Hydrogen Evolution Mediated by Cobalt Diimine-Dioxime Complexes: Insights into the Role of the Ligand Acid/Base Functionalities.

Dongyue Sun (1) , Aparna Karippara Harshan (2) , Jacques Pécaut (3) , Sharon Hammes-Schiffer (4) , Cyrille Costentin (5) , Vincent Artero (1)

1 SolHyCat - Solar fuels, hydrogen and catalysis
2 Department of Chemistry, The Pennsylvania State University
3 CIBEST - Chimie Interface Biologie pour l’Environnement, la Santé et la Toxicologie
4 Department of Chemistry, Yale University
5 DCM - CIRE - Département de Chimie Moléculaire - Chimie Inorganique Redox

The benchmarking of the performance for H-2 evolution of cobalt diimine-dioxime catalysts is provided based on a comprehensive study of their catalytic mechanism. The latter follows an ECE'CC pathway with intermediate formation of a Co(II)-hydride intermediate and second protonation possibly at a basic site of the ligand, acting as a proton relay. This suggests an intramolecular coupling between the hydride and protonated ligand as the proton concentration-independent rate-determining step controlling the turnover frequency for H-2 evolution.

Mots clés: Molecular Catalysis; Hydrogen; Proton Relay; Cobalt hydride; Mechanism; Cyclic Voltammetry

Domaines: Chimie; Catalyse; Energie électrique

Dongyue Sun, Aparna Karippara Harshan, Jacques Pécaut, Sharon Hammes-Schiffer, Cyrille Costentin, et al.. Hydrogen Evolution Mediated by Cobalt Diimine-Dioxime Complexes: Insights into the Role of the Ligand Acid/Base Functionalities.. ChemElectroChem, 2021, 8 (14), pp.2671-2679. ⟨10.1002/celc.202100413⟩. ⟨hal-03320907⟩