Electronic Configuration and Ligand Nature of Five-Coordinate Iron Porphyrin Carbene Complexes: An Experimental Study
- 29 March 2017
- journal article
- research article
- Published by American Chemical Society (ACS) in Journal of the American Chemical Society
- Vol. 139 (14), 5023-5026
- https://doi.org/10.1021/jacs.7b01722
Abstract
The five-coordinate iron porphyrin carbene complexes [Fe(TPP) (CCl2)] (TPP = tetraphenylporphyrin), [Fe(TTP) (CCl2)] (TTP = tetratolylporphyrin) and [Fe(TFPP) (CPh2)] (TFPP = tetra(pentafluorophenyl)porphyrin), utilizing two types of carbene ligands (CCl2 and CPh2), have been investigated by single crystal X-ray, XANES (X-ray absorption near edge spectroscopy), Mössbauer, NMR and UV–vis spectroscopies. The XANES suggested the iron(II) oxidation state of the complexes. The multitemperature and high magnetic field Mössbauer experiments, which show very large quadrupole splittings (QS, ΔEQ), determined the S = 0 electronic configuration. More importantly, combined structural and Mössbauer studies, especially the comparison with the low spin iron(II) porphyrin complexes with strong diatomic ligands (CS, CO and CN–) revealed the covalent bond nature of the carbene ligands. A correlation between the iron isomer shifts (IS, δ) and the axial bond distances is established for the first time for these donor carbon ligands (:C–R).Keywords
Funding Information
- National Natural Science Foundation of China (21371167)
- Chinese Academy of Sciences
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