Methyl- and phenylmercury(II) derivatives of 2-mercaptobenzothiazole. Crystal structure of (2-mercaptobenzothiazolato)methylmercury(II)

The complexes MeHgL and PhHgL (HL = 2-mercaptobenzothiazole) have been obtained from the reaction of the ligand with methylmercury hydroxide and phenylmercury acetate, respectively, in methanol. MeHgL, which has been characterized by single-crystal X-ray diffraction analysis (crystal data: triclinic, space group P1, with a = 8.009 (4) Å, b = 10.042 (4) Å, c = 13.074 (3) Å, α = 101.25 (2)°, β = 102.61(3)°, γ = 101.42 (3)°, R = 0.067), crystallizes with two independent molecules, I and I′, contained in each asymmetric unit with a coordination geometry based on the almost linear C-Hg-S group (Hg-S = 2.369 (6) Å, Hg-C = 2.06 (2) Å, and C-Hg-S = 177.7 (7)° for I; Hg-S = 2.375 (6) Å, Hg-C = 2.10 (3) Å, and C-Hg-S = 178.8 (6)° for I′). A secondary intramolecular interaction between the mercury atom and the C=N group of the ring and some weak intermolecular interactions between the metal and sulfur atoms were also found. The vibrational spectra of this compound and the phenylmercury(II) compound are discussed in light of the crystal structure. Diagnostic criteria of the bonding modes for the ligand are assessed. © 1985 American Chemical Society.

Crystal structures and luminescence properties of La3Zr4F25 and α-LaZr3F15

During a study of the LaF3-ZrF4 system, both La3Zr4F25 and α-LaZr3F15 compounds have been evidenced. Their crystal structures have been determined from single-crystal X-ray diffraction data. La3Zr4F25 crystallises in the cubic system with a = 12.384 Å and 143d space group (no. 220). Its crystal structure is built up of (ZrF6)2- octahedra and (LaF8)5- dodecahedra sharing corners. The low temperature form, α, of LaZr3F15 is orthorhombic (space group Pmmn, no. 59) with a = 15.721 Å, b = 16.299 Å, c = 8.438 Å. Its structure is built of corner-sharing tricaped trigonal prisms surrounding the La3+ ions and both octahedra and monocapped trigonal prisms encompassing the Zr4+ ions. This structure is characterised by dynamically disordered (ZrF6)2- complex anions. The Eu3+ luminescence properties of these phases have been investigated and are discussed in relationship with their crystal structures.

Crystal structures and magnetic properties of CuX2(pdmp)2 complexes (X = Br, Cl)

We report the synthesis and the structural and magnetic characterization of two new compounds: dibromobis-(pdmp)copper(II), CuBr2C22H24N4 (1), and dichlorobis(pdmp)copper(II), CuCl2C22H24N4 (2), where pdmp = 1-phenyl-3,5-dimethylpyrazole. The structures were refined by full-matrix least-squares techniques to R1 = 0.0620 and 0.0777, respectively. Compound 1 belongs to the space group P21/n with a = 8.165(5) Å, b = 10.432(3) Å, c = 13.385(4) Å, β = 100.12(4)̊, and Z = 2. Compound 2 belongs to the space group P21/c with a = 8.379(2) Å, b = 22.630(2) Å, c = 12.256(2) Å, β= 98.43(3)°, and Z = 4. It has the same molecular formula as a compound reported previously but a different crystal structure. Detailed single-crystal EPR measurements were performed for single-crystal samples of 1 and 2 at 9 and 35 GHz and at room temperature. The positions and line widths of the EPR lines were measured as a function of the magnetic field orientation in three orthogonal planes. The data were used to study the electronic properties of the copper ions and to evaluate the exchange interactions between them. Our results are discussed in terms of the electronic pathways for superexchange between copper ions, which are provided by the stacking of pyrazole and phenyl rings of neighboring molecules and by hydrogen-halogen bonds. © 1999 American Chemical Society.

Crystal and supramolecular structures of dysprosium(III) 2-methoxybenzoate tetrahydrate

The compound dysprosium(III) 2-metoxybenzoate, {[Dy(2-MeO-Bz)2μ-(2-MeO-Bz)(H2O)2]2·4H2O}n (2-MeO-Bz = 2- methoxybenzoate), was synthesized from a reaction mixture containing DyCl3 and Na(2-MeO-Bz), and characterized by single-crystal X-ray diffraction. The molecular structure showed dinuclear units in which each Dy(III) ion is coordinated by nine oxygen atoms. The carboxylato groups are bound to the dysprosium centers in two modes: bidentate chelating and tridentate chelating-bridging. Besides this, the occurrence of hydrogen bonds involving a coordinated water molecule and carboxylato groups leads to the formation of helicoidal chains along the crystal lattice, resulting in a supramolecular one-dimensional polymer. 2008 © The Japan Society for Analytical Chemistry.

