Spin−Orbit Coupling in the Oxidative Activation of H−H by FeO+. Selection Rules and Reactivity Effects

Abstract

Spin−orbit coupling (SOC) calculations are performed along the reaction pathway of the oxidation process, FeO+ + H2 → Fe+ + H2O (eq 1). Selection rules are derived for SOC between different spin situations, and are applied to understand the computed SOC patterns along the oxidation pathway, and their relationship to the electronic structure of the various species. The process involves two spin inversion (SI) junctions between sextet and quartet states: near the FeO+/H2 cluster at the entrance channel, and near the Fe+/H2O cluster at the exit channel. The sextet−quartet SOC is significant at the reactant extreme (for FeO+), but decreases at the FeO+/H2 cluster and continues to decrease until it becomes vanishingly small between the 6D−4F states of Fe+ at the product extreme. The results show that while the quartet surface provides a low-energy path, the SI junctions reduce the probability of the oxidation process significantly. In agreement with the deductions of Armentrout et al.,2c the poor bond activat...