Oxygen isotope effects upon reversible O2-binding reactions: Characterizing mononuclear superoxide and peroxide structures.

Identifying intermediates in catalytic oxidation reactions requires the development of new probes of structure and mechanism. Reported here are proof-of-concept studies of oxygen (18O) isotope effects upon reversible O2-binding reactions of classic inorganic compounds. It is shown that the 18O equilibrium isotope effects may be used to differentiate structures where O2 is bound as a side-on peroxide ligand versus an end-on superoxide ligand. The application of 18O equilibrium isotope effects to the interpretation of 18O kinetic isotope effects and the study of O2 activation mechanisms is also discussed.