The activation of dioxygen by iron enzymes generally involves the formation of a high-valent iron oxidant. For heme enzymes, this oxidant is formally an iron(V) species but is best described as an S = 1 oxoiron(IV) unit that is coordinated to a porphyrin radical cation. For most mononuclear nonheme iron enzymes, the high-valent oxidant is likely to be an S = 2 oxoiron(IV) unit that is coordinated to histidine and carboxylate donors. However an oxoiron(V) species is postulated in the case of the Rieske dioxygenases, and a diron(IV) oxidant with an Fe2O2 diamond core is proposed for diiron enzymes such as methane monooxygenase. An important goal of our research effort has been to characterize synthetic high-valent oxoiron complexes that model these biological oxidants. With polydentate ligands of relatively simple design, we have been able to obtain analogs of these biological oxidants and gain insight into their electronic structures and C�H bond cleavage reactivity. Some recent highlights will be presented.

Adventures in modeling high-valent iron

243rd National Meeting (2012)

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