The gas-phase thermochemistry of TiH

Abstract

The homolytic bond dissociation energy of the titanium neutral hydride D0(Ti–H) is determined experimentally for the first time by using guided ion beam tandem mass spectrometry to measure the kinetic energy dependence of the endothermic hydride abstraction reactions of Ti+ with methylamine, dimethylamine, and trimethylamine. From the thresholds of these reactions, the value of D0(Ti–H)=2.12±0.09 eV (48.9±2.1 kcal/mol) at 298 K is derived. Other 298 K thermodynamic values obtained are D0(Ti+–H−)=8.19±0.09 eV (188.8±2.1 kcal/mol), I.E.(TiH)=6.59±0.14 eV, P.A.(Ti−)=15.64±0.09 eV (360.6±2.1 kcal/mol), and ΔfH(TiH)=116.4±2.3 kcal/mol. This thermochemistry is compared with theoretical values and its relationship to hydride bond energies for the other first row transition metals is discussed.