ChemInform Abstract: Reactions of ScO+, TiO+, and VO+ with D2: M+-OH Bond Energies and Effects of Spin Conservation

Cross sections for the reactions of ScO[sup +], TiO[sup +], and VO[sup +] with D[sub 2] have been measured as a function of translational energy in a guided ion beam tandem mass spectrometer. All three MO[sup +] ions react with D[sub 2] to form three products, M[sup +], MD[sup +], and MOD[sup +], in endothermic processes. Production of M[sup +] in all systems is accompanied by formation of water. The energetics measured for these reactions correspond to production of M[sup +] primarily in an excited low-spin electronic state. Formation of ground-state M[sup +] 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[sup +] in these systems are interpreted to give the 0 K bond energies, D[degree](Sc[sup +]-OD) = 5.17 [+-] 0.09, D[degree](Ti[sup +]-OD) = 4.82 [+-] 0.12, and D[degree](V[sup +]-OD) = 4.50 [+-] 0.15, all in electronvolts. The large bond strengths for the M[sup +]-OD species indicate that the lone pairs of electrons on the oxygen atom are involved in the bonding. 48 refs., 9 figs., 4 tabs.