REACTIONS OF SCO+, TIO+, AND VO+ WITH D2 - M+-OH BOND-ENERGIES AND EFFECTS OF SPIN CONSERVATION

Cross sections for the reactions of ScO+, TiO+, and VO+ with D2 have been measured as a function of translational energy in a guided ion beam tandem mass spectrometer. All three MO+ ions react with D2 to form three products, M+, MD+, and MOD+, in endothermic processes. Production of M+ in all systems is accompanied by formation of water. The energetics measured for these reactions correspond to production of M+ primarily in an excited low-spin electronic state. Formation of ground-state M+ is also observed, even though this reaction channel does not conserve spin. Reaction mechanisms and qualitative potential energy surfaces are proposed to explain this behavior. Thresholds for the formation of MOD+ in these systems are interpreted to give the 0 K bond energies, D-degrees(Sc+-OD) = 5.17 +/- 0.09, D-degrees(Ti+-OD) = 4.82 +/- 0. 12, and D-degrees(V+-OD) = 4.50 +/- 0. 1 5, all in electronvolts. The large bond strengths for the M+-OD species indicate that the lone pairs of electrons on the oxygen atom are involved in the bonding.