Nonheme Iron Mediated Oxidation of Light Alkanes with Oxone: Characterization of Reactive Oxoiron(IV) Ligand Cation Radical Intermediates by Spectroscopic Studies and DFT Calculations

Authors

  • Chun-Wai Tse,

    1. 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)
    Search for more papers by this author
    • These authors contributed equally to this work.

  • Dr. Toby Wai-Shan Chow,

    1. 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)
    Search for more papers by this author
    • These authors contributed equally to this work.

  • Dr. Zhen Guo,

    1. 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)
    Search for more papers by this author
  • Prof. Dr. Hung Kay Lee,

    1. Department of Chemistry, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong (China)
    Search for more papers by this author
  • Dr. Jie-Sheng Huang,

    1. 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)
    Search for more papers by this author
  • Prof. Dr. Chi-Ming Che

    Corresponding author
    1. 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)
    2. HKU Shenzhen Institute of Research and Innovation, Shenzhen 518053 (China)
    • 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)

    Search for more papers by this author

  • This work was supported by the Hong Kong Research Grants Council (HKU 700810 and HKU 700813), the National Key Basic Research Program of China (2013CB834802), the University Grants Committee of the Hong Kong Special Administrative Region (AoE/P-03/08), and the CAS-Croucher Foundation Funding Scheme for Joint Laboratories.

Abstract

The oxidation of light alkanes that is catalyzed by heme and nonheme iron enzymes is widely proposed to involve highly reactive {FeV[DOUBLE BOND]O} species or {FeIV[DOUBLE BOND]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[DOUBLE BOND]O} species. A method that employs [FeIII(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 [FeIII(Tp)2]+ and oxone enabled stoichiometric oxidation of propane and ethane. ESI-MS, EPR and UV/Vis spectroscopy, 18O labeling experiments, and DFT studies point to [FeIV(Me3tacn)({Cl-acac}.+)(O)]2+ as the catalytically active species.

Ancillary