Inorganic Chemistry, Vol.59, No.19, 13952-13961, 2020
Oxo-Free Hydrocarbon Oxidation by an Iron(III)-Isoporphyrin Complex
Metal-halides that perform proton coupled electron-transfer (PCET) oxidation are an important new class of high-valent oxidant. In investigating metal-dihalides, we reacted [Fe-III(Cl)(T(OMe) PP)] (1, T-(OMe) PP = meso-tetra( 4-methoxyphenyl)porphyrinyl) with (dichloroiodo)benzene. An Fe-III-meso-chloro-isoporphyrin complex [Fe-III(Cl)(2)(T(OMe)PP-Cl)] (2) was obtained. 2 was characterized by electronic absorption, H-1 NMR, EPR, and X-ray absorption spectroscopies and mass spectrometry with support from computational analyses. 2 was reacted with a series of hydrocarbon substrates. The measured kinetic data exhibited a nonlinear behavior, whereby the oxidation followed a hydrogen-atom-transfer (HAT) PCET mechanism. The meso-chlorine atom was identified as the HAT agent. In one case, a halogenated product was identified by mass spectrometry. Our findings demonstrate that oxo-free hydrocarbon oxidation with heme systems is possible and show the potential for iron-dihalides in oxidative hydrocarbon halogenation.