Synthesis,crystal structure,and magnetic properties of the oxometallates KBaMnO4 and KBaAsO4

Single crystals of KBaMnO₄ and KBaAsO₄ were grown using the hydroflux method and characterized by single crystal X-ray diffraction. Both compounds crystallize in the orthorhombic space group Pnma with a = 7.7795(4) Å, b = 5.8263(3) Å, and c = 10.2851(5) Å for the manganate and a = 7.7773(10) Å, b = 5.8891(8) Å, and c = 10.3104(13) Å for the arsenate. The materials exhibit a three-dimensional crystal structure consisting of isolated MnO₄³⁻ or AsO₄³⁻ tetrahedra, with the charge balance maintained by K⁺ and Ba²⁺. Each tetrahedron is surrounded by six K⁺ and five Ba²⁺, and shares its corner/edge with KO₁₀ polyhedra and corner/edge/face with BaO₉ polyhedra, respectively. The crystal growth, crystal structure and magnetic properties are discussed.     

A new intersecting tunnel structure in the AIMIII[PO3(OH)]2 series for AI = Ag,MIII = In: Analysis of structural relationships

A new indium hydroxyphosphate containing silver, AgIn[PO₃(OH)]₂, has been synthesized using hydrothermal method. It crystallizes in the P2₁/c space group with the cell parameters a = 6.6400(2) Å, b = 14.6269(6) Å, c = 6.6616(4) Å, β = 95.681(5)°, V = 643.82(6) Å³, Z = 4. Its three-dimensional framework, built up of corner-sharing PO₃(OH) tetrahedra and InO₆ octahedra, presents intersecting tunnels running along <111> and [100] directions, in which the Ag⁺ cations are located. The presence of hydroxyl groups has been confirmed from IR spectroscopy studies and hydrogen atoms were located from the single crystal X-ray diffraction study. The structural relationships with the other compounds of general formula A^IM^III[PO₃(OH)]₂ are analyzed.     

Crystal structures of Th(OH)PO4, U(OH)PO4 and Th2O(PO4)2. Condensation mechanism of MIV(OH)PO4 (M = Th,U) into M2O(PO4)2

Three new crystal structures, isotypic with β-Zr₂O(PO₄)₂, have been resolved by the Rietveld method. All crystallize with an orthorhombic cell (S.G.: Cmca) with a = 7.1393(2) Å, b = 9.2641(2) Å, c = 12.5262(4) Å, V = 828.46(4) Å³ and Z = 8 for Th(OH)PO₄; a = 7.0100(2) Å, b = 9.1200(2) Å, c = 12.3665(3) Å, V = 790.60(4) Å³ and Z = 8 for U(OH)PO₄; a = 7.1691(3) Å, b = 9.2388(4) Å, c = 12.8204(7) Å, V = 849.15(7) Å³ and Z = 4 for Th₂O(PO₄)₂. By heating, the M(OH)PO₄ (M = Th, U) compounds condense topotactically into M₂O(PO₄)₂, with a change of the environment of the tetravalent cation that lowers from 8 to 7 oxygen atoms. The lower stability of Th₂O(PO₄)₂ compared to that of U₂O(PO₄)₂ seems to result from this unusual environment for tetravalent thorium.     

Vibrational study and crystal structure refinement of BaHPO4

X-ray single crystal structure of BaHPO₄ is refined in the centric space group Pbnm (No. 62) with a=4.609(1) Å, b=14.195(3) Å, c=17.214(5) Å, V=1126.3(5) Å³, Z=12 and a final R value of 0.036 for 1261 independent reflections. The atomic arrangement consists of anionic linear chains lying parallel to the a direction and strongly linked by hydrogen bonds. Two successive chains are separated by Ba²⁺ cations. A comparison of the anionic networks for some similar compounds is also given. The polarized Raman and infrared absorption spectra are investigated. A factor group analysis leads to determination of internal modes of the PO₄³⁻ anions. The vibrational study confirmed the strong HOP hydrogen bonds to the phosphate groups and indicated a notable hydrogen bridges in BaHPO₄ compound.     

Crystal structure,electronic structure and electrical conductivity of the antimony selenide BaLaSb2Se6

BaLaSb₂S₆ and BaLaSb₂Se₆ were prepared by heating the elements in the stoichiometric ratio under exclusion of air at 850 °C. Both chalcogenides adopt the KThSb₆Se₆ structure type, crystallizing in the space group P2₁/c (Z = 4) with a = 4.324(3) Å, b = 14.7057(16) Å, c = 15.910(2) Å, β = 92.741(3)°, Z = 4 for the sulfide and a = 4.4173(3) Å, b = 15.333(1) Å, c = 16.816(1) Å, β = 92.545(2)°, Z = 4 for the selenide. The structure of BaLaSb₂Se₆ is composed of ribbons of distorted SbSe₆ octahedra and Se₂^2? pairs. Electronic structure calculations show that the selenide is a semiconductor, in accord with the electrical conductivity measurement.     

