A laser ablation-molecular beam/reflectron time-of-flight mass spectrometric technique was used to investigate the ion-molecule reactions that proceed within Ti+(ROH)n (R = C2H5, CF3CH2) heterocluster ions. The mass spectra exhibit a major sequence of cluster ions with the formula Ti+(OR)m(ROH)n (m = 1, 2), which is attributed to sequential insertions of Ti+ into the O-H bond of C2H5OH or CF3CH2OH molecules within the heteroclusters, followed by H eliminations. The TiO+ and TiOH+ ions produced from the reactions of Ti+ with C2H5OH are interpreted as arising from insertion of Ti+ into the C-O bond, followed by C2H5 and C2H6 eliminations, respectively. When Ti+ reacted with CF3CH2OH, by contrast, considerable contributions from TiFOH+, TiF2+, and TiF2OH+ ions were observed in the mass spectrum of the reaction products, indicating that F and OH abstractions are the dominant product channels. Ab initio calculations of the complex of Ti+ with 2,2,2-trifluoroethanol show that the minimum energy structure is that in which Ti+ is attached to the O atom and one of the three F atoms of 2,2,2-trifluoroethanol, forming a five-membered ring. Isotope-labeling experiments additionally show that the chemical reactivity of heterocluster ions is greatly influenced by the presence of fluorine substituents and cluster size. The reaction energetics and formation mechanisms of the observed heterocluster ions are discussed.

A laser ablation-molecular beam/reflectron time-of-flight mass spectrometric technique was used to investigate the ion-molecule reactions that proceed within Ti + (CH3COCH3)n heterocluster ions. The reactions of Ti + with CH3COCH3 clusters were found to be dominated exclusively by an oxidation reaction, which produced TiO + (CH3COCH3)n clusters. These ions were attributed to the insertion of a Ti + ion into the C=O bond of the acetone molecule within the heteroclusters, followed by C3H6 elimination. The mass spectra also indicated the formation of minor sequences of heterocluster ions with the formulas Ti + (C3H4O)(CH3COCH3)n and TiO + (OH)(CH3COCH3)n, which could be attributed to C-H bond insertion followed by H2 elimination and to the sequential OH abstraction by the TiO + ion, respectively. Density functional theory calculations were carried out to model the structures and binding energies of both the association complexes and the relevant reaction products. The reaction pathways and energetics of the TiO + + CH2CHCH3 product channel are presented.