A Reactive, Photogenerated High-Spin (S = 2) FeIV(O) Complex via O2Activation

Jesse B. Gordon, Therese Albert, Aniruddha Dey, Sinan Sabuncu, Maxime A. Siegler, Eckhard Bill, Pierre Moënne-Loccoz, David P. Goldberg

Abstract

Addition of dioxygen at low temperature to the non-heme ferrous complex FeII(Me3TACN)((OSiPh2)2O) (1) in 2-MeTHF produces a peroxo-bridged diferric complex Fe2III(μ-O2)(Me3TACN)2((OSiPh2)2O)2 (2), which was characterized by UV-vis, resonance Raman, and variable field Mössbauer spectroscopies. Illumination of a frozen solution of 2 in THF with white light leads to homolytic O-O bond cleavage and generation of a FeIV(O) complex 4 (ν(Fe=O) = 818 cm-1 δ= 0.22 mm s-1, δEQ = 0.23 mm s-1). Variable field Mössbauer spectroscopy measurements show that 4 is a rare example of a high-spin S = 2 FeIV(O) complex and the first synthetic example to be generated directly from O2. Complex 4 is highly reactive, as expected for a high-spin ferryl, and decays rapidly in fluid solution at cryogenic temperatures. This decay process in 2-MeTHF involves C-H cleavage of the solvent. However, the controlled photolysis of 2 in situ with visible light and excess phenol substrate leads to competitive phenol oxidation, via the proposed transient generation of 4 as the active oxidant.

Original languageEnglish (US)
Pages (from-to)21637-21647
Number of pages11
JournalJournal of the American Chemical Society
Volume143
Issue number51
DOIs
StatePublished - Dec 29 2021

ASJC Scopus subject areas

  • Catalysis
  • Chemistry(all)
  • Biochemistry
  • Colloid and Surface Chemistry

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