The influence of partial substitution of phosphorus by arsenic in monoclinic CsH2PO4. X-ray single crystal,vibrational and phase transitions in the mixed CsH2(PO4)0.72(AsO4)0.28

Partial substitution of P by As, leading to the solid solution CsH₂(PO₄)_1−x(AsO₄)_x, with x=0.28 (abbreviated as CDAP) has been shown. The structural characteristics of the crystals were analyzed by means of X-ray diffraction, which revealed that the new title compound is nearly isomorphous with the monoclinic phase of CsH₂PO₄ (CDP). The structure was solved from 796 independent reflections with R₁=0.0292 and Rw₂=0.0702, refined with 59 parameters. The following results have been obtained: space group P2₁, a=4.9250(4) Å, b=6.4370(3) Å, c=7.9280(6) Å, β=107.316(3)°, V=239.94(3) Å³, Z=2 and ρ_cal=3.349 g cm⁻³. The hydrogen bonds are clearly distinguished in the electron density maps which display distributions corresponding to order of protons. The shorter bond (2.452(4) Å), links the phosphate–arsenate groups into chains running along the b-axis and the longer bond (2.531(3) Å), crosslinks the chains to form (001) layers. The Raman and infrared spectra of CDAP recorded at room temperature in the frequency ranges 15–1200 cm⁻¹ and 400–4000 cm⁻¹, respectively, confirm the presence of PO³⁻₄ and AsO³⁻₄ groups in the crystal. Differential scanning calorimetry traces show three phase transitions at 333, 449 and 490 K in this material, which are characterized by X-ray powder diffraction at high temperature.     

A series of open-framework tin(II) phosphates: A[Sn4(PO4)3] (A=Na,K, NH4)

A new series of isostructural open-framework tin(II) phosphates with general formula A[Sn₄(PO₄)₃], where A=Na, K, NH₄, has been synthesized by hydrothermal methods. The crystal structures of NaSn₄(PO₄)₃ (I) and KSn₄(PO₄)₃ (II) have been solved by single crystal X-ray diffraction methods. Both phases crystallize in the trigonal space group R3c (#161) with Z=6 and cell parameters a=9.5508(13) Å, c=24.083(3) Å for I, and a=9.7124(11) Å, c=24.363(3) Å for II. The structure consists of a negatively charged [Sn₄(PO₄)₃]⁻ framework with channels running parallel to the a- and b-axes where the charge compensating A⁺ cations are located. An interesting feature is that half of the channels are empty due to the specific geometry of the SnO₃ units—the lone electron pair of the tin atoms “protrudes” in these channels thus preventing the insertion of A⁺. The new phases have also been characterized by infrared and thermogravimetric analyses.     

Synthesis and crystal structures of yttrium sulfates Y(OH)(SO4), Y(SO4)F,YNi(OH)3(SO4)-II and Y2Cu(OH)3(SO4)2F·H2O

Y(OH)(SO₄), Y(SO₄)F, YNi(OH)₃(SO₄)-II and Y₂Cu(OH)₃(SO₄)₂F·H₂O are obtained from hydrothermal reactions at 380°C under a pressure of 210 MPa. Their crystal structures were refined from single-crystal X-ray diffraction data. The four compounds have the following space groups and unit cells: Y(OH)(SO₄), P2₁/n, a=7.9498(6), b=10.9530(9), c=8.1447(6) Å, β=93.764(1)°; Y(SO₄)F, Pnma, a=8.3128(9), b=6.9255(7), c=6.3905(7) Å; YNi(OH)₃(SO₄)-II, Pnma, a=6.9695(8), b=7.2615(8), c=10.292(1) Å; Y₂Cu(OH)₃(SO₄)₂F·H₂O, P2₁/n, a=11.6889(7), b=6.8660(4), c=12.5280(8) Å, β=97.092(1)°. The coordination environments of the yttrium atoms in the four structures vary from highly irregular 6+2, 6+3, 7+1 coordination polyhedra to relatively regular dodecahedra.     

