Predictive energetic tuning of C-Nucleophiles for the electrochemical capture of carbon dioxide

This work maps the thermodynamics of electrochemically generated C-nucleophiles for reactive capture of CO(2). We identify a linear relationship between the pK(a), the reduction potential of a protonated nucleophile (E(red)), and the nucleophile’s free energy of CO(2) binding ([Formula: see text]). Through synergistic experiments and computations, this study establishes a three-parameter correlation described by the equation [Formula: see text] for a series of twelve imidazol(in)ium/N-heterocyclic carbene pairs with an R(2) of 0.92. The correlation allows us to predict the [Formula: see text] of C-nucleophiles to CO(2) using reduction potentials or pK(a)s of imidazol(in)ium cations. The carbenes in this study were found to exhibit a wide range CO(2) binding strengths, from strongly CO(2) binding to nonspontaneous. This observation suggests that the [Formula: see text] of imidazol(in)ium-based carbenes is tunable to a desired strength by appropriate structural changes. This work sets the stage for systematic energetic tuning of electrochemically enabled reactive separations.