Reactions of fourth-period metal ions (Ca⁺-Zn⁺) with O₂: Metal-oxide ion bond energies

Abstract

Reactions of Ca+, Zn+ and all first-row atomic transition metal ions with O2 are studied using guided ion beam techniques. While reactions of the ground states of Sc+, Ti +, and V+ are exothermic, the remaining metal ions react with O2 in endothermic processes. Analyses of these endothermic reactions provide new determinations of the M+-O bond energies for these eight elements. Source conditions are varied such that the contributions of excited states of the metal ions can be explicitly considered for Mn +, Co+, Ni+, and Cu+. Results (in eV) at 0 K are D0(Ca+-O) = 3.57 ± 0.05, D 0(Cr+-O) = 3.72 ± 0.12, D0(Mn +-O) = 2.95 ± 0.13, D0(Fe+-O) = 3.53 ± 0.06 (reported previously), D0(Co+-O) = 3.32 ± 0.06, D0(Ni+-O) = 2.74 ± 0.07, D 0(Cu+-O) = 1.62 ± 0.15, and D0(Zn +-O) = 1.65 ± 0.12. These values along with literature data for neutral metal oxide bond energies and ionization energies are critically evaluated. Periodic trends in the ionic metal oxide bond energies are compared with those of the neutral metal oxides and those of other related molecules. © 1990 American Institute of Physics.