Rapid Iron(III)−Fluoride‐Mediated Hydrogen Atom Transfer

We anticipate high‐valent metal–fluoride species will be highly effective hydrogen atom transfer (HAT) oxidants because of the magnitude of the H−F bond (in the product) that drives HAT oxidation. We prepared a dimeric Fe(III)(F)−F−Fe(III)(F) complex (1) by reacting [Fe(II)(NCCH(3))(2)(TPA)](ClO(4))(2) (TPA=tris(2‐pyridylmethyl)amine) with difluoro(phenyl)‐λ(3)‐iodane (difluoroiodobenzene). 1 was a sluggish oxidant, however, it was readily activated by reaction with Lewis or Brønsted acids to yield a monomeric [Fe(III)(TPA)(F)(X)](+) complex (2) where X=F/OTf. 1 and 2 were characterized using NMR, EPR, UV/Vis, and FT‐IR spectroscopies and mass spectrometry. 2 was a remarkably reactive Fe(III) reagent for oxidative C−H activation, demonstrating reaction rates for hydrocarbon HAT comparable to the most reactive Fe(III) and Fe(IV) oxidants.