Sc (or HClO) Activation of a Nonheme Fe-OOH Intermediate for the Rapid Hydroxylation of Cyclohexane and Benzene.

[Fe(β-BPMCN)(CHCN)] (1, BPMCN = N,N' -bis(pyridyl-2-methyl)- N,N' -dimethyl- trans-1,2-diaminocyclo-hexane) is a relatively poor catalyst for cyclohexane oxidation by HO and cannot perform benzene hydroxylation. However, addition of Sc activates the 1/HO reaction mixture to be able to hydroxylate cyclohexane and benzene within seconds at -40 °C. A metastable S = 1/2 Fe-(η-OOH) intermediate 2 is trapped at -40 °C, which undergoes rapid decay upon addition of Sc at rates independent of [substrate] but linearly dependent on [Sc]. HClO elicits comparable reactivity as Sc at the same concentration. We thus postulate that these additives both facilitate O-O bond heterolysis of 2 to form a common highly electrophilic Fe═O oxidant that is comparably reactive to the fastest nonheme high-valent iron-oxo oxidants found to date.