Pulsed-EPR evidence of a manganese(II) hydroxycarbonyl intermediate in the electrocatalytic reduction of carbon dioxide by a manganese bipyridyl derivative

M. Bourrez (1) , M. Orio (2) , F. Molton (1) , H. Vezin (2) , C. Duboc (1) , A. Deronzier (1) , S. Chardon-Noblat (1)

1 DCM - CIRE - Département de Chimie Moléculaire - Chimie Inorganique Redox
2 LASIRE - Laboratoire Avancé de Spectroscopie pour les Intéractions la Réactivité et l'Environnement - UMR 8516

A key intermediate in the electroconversion of carbon dioxide to carbon monoxide, catalyzed by a manganese tris(carbonyl) complex, is characterized. Different catalytic pathways and their potential reaction mechanisms are investigated using a large range of experimental and computational techniques. Sophisticated spectroscopic methods including UV/Vis absorption and pulsed-EPR techniques (2P-ESEEM and HYSCORE) were combined together with DFT calculations to successfully identify a key intermediate in the catalytic cycle of CO₂ reduction. The results directly show the formation of a metal-carboxylic acid-CO₂ adduct after oxidative addition of CO₂ and H⁺ to a Mn⁰ carbonyl dimer, an unexpected intermediate.

Keywords: carbon dioxide; catalysis; electrocatalysis; EPR spectroscopy; manganese

Domains: Theoretical and/or physical chemistry

M. Bourrez, M. Orio, F. Molton, H. Vezin, C. Duboc, et al.. Pulsed-EPR evidence of a manganese(II) hydroxycarbonyl intermediate in the electrocatalytic reduction of carbon dioxide by a manganese bipyridyl derivative. Angewandte Chemie International Edition, 2014, 53, pp.240-243. ⟨10.1002/anie.201306750⟩. ⟨hal-00945389⟩