Transient oxygenation of chelated iron(II) porphyrins: improved kinetics of carbon monoxide replacement by oxygen

Abstract

The kinetics of CO replacement by O₂(Gibson's equation) cannot be applied without modification to the study of unstable oxyheme model compounds which bind oxygen weakly. A generalization of Gibson's equation is proposed. Using the time resolution offered by laser photolysis techniques, the oxygen ‘off’ rates are determined both from the fast oxygen-binding phase following photodissociation of the carboxyhemochrome as well as from the modified kinetics of the subsequent ligand exchange. Applications to chelated tetraphenylporphyrin and deuteroporphyrin model compounds are reported.