Sc ³⁺ (or HClO ₄ ) Activation of a Nonheme Fe ^III -OOH Intermediate for the Rapid Hydroxylation of Cyclohexane and Benzene

[Fe(β-BPMCN)(CH ₃ CN) ₂ ] ²⁺ (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 H ₂ O ₂ and cannot perform benzene hydroxylation. However, addition of Sc ³⁺ activates the 1/H ₂ O ₂ reaction mixture to be able to hydroxylate cyclohexane and benzene within seconds at -40 °C. A metastable S = 1/2 Fe ^III -(η ¹ -OOH) intermediate 2 is trapped at -40 °C, which undergoes rapid decay upon addition of Sc ³⁺ at rates independent of [substrate] but linearly dependent on [Sc ³⁺ ]. HClO ₄ elicits comparable reactivity as Sc ³⁺ 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.