Oxo-Free Hydrocarbon Oxidation by an Iron(III)-Isoporphyrin Complex

Robert Gericke; Lorna M Doyle; Erik R Farquhar; Aidan R McDonald

doi:10.1021/acs.inorgchem.0c01618

Oxo-Free Hydrocarbon Oxidation by an Iron(III)-Isoporphyrin Complex

Inorg Chem. 2020 Oct 5;59(19):13952-13961. doi: 10.1021/acs.inorgchem.0c01618. Epub 2020 Sep 21.

Authors

Robert Gericke¹, Lorna M Doyle¹, Erik R Farquhar², Aidan R McDonald¹

Affiliations

¹ School of Chemistry, College Green, Trinity College Dublin, The University of Dublin, Dublin 2 D02 PN40, Ireland.
² National Synchrotron Light Source II, Brookhaven National Laboratory, Case Western Reserve University Center for Synchrotron Biosciences, Upton, New York 11973, United States.

PMID: 32955871
DOI: 10.1021/acs.inorgchem.0c01618

Abstract

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, ¹H 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.