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

1 INTRODUCTION Tungsten and molybdenum are chemically analogous elements. Because of their great similari- ties in properties, it was reasonable that the insight into catalytic role of Mo in various enzymes may be provided by replacing Mo with W. In order to un- derstand the chemistry and oxo-transfer properties of these enzymes, numerous dioxo-Mo(VI) and di- oxo-W(VI) complexes with a wide range of ligands have been prepared and structurally characteriz- ed[1～5]. Moreover, hydroxyca…

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.