title: Catalytic two-electron reduction of dioxygen by ferrocene derivatives with manganese(V) corroles.
abstract: Electron transfer from octamethylferrocene (Me8Fc) to the manganese(V) imidocorrole complex (tpfc)Mn(V)(NAr) [tpfc = 5,10,15-tris(pentafluorophenyl)corrole; Ar = 2,6-Cl2C6H3] proceeds efficiently to give an octamethylferrocenium ion (Me8Fc(+)) and [(tpfc)Mn(IV)(NAr)](-) in acetonitrile (MeCN) at 298 K. Upon the addition of trifluoroacetic acid (TFA), further reduction of [(tpfc)Mn(IV)(NAr)](-) by Me8Fc gives (tpfc)Mn(III) and ArNH2 in deaerated MeCN. TFA also results in hydrolysis of (tpfc)Mn(V)(NAr) with residual water to produce a protonated manganese(V) oxocorrole complex ([(tpfc)Mn(V)(OH)](+)) in deaerated MeCN. [(tpfc)Mn(V)(OH)](+) is rapidly reduced by 2 equiv of Me8Fc in the presence of TFA to give (tpfc)Mn(III) in deaerated MeCN. In the presence of dioxygen (O2), (tpfc)Mn(III) catalyzes the two-electron reduction of O2 by Me8Fc with TFA in MeCN to produce H2O2 and Me8Fc(+). The rate of formation of Me8Fc(+) in the catalytic reduction of O2 follows zeroth-order kinetics with respect to the concentrations of Me8Fc and TFA, whereas the rate increases linearly with increasing concentrations of (tpfc)Mn(V)(NAr) and O2. These kinetic dependencies are consistent with the rate-determining step being electron transfer from (tpfc)Mn(III) to O2, followed by further proton-coupled electron transfer from Me8Fc to produce H2O2 and [(tpfc)Mn(IV)](+). Rapid electron transfer from Me8Fc to [(tpfc)Mn(IV)](+) regenerates (tpfc)Mn(III), completing the catalytic cycle. Thus, catalytic two-electron reduction of O2 by Me8Fc with (tpfc)Mn(V)(NAr) as a catalyst precursor proceeds via a Mn(III)/Mn(IV) redox cycle.
authors: †Department of Material and Life Science, Graduate School of Engineering, Osaka University, ALCA and SENTAN, Japan Science and Technology Agency (JST), Suita, Osaka 565-0871, Japan.|‡Department of Bioinspired Science, Ewha Womans University, Seoul 120-750, Korea.
authors: Jieun
authors: J
authors: Jung
authors: §Department of Chemistry, Purdue University, 560 Oval Drive, West Lafayette, Indiana 47907, United States.
authors: Shuo
authors: S
authors: Liu
authors: †Department of Material and Life Science, Graduate School of Engineering, Osaka University, ALCA and SENTAN, Japan Science and Technology Agency (JST), Suita, Osaka 565-0871, Japan.
authors: Kei
authors: K
authors: Ohkubo
authors: §Department of Chemistry, Purdue University, 560 Oval Drive, West Lafayette, Indiana 47907, United States.
authors: Mahdi M
authors: MM
authors: Abu-Omar
authors: †Department of Material and Life Science, Graduate School of Engineering, Osaka University, ALCA and SENTAN, Japan Science and Technology Agency (JST), Suita, Osaka 565-0871, Japan.|‡Department of Bioinspired Science, Ewha Womans University, Seoul 120-750, Korea.|∥Faculty of Science and Engineering, Meijo University, ALCA and SENTAN, Japan Science and Technology Agency (JST), Nagoya, Aichi 468-0073, Japan.
authors: Shunichi
authors: S
authors: Fukuzumi
mesh_terms: D002384:Catalysis; D004579:Electron Transport; D004583:Electrons; D005296:Ferrous Compounds / Q000737:chemistry*; D006859:Hydrogen / Q000737:chemistry; D006861:Hydrogen Peroxide; D007700:Kinetics; D008345:Manganese / Q000737:chemistry*; D000075163:Metallocenes; D010084:Oxidation-Reduction; D010100:Oxygen / Q000737:chemistry*; D011166:Porphyrins / Q000737:chemistry*; D011522:Protons; D014269:Trifluoroacetic Acid / Q000737:chemistry
chemical_list: D005296:Ferrous Compounds; D000075163:Metallocenes; D011166:Porphyrins; D011522:Protons; C431863:corrole; D008345:Manganese; D006859:Hydrogen; D006861:Hydrogen Peroxide; D014269:Trifluoroacetic Acid; D010100:Oxygen; C004998:ferrocene