformations are described by a rotation of the [HgBr₆]²⁻ octahedra around the c-axis, and this behaviour is attributed to an orientational disorder of ammonium groups. Index abstract Structural analysis of the phase transitions of (NH₄)₄HgBr₆; M. Loukil, A. Kabadou, I. Svoboda, A. Ben Salah and H. Fuess; The phase transformations in (NH₄)₄HgBr₆ are explained by large rotation of [HgBr₆]²⁻ octahedra around the c-axis.      

Synthesis and Structure of [Fe<Subscript>3</Subscript>O(O<Subscript>2</Subscript>CCH<Subscript>2</Subscript>OMe)<Subscript>6</Subscript>(H<Subscript>2</Subscript>O)<Subscript>3</Subscript>][FeCl<Subscript>4</Subscript>]

Abstract  The structure of [Fe₃O(O₂CCH₂OMe)₆(H₂O)₃][FeCl₄] · 2.5H₂O has been determined. The three iron atoms and the μ₃-oxo are coplanar. Each carboxylic ligand is bidentate and links two iron atoms in the cluster. The clusters are linked by intra-trimer hydrogen bonding to form a zigzag motif that forms sheets via hydrogen bonding involving disordered waters of hydration. The [FeCl₄]⁻ anion is intercalated between the hydrogen-bonded sheets. Crystal data: space group P2₁/n, a = 10.276(2), b = 22.793(5), c = 17.091(3) ?, β = 96.66(3)°, V = 3976(1) ?³, Z = 4, R = 0.0837, wR ₂ = 0.1836. Graphical Abstract  The structure of [Fe₃O(O₂CCH₂OMe)₆(H₂O)₃][FeCl₄] · 2.5H₂O has been determined in which the clusters are linked by intra-trimer hydrogen bonding to form a zigzag motif that forms sheets via hydrogen bonding involving disordered waters of hydration.      

Crystal structure of new decaborate Na<Subscript>2</Subscript>Ba<Subscript>2</Subscript>[B<Subscript>10</Subscript>O<Subscript>17</Subscript>(OH)<Subscript>2</Subscript>]

The crystal structure of a newly synthesized compound Na₂Ba₂[B₁₀O₁₇(OH)₂] has been determined (Syntex \(P\bar 1\) diffractometer, MoK_α radiation, 1784 crystallographically nonequivalent reflections, anisotropic approximation, R = 1.7%). The parameters of the monoclinic unit cell are a = 11.455(7), b = 6.675(4), c = 9.360(7) Å, β = 93.68(5)°, Z = 2, sp. gr. C2. The structure consists of double pseudohexagonal layers built by BO₄-tetrahedra and BO₃-triangles forming three-membered rings of two mutually orthogonal orientations. The neighboring layers along the [001] direction are bound by Na-polyhedra and hydrogen bonds with participation of OH groups. The interlayer tunnels along the [100] direction are filled with columns of Ba-polyhedra. The crystallochemical characteristics of a number of synthetic Ba-borates (to which the structure of new decaborate is related) are considered in terms of borate building blocks singled out in the structure.