Gas-Phase Reactions of Cationic Vanadium-Phosphorus Oxide Clusters with C2Hx (x=4, 6): A DFT-Based Analysis of Reactivity Patterns

The reactivities of the adamantane-like heteronuclear vanadium-phosphorus oxygen cluster ions [V(x)P(4-x)O(10)](.+) (x=0, 2-4) towards hydrocarbons strongly depend on the V/P ratio of the clusters. Possible mechanisms for the gas-phase reactions of these heteronuclear cations with ethene and ethane have been elucidated by means of DFT-based calculations; homolytic C-H bond activation constitutes the initial step, and for all systems the P-O(.) unit of the clusters serves as the reactive site. More complex oxidation processes, such as oxygen-atom transfer to, or oxidative dehydrogenation of the hydrocarbons require the presence of a vanadium atom to provide the electronic prerequisites which are necessary to bring about the 2e(-) reduction of the cationic clusters.