Geometric and Electronic Structures of VB Clusters and Reactivity of the Cationic Cluster with Methane from Quantum Chemical Calculations.

Quantum chemical methods have been employed to study the geometric and electronic structures of VB clusters and the mechanism of the reaction of the cationic clusters with methane. It was found that the ground states of the neutral and cationic clusters were A' and A' of a planar isomer in symmetry in which vanadium atom side-on binds to the rhombic B moiety. The ionization energy of the neutral cluster was calculated to be 7.13 eV at the CCSD(T) level. The reaction pathways on the triplet and quintet potential energy profiles of the dehydrogenation and elimination of V in the reaction of VB cluster with methane were established based on the BPW91 functional calculations. Both of the dehydrogenation and elimination of V in the reaction of VB cluster with methane were initiated by the B moiety of the VB cluster, and these two reaction channels were thermodynamically and kinetically favorable. The dehydrogenation and elimination of V in the reaction of VB cluster with methane were exothermic processes.