title: Nonheme iron mediated oxidation of light alkanes with oxone: characterization of reactive oxoiron(IV) ligand cation radical intermediates by spectroscopic studies and DFT calculations.
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 {Fe=O} species. A method that employs [Fe(III)(Me3tacn)(Cl-acac)Cl](+) as a catalyst in the presence of oxone was developed for the oxidation of hydrocarbons, including cyclohexane, propane, and ethane (Me3tacn=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)(Me3tacn)({Cl-acac}(.+))(O)](2+) as the catalytically active species.
authors.affiliation: State Key Laboratory of Synthetic Chemistry, Institute of Molecular Functional Materials and Department of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong (China).
authors.forename: Chun-Wai
authors.initials: CW
authors.lastname: Tse
authors.forename: Toby Wai-Shan
authors.initials: TW
authors.lastname: Chow
authors.forename: Zhen
authors.initials: Z
authors.lastname: Guo
authors.forename: Hung Kay
authors.initials: HK
authors.lastname: Lee
authors.forename: Jie-Sheng
authors.initials: JS
authors.lastname: Huang
authors.forename: Chi-Ming
authors.initials: CM
authors.lastname: Che
mesh_terms: D000473:Alkanes / Q000737:chemistry*; D056831:Coordination Complexes / Q000138:chemical synthesis / Q000737:chemistry; D003510:Cyclohexanes / Q000737:chemistry; D004578:Electron Spin Resonance Spectroscopy; D007501:Iron / Q000737:chemistry*; D008024:Ligands; D010084:Oxidation-Reduction; D011789:Quantum Theory; D013464:Sulfuric Acids / Q000737:chemistry*
chemical_list: D000473:Alkanes; D056831:Coordination Complexes; D003510:Cyclohexanes; D008024:Ligands; D013464:Sulfuric Acids; D007501:Iron; C048813:potassium peroxymonosulfuric acid
keywords: alkanes; iron; nonheme iron complexes; oxidation; oxoiron complexes