Redox-inactive metal ions modulate the reactivity and oxygen release of mononuclear non-haem iron(III)-peroxo complexes

Suhee Bang, Yong Min Lee, Seungwoo Hong, Kyung Bin Cho, Yusuke Nishida, Mi Sook Seo, Ritimukta Sarangi, Shunichi Fukuzumi, Wonwoo Nam

Research output: Contribution to journalArticlepeer-review

106 Scopus citations

Abstract

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)FeIII-(μ η22-O2)-Mn+ (Mn+= Sr2+, Ca2+, Zn2+, Lu3+, Y3+ and Sc3+; TMC, 1,4,8,11-tetramethyl-1,4,8,11-tetraazacyclotetradecane). We demonstrate that the Ca2+ and Sr2+ 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 Ca2+ or Sr2+ 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 Ca2+ ion in the oxidation of water to dioxygen by the oxygen-evolving complex.

Original languageEnglish
Pages (from-to)934-940
Number of pages7
JournalNature Chemistry
Volume6
Issue number10
DOIs
StatePublished - 1 Oct 2014

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