Gas-phase chemistry of vanadium oxide cluster cations. 1. Reactions with C₂F₆ and CH₃CF₃

The reactivities of mass-selected vanadium oxide cluster cations with fluorocarbons were studied by using a triple-quadrupole mass spectrometer coupled with a laser vaporization source. The vanadium oxide species V₂O_4-7+, V₃O_6-9+, V₄O_8-11+, V₅O_11-13+, V₆O_13-16+, and V₇O_16-18+ displayed unique reactivities with CH₃-CF₃ and C₂F₆. Among the reaction pathways observed were association, HF elimination, cracking of the carbon-carbon bond, and fluorine abstraction with oxygen transfer from the cluster to the neutral reactant molecule. Interestingly, the reactions differed for clusters within the same series and also from series to series. For example, the reaction of V₂O₄₊ with CH₃CF₃ produces the HF-elimination product V₂O₄·HF⁺. However, the cluster V₂O₅₊ reacts with CH₃CF₃ to produce the cracking product V₂O₅·CF₃₊ but also reacts to abstract 2 fluorine atoms with transfer of an oxygen atom to the neutral reactant molecule. The reaction of these 2 clusters with C₂F₆ generates only association products.