Synthesis and Crystal Structure of Ammonium cis-Dioxo Dibenzilato Tungstate (VI) Dihydrate

A mononuclear tungsten-benzilate, (NH4)2[WO2(Ph2COCOO)2]?H2O was ob- tained by the reaction of ammonium tungstate(VI) with excess benzilic acid in ethanol solution at pH 5~6. The title compound crystallizes in monoclinic system, space group P21/n with a = 8.1078(5), b = 25.797(2), c = 13.6815(8) ? b = 91.001(1)? V = 2861.1(3) 3, Dc = 1.719 g/cm3, F(000) = 1472, C28H32N2O10W, Mr = 740.41, m(MoKa) = 4.097 mm-1 and Z = 4. The full-matrix least-squares refinement resulted in R = 0.033 and Rw = 0.068 for 3974 observed reflections with I >2s(I). The tungsten atom is six-coordinated by two cis-oxo groups and two bidentate benzilate ligands through deprotonated a-alkoxyl and a-carboxyl groups, forming a stable five-membered chelate ring. The compound has a distorted octahedral geometry, which is mainly attributable to the bulky ligand-ligand repulsions.

Determination of Proton Diffusion Coefficient in Spherical Nickel Hydroxide Using Potential Step Measurement on Single Beads

The Potential step measurements are carried out on single beads of nickel hydroxide and the results are interpreted with a dual structure model featuring fast and slow diffusing components. The intrinsic diffusion coefficients for the two components are found to be in the order of magnitude 10-7 and 10-13~10-14 cm2s-1, respectively, with an apparent value for the slow component in the order of 10-10cm2s-1.

Preparations of Pure Alkaline Earth Molybdate Phases from Single Molecular Precursors

The pure phases of alkaline earth molybdates MMoO 4, where M=Mg, Ca, Sr or Ba, were synthesized via the calcination of the related citrato oxomolybdate complexes. The mixed metal oxides can be highly dispersed at the atomic level due to the existence of uniform citrato oxomolybdenum precursors in definite composition. The complexing effect helps to produce the fine-grained oxides with particle size in the ultrafine scale(<100 nm) at heat-treatment temperatures below 500 ℃. The structures of the precursor complexes and the finally heat-treated particles were studied by means of IR, XRD, DSC, DTA and TG techniques. The morphologies of the particles were observed by using the SEM technique. The average particle sizes were calculated to be in the range of 30_50 nm based on X-ray diffraction line-broadening and SEM images, indicating the poor conglomeration of crystallite at low temperatures.

Hydro(solvo)thermal Construction of a Copper Coordination Polymer Involving in Situ Ligand Synthesis: Preparation and Structure of [Cu_3(bdcO)_2(H_2O)_2]_n

A hydro(solvo)thermal reaction of 1,3-benzenedicarboxylic acid (bdcH2) and CuSO4?5H2O produced a coordination polymer [Cu3(bdcO)2(H2O)2]n 1. The alkoxyl-1,3-benzene- dicarboxylate trianion (bdcO3-) found in the final product was in situ generated by the hydroxy- lation of bdcH2 during the synthesis. Its crystal structure has been determined by X-ray structural analysis. The complex belongs to a monoclinic system, space group P21/c with C16H10Cu3O12, Mr = 584.86, a = 5.0349(3), b = 10.422(1), c = 15.639(1) ?, β = 91.977(2)o, V = 820.1(1) ?3, Z = 2, Dc= 2.368 g/cm3, μ = 3.931 mm―1, λ(MoKα) = 0.71073 ?, F(000) = 578, the final R = 0.0328 and wR = 0.0742 for 1730 observed reflections with I≥2σ(I). The copper atoms show different coordination environments. Each bdcO group is binds to three copper atoms through oxygen atoms of carboxy- lates and deprononated hydroxy group in bridging and chelating fashions, affording a copper atom coordinated by two [Cu2(bdcO)2]2- ‘matallo-ligand’ to yield an extending zigzagged layer perpen- dicular to the c axis.