Oxygen isotope effects as structural and mechanistic probes in inorganic oxidation chemistry

Oxidative transformations using molecular oxygen are widespread in nature but remain a major challenge in chemical synthesis. Limited mechanistic understanding presents the main obstacle to exploiting O(2) in "bioinspired" industrial processes. Isotopic methods are presently being applied to characterize reactions of natural abundance O(2) including its coordination to reduced transition metals and cleavage of the O-O bond. This review describes the application of competitive oxygen-18 isotope effects, together with Density Functional Theory, to examine O(2) reductive activation under catalytically relevant conditions. The approach should be generally useful for probing small-molecule activation by transition-metal complexes.