Trapping of a Highly Reactive Oxoiron(IV) Complex in the Catalytic Epoxidation of Olefins by Hydrogen Peroxide

Angew Chem Int Ed Engl. 2019 Mar 18;58(12):4012-4016. doi: 10.1002/anie.201812758. Epub 2019 Feb 14.

Abstract

The generation of a nonheme oxoiron(IV) intermediate, [(cyclam)FeIV (O)(CH3 CN)]2+ (2; cyclam=1,4,8,11-tetraazacyclotetradecane), is reported in the reactions of [(cyclam)FeII ]2+ with aqueous hydrogen peroxide (H2 O2 ) or a soluble iodosylbenzene (sPhIO) as a rare example of an oxoiron(IV) species that shows a preference for epoxidation over allylic oxidation in the oxidation of cyclohexene. Complex 2 is kinetically and catalytically competent to perform the epoxidation of olefins with high stereo- and regioselectivity. More importantly, 2 is likely to be the reactive intermediate involved in the catalytic epoxidation of olefins by [(cyclam)FeII ]2+ and H2 O2 . In spite of the predominance of the oxoiron(IV) cores in biology, the present study is a rare example of high-yield isolation and spectroscopic characterization of a catalytically relevant oxoiron(IV) intermediate in chemical oxidation reactions.

Keywords: bioinorganic chemistry; catalysis; nonheme oxoiron intermediates; regioselectivity; stereoselective epoxidation.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Alkenes / chemistry*
  • Catalysis
  • Coordination Complexes / chemistry*
  • Hydrogen Bonding
  • Hydrogen Peroxide / chemistry*
  • Iron / chemistry*
  • Oxidation-Reduction
  • Stereoisomerism

Substances

  • Alkenes
  • Coordination Complexes
  • Hydrogen Peroxide
  • Iron