Ion-Molecule Reaction of Ti⁺ Ion with Trifluoroacetone in the Gas Phase

Gas-phase ion-molecule reactions of Ti⁺ with 1,1,1-trifluoroacetone were studied by laser ablation/molecular-beam method and density function theory calculations. In the reaction of the Ti⁺ ions with acetone, Ti⁺ ion insertion into the C=O bond is the preferred decomposition pathway and produce TiO⁺ predominantly. Substitution of CH₃ in acetone molecule with electronegative CF₃ group greatly alters the reaction pathway, which is confirmed from TiF₂⁺ and TiO⁺ observations by mass spectrometry. This is interpreted as the dominant reaction channels via Ti⁺ insertions into C–F and C=O bonds of trifluoroacetone molecule. In addition, geometries and energies of the intermediates and transition states involved in two pathways are located by DFT calculations. On the basis of these results, two pathways are considered as competitive and the most favorable pathway proceeds via Ti⁺ induced C–F bond activation processes.