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Selective Formation of an Fe IV O or an Fe III OOH Intermediate From Iron(II) and H 2 O 2 : Controlled Heterolytic versus Homolytic Oxygen–Oxygen Bond Cleavage by the Second Coordination Sphere
Author(s) -
Cheaib Khaled,
Mubarak M. Qadri E.,
SénéchalDavid Katell,
Herrero Christian,
Guillot Régis,
Clémancey Martin,
Latour JeanMarc,
de Visser Sam P.,
Mahy JeanPierre,
Banse Frédéric,
Avenier Frédéric
Publication year - 2019
Publication title -
angewandte chemie
Language(s) - English
Resource type - Journals
eISSN - 1521-3757
pISSN - 0044-8249
DOI - 10.1002/ange.201812724
Subject(s) - heterolysis , chemistry , homolysis , bond cleavage , electron transfer , reactivity (psychology) , proton coupled electron transfer , electron paramagnetic resonance , photochemistry , crystallography , radical , reaction mechanism , stereochemistry , medicinal chemistry , catalysis , nuclear magnetic resonance , organic chemistry , medicine , physics , alternative medicine , pathology
We demonstrate that the devised incorporation of an alkylamine group into the second coordination sphere of an Fe II complex allows to switch its reactivity with H 2 O 2 from the usual formation of Fe III species towards the selective generation of an Fe IV ‐oxo intermediate. The Fe IV ‐oxo species was characterized by UV/Vis absorption and Mössbauer spectroscopy. Variable‐temperature kinetic analyses point towards a mechanism in which the heterolytic cleavage of the O−O bond is triggered by a proton transfer from the proximal to the distal oxygen atom in the Fe II ‐H 2 O 2 complex with the assistance of the pendant amine. DFT studies reveal that this heterolytic cleavage is actually initiated by an homolytic O−O cleavage immediately followed by a proton‐coupled electron transfer (PCET) that leads to the formation of the Fe IV ‐oxo and release of water through a concerted mechanism.