Quantum Chemical Study on the Multi-Electron Transfer of Keggin-Type Polyoxotungstate Anions: The Relation of Redox Potentials to the Bond Valence of µ₄-O-W

Abstract

By selectively investigating the effect of the bond valence using the hypothetical [(PO₄)W₁₂O₃₆]^3– species having various bond valences, we could clearly reveal the origin of the linear dependence of the LUMO energy (or the redox potential) on the bond valence. The LUMO of the Keggin-type polyoxotungstates mainly consists of W 5d. The energy of W 5d as well as of the LUMO goes down as the bond valence becomes large (i.e., as the net electron population on W decreases due to the electron-withdrawing effect of the μ₄-O atoms). This is the origin of the linear dependence of LUMO energy on the bond valence.