A Naphthalene Monoimide Meisenheimer Complex as Strong Organic Hydride Donor for Metal-Free CO₂ Reduction

Selective CO₂ reduction to formate is challenging due to similar thermodynamics for the reaction to other products such as carbon monoxide and molecular hydrogen. Formate production can be achieved via hydride transfer from metal-hydride complexes or organic catalysts; the latter being inspired by the structure and activity of the NAD(P)H cofactor in natural photosynthesis. Most known synthetic NAD(P)H mimics can selectively produce formate, yet they suffer from sluggish kinetics, which limits their applicability. In a combined experimental and theoretical study, we demonstrate that naphthalene monoimide Meisenheimer complex NMI(H)^- is a strong organic hydride donor with the ability to reduce CO₂ to formate. DFT calculations are used to benchmark the thermodynamic hydricity of NMI(H)^- in comparison with previously known NAD(P)H mimics.