Sc3+ (or HClO4) Activation of a Nonheme FeIII-OOH Intermediate for the Rapid Hydroxylation of Cyclohexane and Benzene

[Fe(beta-BPMCN)(CH3CN)(2)](2+) (1, BPMCN = N,N'-bis (pyridyl-2-methyl)-N,N'-dimethyl-trans-1,2-diamino-cyclo-hexane) is a relatively poor catalyst for cyclohexane oxidation by H2O2 and cannot perform benzene hydroxylation. However, addition of Sc3+ activates the 1/H2O2 reaction mixture to be able to hydroxylate cyclohexane and benzene within seconds at -40 degrees C. A metastable S = 1/2 Fe-III-(eta 1-OOH) intermediate 2 is trapped at -40 degrees C, which undergoes rapid decay upon addition of Sc3+ at rates independent of [substrate] but linearly dependent on [Sc3+]. HClO4 elicits comparable reactivity as Sc3+ 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-v=O oxidant that is comparably reactive to the fastest nonheme high-valent iron-oxo oxidants found to date.