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

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. In conclusion, 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. Furthermore, 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.
Authors:
 [1] ;  [1] ;  [1] ;  [1] ;  [2] ;  [1] ;  [3] ;  [4] ;  [1]
  1. Ewha Womans Univ., Seoul (Korea)
  2. Osaka Univ. and ALCA, Japan Science Technology Agency (JST), Osaka (Japan)
  3. SLAC National Accelerator Lab., Menlo Park, CA (United States)
  4. Ewha Womans Univ., Seoul (Korea); Osaka Univ. and ALCA, Japan Science Technology Agency (JST), Osaka (Japan)
Publication Date:
OSTI Identifier:
1291342
Grant/Contract Number:
NRF-2012R1A3A2048842; NRF-2010-00353; 2013R1A1A2062737; P41 RR001209
Type:
Accepted Manuscript
Journal Name:
Nature Chemistry
Additional Journal Information:
Journal Volume: 6; Journal Issue: 10; Journal ID: ISSN 1755-4330
Publisher:
Nature Publishing Group
Research Org:
SLAC National Accelerator Laboratory (SLAC), Menlo Park, CA (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22); USDOE Office of Science (SC), Biological and Environmental Research (BER) (SC-23); National Inst. of Health (NIH); KOSEF/MEST of Korea
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY redox-inactive metal ions