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Multi‐Electron Oxidation of Anthracene Derivatives by Nonheme Manganese(IV)‐Oxo Complexes
Author(s) -
Sharma Namita,
Jung Jieun,
Lee YongMin,
Seo Mi Sook,
Nam Wonwoo,
Fukuzumi Shunichi
Publication year - 2017
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.201700666
Subject(s) - anthracene , anthraquinone , manganese , electron transfer , chemistry , photochemistry , medicinal chemistry , ion , yield (engineering) , inorganic chemistry , organic chemistry , materials science , metallurgy
Six‐electron oxidation of anthracene to anthraquinone by a nonheme Mn IV ‐oxo complex, [(Bn‐TPEN)Mn IV (O)] 2+ , proceeds through a rate‐determining electron transfer from anthracene to [(Bn‐TPEN)Mn IV (O)] 2+ , followed by subsequent fast oxidation reactions to give anthraquinone. The reduced Mn II complex ([(Bn‐TPEN)Mn II ] 2+ ) is oxidized by [(Bn‐TPEN)Mn IV (O)] 2+ rapidly to produce the μ‐oxo dimer ([(Bn‐TPEN)Mn III ‐O‐Mn III (Bn‐TPEN)] 4+ ). The oxygen atoms of the anthraquinone product were found to derive from the manganese‐oxo species by the 18 O‐labelling experiments. In the presence of Sc 3+ ion, formation of an anthracene radical cation was directly detected in the electron transfer from anthracene to a Sc 3+ ion‐bound Mn IV (O) complex, [(Bn‐TPEN)Mn IV (O)‐(Sc(OTf) 3 ) 2 ] 2+ , followed by subsequent further oxidation to yield anthraquinone. When anthracene was replaced by 9,10‐dimethylanthracene, electron transfer from 9,10‐dimethylanthracene to [(Bn‐TPEN)Mn IV (O)‐(Sc(OTf) 3 ) 2 ] 2+ occurred rapidly to produce stable 9,10‐dimethylanthracene radical cation. The driving force dependence of the rate constants of electron transfer from the anthracene derivatives to [(Bn‐TPEN)Mn IV (O)] 2+ and [(Bn‐TPEN)Mn IV (O)‐(Sc(OTf) 3 ) 2 ] 2+ was well‐evaluated in light of the Marcus theory of electron transfer.