Hydrothermal synthesis and crystal structure of a copper(ii) coordination polymer with bridging dicarboxylate and diamine ligands

This work reports on the synthesis of a copper(II) coordination compound with 4,4-oxibis(benzoate) (obb) and trans-1,2- bis(4-pyridyl)ethene (bpe) ligands. The complex was characterized by single-crystal X-ray diffraction, which showed a 3D polymeric structure. Each copper center is surrounded by four oxygen atoms at the basal plane and one nitrogen atom and one copper atom at the axial positions, revealing a distorted octahedral geometry. Four carboxylic groups bridge two copper atoms, forming a cage-like structure, with the distance between the metallic centers being 2.656(1)Å. 2008 © The Japan Society for Analytical Chemistry.

Molecular and crystal structure of trans-(dicyanato)-bis(triphenylphosphine)palladium(II)

The triphenylphosphine (PPh3) displaces the acetonitrile from [PdCl2(CH3CN)2], and subsequent addition of the potassium cyanate causes substitution of the chloro ligand by NCO- to yield trans-[Pd(NCO)2(PPh3)2]. The complex was characterized by elemental analysis, IR spectroscopy and single-crystal X-ray diffraction. The title compound was crystallized in a triclinic system, space group P1 with a = 9.213(3)Å, b = 9.781(7)Å, c = 10.483(5)Å, α = 111.39(5)°, β = 93.49(3)°, γ = 103.81(4)°, V = 845.0(1)Å3, Z = 1. The coordination geometry around Pd(II) in this complex is nearly square-planar, with the ligands in a trans relationship. 2008 © The Japan Society for Analytical Chemistry.

Crystal and molecular structure of dinuclear palladium(II) complex containing nitrogen and phosphorus donor ligands, [Pd2(N3)4(PPh3)2(μ-ted)]

The dinuclear azido-palladium(II) complex [Pd2(N3)4(PPh3)2(μ-ted)], where PPh3 = triphenylphosphine and ted = triethylenediamine, was synthesized and characterized by single-crystal X-ray diffraction. The title compound was crystallized in a triclinic system, space group P1 with a = 11.5875(2)Å, b = 13.0817(3)Å, c = 15.2618(3)Å, α = 93.306(2)°, β =110.040(1)°, γ = 98.486(1)°, V = 2134.95(8)Å3, Z = 2. Each Pd(II) center displays a distorted squareplanar coordination environment formed by two N atoms from two trans terminally coordinated azido groups, one P atom from the phosphine and one N atom from the bridging ted ligand. 2008 © The Japan Society for Analytical Chemistry.

Molecular and crystal structure of Di(μ-N,S-thiocyanato)-bis[(N,N-dimethylbenzylamine-C2, N)palladium(II)]

The cyclopalladated complex [Pd(C2,N-dmba)(μ-SCN)]2, where dmba = N,N-dimethylbenzylamine, was structurally characterized by single-crystal X-ray diffraction. This compound crystallizes in the monoclinic system, space group P21/n with a = 9.578(1)Å, b = 12.323(2)Å, c = 10.279(2)Å, β = 117.03(1)°, V = 1080.7(3)Å3, Z = 2. Each Pd(II) center displays a distorted square-planar coordination environment, formed by the C and N atoms from the dmba ligand, and one set of N and S atoms from the bridging SCN groups. 2009 © The Japan Society for Analytical Chemistry.

Characterization, and crystal structure of thiophenyl-2-methylidene-2- aminophenol

The Schiff base thiophenyl-2-methylidene-2-aminophenol (ImineOH) is obtained from a stoichiometric mixture of 2-thiophenecarboxaldehyde and 2-aminophenol in ethanol under reflux at 90 C. Its crystal structure is determined by single crystal X-ray diffraction. ImineOH packs in an orthorhombic unit cell in the Pbca space group with the unit cell parameters a = 16.942(4) Å, b = 13.4395(11) Å, and c = 17.5857(12) Å, V = 4004.1(10) Å3, Z = 16. Strong hydrogen bonds are present in the ImineOH structure. Apart from the X-ray study, ImineOH was characterized by elemental analysis (CHN-S) and FT-IR (4000 cm-1 to 400 cm-1), UV-Vis and 13C, 1H, and 15N NMR spectroscopic measurements. © 2013 Pleiades Publishing, Ltd.

