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

Abstract 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 2 O 2 effectively. To get mechanistic insight into this unusual reactivity, detailed density functional theory calculations on the mechanism of C 6 F 6 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.