Meet the Cerium(IV) Phosphate Sisters: CeIV(OH)PO4 and CeIV2O(PO4)2

Two new cerium(IV) phosphates were obtained: cerium(IV) hydroxidophosphate, Ce(OH)PO₄, and cerium(IV) oxidophosphate, Ce₂O(PO₄)₂, which were shown to complement the classes of isostructural compounds M(OH)PO₄ and R₂O(PO₄)₂, where M=Th, U and R=Th, U, Np, Zr. Ce₂O(PO₄)₂ oxidophosphate is formed by elimination of H₂O from the crystal structure of Ce(OH)PO₄ during its thermal decomposition. The structures of Ce(OH)PO₄ and Ce₂O(PO₄)₂ are related to each other with the same Cmce space group and similar unit cell parameters (a=6.9691(3) Å, b=9.0655(4) Å, c=12.2214(4) Å, V=772.13(8) ų, Z=8; a=7.0220(4) Å, b=8.9894(5) Å, c=12.544(1) Å, V=791.8(1) ų, Z=4, respectively).     

A new layered indium selenium oxychloride material: Synthesis,structure, and characterization of InSeO3Cl

A new layered indium selenium oxychloride material, InSeO₃Cl has been synthesized by a standard solid-state reaction using In₂O₃, InCl₃, and SeO₂ as reagents. Single-crystal X-ray diffraction was used to determine the structure of the reported material. InSeO₃Cl crystallizes in the orthorhombic space group Pbca (No. 61), with a = 7.0580(14) Å, b = 7.0390(14) Å, c = 16.206(3) Å, V = 805.1(3) Å³, and Z = 8. InSeO₃Cl has a layered structure consisting of distorted InO₄Cl₂ octahedra and SeO₃ polyhedra. The Se⁴⁺ cations are in asymmetric coordination environment attributed to their stereoactive lone pairs. The lone pairs on the Se⁴⁺ cations approximately point in the [101], [?10-1], [10-1], and [?101] direction. A separation of the halophile and the chalcophile moieties is observed from the reported material. Detailed structural analysis with full characterization including infrared spectroscopy, bond valence calculations, thermogravimetric analysis, elemental analysis, and dipole moment calculations are reported.     

Organic derivatives of tin (II/IV): Investigation of their structure

The structures of tin(II)-oxalate, tin(IV)Na–EDTA and tin(IV)Na₈-inositol hexaphosphate were investigated using XRD analysis. Samples were identified using the Mössbauer study, thermal analysis and FTIR spectrometry. The Mössbauer study determined two different oxidation states of tin atoms, and consequently two different tin surroundings in the end products. The tin oxalate was found to be orthorhombic with space group Pnma, a=9.2066(3) Å, b=9.7590(1) Å, c=13.1848(5) Å, V=1184.62 Å³ and Z=8. SnNa–EDTA was found to be monoclinic with space group P2₁/c₁, a=10.7544(3) Å, b=10.1455(3) Å, c=16.5130(6) Å, β=98.59(2)°, V=1781.50(4) Å³ and Z=4. Sn(C₆H₆Na₈O₂₄P₆) was found to be amorphous.     

Crystal structure and thermal analysis of the tetramethylammonium dichromate and trichromate

The structures of the tetramethylammonium dichromate, [(CH₃)₄N]₂Cr₂O₇ and trichromate, [(CH₃)₄N]₂Cr₃O₁₀, were determined from single-crystal X-ray diffraction data. These compounds crystallize in the orthorhombic system (space group Pnma, with Z=4 and a=17.192(1) Å, b=8.55(1) Å, c=10.637(1) Å), for the dichromate and in the monoclinic system (space group P2₁/n, with Z=4 and a=11.366(2) Å, b=8.493(2) Å, c=20.187(4) Å, β=103.98(3)° for the trichromate. The structures consist of discrete dichromate anions (Cr₂O₇)^2– or trichromate anions (Cr₃O₁₀)^2–, respectively, stabilized by quaternary ammonium [(CH₃)₄N]⁺. Phase transitions in [(CH₃)₄N]₂Cr₂O₇ have been evidenced by differential scanning calorimetry as well as a new allotropic variety of [(CH₃)₄N]₂Cr₂O₇ which was characterized by X-ray powder diffraction. It crystallizes in an orthorhombic system with the unit cell parameters a=24.49(1) Å, b=8.85(1) Å, c=8.705(8) Å.     

