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 [W 4(μ 3-Te) 4(CN) 12] 6− and Ca 2+ complex units has been prepared by the reaction of aqueous solution of K 6[W 4(μ 3-Te) 4(CN) 12] · 5H 2O with the solution of a Ca(NO 3) 2 and phen(1,10-phenanthroline) (1:2 molar ratio) in a solvent mixture of H 2O/EtOH. The structure of [{Ca(phen) 2(H 2O)}{Ca(phen)(H 2O) 4}{Ca(phen) 2(H 2O) 3}][W 4Te 4(CN) 12] · 5H 2O 1 has been determined by X-ray crystallography. Compound 1 contains [{Ca(phen)(H 2O) 4}{Ca(phen) 2(H 2O) 3}][W 4(μ 3- Te) 4(CN) 12] units bridged by {Ca(phen) 2(H 2O)} 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.