RBaCuCoO<Subscript>5 + δ</Subscript> (R = Nd,Sm, Gd) layered cuprocobaltites: Synthesis,structure, and properties

Cuprocobaltites RBaCuCoO_{5 + gd}(R = Nd, Sm, Gd) were prepared. Their unit cell parameters were determined, and thermal expansion, electrical conductivity (σ), and Seebeck coefficient (S) were studied in air in the range 300–1100 K. The compounds have tetragonal structures (space group P4/mmm, Z = 1). Their unit cell parameters are a = 0.3906(2) nm, c= 0.7648(7) nm for NdBaCuCoO_5.21; a = 0.3904(2) nm, c = 0.7609(6) nm for SmBaCuCoO_5.06; and a = 0.3891(2), c = 0.7592(6) nm for GdBaCuCoO_5.02. The RBaCuCoO_{5 + δ} cuprocobaltites at room temperature are p-type semiconductors, whose electrical conductivity and linear thermal expansion coefficient (LTEC) increase with increasing R³⁺ ionic radius, whereas the Seebeck coefficient decreases. The LTECs of RBaCuCoO_{5 + δ} phases in the range 500–575 K increase by a factor of 1.2–1.5 because of the elimination of weakly bound oxygen. S = f(T) curves for RBaCuCoO_{5 + δ} (R = Nd, Sm, Gd) feature maxima at 510 K for R = Sm and 365 K for R = Gd, probably, due to the change in the spin state of cobalt cations in these phases.     

New complex of Zn(II) with 3,4,5-trimethoxybenzoate and 2-methylimidazolyl: Synthesis,structure, and luminescence properties

A new zinc(II) complex Zn(TMB)₂(2-MIM)(H₂O)₂ (I), where HTMB is 3,4,5-trimethoxybenzoic acid, 2-MIM is 2-methylimidazole, was synthesized and characterized by Powder X-ray diffraction, FT-IR and photoluminescence spectrum. The complex crystallizes in the monoclinic crystal system (space group C2/c) with the unit cell parameters: a = 18.104(9), b = 8.509(4), c = 17.688(9) Å, β = 103.185(9)°, Z = 4, R ₁ = 0.0740 and wR ₂ = 0.1790. At room temperature the photoluminescence spectrum of complex I in the solid state exhibits maximum excitation at 314 nm and maximum emission at 337 nm.     

Synthesis and crystal structure of a novel two-dimensional network complex [Mn(O<Subscript>2</Subscript>CCH<Subscript>2</Subscript>Cl)<Subscript>2</Subscript>(phen)]<Subscript><Emphasis Type="Italic">n</Emphasis></Subscript>

A novel two-dimensional network manganese(II) polymer complex [Mn(O₂CCH₂CI)₂-(phen)] _n has been synthesized and characterized by elemental analysis and IR spectrum. The crystal structure of title complex has also been determined, which is in monoclinic of a space group P2₁/c with the following unit cell parameters at 294K:a =1.9738 (4) nm,b=1.1384 (2) nm,c =0.74915(14) nm,V = 1.6795(5) nm³, Z= 2.     

Sm<Subscript>2</Subscript>S<Subscript>3</Subscript>-Sm<Subscript>2</Subscript>O<Subscript>3</Subscript> phase diagram

The Sm₂S₃-Sm₂O₃ phase diagram was studied by physicochemical methods of analysis from 800 K up to melting. Two oxysulfides are formed in the system: Sm₁₀S₁₄O with tetragonal crystal structure (space group I41/acd; unit cell parameters: a = 1.4860 nm, c = 1.9740 nm; microhardness: H = 4700 MPa; solid decomposition temperature: 1500 K) and Sm₂O₂S with hexagonal structure (space group P-3m1; a = 0.3893 nm, c = 0.6717 nm; H = 4500 MPa; congruent melting temperature: 2370 K). Within the extent of the Sm₂O₂S-based solid solution (61–70 mol % Sm₂O₃) at 1070 K, a singular point appears at the compound composition on property-composition curves. The eutectic coordinates: 23 mol % Sm₂O₃ and 1850 K; 80 mol % Sm₂O₃ and 2290 K.     

