1
|
Gericke R, Doyle LM, Farquhar ER, McDonald AR. Oxo-Free Hydrocarbon Oxidation by an Iron(III)-Isoporphyrin Complex. Inorg Chem 2020; 59:13952-13961. [PMID: 32955871 DOI: 10.1021/acs.inorgchem.0c01618] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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 [FeIII(Cl)(T(OMe)PP)] (1, T(OMe)PP = meso-tetra(4-methoxyphenyl)porphyrinyl) with (dichloroiodo)benzene. An FeIII-meso-chloro-isoporphyrin complex [FeIII(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.
Collapse
Affiliation(s)
- Robert Gericke
- School of Chemistry, College Green, Trinity College Dublin, The University of Dublin, Dublin 2 D02 PN40, Ireland
| | - Lorna M Doyle
- School of Chemistry, College Green, Trinity College Dublin, The University of Dublin, Dublin 2 D02 PN40, Ireland
| | - Erik R Farquhar
- National Synchrotron Light Source II, Brookhaven National Laboratory, Case Western Reserve University Center for Synchrotron Biosciences, Upton, New York 11973, United States
| | - Aidan R McDonald
- School of Chemistry, College Green, Trinity College Dublin, The University of Dublin, Dublin 2 D02 PN40, Ireland
| |
Collapse
|
2
|
Nehrkorn J, Bonke SA, Aliabadi A, Schwalbe M, Schnegg A. Examination of the Magneto-Structural Effects of Hangman Groups on Ferric Porphyrins by EPR. Inorg Chem 2019; 58:14228-14237. [PMID: 31599581 DOI: 10.1021/acs.inorgchem.9b02348] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Ferric hangman porphyrins are bioinspired models for haem hydroperoxidase enzymes featuring an acid/base group in close vicinity to the metal center, which results in improved catalytic activity for reactions requiring O-O bond activation. These functional biomimics are examined herein with a combination of EPR techniques to determine the effects of the hanging group on the electronics of the ferric center. These results are compared to those for ferric octaethylporphyrin chloride [Fe(OEP)Cl], tetramesitylporphyrin chloride [Fe(TMP)Cl], and the pentafluorophenyl derivative [Fe(TPFPP)Cl], which were also examined herein to study the electronic effects of various substituents. Frequency-domain Fourier-transform THz-EPR combined with field domain EPR in a broad frequency range from 9.5 to 629 GHz allowed the determination of zero-field splitting parameters, revealing minor rhombicity E/D and D values in a narrow range of 6.24(8) to 6.85(5) cm-1. Thus, the hangman porphyrins display D values in the expected range for ferric porphyrin chlorides, though D appears to be correlated with the Fe-Cl bond length. Extrapolating this trend to the ferric hangman porphyrin chlorides, for which no crystal structure has been reported, indicates a slightly elongated Fe-Cl bond length compared to the non-hangman equivalent.
Collapse
Affiliation(s)
- Joscha Nehrkorn
- EPR Research Group , Max-Planck-Institut für Chemische Energiekonversion , Stiftstraße 34-36 , 45470 Mülheim an der Ruhr , Germany.,Institut für Anorganische und Angewandte Chemie , Universität Hamburg , Martin-Luther-King-Platz 6 , 20146 Hamburg , Germany.,Institut Nanospektroskopie , Helmholtz-Zentrum Berlin für Materialien und Energie , Kekuléstraße 5 , 12489 Berlin , Germany
| | - Shannon A Bonke
- EPR Research Group , Max-Planck-Institut für Chemische Energiekonversion , Stiftstraße 34-36 , 45470 Mülheim an der Ruhr , Germany.,Institut Nanospektroskopie , Helmholtz-Zentrum Berlin für Materialien und Energie , Kekuléstraße 5 , 12489 Berlin , Germany
| | - Azar Aliabadi
- Institut Nanospektroskopie , Helmholtz-Zentrum Berlin für Materialien und Energie , Kekuléstraße 5 , 12489 Berlin , Germany
| | - Matthias Schwalbe
- Institut für Chemie , Humboldt Universität zu Berlin , Brook-Taylor-Straße 2 , 12489 Berlin , Germany
| | - Alexander Schnegg
- EPR Research Group , Max-Planck-Institut für Chemische Energiekonversion , Stiftstraße 34-36 , 45470 Mülheim an der Ruhr , Germany.,Institut Nanospektroskopie , Helmholtz-Zentrum Berlin für Materialien und Energie , Kekuléstraße 5 , 12489 Berlin , Germany
| |
Collapse
|