Hydrocarbon Oxidation by a Porphyrin‐π‐Cation Radical Complex

Abstract

Heme and chlorin π‐cation radical oxidants are widely implicated in biological and synthetic oxidation catalysis. Little insight into the role of π‐cation radicals in proton coupled electron transfer (PCET) oxidation is available. We prepared a NiII‐porphyrin‐π‐cation complex ([NiII(P⋅+)]) and found it to be capable of the oxidation of a variety of simple hydrocarbon substrates. Interestingly, some of the products were hydroxylated, with ([NiII(P⋅+)]) working in concert with atmospheric O2 to yield hydroxylated hydrocarbons. Kinetic data suggested that the porphyrin‐π‐cation radical species oxidised substrates through a concerted PCET mechanism, where the porphyrin‐π‐cation radical accepted the electron, and the proton was transferred to a free anion. Our findings highlight the potential role of π‐cation radicals as hydrocarbon activators, demonstrating that porphyrin ligand non‐innocence could be a readily manipulated resource for oxidation catalyst development.