C-H Oxidation by a Diiron Complex with Facially Opposing Active Sites

C-H oxidation is catalyzed by a high-spin ferrous dimer, [(L-1)(2)Fe-2(CH3CN)(2)](PF6)(4) (1), that offers two identical functional sites, separated by > 7 angstrom. The complex provides a unique contrast to both mononuclear and binuclear non-heme enzyme active sites as well as biomimetic complexes. The oxidative activity of 1 was examined using a range of substrates (cyclohexene, 9,10-dihydroanthracene, xanthene, triphenylmethane, triphenylphosphine, and cyclohexane) and PhIO as an oxidant. The studies establish the O-atom transfer and H-atom abstraction ability of the diiron complex. We further probe the energetics of cyclohexene oxidation by 1 and derive putative mechanisms for the pathways of allylic alcohol and epoxide formation using density functional theory (DFT) calculations. The DFT calculations indicate that the oxidation reactions proceed via a Fe-IV = O species in the triplet state, and that both iron centers can act independently of each other. The combined results provide insight into hydrocarbon oxidation by non-coupled binuclear systems.