Spin state tuning of non-heme iron-catalyzed hydrocarbon oxidations:: participation of FeIII-OOH and FeV=O intermediates

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 stereo-selective 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-V=O 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.