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

Abstract

A new heterometallic 3d–4f cluster-containing polyoxotungstate KNa₅{K₂Dy₂Cu₂(H₂O)₈(SbW₉O₃₃)₂}·17H₂O (1) was designed and synthesized by reaction of the preformed large cluster [N(CH₃)₄]₁₀Na₁₂[Na₂Sb₈W₃₆O₁₃₂(H₂O)₄]·26H₂O ({Sb₈W₃₆}), transition-metal (TM) and Ln³⁺ 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 O₂, and a direct 4-electron electrochemical reduction process of O₂ was achieved in 1-containing aqueous solution.