A polyoxometalate supported copper dimeric complex: Synthesis, structure and electrocatalysis

Abstract

A polyoxometalate (POM) supported copper dimeric complex, [Mo8O26{Cu2(2,2′-bpy)2 (CH3COO)2H2O}2]٠H4Mo8O26·16H2O (1) has been synthesized using conventional wet synthesis. The compound has been characterized using routine spectral techniques and its molecular structure has been elucidated using single crystal X-ray crystallography. The two copper(II) ions are bridged by acetate ions and each copper ion is also coordinated to 2,2′-bipyridine molecule. In each dimer, one of the copper ions is bonded to the POM anion from one side, whereas the other copper ion is bonded to a water molecule, hence acquiring a penta-coordinated square pyramidal structure around each copper center. The lattice water molecules play an important role to stabilize the system, by forming a water pentamer, which binds both the polyoxometalate supported transition metal complex and the other POM anion [Mo8O26]4–. Interestingly, compound 1 is found to function as a versatile heterogeneous electro-catalyst for water oxidation, proton reduction and hydrogen peroxide reduction.