Bi-antimony capped Keggin polyoxometalate modified with Cu-ligand fragment

Three polyoxometalates consisting of bi-antimony capped Keggin-type clusters: [Cu(mbpy)(2)](2) [PMo12O40Sb2]center dot 4H(2)O (1), [Cu(mbpy)(2)][PMo12O40Sb2] (2) and {Cu(mbpy)[Cu(mbpy)(2)](2)}[VMo8V4O40Sb2]. 2H(2)O (3) (mbpy=4,4'-dimethyl-2,2'- dipyridyl in 1 and 2; 5,5'-dimethyl-2,2'-dipyridyl in 3) have been synthesized and characterized by IR, X-ray powder diffraction, TG analysis and electrochemical property. Single-crystal analysis revealed that all of three compounds are built upon bi-antimony capped Keggin-type polyoxoanions and Cu-mbpy cations. In 1-3, two Sb-III centers located at the two opposite of anionic surface adopt fundamentally tetragonal pyramidal coordination geometry. Both compounds 1 and 2 consist of P-centered Keggin structure, while compound 3 presents a V-centered Keggin anion. The Keggin-type anions present different structural features: isolated cluster in 1 and Cu-ligand-supported cluster in 2 and 3. (C) 2012 Elsevier Inc. All rights reserved.