Acid-Induced, Oxygen-Atom Defect Formation in Reduced Polyoxovanadate-Alkoxide Clusters.

Here, we present the first example of acid-induced, oxygen-atom abstraction from the surface of a polyoxometalate cluster. Generation of the oxygen-deficient vanadium oxide, [V6O6(OC2H5)12]1-, was confirmed via independent synthesis. Spectroscopic analysis using infrared and electronic absorption spectroscopies affords resolution of the electronic structure of the oxygen-deficient cluster (oxidation state distribution = [VIIIVIV5]). This work has direct implications toward the elucidation of possible mechanisms of acid-assisted vacancy formation in bulk transition metal oxides, in particular electron-proton codoping that has recently been described for vanadium oxide (VO2). Ultimately, these molecular models deepen our understanding of proton-dependent redox chemistry of transition metal oxide surfaces.