THE GAS-PHASE THERMOCHEMISTRY OF TIH

The homolytic bond dissociation energy of the titanium neutral hydride D 0(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 D 0(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 D 0(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 DELTA-f-H(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.