Spin state tuning of non-heme iron-catalyzed hydrocarbon oxidations: participation of FeIII–OOH and FeVO intermediates

Abstract

We have found a family of non-heme iron complexes [Fe^II(L)(CH₃CN)₂] (L = tetradentate pyridine containing ligand) with cis labile sites that catalyze highly stereoselective hydrocarbon oxidations using H₂O₂ as oxidant. The hydrocarbon oxidation reactivity patterns of this family of catalysts divide them into two subgroups: Category A catalysts which carry out highly stereoselective alkane hydroxylation, olefin epoxidation, and olefin cis-dihydroxylation via low-spin Fe^III–OOH, Fe^VO intermediates and Category B catalysts which form high-spin Fe^III–OOH intermediates and strongly favor olefin cis-dihydroxylation in which both diol oxygen atoms derive from H₂O₂. 6-Methyl substituents on the ligands play an important role in tuning the spin states of the iron centers to afford a family of non-heme iron complexes that catalyze a remarkable array of hydrocarbon oxidation reactions.