Differences and Commonalities in the Gas-Phase Reactions of Closed-Shell Metal Dioxide Clusters [MO2]+ (M=V, Nb, and Ta) with Methane

High-level electronic structure calculations, in combination with Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometric studies, permit the mechanism by which closed-shell, naked [TaO2](+) brings about C-H bond activation of methane to be revealed. These studies also help to understand why the lighter congeners of [MO2](+) (M=V, Nb) are unreactive under ambient conditions.