1H NMR spectra and electronic structure of reduced iron porphyrins: Fe(II), Fe(I) and Fe(0) porphyrins

Sinyakov, G. N.; Шульга, А. М.

doi:10.1016/0022-2860(93)85001-b

Cited by 18 publications

(10 citation statements)

References 38 publications

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“…Because reduction of [FeTPP] can occur either at the metal or at the ligand, the exact nature of the electronic ground state of the reduced iron species [FeTPP] − and [FeTPP] 2– has long been controversial. A variety of spectroscopic studies, including Mössbauer, − electron paramagnetic resonance (EPR), − nuclear magnetic resonance (NMR), ,− X-ray, ,, UV/vis, ,,, and resonance Raman − experiments have been published, partially supporting different electronic ground state formulations. − Additionally, so far, resonance Raman experiments have been performed in solution, giving rise to solvent dependency of the electronic ground states. [FeTPP] and [FeTPP] − are even known to change their spin state upon axial ligation of solvent molecules .…”

Section: Introductionmentioning

confidence: 99%

Electronic Structure and Spin Multiplicity of Iron Tetraphenylporphyrins in Their Reduced States as Determined by a Combination of Resonance Raman Spectroscopy and Quantum Chemistry

Römelt

Bill

et al. 2018

Inorg. Chem.

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Iron tetraphenylporphyrins are prime candidates as catalysts for CO reduction. Yet, even after 40 years of research, fundamental questions about the electronic structure of their reduced states remain, in particular as to whether the reducing equivalents are stored at the iron center or at the porphyrin ligand. In this contribution, we address this question by a combination of resonance Raman spectroscopy and quantum chemistry. Analysis of the data allows for an unequivocal identification of the porphyrin as the redox active moiety. Additionally, determination of the spin state of iron is possible by comparing the characteristic shifts of spin and oxidation-state-sensitive marker bands in the Raman spectrum with calculations of planar porphyrin model structures.

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Section: Introductionmentioning

confidence: 99%

Electronic Structure and Spin Multiplicity of Iron Tetraphenylporphyrins in Their Reduced States as Determined by a Combination of Resonance Raman Spectroscopy and Quantum Chemistry

Römelt

Bill

et al. 2018

Inorg. Chem.

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“…electron configuration of Fe(II) ions, suggested on the basis of NMR measurements [2], for the Fe(OEP) and Fe-azaporphyrin complexes (which corresponds to the intermediate spin state S = 1), the last two factors can cause increase in the quadrupole splitting as a result of the aza substitution. However, another electron distribution in d-orbitals of Fe(II) ions is also possible, for example (d xy )…”

Section: Iron(ii) Derivativesmentioning

confidence: 99%

“…(the latter suggested on the basis of NMR study [2]). The former configuration confirm EPR data [17].…”

Section: Iron(i) Derivativesmentioning

confidence: 99%

“…The electronic structure of the reduction products is still controversial. Depending on a solvent used in the reduction process, kind of the reduction process (chemical or electrochemical), and the molecular structure of porphyrin ligands, Fe(II) ions can exist in all the possible spin states (S = 0, S = 1 and S = 2) [2]. Results obtained from different experimental methods, even for the same Fe(II)-octaethylporphyrin complex, generated by reduction in the tetrahydrofuran (THF) solvent were interpreted ambiguously [3][4][5].…”

Section: Introductionmentioning

confidence: 99%

“…2 electron configuration of the Fe(I) ion was suggested in paper [2] while the authors of paper [6] proposed the (d xy )…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Mössbauer Study of a Reduction Process in Iron Azaporphyrins

et al. 2009

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Substituent Effects in Iron Porphyrin Catalysts for the Hydrogen Evolution Reaction**

Heppe

Gallenkamp

Paul

et al. 2023

Chemistry A European J

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For a future hydrogen economy, non-precious metal catalysts for the water splitting reactions are needed that can be implemented on a global scale. Metal-nitrogencarbon (MNC) catalysts with active sites constituting a metal center with fourfold coordination of nitrogen (MN 4 ) show promising performance, but an optimization rooted in structure-property relationships has been hampered by their low structural definition. Porphyrin model complexes are studied to transfer insights from well-defined molecules to MNC systems. This work combines experiment and theory to evaluate the influence of porphyrin substituents on the electronic and electrocatalytic properties of MN 4 centers with respect to the hydrogen evolution reaction (HER) in aqueous electrolyte. We found that the choice of substituent affects their utilization on the carbon support and their electrocatalytic performance. We propose an HER mechanism for supported iron porphyrin complexes involving a [Fe II (P * )] À radical anion intermediate, in which a porphinic nitrogen atom acts as an internal base. While this work focuses on the HER, the limited influence of a simultaneous interaction with the support and an aqueous electrolyte will likely be transferrable to other catalytic applications.

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1H NMR spectra and electronic structure of reduced iron porphyrins: Fe(II), Fe(I) and Fe(0) porphyrins

Cited by 18 publications

References 38 publications

Electronic Structure and Spin Multiplicity of Iron Tetraphenylporphyrins in Their Reduced States as Determined by a Combination of Resonance Raman Spectroscopy and Quantum Chemistry

Electronic Structure and Spin Multiplicity of Iron Tetraphenylporphyrins in Their Reduced States as Determined by a Combination of Resonance Raman Spectroscopy and Quantum Chemistry

Mössbauer Study of a Reduction Process in Iron Azaporphyrins

Substituent Effects in Iron Porphyrin Catalysts for the Hydrogen Evolution Reaction**

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