title: Tuning the Redox Properties of a Nonheme Iron(III)-Peroxo Complex Binding Redox-Inactive Zinc Ions by Water Molecules.
abstract: Redox-inactive metal ions play important roles in tuning chemical properties of metal-oxygen intermediates. Herein we report the effect of water molecules on the redox properties of a nonheme iron(III)-peroxo complex binding redox-inactive metal ions. The coordination of two water molecules to a Zn(2+) ion in (TMC)Fe(III) -(O2 )-Zn(CF3 SO3 )2 (1-Zn(2+) ) decreases the Lewis acidity of the Zn(2+) ion, resulting in the decrease of the one-electron oxidation and reduction potentials of 1-Zn(2+) . This further changes the reactivities of 1-Zn(2+) in oxidation and reduction reactions; no reaction occurred upon addition of an oxidant (e.g., cerium(IV) ammonium nitrate (CAN)) to 1-Zn(2+) , whereas 1-Zn(2+) coordinating two water molecules, (TMC)Fe(III) -(O2 )-Zn(CF3 SO3 )2 -(OH2 )2 [1-Zn(2+) -(OH2 )2 ], releases the O2 unit in the oxidation reaction. In the reduction reactions, 1-Zn(2+) was converted to its corresponding iron(IV)-oxo species upon addition of a reductant (e.g., a ferrocene derivative), whereas such a reaction occurred at a much slower rate in the case of 1-Zn(2+) -(OH2 )2 . The present results provide the first biomimetic example showing that water molecules at the active sites of metalloenzymes may participate in tuning the redox properties of metal-oxygen intermediates.
authors.affiliation: Department of Chemistry and Nano Science, Ewha Womans University, Seoul 120-750 (Korea), Fax: (+82) 2-3277-4114.
authors.forename: Yong-Min
authors.initials: YM
authors.lastname: Lee
authors.affiliation: Department of Chemistry and Nano Science, Ewha Womans University, Seoul 120-750 (Korea), Fax: (+82) 2-3277-4114.
authors.forename: Suhee
authors.initials: S
authors.lastname: Bang
authors.affiliation: Department of Material and Life Science, Graduate School of Engineering, ALCA, Japan Science and Technology Agency (JST), Osaka University, Suita, Osaka 565-0871 (Japan).
authors.forename: Heejung
authors.initials: H
authors.lastname: Yoon
authors.affiliation: Department of Chemistry and Nano Science, Ewha Womans University, Seoul 120-750 (Korea), Fax: (+82) 2-3277-4114.
authors.forename: Seong Hee
authors.initials: SH
authors.lastname: Bae
authors.affiliation: Department of Chemistry and Nano Science, Ewha Womans University, Seoul 120-750 (Korea), Fax: (+82) 2-3277-4114.
authors.forename: Seungwoo
authors.initials: S
authors.lastname: Hong
authors.affiliation: Department of Chemistry and Nano Science, Ewha Womans University, Seoul 120-750 (Korea), Fax: (+82) 2-3277-4114.
authors.forename: Kyung-Bin
authors.initials: KB
authors.lastname: Cho
authors.affiliation: Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Menlo Park, CA 94025 (USA).
authors.forename: Ritimukta
authors.initials: R
authors.lastname: Sarangi
authors.affiliation: Department of Chemistry and Nano Science, Ewha Womans University, Seoul 120-750 (Korea), Fax: (+82) 2-3277-4114. fukuzumi@chem.eng.osaka-u.ac.jp.|Department of Material and Life Science, Graduate School of Engineering, ALCA, Japan Science and Technology Agency (JST), Osaka University, Suita, Osaka 565-0871 (Japan). fukuzumi@chem.eng.osaka-u.ac.jp.|Faculty of Science and Technology, Meijo University, ALCA and SENTAN, Japan Science and Technology Agency (JST), Shiogamaguchi, Tempaku, Nagoya, Aichi 468-8502 (Japan). fukuzumi@chem.eng.osaka-u.ac.jp.
authors.forename: Shunichi
authors.initials: S
authors.lastname: Fukuzumi
authors.affiliation: Department of Chemistry and Nano Science, Ewha Womans University, Seoul 120-750 (Korea), Fax: (+82) 2-3277-4114. wwnam@ewha.ac.kr.
authors.forename: Wonwoo
authors.initials: W
authors.lastname: Nam
mesh_terms: D002413:Cations, Divalent / Q000737:chemistry; D002563:Cerium / Q000737:chemistry; D005290:Ferric Compounds / Q000737:chemistry*; D009566:Nitrates / Q000737:chemistry; D010084:Oxidation-Reduction; D010100:Oxygen / Q000737:chemistry; D014867:Water / Q000737:chemistry*; D015032:Zinc / Q000737:chemistry*
chemical_list: D002413:Cations, Divalent; D005290:Ferric Compounds; D009566:Nitrates; C532772:cerium(IV) ammonium nitrate; D014867:Water; D002563:Cerium; D015032:Zinc; D010100:Oxygen
keywords: bioinorganic chemistry; metal-oxygen intermediates; oxygen-evolving complexes; redox reactions; water oxidation