Molecular mechanism of C–H bond cleavage at transition metal oxide clusters

The molecular mechanism of the cleavage of the C–H bond at oxide surfaces seems to be different from the oxidative addition and from the simple result of the interaction with an M–O site at the surface, representing an acid–base pair. In this Letter a novel mechanism of this process is proposed where both fragments of the cleaved C–H bond become attached to the surface oxide ions. The proton forms an OH group, the hydrocarbon fragment forms an alkoxy group. Simultaneously, the two electrons of the cleaved bond are injected into the conductivity band. The proposed mechanism is based on results of density functional theory calculations for methane molecule interacting as well with small vanadium oxide particles as cluster models mimicking fragments of the oxide surface.