Synthesis, structure, and heterogeneous catalytic activity of tungsten chalcogenide cubane cluster containing alkaline earth metal complex

Abstract

A new compound containing a cubane tungsten chalcogenide cluster [W4(μ3-Te)4(CN)12]6- and Ca2+ complex units has been prepared by the reaction of aqueous solution of K6[W4(μ3-Te)4(CN)12] · 5H2O with the solution of a Ca(NO3)2 and phen(1,10-phenanthroline) (1:2 molar ratio) in a solvent mixture of H2O/EtOH. The structure of [{Ca(phen)2(H2O)}{Ca(phen)(H2O)4}{Ca(phen)2(H2O)3}][W4Te4(CN)12] · 5H2O 1 has been determined by X-ray crystallography. Compound 1 contains [{Ca(phen)(H2O)4}{Ca(phen)2(H2O)3}][W4(μ3- Te)4(CN)12] units bridged by {Ca(phen)2(H2O)}2+ units to form an one-dimensional zigzag chain structure. Interestingly, compound 1 showed a heterogeneous catalytic activity in the transesterification of a range of esters with methanol under the mild conditions. Moreover, it can be reused without any loss of activity through 10 runs with ester. © 2007 Elsevier B.V. All rights reserved.