Optimized Light-Driven CO₂ Reduction and Carbonylation Reaction Using Cobalt, Nickel, and Ferrocene Complexes in a Flow Chemistry Reactor

The photocatalytic carbonylation of aryl iodides represents a significant advancement in the field of organic synthesis, particularly in the context of sustainable chemistry and carbon dioxide utilization. The use of CO2 as a starting material for the synthesis of chemical reagents and fuels has the potential to provide economic and environmental benefits. Photocatalysis is a promising strategy to provide a long-term solution to mitigating CO2 emissions. Recent studies have shown favorable results in the use of cobalt-based catalysts for CO2 reduction. This study incorporates multiple species, each playing a distinct role in promoting the reactions. This study explores the innovative approach of reducing CO2 to CO through the application of a newly developed cobalt complex, which is engineered to enhance the efficiency of the carbonylation process. Central to this research is the design and synthesis of a ferrocene-based Schiff base, which serves as a robust molecule, facilitating stabilization of the cobalt center and promoting its photocatalytic activity. In this work, we detail the mechanistic pathways involved in the photocatalytic cycle, highlighting the role of nickel redox catalysis in the formation of carbonyl-based compounds. The integration of these two catalytic systems not only improves the overall reaction efficiency but also allows for the effective utilization of CO2 as a feedstock, thereby addressing environmental concerns associated with carbon emissions. The mechanism of this reaction was thoroughly examined and supported by quantum mechanical methods. The natural transition orbital analysis within the hole–electron framework provided a detailed picture of the photosensitizer activity of the ferrocene-based imine and enabled a comprehensive characterization of the electronic excitations.