title: Efficient Epoxidation of Styrene Derivatives by a Nonheme Iron(IV)-Oxo Complex via Proton-Coupled Electron Transfer with Triflic Acid.
abstract: Styrene derivatives are not oxidized by [(N4Py)Fe(IV)(O)](2+) (N4Py = N,N-bis(2-pyridylmethyl)-N-bis(2-pyridyl)methylamine) in acetonitrile at 298 K, whereas epoxidation of styrene derivatives by the iron(IV)-oxo complex occurs efficiently in the presence of triflic acid (HOTf) via proton-coupled electron transfer (PCET) from styrene derivatives to the diprotonated species of [(N4Py)Fe(IV)(O)](2+) with HOTf. Logarithms of the first-order rate constants of HOTf-promoted expoxidation of styrene derivatives with [(N4Py)Fe(IV)(O)](2+) and PCET from electron donors to [(N4Py)Fe(IV)(O)](2+) in the precursor complexes exhibit a remarkably unified correlation with the driving force of PCET in light of the Marcus theory of electron transfer when the differences in the formation constants of precursor complexes are taken into account. The same PCET driving force dependence is obtained for the first-order rate constants of HOTf-promoted oxygen atom transfer from thioanisols to [(N4Py)Fe(IV)(O)](2+) and HOTf-promoted hydrogen atom transfer from toluene derivatives to [(N4Py)Fe(IV)(O)](2+) in the precursor complexes. Thus, HOTf-promoted epoxidation of styrene derivatives by [(N4Py)Fe(IV)(O)](2+) proceeds via the rate-determining electron transfer from styrene derivatives to the diprotonated species of [(N4Py)Fe(IV)(O)](2+), as shown in the reactions of HOTf-promoted oxygen atom transfer from thioanisols to [(N4Py)Fe(IV)(O)](2+) and HOTf-promoted hydrogen atom transfer from toluene derivatives to [(N4Py)Fe(IV)(O)](2+).
authors.affiliation: †Department of Material and Life Science, Graduate School of Engineering, ALCA and SENTAN, Japan Science and Technology Agency (JST), Osaka University, Yamadaoka 2-1, Suita, Osaka 565-0871, Japan.
authors.forename: Jiyun
authors.initials: J
authors.lastname: Park
authors.affiliation: ‡Department of Chemistry and Nano Science, Ewha Womans University, Seoul 120-750, Korea.
authors.forename: Yong-Min
authors.initials: YM
authors.lastname: Lee
authors.affiliation: †Department of Material and Life Science, Graduate School of Engineering, ALCA and SENTAN, Japan Science and Technology Agency (JST), Osaka University, Yamadaoka 2-1, Suita, Osaka 565-0871, Japan.|‡Department of Chemistry and Nano Science, Ewha Womans University, Seoul 120-750, Korea.
authors.forename: Kei
authors.initials: K
authors.lastname: Ohkubo
authors.affiliation: ‡Department of Chemistry and Nano Science, Ewha Womans University, Seoul 120-750, Korea.
authors.forename: Wonwoo
authors.initials: W
authors.lastname: Nam
authors.affiliation: †Department of Material and Life Science, Graduate School of Engineering, ALCA and SENTAN, Japan Science and Technology Agency (JST), Osaka University, Yamadaoka 2-1, Suita, Osaka 565-0871, Japan.|‡Department of Chemistry and Nano Science, Ewha Womans University, Seoul 120-750, Korea.|§Faculty of Science and Technology, ALCA and SENTAN, Japan Science and Technology Agency (JST), Meijo University, Nagoya, Aichi 468-8502, Japan.
authors.forename: Shunichi
authors.initials: S
authors.lastname: Fukuzumi
mesh_terms: D004579:Electron Transport; D004852:Epoxy Compounds / Q000737:chemistry*; D006418:Heme / Q000737:chemistry; D058085:Iron Compounds / Q000737:chemistry*; D008698:Mesylates / Q000737:chemistry*; D011522:Protons; D020058:Styrene / Q000737:chemistry*
chemical_list: D004852:Epoxy Compounds; D058085:Iron Compounds; D008698:Mesylates; D011522:Protons; D006418:Heme; D020058:Styrene; C012077:trifluoromethanesulfonic acid