title: Molecular Cobalt Complexes with Pendant Amines for Selective Electrocatalytic Reduction of Carbon Dioxide to Formic Acid.
abstract: We report here on a new series of CO2-reducing molecular catalysts based on Earth-abundant elements that are very selective for the production of formic acid in dimethylformamide (DMF)/water mixtures (Faradaic efficiency of 90 ± 10%) at moderate overpotentials (500-700 mV in DMF measured at the middle of the catalytic wave). The [CpCo(PR2NR'2)I]+compounds contain diphosphine ligands, PR2NR'2, with two pendant amine residues that act as proton relays during CO2-reduction catalysis and tune their activity. Four different PR2NR'2ligands with cyclohexyl or phenyl substituents on phosphorus and benzyl or phenyl substituents on nitrogen were employed, and the compound with the most electron-donating phosphine ligand and the most basic amine functions performs best among the series, with turnover frequency >1000 s-1. State-of-the-art benchmarking of catalytic performances ranks this new class of cobalt-based complexes among the most promising CO2-to-formic acid reducing catalysts developed to date; addressing the stability issues would allow further improvement. Mechanistic studies and density functional theory simulations confirmed the role of amine groups for stabilizing key intermediates through hydrogen bonding with water molecules during hydride transfer from the Co center to the CO2molecule.
authors.affiliation: Laboratoire de Chimie et Biologie des Métaux, Université Grenoble Alpes , CEA, CNRS, 17 rue des Martyrs, 38000 Grenoble, France.
authors.forename: Souvik
authors.identifier: 0000-0003-0146-5283
authors.initials: S
authors.lastname: Roy
authors.affiliation: Institut Parisien de Chimie Moléculaire, UMR 8232, Sorbonne Universités , UPMC Univ. Paris 06, CNRS, 75005 Paris, France.
authors.forename: Bhaskar
authors.initials: B
authors.lastname: Sharma
authors.affiliation: Reconnaissance Ionique et Chimie de Coordination, DRF-INAC-SyMMES, Université Grenoble Alpes , CNRS, CEA, 17 rue des Martyrs, 38000 Grenoble, France.
authors.forename: Jacques
authors.initials: J
authors.lastname: Pécaut
authors.affiliation: Laboratoire de Chimie des Processus Biologiques, Collège de France, Université Pierre et Marie Curie , CNRS UMR 8229, 11 place Marcelin Berthelot, 75005 Paris, France.
authors.forename: Philippe
authors.initials: P
authors.lastname: Simon
authors.affiliation: Laboratoire de Chimie des Processus Biologiques, Collège de France, Université Pierre et Marie Curie , CNRS UMR 8229, 11 place Marcelin Berthelot, 75005 Paris, France.
authors.forename: Marc
authors.identifier: 0000-0002-8016-4747
authors.initials: M
authors.lastname: Fontecave
authors.affiliation: Laboratoire de Chimie et Biologie des Métaux, Université Grenoble Alpes , CEA, CNRS, 17 rue des Martyrs, 38000 Grenoble, France.|Department of Advanced Materials Science and Nanotechnology, University of Science and Technology of Hanoi, Vietnam Academy of Science and Technology , 18 Hoang Quoc Viet, Cau Giay, 122102 Hanoi, Vietnam.
authors.forename: Phong D
authors.identifier: 0000-0002-9561-6881
authors.initials: PD
authors.lastname: Tran
authors.affiliation: Institut Parisien de Chimie Moléculaire, UMR 8232, Sorbonne Universités , UPMC Univ. Paris 06, CNRS, 75005 Paris, France.
authors.forename: Etienne
authors.identifier: 0000-0002-8637-2707
authors.initials: E
authors.lastname: Derat
authors.affiliation: Laboratoire de Chimie et Biologie des Métaux, Université Grenoble Alpes , CEA, CNRS, 17 rue des Martyrs, 38000 Grenoble, France.
authors.forename: Vincent
authors.identifier: 0000-0002-6148-8471
authors.initials: V
authors.lastname: Artero