Design of CO2 hydrogenation catalysts based on phosphane/borane frustrated Lewis pairs and xanthene-derived scaffolds

New naphtho[2,1,8,7-klmn]xanthene and benzo[kl]xanthene-based intramolecular phosphane-borane frustrated Lewis pairs (FLPs) were investigated in catalyzed H-2 activation and CO2 hydrogenation processes. According to DFT predictions at the B3LYP-D3 level, the presence of rigid scaffolds and increased P center dot center dot center dot B distances in the investigated FLPs lead to a remarkable drop in the energy barrier for CO2 hydrogenation (by up to 19.2 kcal mol(-1), compared to the parent dimethylxanthene-based FLP). Furthermore, the energy differences between the transition states for H-2 activation and CO2 hydrogenation are significantly reduced, making both processes feasible under relatively mild experimental conditions.

Automated summary

New naphtho[2,1,8,7-klmn]xanthene and benzo[kl]xanthene-based intramolecular phosphane-borane frustrated Lewis pairs (FLPs) were studied for catalyzed H-2 activation and CO2 hydrogenation processes. According to DFT predictions, the presence of rigid scaffolds and increased P···B distances in the investigated FLPs significantly reduced the energy barrier for CO2 hydrogenation and minimized the energy differences between the transition states for H-2 activation and CO2 hydrogenation, making both processes feasible under relatively mild experimental conditions.