Fine Control of the Redox Reactivity of a Nonheme Iron(III)–Peroxo Complex by Binding Redox‐Inactive Metal Ions

Redox‐inactive metal ions are one of the most important co‐factors involved in dioxygen activation and formation reactions by metalloenzymes. In this study, we have shown that the logarithm of the rate constants of electron‐transfer and C−H bond activation reactions by nonheme iron(III)–peroxo complexes binding redox‐inactive metal ions, [(TMC)FeIII(O2)]+‐Mn+ (Mn+=Sc3+, Y3+, Lu3+, and La3+), increases linearly with the increase of the Lewis acidity of the redox‐inactive metal ions (ΔE), which is determined from the gzz values of EPR spectra of O2.−‐Mn+ complexes. In contrast, the logarithm of the rate constants of the [(TMC)FeIII(O2)]+‐Mn+ complexes in nucleophilic reactions with aldehydes decreases linearly as the ΔE value increases. Thus, the Lewis acidity of the redox‐inactive metal ions bound to the mononuclear nonheme iron(III)–peroxo complex modulates the reactivity of the [(TMC)FeIII(O2)]+‐Mn+ complexes in electron‐transfer, electrophilic, and nucleophilic reactions. Inactive but influential: The Lewis acidity of the redox‐inactive metal ions bound to a mononuclear nonheme iron(III)–peroxo complex, [(TMC)FeIII(O2)]+‐Mn+ (1‐Mn+; Mn+=Sc3+, Y3+, Lu3+, and La3+), determines the reactivities of 1‐Mn+ in electron‐transfer, electrophilic, and nucleophilic reactions.