Organoboron catalysts: From structural design to functional application in CO2 conversions

Carbon dioxide (CO2), which is closely associated with global warming and climate change, also represents a highly valuable C1 resource for its remarkable features such as natural abundance, easy availability, and renewability. As a thermodynamically stable molecule, CO2 demands high energy for activation and chemical conversion. Although metal complexes have demonstrated remarkable catalytic performance in homogeneous systems for CO2 hydrogenations, carboxylation reactions, and carbonate formation reactions, they are associated with limitations such as product coloration, inherent toxicity, and complicated preparation process. Metal-free organoboron catalysts offer an effective solution to these limitations, providing a safer and more efficient alternative for catalyzing CO2 conversion reactions. This review summarizes recent advances in organoboron catalysts, focusing on their structural diversity-including intermolecular/binary systems, intramolecular/bifunctional configurations and polymeric architectures-along with their corresponding synthetic strategies. After fully discussing the structural types of catalysts and the CO2 activation mechanisms, the applications of organoboron catalysts are explored in two directions, including the CO2 reduction reactions (CO2RRs) and the carbonate formation reactions. Notably, comparative evaluation reveals that the organoboron catalysts applied in CO2RRs, particularly intermolecular and intramolecular frustrated Lewis pairs (FLPs), despite differences in the acidity of the organoboron and its substituent groups, have been demonstrated to be effective in catalyzing the coupling or copolymerization of CO2 and epoxides. This cross-reaction applicability of organoborons establishes valuable precedents for innovating novel CO2 conversion pathways.