Reactions of vanadium oxide cluster ions with 1,3-butadiene and isomers of butene

The gas-phase reactions of vanadium oxide cluster ions with 1,3-butadiene and the isomers of butene are examined. The correlation between the reaction products and the cluster stoichiometry, oxidation and charge-state are explored by studying the reactivity of 1,3-butadiene (C₄H₆) and the deuterated 1,3-butadienes C₄D₆ and 1,1,4,4-C₄D₄H₂ with the clusters cations V₃O₆⁺, V₃O₇⁺, and V₃O₈⁺ and the anions VO_2.3^-, V₂O_4-6^-, V₃O_6-9^- and V₄O_10.11^-. These studies further our understanding of the reactions of V_xO_y⁺ clusters with hydrocarbons, as reported previously [Bell, R. C.; Zemski, K. A.; Kerns, K. P.; Deng, H. T.; Castleman, Jr., A. W. J. Phys. Chem. A 1998, 102, 1733], by examining the reaction of the anions (V_xO_y^-), deuterated butadiene species and the 2-butenes. The reactions of C₄D₆ and 1,1,4,4-C₄D₄H₂ with the cluster V₃O₇⁺ demonstrate pathways for the loss of a single oxygen, oxidative dehydrogenation, and molecular association, as well as other minor products, analogous to the products previously reported for the reactions of these clusters with C₄H₆. The reactions of V₃O₇⁺ with the isomers of butene (1-butene, cis-2-butene and trans-2-butene) display many of the same reaction pathways that are observed for 1,3-butadiene, namely, oxidation of the hydrocarbon, oxidative dehydrogenation, and molecular association. In addition, a major channel representing the dehydrogenation of the alkene and a minor channel for C2-C3 cracking of the alkene, along with other minor products is also observed. The anionic clusters VO_2.3^-, V₂O_4.5, V₃O_6-8^-, and V₄O₁₀^- do not react with either 1,3-butadiene or 1-butene, whereas clusters of higher oxygen content, V₂O₆^-, V₃O₉^-, and V₄O₁₁^- display a minor reaction channel for the loss of a single oxygen atom, presumably through oxidation of the hydrocarbon and resulting in the cluster V_xO_y-1^-.