New barium bismuth oxides: BaBi<Subscript>4</Subscript>O<Subscript>7</Subscript> and BaBi<Subscript>15</Subscript>O<Subscript>23.5</Subscript>

New barium bismuth oxides have been synthesized under an argon atmosphere at 530 and 430°C, respectively: a Ba: Bi = 1 : 4 phase has a tetragonal perovskite structure, and a 1 : 15 phase has a rhombohedral structure. For the 1 : 4 phase, the unit cell parameters are a = 4.297(2) Å and c = 4.472(2) Å as determined by powder X-ray diffraction (XRD). Electron diffraction (ED) patterns show superstructure reflections with the vectors q ₁= 1/17[530], q ₂ = 1/17[3\(\bar 5\)0], and q ₃ = 1/5[002]. These reflections point to an ordered arrangement of barium and bismuth ions in the supercell with the parameters √17a and 5c. The supercell of the 1 : 4 phase includes a ten-layer stack of metal-oxygen planes along the c axis. The rhombohedral 1 : 15 phase has the following hexagonal unit cell parameters as determined by XRD: a= 6.018(2) Å, c = 4.070(2) Å. In view of the superstructure on the ED patterns, the supercell parameters of the rhombohedral phase are 4a and 2c. The supercell of the 1 : 15 phase contains a six-layer stack of planes along the c axis.     

Crystal structures of SrLnCuS<Subscript>3</Subscript> (Ln = Gd,Lu)

The crystal-chemical characteristics of new complex sulfides SrLnCuS₃ (Ln = Gd, Lu) are determined from the data of X-ray powder diffraction patterns. SrGdCuS₃ crystallizes in the orthorhombic crystal system (space group Pnma) and belongs to the Eu₂CuS₃ structure type with the unit cell parameters a = 10.3282(8) Å, b = 3.9624(2) Å, and c = 12.9364(9) Å. The structure of SrLuCuS₃ is orthorhombic: the KZrCuS₃ structure type, space group Cmcm, and unit cell parameters are a = 3.9105(2) Å, b = 12.9419(9) Å, and c = 10.0191(8) Å. A substantial role of crystal-chemical contraction inside the [LnCuS₃] dimeric block in the stabilization of structure types based on Eu₂CuS₃ and KZrCuS₃ is shown.     

Supramolecular architecture of the 1:1 complex of phloroglucinol with dimethyl sulfoxide

The phase diagram of the phloroglucinol (1,3,5-trioxybenzol)-dimethyl sulfoxide system is studied. The system is found to form a 1:1 molecular complex of phloroglucinol with dimethyl sulfoxide. The crystal structure of the complex is determined. The crystallographic data for C₈H₁₂O₄S, M = 204.24, monoclinic system, P2₁/n space group, unit cell parameters: a = 9.0345(2)Å, b = 9.6895(3)Å, c = 10.9960(3)Å, β = 98.865(1)°, V = 951.09(4) ų, Z = 4, d _x = 1.426 g/cm³, R1 = 0.0283, T = 150 K. The molecules are joined in a supramolecular ensemble via O-H...O hydrogen bonds.     

Structure and charge-transport properties of LnBaCuCoO<Subscript>5 + δ</Subscript> (Ln = Y,Dy) cuprocobaltites

LnBaCuCoO_{5 + δ} (Ln = Y, Dy) cuprocobaltites were prepared. Their unit cell parameters were determined and their thermal expansion, electrical conductivity (σ), and Seebeck coefficient (S) were studied in air in the range 300–1100 K. The compounds have tetragonal structures (space group P4/mmm). Their unit cell parameters are a = 0.3867(2) nm, c = 0.7550(7) nm, V = 112.9(2) × 10^?3 nm³ for YBaCuCoO_4.98; and a = 0.3872(2) nm, c = 0.7562(7) nm, V = 113.4(2) × 10^?3 nm³ for DyBaCuCoO_5.01. They are p-type semiconductors. The electrical conductivity of DyBaCuCoO_{5 + δ} is slightly lower and its Seebeck coefficient is 1.5–2 times higher than the respective values for YBaCuCoO_{5 + δ} apparently because of different electronic configurations of the rare-earth cations in LnBaCuCoO_{5 + δ} (4d ⁰ for Y³⁺ and 4f ⁹ for Dy³⁺). Dilatometric measurements show that the LnBaCuCoO_{5 + δ} phases in the range 300–1100 K do not experience structural phase transitions, and their linear thermal expansion coefficients (LTEC) are 14.3 × 10^?6 K^?1 for Ln = Y and 14.7 × 10^?6 K^?1 for Ln = Dy.     

