Heterogenized Molecular Nickel Terpyridine Catalysts for the Electrochemical Formation of C–N Bonds

The electrochemical formation of C–N bonds from abundant feedstocks, such as CO2 and NO3–, is an emerging research area driven by the increasing demand to decarbonize chemical synthesis. Recent research in this area has predominantly focused on heterogeneous electrocatalysts, leaving critical mechanistic details still lacking due to the complexity of their active sites. On the other hand, molecular catalysts with well-defined and tunable active sites render them ideal for fundamental studies, though reaction rates are often limited. To this end, we have developed a model system for the electrochemical production of C–N bonds using heterogenized nickel terpyridine (NitpyR) complexes with various functional groups (R = NH2, OH, OMe, CF3). The heterogenized monoamine terpyridine complex (NitpyNH2) exhibited superior performance relative to its homogeneous analogue with the formation of formamide, reaching a maximum FE of 8.79%. Notably, variations in catalytic performance and stability were observed for different functionalizations of the terpyridine ligands and were attributed to electronic effects. In situ methods offered complementary insights into the reaction mechanisms, enabling the identification of potential intermediates, coupling mechanisms, and rational routes for further improvement.