Heterometallic 3d-4f cluster-containing polyoxotungstate obtained by partial disassembly of preformed large clusters

A new heterometallic 3d-4f cluster-containing polyoxotungstate KNa5{K2Dy2Cu2(H2O)(8)(SbW9O33)(2)}center dot 17H(2)O (1) was designed and synthesized by reaction of the preformed large cluster [N(CH3)(4)](10)Na-12[Na2Sb8W36O132(H2O)(4)]center dot 26H(2)O({Sb8W36}), transition-metal (TM) and Ln(3+) cations. Compound 1 is the first 3d-4f heterometallic cluster-containing sandwich-type tungstoantimonite obtained by partial decomposition of a preformed large cluster. Further, the sandwich-type polyoxoanion combines with two additional 4p cations resulting in a ring-like 3d-4f-4p cluster {K2Dy2Cu2(H2O)(8)}containing polyoxotungstate. The sandwich polyoxoanion {K2Dy2Cu2(H2O)(8)(SbW9O33)(2)} was structurally similar to the well-known anion {K3Cu3(H2O)(10)(SbW9O33)(2)}, in which one alkali metal cation and one TM cation were both replaced by the rare earth metal cations. Furthermore, the 3d-4f-4p cluster-containing polyoxoanions were bridged by the K+ ion located at their central metal belt into a one-dimensional (1D) wavelike chain. An electrochemical study revealed that compound 1 exhibited electrocatalytic activity for reduction of the NO2- and O-2, and a direct 4-electron electrochemical reduction process of O-2 was achieved in 1-containing aqueous solution.