Mechanism of Oxidative Activation of Fluorinated Aromatic Compounds by N-Bridged Diiron-Phthalocyanine: What Determines the Reactivity?

Author(s) Colomban, C.; Tobing, A.H.; Mukherjee, G.; Sastri, C.V.; Sorokin, A.B.; de Visser, S.P.
Journal Chemistry
Date Published 2019 Nov 13

The biodegradation of compounds with C-F bonds is challenging due to the fact that these bonds are stronger than the C-H bond in methane. In this work, results on the unprecedented reactivity of a biomimetic model complex that contains an N-bridged diiron-phthalocyanine are presented; this model complex is shown to react with perfluorinated arenes under addition of H O effectively. To get mechanistic insight into this unusual reactivity, detailed density functional theory calculations on the mechanism of C F activation by an iron(IV)-oxo active species of the N-bridged diiron phthalocyanine system were performed. Our studies show that the reaction proceeds through a rate-determining electrophilic C-O addition reaction followed by a 1,2-fluoride shift to give the ketone product, which can further rearrange to the phenol. A thermochemical analysis shows that the weakest C-F bond is the aliphatic C-F bond in the ketone intermediate. The oxidative defluorination of perfluoroaromatics is demonstrated to proceed through a completely different mechanism compared to that of aromatic C-H hydroxylation by iron(IV)-oxo intermediates such as cytochrome P450 Compound I.

DOI 10.1002/chem.201902934
ISSN 1521-3765
Citation Chemistry. 2019;25(63):1432014331.

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