Inorganic Chemistry, Vol.51, No.21, 11574-11581, 2012
Synthesis and Reversible Transformation of Cu-n-Bridged (n=1, 2, or 4) Silicodecatungstate Dimers
Three copper-bridged sandwich-type silicodecatungstate dimers, TBA(8)[Cu(gamma-SiW10O34)(2)(CH3CONH)(2)]center dot 4H(2)O (Cu-1, TBA = tetra-n-butylammonium), TBA(8)H(4)[Cu-2(gamma-SiW10O36)(2)H2O]center dot 11H(2)O center dot CH3COCH3 (Cu-2), and TBA(8)H(2)[Cu-4(gamma-SiW10O36)(2)(CH3COO)(2)]center dot 5H(2)O (Cu-4) have been selectively synthesized by reactions of divacant lacunary TBA(4)-[H-4(gamma-SiW10O36)] (SiW10) with copper acetate in organic media. The copper cation(s) in Cu-1, Cu-2, and Cu-4 possess square-planar four-coordinate (Cu-1), square-pyramidal five-coordinate (Cu-2), and octahedral six-coordinate (Cu-4) geometries, respectively. These compounds can reversibly be transformed simply by controlling the copper/SiW10 molar ratios in solutions.