Single crystal growth and structural characterization of ternary transition-metal uranium oxides: MnUO4, FeUO4, and NiU2O6

Single crystals of MnUO₄, FeUO₄, and NiU₂O₆ were grown for the first time. The use of chloride fluxes facilitated the crystal growth. MnUO₄, a hexavalent uranium compound, crystallizes in the orthorhombic space group, Imma, with a = 6.6421(19) Å, b = 6.978(2) Å, and c = 6.748(2) Å, and exhibits typical uranyl, UO₂²⁺, coordination. FeUO₄ and NiU₂O₆ contain pentavalent uranium and are structurally related, exhibiting three-dimensional connectivity. FeUO₄ crystallizes in the orthorhombic space group, Pbcn, with a = 4.8844(2) Å, b = 11.9328(5) Å, c = 5.1070(2) Å. NiU₂O₆ crystallizes in the trigonal space group, P321, with a = 9.0148(3) Å, c = 5.0144(3) Å.     

Hydroflux synthesis and crystal structure of new lanthanide tungstate oxyhydroxides

Single crystals of Na₅Ln(OH)₆WO₄ where Ln = Er, Tm, and Yb were grown out of a NaOH hydroflux. The crystals were characterized by single crystal X-ray diffraction and were found to crystallize in the monoclinic space group I2/a. The lattice parameter ranges for the three structures are a = 11.2024(7) Å–11.2412(6) Å, b = 16.1850(10) Å–16.2220(10) Å, and c = 11.9913(7) Å–12.0323(7) Å while the β angle range is 101.999(2)°–102.025(2)°.     

Synthesis,structure and solid state NMR analysis of a new templated titanium(III/IV) fluorophosphate

The title compound MIL-131 (MIL stands for Material from Institut Lavoisier) was prepared hydrothermally (4 days, 473 K, autogenous pressure) in the presence of an organic base (N((CH₂)₂NH₂)₃). The structure of MIL-131 or Ti^IIITi^IV(OH)F₄(HPO₄)·(PO₄)·(N((CH₂)₂NH₃)₃) has been determined ab initio from X-Ray synchrotron powder diffraction data using simulated annealing methods and was refined in the triclinic space group P-1 (no. 2). MIL-131 exhibits a one-dimensional structure built up from inorganic chains of corner sharing TiO₅(OH) titanium(III) octahedra and PO₄ and HPO₄ phosphate tetrahedra, related to TiO₂F₄ titanium octahedra. Protonated triamine cations are located between the inorganic motifs, and interact strongly with the mineral network through hydrogen bondings both with terminal fluorine atoms and hydroxo or oxo groups. Multinuclear solid state NMR has allowed a clear attribution of the protons, fluoride, and phosphate groups environment within the framework of MIL-131. The large values of chemical shift anisotropy together with the absence of any ¹³C NMR response confirmed the presence of paramagnetic titanium(III) species deduced from the crystal structure. Finally, 2D MAS ¹H-³¹P CP-HETCOR NMR correlation experiment gives some insight on the nature of the intra-framework hydrogen bonding.Crystal data for MIL-131: a = 14.109(1) Å, b = 8.462(3) Å, c = 7.179(1) Å, α = 93.772(1)°, β = 96.566(2)°, γ = 98.004(1)°, V = 840.36(2) ų, z = 2.     

Crystal structure and ionic conductivity of AgCr2(PO4)(P2O7)

Single crystals of a new phosphate AgCr₂(PO₄)(P₂O₇) have been prepared by the flux method and its structural and the infrared spectrum have been investigated. This compound crystallizes in the monoclinic system with the space group C2/c and the parameters are, a = 11.493 (3) Å, b = 8.486 (3) Å, c = 8.791 (2) Å, β = 114.56 (2)°, V = 779.8 (3) ųand Z = 4. Its structure consists of CrO₆ octahedra sharing corners with P₂O₇ units to form undulating chains extending infinitely along the [110] direction. These chains are connected by the phosphate tetrahedra giving rise to a 3D framework with six-sided tunnels parallel to the [101] direction, where the Ag⁺ ions are located. The infrared spectrum of this compound was interpreted on the basis of P₂O₇^4? and PO₄^3? vibrations. The appearance of ν_sP–O–P in the spectrum suggests a bent P–O–P bridge for the P₂O₇^4? ions in the compound, which is in agreement with the X-ray data. The electrical measurements allow us to obtain the activation energy of (1.36 eV) and the conductivity measurements suggest that the charge carriers through the structure are the silver captions.     