Synthesis, crystal structure and photoluminescence of a binuclear complex of europium(III) containing 3,5-dicarboxypyrazolate and succinate

The new europium binuclear complex [Eu2(dcpz) 2(suc)(H2O)8]·(H2O) 1.5 (dcpz = 3,5-dicarboxypyrazolate and suc = succinate) has been synthesized and structurally characterized by single crystal X-ray diffraction methods. The binuclear complex crystallizes in the triclinic space group P1̄ and consists of two lanthanide ions linked by two different bridging organic ligands. 3D supramolecular framework is constructed by hydrogen bonds. The compound shows strong red emission under UV excitation at room temperature associated to IL transitions indicating a ligand to metal energy transfer mechanism since the triplet energy level lies higher than that of europium 5D0 level. Magnetic susceptibility studies showed weak temperature dependence characteristic of the Van Vleck paramagnetism. © 2013 Elsevier Ltd. All rights reserved.

Terbium(III) and dysprosium(III) 8-connected 3D networks containing 2,5-thiophenedicarboxylate anion: Crystal structures and photoluminescence studies

Two novel coordination polymers with the formula {[Ln(2)(2,5-tdc)(3)(dmso)(2)].H2O}(n) (Ln = Tb(III) for (1) and Dy(III) for (2)), (2,5-tdc(2-) = 2,5-thiophenedicarboxylate and dmso = dimethylsulfoxide) have been synthesized by the diffusion method and characterized by thermal analysis, vibrational spectroscopy and single crystal X-ray diffraction analysis. Structure analysis reveals that 2,5-tdc(2-) play a versatile role toward different lanthanide ions to form three-dimensional metal-organic frameworks (MOFs) in which the lanthanides ions are heptacoordinated. Photophysical properties were studied using excitation and emission spectra, where the photoluminescence data show the high emission intensity of the characteristic transitions D-5(4 ->) F-7(J) (J= 6, 5, 4 and 3) for (1) and (F9/2 -> HJ)-F-4-H-6 (J = 15/2, 13/2 and 11/2) for (2), indicating that 2,5-tdc(2-) is a good sensitizer. (C) 2012 Elsevier Ltd. All rights reserved.

Spectroscopic characterization and crystal structure of cis-Bis(N-(2-benzoyl)-N ',N '-diphenylthioureato-k O-2,S)nickel(II)

The title compound [Ni(C20H15N2OS)(2)] is prepared by the reaction of metal acetate with the corresponding acylthiourea derivative. The complex is characterized by elemental analysis, IR, H-1 and C-13 NMR, and its structure is determined by single crystal X-ray diffraction. The Ni(II) ion is coordinated by the S and O atoms of two N-benzoyl-N',N'-diphenylthiourea ligands in a slightly distorted square-planar coordination geometry. The two O and two S atoms are mutually cis to each other. The substance crystallizes triclinic (P-1 space group) with cell dimensions a = 10.7262(9) , b = 12.938(3) , c = 14.2085(12) , alpha = 74.650(4)A degrees, beta = 78.398(4)A degrees, gamma = 68.200(5)A degrees, and two formula units in the unit cell. The structure is very close to the related N-(2-furoyl) Ni complex reported previously.

Carlosbarbosaite, ideally (UO2)(2)Nb2O6(OH)(2)center dot 2H(2)O, a new hydrated uranyl niobate mineral with tunnels from Jaguaracu, Minas Gerais, Brazil: description and crystal structure