Study of the Re<Subscript>0.50</Subscript>Rh<Subscript>0.50</Subscript> products of thermobaric treatment

The products of thermobaric treatment of the metastable Re_0.50Rh_0.50 nanocrystalline phase (a= 2.733(2) Å, c = 4.364(4) Å, space group P6₃/mmc, CSR ～5 nm) in a high-pressure chamber were studied. Storage of the phase at 2000°C and 1.5 GPa for 3 min led to the formation of a fused particle (Ø～1 mm). The initial composition did not change, but the coherent scattering region (CSR) increased to 52 nm. An increase to 4 GPa in pressure also did not lead to a decomposition of the metastable Re_0.50Rh_0.50 phase, the unit cell parameters remained the same, and the size of the CSR increased by a factor of four.     

Crystal structures of EuLnCuS<Subscript>3</Subscript> (Ln = Nd and Sm)

The compound sulfides EuLnCuS₃ (Ln = Nd and Sm) were obtained for the first time. Their crystal structures were determined from X-ray powder diffraction data. The crystals of both compounds are orthorhombic (space group Pnma). The compound EuNdCuS₃ is isostructural with BaLaCuS₃; the unit cell parameters are a = 11.0438(2) Å, b = 4.0660(1) Å, c = 11.4149(4) Å. The compound EuSmCuS₃ is isostructural with Eu₂CuS₃; the unit cell parameters are a = 10.4202(2) Å, b = 3.9701(1) Å, c = 12.8022(2) Å.     

Formation of the high-pressure modification of hydrated talc at 450°C and 4 GPa: <Emphasis Type="Italic">In situ</Emphasis> diffraction study

The formation of the high-pressure hydrous phase Mg₃Si₄O₁₀(OH)₂?xH₂O (10 Å phase) through the reaction “talc + water” at 450°C and 4 GPa was studied using diamond anvil cell. The powder diffraction measurements in situ, performed at the Siberian Center of Synchrotron and Terahertz Radiation (SSTRC), were applied to refine the lattice parameters, atomic coordinates and the occupancy of interlayer H₂O site in the structure of 10 Å phase at 450°C and 4 GPa. The lattice parameters are a = 5.234(1) Å, b = 9.053(2) Å, c = 10.87(1) Å, β = 99.2(1)°, and V = 508.5(6) ų (space group C2/m). The results of Rietveld refinement show the best fit for the trioctahedral mica structure with split position Ow of the interlayer H₂O molecule. The half occupancy of the Ow site corresponds to one H₂O molecule per formula unit.     

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.     

Structure and Thermal Stability of Nanostructured Precursor Powders of Copper(I) Sulfide and Selenide

The hydrochemical precipitation method at 298 and 333 K with, respectively, thiocarbamide and sodium selenosulfate was used to obtain nanostructured powders of copper sulfide with formula composition Cu₂S, which are composed of globules 200–500 nm in diameter, formed by 70–100-nm particles, and copper(I) selenide, composed of crystallites with polyhedral shape, sizes of 80 to 500 nm, and a formula composition Cu_1.84Se. An X-ray diffraction analysis revealed the orthorhombic Cu₂S structure (space group no. 39-Abm2) with unit cell parameters a = 1.182 nm, b = 2.705 nm, and c = 1.343 nm. Powders of Cu_1.84Se copper selenide have a cubic structure (space group Fm3m) with lattice constant a = 0.5693 nm. A thermal analysis demonstrated that the chemically precipitated Cu₂S and Cu_1.84Se powders have a stable elemental composition up to 200–240°C. An intense oxidation of the samples begins at a temperature exceeding 250°C and is accompanied by a sharp decrease in their content of sulfur (selenium) and by an increase in the content of oxygen.     