Ce(H2O)(PO4)3/2(H3O)1/2(H2O)1/2, a second entry in the structural chemistry of cerium(IV) phosphates

A cerium(IV) phosphate has been prepared using precipitation methods and its structure has been solved by single crystal X-ray diffraction (R₁ = 0.0292 for 3092 reflections with I>2σ(I) and wR₂ = 0.0540). Ce(H₂O)(PO₄)_3/2(H₃O)_1/2(H₂O)_1/2 crystallises in the monoclinic space group C2/c (a = 15.7058(17) Å, b = 9.6261(9) Å, c = 10.1632(4) Å, ß = 121.623(7)°, and V = 1308.4 (2) Å³). Its structure is based on a negatively charged 3D framework, made of cerium atoms connected by PO₄ tetrahedra. There are two types of PO₄ units; one shares only corners with the cerium coordination polyhedra while the other one shares edges and corners. This structure also includes hydronium cations, to balance the framework charge, and water molecules. One special feature of this 3D framework is the formation of interconnected tunnels which extend along the c axis and contain the hydronium cations and the water molecules. This open framework and the presence of cationic species in the tunnels are in perfect agreement with the previously reported ion exchange properties.     

Crystal structure of Pb3O2(OH)Br,a Br-analogue of damaraite

The crystal structure of Pb₃O₂(OH)Br (orthorhombic, Pmc2₁, a=5.8447(8), b=7.0715(10), c=15.309(2) Å, V=632.75(15) Å³) has been solved by direct methods and refined to R₁=0.046 (wR=0.077). The structure is based on [O₂Pb₃] chains of edge-sharing OPb₄ oxocentered tetrahedra that extend parallel to the a axis and occur in two orientations inclined to each other by ∼50°. The [O₂Pb₃] chains are linked through OH(3) groups to form an [Pb₃O₂](OH) sheet that is parallel to (010). Additional OH(4) groups are attached to the [O₂Pb₃] chains. The OH groups form two short (OH)Pb bonds that results in (OH)Pb₂ dimers.     

Syntheses and crystal structures of new vanadium(IV) oxyphosphates M(VO)2(PO4)2 with M = Co,Ni

We have extended our research interest on titanium oxyphosphates (M^II(TiO)₂(PO₄)₂, with M^II = Mg, Fe, Co, Ni, Cu, Zn) to vanadium oxyphosphates M^II(V^IVO)₂(PO₄)₂ (M^II = Co, Ni). For each compound two phases, named α and β according to synthesis conditions, have been stabilized at room temperature, then characterized. The four crystal structures M(VO)₂(PO₄)₂ (α and β for M = Co, Ni) have been determined in monoclinic P2₁/c space group using X-ray single crystals diffraction data. Structure of the α phase is derived from the Li(TiO)(PO₄) (orthorhombic Pnma) and LiNi_0.50(TiO)₂(PO₄)₂ (monoclinic P2₁/c) types, with cell parameters: a = 6.310(1) Å, b = 7.273(1) Å, c = 7.432(1) Å, β = 90.43(1)° for M = Co, and a = 6.297(2) Å, b = 7.230(2) Å, c = 7.421(2) Å, β = 90.36(2)° for M = Ni. Structure of the β phase is derived from the Ni(TiO)₂(PO₄)₂-type (monoclinic P2₁/c) with cell parameters: a = 7.2742(2) Å, b = 7.2802(2) Å, c = 7.4550(2) Å, β = 120.171(2)° for M = Co, and a = 7.2691(2) Å, b = 7.2366(2) Å, c = 7.4453(2) Å, β = 120.231(2)° for M = Ni. All these structures consist of a three dimensional (3D) framework built up of infinite chains of tilted corner-sharing [VO₆] octahedra, cross-linked by corner-sharing [PO₄] tetrahedra. The M²⁺ ion (M = Co, Ni) is located in a triangular based antiprism which shares faces with two [VO₆] octahedra. Structural filiation is discussed based on a common structural unit, a sheet where divalent cations M²⁺ (M = Co, Ni) are inserted. A thermal study of the α ? β transition is also presented.     

K2[Te4O8(OH)10]: synthesis,crystal structure and thermal behavior

Dipotassium octaoxodecahydroxotetratellurate, K₂[Te₄O₈(OH)₁₀], has been prepared hydrothermally in acidic medium under autogenous pressure. It crystallizes in space group P2₁/c of the monoclinic system with Z=2 in a cell of dimensions a=5.592(1) Å, b=8.283(2) Å, c=16.255(3) Å, and β=99.62(3)°. The outstanding feature of the structure is a tetrameric [Te₄O₈(OH)₁₀]^2– anion built up from edge and corner sharing TeO₆ octahedra. These anions and K⁺ cations are held together by electrostatic interactions and by hydrogen bonds. The compound decomposes in two steps at 350 and 420 °C, corresponding to a water and an oxygen loss, respectively, and affording the mixed valence oxide K₂Te^VI₃Te^IVO₁₂.