Gas-phase chemistry of vanadium oxide cluster cations. 2. Reactions with CH2F2

Reactions comprised of oxygen transfer in conjunction with the abstraction of two fluorine atoms from difluoromethane are observed in the gas-phase ch emistry of various selected vanadium oxide cluster ions. These studies were performed on a triple quadrupole mass spectrometer coupled with a laser va porization source. Aside from the oxygen transfer reactions, channels for t he loss of molecular oxygen and the association of CH2F2 to the clusters we re also observed. For example, the cluster V3O7+ reacted with CH2F2 to prod uce V3O6F2+ in addition to the association product V3O7. CH2F2+ with both c hannels occurring under single collision conditions and near thermal energi es at ambient temperature. The vanadium oxide species V2O4-6+, V3O6-8+, V4O 8-11+, V5O11-13+, V6O13-15+, and V7O16-18+ were individually selected and t heir reactivities compared by examining the relative product branching rati os. The reactivity of the VxOy+ species with difluoromethane displayed a di stinct dependence on the size of the clusters. The smaller clusters were mo st reactive while the larger clusters were observed to be inert toward reac tion with difluoromethane with the exception of the oxygen-rich clusters, w hich simply lost molecular oxygen upon collision with the reactant gas.