Reactions of alkyl and fluoroalkyl radicals with nickel, iron, and manganese porphyrins

Guldi, Dirk M.; Kumar, Manmohan; Neta, P.; Hambright, Peter

doi:10.1021/j100202a092

Cited by 22 publications

(10 citation statements)

References 6 publications

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“…The formation of transients containing FeϪalkyl bonds is analogous to the formation of transient complexes in the reaction of alkyl radicals with iron() complexes, [18] and other low valent transition metal complexes, [16] in homogeneous solutions.…”

Section: Formation Of Alkanes During the Dissolution Of Analytical Mementioning

confidence: 99%

Reaction of Methyl Radicals with Metal Powders Immersed in Aqueous Solutions

et al. 2003

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Methyl radicals radiolytically produced in aqueous solutions react efficiently with Cr0, Mn0, Fe0, Ni0, Cu0 and Zn0 powders immersed in the solution. The Cr0, Mn0, Fe0, Ni0 and Zn0 powders reduce the radicals to form methane. On the other hand the Cu0 powder seems to oxidize the radicals. Surprisingly a part of the energy absorbed by the Cr0, Fe0, Ni0 and Zn0 powders is transferred to the aqueous solution, thus increasing the radical yield. CH4, C2H4, C2H6, C3H6 and C3H8 are formed when an aqueous deaerated buffer solution, pH 4−5, is added to powders of analytical iron, zinc, manganese and chromium. The source of these gases is carbon traces present, as atoms or atom clusters, in the “analytical” metal powders. These carbon atoms, when present on the surface of the metals, are reduced by the metal particles in aqueous solutions. This mechanism might be the source of light alkanes and alkenes in the prebiotic era. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)

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Section: Formation Of Alkanes During the Dissolution Of Analytical Mementioning

confidence: 99%

Reaction of Methyl Radicals with Metal Powders Immersed in Aqueous Solutions

et al. 2003

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“…At −1.0 V vs Ag/Ag + , the Mn(III), present at open circuit conditions, was completely converted Mn(II), as evidenced by the shift of the Soret band to 442 nm (Figure c) . Ligand-based reductions in porphyrins are typically accompanied by changes at longer wavelengths, indicating that the reduction was solely metal-centered. , Tracking the ratio of the Mn(III) to Mn(II) Soret bands revealed the redox potential of the Mn to be centered at −0.8 V (Figure d).…”

Section: Results and Discussionmentioning

confidence: 94%

“…42 Ligand-based reductions in porphyrins are typically accompanied by changes at longer wavelengths, indicating that the reduction was solely metalcentered. 43,44 Tracking the ratio of the Mn(III) to Mn(II) Soret bands revealed the redox potential of the Mn to be centered at −0.8 V (Figure 2d).…”

Section: ■ Results and Discussionmentioning

confidence: 99%

Electrochemically Triggered Dynamics within a Hybrid Metal–Organic Electrocatalyst

et al. 2020

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A wide array of systems, ranging from enzymes to synthetic catalysts, exert adaptive motifs to maximize their functionality. In a related manner, select metal-organic frameworks (MOFs) and related systems exhibit structural modulations under stimuli such as the infiltration of guest species. Probing their responsive behavior in-situ is a challenging but important step towards understanding their function and subsequently building from there. In this report, we investigate the dynamic behavior of an electrocatalytic Mn-porphyrin containing MOF system (Mn-MOF). We discover, using a combination of electrochemistry and in-situ probes of UV-Vis absorption, resonance Raman and infrared spectroscopy, a restructuration of this system via a reversible cleavage of the porphyrin carboxylate ligands under an applied voltage. We further show, by combining experimental data and DFT calculations, as a proof of concept, the capacity to utilize the Mn-MOF for electrochemical CO2 fixation and to spectroscopically capture the reaction intermediates in its catalytic cycle. The findings of this work and methodology developed opens opportunities in the application of MOFs as dynamic, enzyme-inspired electrocatalytic systems.

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“…Fuhrhop et al [9] characterized Mn(P) − as a manganese(II) radical anion, as did Kelly and Kadish [10] and Boucher and Garber [11]. Additional information confirming the radical anion structure was provided by Guldi et al [12], who observed a broad absorption band around 770 nm, which is characteristic of porphyrin π-radical anions. On the other hand, DFT calculations by Liao and Huang [13] predicted a Mn(I) structure for manganese porphine.…”

Section: Introductionmentioning

confidence: 84%

Visible and infrared spectroelectrochemistry of zinc and manganese porphinones: Metal vs. porphyrin reduction

Tutunea

Atifi

2015

Journal of Electroanalytical Chemistry

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Abstract:The visible and infrared spectroelectrochemistry of zinc and manganese porphinones and porphinediones was carried out in THF solutions. The aim of this work was to use FTIR spectroelectrochemistry and DFT calculation to determine whether the reduction was centered predominantly on the metal or the macrocycle. For zinc(II), the first one-electron reduction must occur on the macrocyclic ring because the metal's d-orbitals are filled (d 10 ). The carbonyl bands on the macrocyclic ring were used to probe the electronic structure because they can be readily observed in the infrared spectra. The results of this study are complementary to previous spectroelectrochemical studies that have been reported for the iron and cobalt complexes of the same macrocycles. As expected for the formation of a π-NOT THE PUBLISHED VERSION; this is the author's final, peer-reviewed manuscript. The published version may be accessed by following the link in the citation at the bottom of the page. Chemistry, Vol. 744 (May 1, 2015): pg. 17-24. DOI. This article is © Elsevier and permission has been granted for this version to appear in e-Publications@Marquette. Elsevier does not grant permission for this article to be further copied/distributed or hosted elsewhere without the express permission from Elsevier. Journal of Electroanalytical2 radical anion species, significant downshifts in the carbonyl bands were observed. DFT calculations showed that the behavior of the porphinedione complexes were most sensitive to the electronic structure of the M(OEPdione) − species. If a M I species is formed, the two carbonyl groups will be downshifted by similar energies. For M II -radical anions, one carbonyl will be downshifted significantly, and the second one will be downshifted by a small amount. On the basis of this criterion, it was determined that cobalt(I) and iron(I) complexes were formed, while zinc and manganese formed π-radical anion species. The visible spectroelectrochemistry was also consistent with these electronic structures. Graphical abstract:The visible and infrared spectroelectrochemistry of zinc and manganese porphinones and porphinediones was carried out in THF solutions. The carbonyl bands on the macrocyclic ring were used to probe the electronic structure. DFT calculations showed that the shifts in the carbonyl bands of the porphinedione (OEPdione) complexes were sensitive to the electronic structure of the M(OEPdione) − species. On this basis, the oxidation state of the metal in these complexes could be assigned.

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Reactions of alkyl and fluoroalkyl radicals with nickel, iron, and manganese porphyrins

Cited by 22 publications

References 6 publications

Reaction of Methyl Radicals with Metal Powders Immersed in Aqueous Solutions

Reaction of Methyl Radicals with Metal Powders Immersed in Aqueous Solutions

Electrochemically Triggered Dynamics within a Hybrid Metal–Organic Electrocatalyst

Visible and infrared spectroelectrochemistry of zinc and manganese porphinones: Metal vs. porphyrin reduction

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