Open AccessRedox-inactive metal ions modulate the reactivity and oxygen release of mononuclear non-haem iron(III)–peroxo complexes
Author(s) -
Suhee Bang,
Yong Min Lee,
Seung-Woo Hong,
KyungBin Cho,
Yusuke Nishida,
Mi Sook Seo,
Ritimukta Sarangi,
Shunichi Fukuzumi,
Wonwoo Nam
Publication year - 2014
Publication title -
nature chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 9.996
H-Index - 232
eISSN - 1755-4349
pISSN - 1755-4330
DOI - 10.1038/nchem.2055
Subject(s) - chemistry , redox , reactivity (psychology) , metal ions in aqueous solution , metal , oxygen , electrochemistry , lewis acids and bases , photochemistry , inorganic chemistry , electron acceptor , photosystem ii , medicinal chemistry , catalysis , organic chemistry , photosynthesis , medicine , biochemistry , alternative medicine , electrode , pathology
Redox-inactive metal ions that function as Lewis acids play pivotal roles in modulating the reactivity of oxygen-containing metal complexes and metalloenzymes, such as the oxygen-evolving complex in photosystem II and its small-molecule mimics. Here we report the synthesis and characterization of non-haem iron(III)-peroxo complexes that bind redox-inactive metal ions, (TMC)Fe(III)-(μ,η(2):η(2)-O2)-M(n+) (M(n+) = Sr(2+), Ca(2+), Zn(2+), Lu(3+), Y(3+) and Sc(3+); TMC, 1,4,8,11-tetramethyl-1,4,8,11-tetraazacyclotetradecane). We demonstrate that the Ca(2+) and Sr(2+) complexes showed similar electrochemical properties and reactivities in one-electron oxidation or reduction reactions. However, the properties and reactivities of complexes formed with stronger Lewis acidities were found to be markedly different. Complexes that contain Ca(2+) or Sr(2+) ions were oxidized by an electron acceptor to release O2, whereas the release of O2 did not occur for complexes that bind stronger Lewis acids. We discuss these results in the light of the functional role of the Ca(2+) ion in the oxidation of water to dioxygen by the oxygen-evolving complex.