Cobalt Complex of a Tetraamido Macrocyclic Ligand as a Precursor for Electrocatalytic Hydrogen Evolution

Abstract

Hydrogen (H2) is a clean fuel that can potentially store renewable energy and overcome some of the environmental problems that arise from fossil-fuel consumption. One attractive approach is to produce H2 from water electrocatalytically using molecular complexes that can be systematically improved through ligand modifications. We report cobalt and nickel complexes supported by tetraamido macrocyclic ligands (TAMLs), which exclusively consist of earth-abundant elements. Although TAML systems are well established in high-valent transition-metal chemistry, little is known about their reactivity in reductive catalysis despite the electron-rich nature of the tetraanionic TAML. Thus we explored the utility of these nucleophilic -ate complexes as potential electrocatalysts for H2 evolution using water as the proton source. Controlled potential electrolysis experiments were performed, and the cobalt TAML variant exhibited catalytic H2 evolution activity in acetonitrile containing 1.0 M water but was inactive in pu...