Phase equilibria in the BaS–Ga<Subscript>2</Subscript>S<Subscript>3</Subscript> system

In the BaS–Ga₂S₃ system, the following compounds form: congruently melting compound BaGa₄S₇ (rhombic system, space group Pmn2₁, a = 1.477 nm, b = 0.624 nm, c = 0.593 nm, and T_melt = 1490 K) and incongruently melting compounds BaGa₂S₄ (cubic system, space group Pa3, a = 1.2661 nm, and Tmelt = 1370 K), Ba₂Ga₂S₅ (monoclinic system, space group C2/c, a = 1.529, b = 1.479, c = 0.858 nm, ß = 106.04°, and T_melt = 1150 K), Ba₃Ga₂S₆ (monoclinic system, space group C2/c, a = 0.909 nm, b = 1.448 nm, c = 0.903 nm, ß = 91.81°, and T_melt = 1190 K), Ba₄Ga₂S₇ (monoclinic system, space group P2₁/m, a = 1.177 nm, b = 0.716 nm, c = 0.903 nm, ß = 108.32°, and T_melt = 1230 K), and Ba₅Ga₂S₈ (rhombic system, space group Cmca, a = 2.249 nm, b = 1.215 nm, c = 1.189 nm, and T_melt = 1480 K). The compositions of eutectics are 38 and 72 mol % Ga₂S₃, and their melting points are 1120 and 1160 K, respectively. The BaS solubility in γ-Ga₂S₃ at 1070 K reaches 3 mol %.     

Crystal structure and properties of AHoCuS<Subscript>3</Subscript> (A = Sr or Eu)

The structures of complex sulfides AHoCuS₃ (A = Sr or Eu) have been determined by X-ray powder diffraction. The crystals of the compounds belong to the orthorhombic crystal system; they are isostructural (space group, Pnma; structure type Eu₂CuS₃). The unit cell parameters for SrHoCuS₃ and EuHoCuS₃ are a = 10.1487(1) Å, b = 3.9332(1) Å, c = 12.9524(2) Å and a = 10.1484(2) Å, b = 3.9195(1) Å, c = 12.8499(2) Å, respectively. The temperatures and enthalpies of phase transformations of complex sulfides AHoCuS₃ (A = Sr or Eu) have been determined.     

Structure of the 1:1 complex of dimethyl sulfoxide with hydroquinone: Supramolecular architecture based on D-H⋯A hydrogen bonds (D = O,C; A = O, π)

The hydroquinone-dimethyl sulfoxide-toluene system was investigated by thermal and X-ray diffraction analyses. The crystal structure of the 1:1 complex of hydroquinone with dimethyl sulfoxide was determined. Crystal data: C₈H₁₂O₃S, M = 188.24, triclinic system, space group P1¯, unit cell parameters: a = 7.4202(2) Å, b = 8.4046(3) Å, c = 8.7340(3) Å; α = 100.830(1)°, β = 99.794(1)°, γ = 114.129(1)°; V = 469.35(4) ų, Z = 2, d _calc = 1.332 g/cm³, R1 = 0.028, T = 100 K. The molecules are linked in a supramolecular assembly via D-H...A hydrogen bonds (D = O, C; A = O, π).     

Synthesis,characterization, and crystal structures of dioxomolybdenum(VI) complexes with O,N,N type tridentate hydrazone ligands as catalyst for oxidation of olefins

The preparation of Mo(VI) hydrazone complexes, cis-[MoO₂L¹(CH₃OH)] (I) and cis-[MoO₂L₂(CH₃OH)] (II), derived from N'-(3-bromo-2-hydroxybenzylidene)-2-chlorobenzohydrazide (H₂L¹) and N'-(3-bromo-2-hydroxybenzylidene)-4-bromobenzohydrazide (H₂L²), respectively, is reported. The complexes were characterized by elemental analyses, infrared and electronic spectroscopy, and single crystal structure analysis (CIF files ССDС nos. 1426875 (I), 1426871 (II)). The Mo atoms are coordinated by two cis terminal oxygen, ONO from the hydrazone ligand, and methanol oxygen. Even though the hydrazone ligands and the coordination sphere in both complexes are similar, the unit cell dimensions and the space groups are different. Complex I crystallized as orthorhombic space group Pca21 with unit cell dimensions a = 27.887(2), b = 8.0137(7), c = 15.544(1) Å, V = 3473.8(5) ų, Z = 8, R ₁ = 0.0450, wR ₂ = 0.0539. Complex II crystallized as triclinic space group P1, with unit cell dimensions a = 8.2124(4), b = 8.5807(5), c = 12.9845(8) Å, α = 83.366(2)°, β = 79.201(2)°, γ = 80.482(2)°, V = 883.03(9) Å3, Z = 2, R ₁ = 0.0278, wR ₂ = 0.0569. The complexes were tested as catalyst for the oxidation of olefins, and showed effective activity.     

