Oxygen-Atom Vacancy Formation at Polyoxovanadate Clusters: Homogeneous Models for Reducible Metal Oxides

We report the first example of oxygen-atom vacancy formation at the surface of a polyoxometalate, highlighting the ability of a polyoxovanadate-alkoxide cluster, [V₆O₇(OCH₃)₁₂]^1-, to function as a homogeneous model for reducible metal oxides. The removal of an oxide ion from [V₆O₇(OCH₃)₁₂]^1- results in the formation of a reactive vanadium(III) cation within the multimetallic framework. Generation of [V₆O₆(OCH₃)₁₂]^1- is confirmed by ¹H NMR, infrared and electronic absorption spectroscopies, as well as electrospray ionization mass spectrometry. The consequences of oxygen atom removal on the electrochemical profile of the assembly are assessed, revealing that stabilization of the reduced cluster is achieved through delocalized electron density. The oxygen-atom vacancy permits activation of O₂, demonstrating the ability of polyoxovanadate-alkoxide clusters to serve as both structural and functional models of reducible metal oxides.