Defluorination of Fluorophenols by a Nonheme Iron(IV)-Oxo Species: Observation of a New Intermediate Along the...

High-valent iron(IV)-oxo intermediates are versatile oxidants in the biotransformation of various substrates by metalloenzymes and catalyze essential reactions for human health as well as in the biodegradation of toxic organic pollutants in the environment. Herein, we report a biomimetic system that efficiently reacts with halophenols through defluorination reactions and characterize various short-lived intermediates along the reaction mechanism. We study the reactivity pattern of a nonheme iron(IV)-oxo species with a series of trihalophenols (X=F, Cl, Br). A combined experimental and computational study reveals that the oxidative dehalogenation of 2,4,6-trifluorophenol is initiated with an H-atom abstraction from the phenolic group by the iron(IV)-oxo species resulting in the formation of a phenolate radical and an iron(III)-hydroxo species. This iron(III)-hydroxo species forms an adduct with the oxidized substrate with λ_max at 558 nm which subsequently decays to give quinones as products.