Tuning the Redox Properties of a Nonheme Iron(III)–Peroxo Complex Binding Redox‐Inactive Zinc Ions by Water Molecules. Issue 30 (19th June 2015)

• Record Type: Journal Article
• Authors: Lee, Yong‐Min; Bang, Suhee; Yoon, Heejung; Bae, Seong Hee; Hong, Seungwoo; Cho, Kyung‐Bin; Sarangi, Ritimukta; Fukuzumi, Shunichi; Nam, Wonwoo
• Is Part Of: Chemistry. Volume 21:Issue 30(2015)
• Page Start: 10676
• Page End: 10680
• Publication Date: 2015-06-19
• Subjects: Chemistry -- Periodicals; 540
• DOI: 10.1002/chem.201502143
• Languages: English
• ISSNs: 0947-6539

Abstract

<abstract abstract-type="main" xml:lang="en"> <title>Abstract</title> <p>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<sup>2+</sup> ion in (TMC)Fe<sup>III</sup>‐(O<sub>2</sub>)‐Zn(CF<sub>3</sub>SO<sub>3</sub>)<sub>2</sub> (<bold>1</bold>‐Zn<sup>2+</sup>) decreases the Lewis acidity of the Zn<sup>2+</sup> ion, resulting in the decrease of the one‐electron oxidation and reduction potentials of <bold>1</bold>‐Zn<sup>2+</sup>. This further changes the reactivities of <bold>1</bold>‐Zn<sup>2+</sup> in oxidation and reduction reactions; no reaction occurred upon addition of an oxidant (e.g., cerium(IV) ammonium nitrate (CAN)) to <bold>1</bold>‐Zn<sup>2+</sup>, whereas <bold>1</bold>‐Zn<sup>2+</sup> coordinating two water molecules, (TMC)Fe<sup>III</sup>‐(O<sub>2</sub>)‐Zn(CF<sub>3</sub>SO<sub>3</sub>)<sub>2</sub>‐(OH<sub>2</sub>)<sub>2</sub> [<bold>1</bold>‐Zn<sup>2+</sup>‐(OH<sub>2</sub>)<sub>2</sub>], releases the O<sub>2</sub> unit in the oxidation reaction. In the reduction reactions, <bold>1</bold>‐Zn<sup>2+</sup> 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 <bold>1</bold>‐Zn<sup>2+</sup>‐(OH<sub>2</sub>)<sub>2</sub>. 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.</p> </abstract>