Work

Solvent driven spontaneous reduction of Fe(III) porphyrins under CO: a mechanistic and spectroscopic study

Year: 2026

Type: article

Abstract: Iron porphyrins are prototypical complexes for redox transformations involving small molecules such as O 2 , CO and CO₂. For example, the [(pTMA)Feᴵᴵᴵ(Cl)]⁴⁺ catalyzed CO₂ electroreduction to CO with high rate and selectivity from the Fe⁰ formal oxidation state. We report here and rationalize the spontaneous, unexpected interaction between [(pTMA)Feᴵᴵᴵ(Cl)]⁴⁺ and CO, which reveals a reduction process of Feᴵᴵᴵ to an Fe II (CO) adduct occurring at open circuit potential. This process is exquisitely dependent on the porphyrin concentration, coordination environment and the nature of the solvent. Notably, tetrahydrofuran (THF) uniquely suppresses the reaction process, suggesting that the solvent itself may act as the electron donor. Although the reductant could not be directly identified, electrochemical and spectroelectrochemical results collectively point to a spontaneous redox interplay between CO coordination and solvent reactivity.

Source: Electrochimica Acta

DOI: 10.1016/j.electacta.2026.150044

Authors: Aude Salamé, Mun Hon Cheah, Julien Bonin, Marc Robert, Elodie Anxolabéhère-Mallart