Chemical Reactivity of Ti+within Water, Dimethyl Ether, and Methanol Clusters

Abstract

The intracluster ion-molecule reactions of Ti + (H2O)n, Ti + (CH3OCH3)n, and Ti + (CH3OD)n complexes produced by the mixing of the laser-vaporized plasma and the pulsed supersonic beam were studied using a reflectron time-of-flight mass spectrometer. The reactions of Ti + with water clusters were dominated by the dehydrogenation reaction, which produces TiO + (H2O)n clusters. The mass spectra resulting from the reactions of Ti + with CH3OCH3 clusters exhibit a major sequence of Ti + (OCH3)m(CH3OCH3)n cluster ions, which is attributed to the insertion of Ti + ion into C-O bond of CH3OCH3 followed by CH3 elimination. The prevalence of Ti + (OCH3)m(CH3OD)n ions in the reaction of Ti + with CH3OD clusters suggests that D elimination via O-D bond insertion is the preferred decomposition pathway. In addition, the results indicate that consecutive insertion reactions by the Ti + ion occur for up to three precursor molecules. Thus, examination of Ti + insertion into three different molecules establishes the reactivity order: O-H > C-O > C-H. The experiments additionally show that the chemical reactivity of heterocluster ions is greatly influenced by cluster size and argon stagnation pressure. The reaction energetics and formation mechanisms of the observed heterocluster ions are also discussed.