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A mononuclear nonheme iron(III)-peroxo complex binding redox-inactive metal ions
- A mononuclear nonheme iron(III)-peroxo complex binding redox-inactive metal ions
- Lee, YM[Lee, Yong-Min]; Bang, S[Bang, Suhee]; Kim, YM[Kim, Yun Mi]; Cho, J[Cho, Jaeheung]; Hong, S[Hong, Seungwoo]; Nomura, T[Nomura, Takashi]; Ogura, T[Ogura, Takashi]; Troeppner, O[Troeppner, Oliver]; Ivanovic-Burmazovic, I[Ivanovic-Burmazovic, Ivana]; Sarangi, R[Sarangi, Ritimukta]; Fukuzumi, S[Fukuzumi, Shunichi]; Nam, W[Nam, Wonwoo]
- DGIST Authors
- Cho, J[Cho, Jaeheung]
- Issue Date
- Chemical Science, 4(10), 3917-3923
- Article Type
- Binding Energy; Biomimetic Compounds; Biomimetic Reactions; Biomimetics; Chemical Activation; Electron-Transfer Reactions; Electrons; Ionization of Gases; Iron Compounds; Metal Complexes; Metal Ions; Non-Heme Iron Enzymes; One-Electron Reductions; Organometallics; Oxidation; Oxidation Potentials; Peroxides; Rate Determining Step; Redox Reactions; Reduction; Reorganization Energies; Scandium
- Redox-inactive metal ions that function as Lewis acids play pivotal roles in modulating reactivities of oxygen-containing metal complexes in a variety of biological and biomimetic reactions, including dioxygen activation/formation and functionalization of organic substrates. Mononuclear nonheme iron(iii)-peroxo species are invoked as active oxygen intermediates in the catalytic cycles of dioxygen activation by nonheme iron enzymes and their biomimetic compounds. Here, we report mononuclear nonheme iron(iii)-peroxo complexes binding redox-inactive metal ions, [(TMC)FeIII(O2)] +-M3+ (M3+ = Sc3+ and Y 3+; TMC = 1,4,8,11-tetramethyl-1,4,8,11-tetraazacyclotetradecane), which are characterized spectroscopically as a 'side-on' iron(iii)-peroxo complex binding a redox-inactive metal ion, (TMC)FeIII-(μ, η2:η2-O2)-M3+ (2-M). While an iron(iii)-peroxo complex, [(TMC)FeIII(O2)]+, does not react with electron donors (e.g., ferrocene), one-electron reduction of the iron(iii)-peroxo complexes binding redox-inactive metal ions occurs readily upon addition of electron donors, resulting in the generation of an iron(iv)-oxo complex, [(TMC)FeIV(O)]2+ (4), via heterolytic O-O bond cleavage of the peroxide ligand. The rates of the conversion of 2-M to 4 are found to depend on the Lewis acidity of the redox-inactive metal ions and the oxidation potential of the electron donors. We have also determined the fundamental electron-transfer properties of 2-M, such as the reduction potential and the reorganization energy in electron-transfer reaction. Based on the results presented herein, we have proposed a mechanism for the reactions of 2-M and electron donors; the reduction of 2-M to the reduced species, (TMC)FeII-(O2)-M3+ (2′-M), is the rate-determining step, followed by heterolytic O-O bond cleavage of the reduced species to form 4. The present results provide a biomimetic example demonstrating that redox-inactive metal ions bound to an iron(iii)-peroxo intermediate play a significant role in activating the peroxide O-O bond to form a high-valent iron(iv)-oxo species. © 2013 The Royal Society of Chemistry.
- Royal Society of Chemistry
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