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Nonheme Iron Mediated Oxidation of Light Alkanes with Oxone: Characterization of Reactive Oxoiron(IV) Ligand Cation Radical Intermediates by Spectroscopic Studies and DFT Calculations
Author(s) -
Tse ChunWai,
Chow Toby WaiShan,
Guo Zhen,
Lee Hung Kay,
Huang JieSheng,
Che ChiMing
Publication year - 2014
Publication title -
angewandte chemie international edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 1433-7851
DOI - 10.1002/anie.201305153
Subject(s) - chemistry , catalysis , ligand (biochemistry) , denticity , radical , cyclohexane , reactive intermediate , electron paramagnetic resonance , propane , photochemistry , stoichiometry , inorganic chemistry , medicinal chemistry , organic chemistry , metal , biochemistry , physics , receptor , nuclear magnetic resonance
Abstract The oxidation of light alkanes that is catalyzed by heme and nonheme iron enzymes is widely proposed to involve highly reactive {Fe V O} species or {Fe IV O} ligand cation radicals. The identification of these high‐valent iron species and the development of an iron‐catalyzed oxidation of light alkanes under mild conditions are of vital importance. Herein, a combination of tridentate and bidentate ligands was used for the generation of highly reactive nonheme {FeO} species. A method that employs [Fe III (Me 3 tacn)(Cl‐acac)Cl] + as a catalyst in the presence of oxone was developed for the oxidation of hydrocarbons, including cyclohexane, propane, and ethane (Me 3 tacn=1,4,7‐trimethyl‐1,4,7‐triazacyclononane; Cl‐acac=3‐chloro‐acetylacetonate). The complex [Fe III (Tp) 2 ] + and oxone enabled stoichiometric oxidation of propane and ethane. ESI‐MS, EPR and UV/Vis spectroscopy, 18 O labeling experiments, and DFT studies point to [Fe IV (Me 3 tacn)({Cl‐acac} .+ )(O)] 2+ as the catalytically active species.