A Free Energy Landscape of CO₂ Capture by Frustrated Lewis Pairs

Frustrated Lewis pairs (FLPs) are known for their ability to capture CO₂. Although many FLPs have been reported experimentally and several theoretical studies have been carried out to address the reaction mechanism, the individual roles of the Lewis acid and base of FLPs in the capture of CO₂ are still unclear. In this study, we employed density functional theory (DFT) based metadynamics simulations to investigate the complete reaction path for the capture of CO₂ by the tBu₃P/B(C₆F₅)₃ pair and to understand the roles of the Lewis acid and base. Interestingly, we find that the Lewis acid plays a more important role than the Lewis base. Specifically, the Lewis acid is crucial for the catalytic properties and is responsible for both kinetic and thermodynamics control. The Lewis base, however, has less of an effect on the catalytic performance and is mainly responsible for the formation of a FLP system. On the basis of these findings, we propose a rule of thumb for the future synthesis of FLP-based catalysts for the capture of CO₂.