Carlosbarbosaite, ideally (UO2)(2)Nb2O6(OH)(2)center dot 2H(2)O, is a new mineral which occurs as a late cavity filling in albite in the Jaguaracu pegmatite, Jaguaracu municipality, Minas Gerais, Brazil. The name honours Carlos do Prado Barbosa (1917-2003). Carlosbarbosaite forms long flattened lath-like crystals with a very simple orthorhombic morphology. The crystals are elongated along [001] and flattened on (100); they are up to 120 mu m long and 2-5 mu m thick. The colour is cream to pale yellow, the streak yellowish white and the lustre vitreous. The mineral is transparent (as individual crystals) to translucent (massive). It is not fluorescent under either long-wave or short-wave ultraviolet radiation. Carlosbarbosaite is biaxial(+) with alpha = 1.760(5), beta = 1.775(5), gamma = 1.795(5), 2V(meas) = 70(1)degrees, 2V(calc) = 83 degrees. The orientation is X parallel to a, Y parallel to b, Z parallel to c. Pleochroism is weak, in yellowish green shades, which are most intense in the Z direction. Two samples were analysed. For sample I, the composition is: UO3 54.52, CaO 2.07, Ce2O3 0.33, Nd2O3 0.49, Nb2O5 14.11, Ta2O5 15.25, TiO2 2.20, SiO2 2.14, Fe2O3 1.08, Al2O3 0.73, H2O (calc.) 11.49, total 104.41 wt.%; the empirical formula is (square 0.68Ca0.28Nd0.02Ce0.02)(Sigma=1.00)[U-1.44 square O-0.56(2.88)(H2O)(1.12)](Nb0.80Ta0.52Si0.27Ti0.21Al0.11Fe0.10)(Sigma=2.01) O-4.72(OH)(3.20)(H2O)(2.08). For sample 2, the composition is: UO3 41.83, CaO 2.10, Ce2O3 0.31, Nd2O3 1.12, Nb2O5 14.64, Ta2O5 16.34, TiO2 0.95, SiO2 3.55, Fe2O3 0.89, Al2O3 0.71, H2O (calc.) 14.99, total 97.43 wt.%; the empirical formula is (square 0.67Ca0.27Nd0.05Ce0.01)(Sigma=1.00)[U-1.04 square O-0.96(2.08)(H2O)(1.92)] (Nb0.79Ta0.53Si0.42Ti0.08Al0.10Fe0.08)(Sigma=2.00)O-4.00(OH)(3.96)(H2O)(2.04). The ideal endmember formula is (UO2)(2)Nb2O6(OH)(2)center dot 2H(2)O. Calculated densities are 4.713 g cm(-3) (sample 1) and 4.172 g cm(-3) (sample 2). Infrared spectra show that both (OH) and H2O are present. The strongest eight X-ray powder-diffraction lines [listed as d in angstrom(I)(hkl)] are: 8.405(8)(110), 7.081(10)(200), 4.201(9)(220), 3.333(6)(202), 3.053(8)(022), 2.931(7)(420), 2.803(6)(222) and 2.589(5)(040,402). The crystal structure was solved using single-crystal X-ray diffraction (R = 0.037) which gave the following data: orthorhombic, Cmem, a = 14.150(6), b = 10.395(4), c = 7.529(3) angstrom, V = 1107(1) angstrom(3), Z = 4. The crystal structure contains a single U site with an appreciable deficiency in electron scattering, which is populated by U atoms and vacancies. The U site is surrounded by seven 0 atoms in a pentagonal bipyramidal arrangemet. The Nb site is coordinated by four 0 atoms and two OH groups in an octahedral arrangement. The half-occupied tunnel Ca site is coordinated by four 0 atoms and four H2O groups. Octahedrally coordinated Nb polyhedra share edges and comers to form Nb2O6(OH)(2) double chains, and edge-sharing pentagonal bipyramidal U polyhedra form UO5 chains. The Nb2O6(OH)(2) and UO5 chains share edges to form an open U-Nb-phi framework with tunnels along [001] that contain Ca(H2O)(4) clusters. Carlosbarbosaite is closely related to a family of synthetic U-Nb-O framework tunnel structures, it differs in that is has an (OH)-bearing framework and Ca(H2O)(4) tunnel occupant. The structure of carlosbarbosaite resembles that of holfertite.

The influence of the Pt crystalline surface orientation on the glycerol electro-oxidation in acidic media

We investigated the electrochemical oxidation of glycerol on low-index Pt single crystals in acidic media (H2SO4 and HClO4) by cyclic voltammetry and Fourier Transform Infrared (FTIR) spectroscopy and we verified that this is a surface sensitive reaction. Pt(100) and Pt(110) surface structures favor the breaking of the C-C-C bond at low potentials (say 0.05 V), as seen by the formation of CO, one of the adsorbed residues of the glycerol dissociation, which poisons these surfaces even at high potentials. Pt(111) surface structure does not favor the C-C-C bond breaking at potentials as low as 0.05 V. However, Pt(111) is less poisoned by residues of glycerol dissociation and, for this reason, it is more active for glycerol oxidation than Pt(100) and Pt(110) at low potentials. Carbonyl containing compounds and CO2 were detected as reaction products of the glycerol oxidation on all investigated single-crystal Pt surfaces. The ratio between CO2 and carbonyl containing compounds is clearly much higher for Pt(100) and Pt(110) than for Pt(111). (C) 2012 Elsevier Ltd. All rights reserved.

Microstructure and metal-insulator transition in single crystalline KMo4O6

High quality KMo4O6 single crystals with tetragonal structure (space group P4/mbm) have been prepared by fused salt electrolysis. The crystals were studied by scanning electron microscopy (SEM), X-ray diffractometry, electrical resistivity, and magnetization measurements. X-ray powder diffraction patterns and SEM have given some information on the growth of single crystals. Electrical resistivity as a function of temperature shows that the KMo4O6 compound is a bad metal with resistivity change of approximately 30% in the temperature range from 2 to 300K. A metal-insulator transition (MIT), observed at approximately 110K, has been also confirmed for this material. Magnetization as a function of temperature agrees with previous report, however a magnetic ordering has been observed in M(H) curves in the whole temperature range.