Stoichiometric Formation of an Oxoiron(IV) Complex by a Soluble Methane Monooxygenase Type Activation of O at an Iron(II)-Cyclam Center.

In soluble methane monooxygenase enzymes (MMO), dioxygen (O) is activated at a diiron(II) center to form an oxodiiron(IV) intermediate that performs the challenging oxidation of methane to methanol. An analogous mechanism of O activation at mono- or dinuclear iron centers is rare in the synthetic chemistry. Herein, we report a mononuclear non-heme iron(II)-cyclam complex, -, that activates O to form the corresponding iron(IV)-oxo complex, -, via a mechanism reminiscent of the O activation process in MMO. The conversion of - to - proceeds via the intermediate formation of an iron(III)-superoxide species , which could be trapped and spectroscopically characterized at -50 °C. Surprisingly, is a stronger oxygen atom transfer (OAT) agent than -; performs OAT to - or PPh to yield - quantitatively. Furthermore, - oxidizes the aromatic C-H bonds of 2,6-di--butylphenol, which, together with the strong OAT ability of , represents new domains of oxoiron(IV) and superoxoiron(III) reactivities.