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 H2 activation CO2 hydrogenation processes. According to DFT predictions at the B3LYP-D3 level, presence of rigid scaffolds increased P···B distances FLPs lead a remarkable drop energy barrier for (by up 19.2 kcal mol−1, compared parent dimethylxanthene-based FLP). Furthermore, differences between transition states are significantly reduced, making both processes feasible under relatively mild experimental conditions.