Alkane functionalization at nonheme iron centers. Mechanistic insights

Biological catalysts capable of functionalizing alkanes include cytochrome P450 (which contains a heme active site) and methane monooxygenase (MMO, which has a nonheme diiron active site). For cytochrome P450, an oxoiron (IV)(porphyrin cation radical) complex derived from the heterolysis of the O-O bond in an intermediate ferric peroxide is strongly implicated as the active species in the cytochrome P-450 mechanism. Little mechanistic insight into the nature of the oxidizing species has been obtained from these investigations. The authors intiated an investigation of the reactivity of iron complexes with tripodal ligands in combination with t-butyl hydroperoxide to gain insight into how nonheme iron centers may effect such chemistry. The tripodal ligands selected for this study offer the important advantage of systematic control over the ligand environment at a labile iron center.