Phase equilibria in the thiourea-benzene system

Phase equilibria in the thiourea (host)-benzene (guest) binary system with clathrate formation were studied over the temperature range 260–460 K by physicochemical analysis methods. The stoichiometry and conditions of the existence of the 2.40(±0.02)(NH₂)₂CS · C₆H₆ compound, which incongruently decomposed at 358.7 K into rhombic thiourea and the guest component, were determined. The parameters of the Bravaisrhombohedral cell of the clathrate (space group R \(\bar 3\) c) were found to be a = 15.921(6), c = 12.417(8) Å, and V = 2725(5) ų; d _calc = 1.192 g/cm³ and d _expt = 1.195(7) g/cm³. The packing of guest molecules in the rhombohedral host framework was modeled taking into account stoichiometry and unit cell parameters to show that benzene molecule planes were tilted with respect to the c channel axis with the formation of a monomolecular closely packed chain in the guest subsystem.     

Synthesis and structure of a new molecular octahedral cluster complex Mo<Subscript>6</Subscript>Se<Subscript>8</Subscript>(Ph<Subscript>3</Subscript>P)<Subscript>6</Subscript>·2H<Subscript>2</Subscript>O

Mo₆Se₈(Ph₃P)₆·2H₂O cluster complex has been synthesized and its structure has been defined. The compound is triclinic, space group P1ˉ, with unit cell parameters a = 14.3356(5) Å, b = 15.7882(4) Å, c = 25.3949(8) Å, = 95.9750(10)°, β = 91.1030(10)°, γ= 112.2570(10)°, V = 5279.8(3) ų, Z = 2, ρ_calc = 1.772 g/cm³. The complex has a molecular structure. The molybdenum atoms of the {Mo₆Se₈} cluster nucleus are coordinated by the phosphorus atoms of triphenylphosphine molecules. Original Russian Text Copyright ? 2007 by Yu. V. Mironov, Zh. S. Kozhomuratova, D. Yu. Naumov, and V. E. Fedorov __________ Translated from Zhurnal Strukturnoi Khimii, Vol. 48, No. 2, pp. 389–393, March–April, 2007.     

Phase equilibria in the systems SrS-Cu<Subscript>2</Subscript>S-Ln<Subscript>2</Subscript>S<Subscript>3</Subscript> (Ln = La or Nd)

Phase equilibria in the systems SrS-Cu₂S-Ln₂S₃ (Ln = La or Nd) have been studied along the isothermal section at 1050 K and vertical sections CuLnS₂-SrS and Cu₂S-SrLnCuS₃, which are partially quasibinary joins. Compounds SrLnCuS₃ with Ln = La or Nd have been synthesized for the first time. They crystallize in orthorhombic space group Pnma, the BaLaCuS₃ structure type, with the following unit cell parameters: for SrLaCuS₃, a = 1.1157(2) nm, b = 0.41003(6) nm, c = 1.1545(2) nm; for SrNdCuS₃, a = 1.1083(1) nm, b = 0.40887(7) nm, c = 1.1477(2) nm. Noticeable homogeneity regions for SrLnCuS₃ are not found. The compounds melt congruently by the reaction SrLnCuS₃ ? SrS + L at 1365 K for SrLaCuS₃ and 1400 K for SrNdCuS₃. The tie-lines at 1050 K in the systems SrS-Cu₂S-Ln₂S₃ radiate from SrLnCuS₃ toward phases SrS, Cu₂S, CuLnS₂, and SrLn₂S₄, lying between the phases CuLnS₂ and compositions from the γ-Ln₂S₃-SrLn₂S₄ solid-solution field. Eutectics are formed between the compounds CuLaS₂ and SrLaCuS₃ at 21.0 mol % SrS, T = 1345 K; between the compounds CuNdS₂ and SrNdCuS₃ at 31.0 mol % SrS, T = 1310 K; and between the phases Cu₂S and SrLnCuS₃ at 14.0 mol % SrLaCuS₃, T = 1075 K and 8.0 mol % SrNdCuS₃, T = 1055 K.