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Tuning the Redox Properties of a Nonheme Iron(III)–Peroxo Complex Binding Redox‐Inactive Zinc Ions by Water Molecules
Author(s) -
Lee YongMin,
Bang Suhee,
Yoon Heejung,
Bae Seong Hee,
Hong Seungwoo,
Cho KyungBin,
Sarangi Ritimukta,
Fukuzumi Shunichi,
Nam Wonwoo
Publication year - 2015
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201502143
Subject(s) - redox , chemistry , inorganic chemistry , molecule , metal , cerium , metal ions in aqueous solution , zinc , photochemistry , organic chemistry
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 ‐(O 2 )‐Zn(CF 3 SO 3 ) 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 ‐(O 2 )‐Zn(CF 3 SO 3 ) 2 ‐(OH 2 ) 2 [ 1 ‐Zn 2+ ‐(OH 2 ) 2 ], releases the O 2 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+ ‐(OH 2 ) 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.