Design and Construction of Novel Frustrated Lewis Pairs Based on Modified Lewis Acid B(C6F5)3

The unique structural features of the frustrated Lewis pairs (FLPs) have made them highly attractive for small molecules activation. In this study, the -C₆F₅ groups of the archetypal Lewis acid B(C₆F₅)₃ were substituted with -H, -C₆Cl₅, -C₆Br₅ and -C₆I₅ groups. And the resulting analogues were paired with the Lewis base I t Bu to construct a series of FLPs, which were subsequently investigated via theoretical calculation methods. The intrinsic nature of the substituent effects on the binding energy of FLPs was elucidated through the analyses of energy decomposition (sobEDA), orbital, and molecular fragment density difference (MFDD). These results demonstrate that the interaction strength of the hydrogen-substituted B(C₆F₅)₂H-I t Bu is significantly enhanced, which stems from its relatively low steric hindrance effect. For B(C₆F₅) _x (C₆Y₅) _3-x -I t Bu (x = 0, 1; Y = Cl, Br, I), the coexistence of ligand effects and dispersion effects ensures that their interaction strengths remain larger than that of B(C₆F₅)₃-I t Bu, despite the presence of strong steric hindrance effects. However, for B(C₆F₅)₂(C₆Y₅)-I t Bu (Y = Cl, Br, I), the interaction is weakened by the combination of a weak ligand effect and significant steric hindrance. Consequently, B(C₆F₅)₂(C₆Y₅)-I t Bu (Y = Cl, Br, I) exhibits promising potential as catalysts for small molecules activation, offering a theoretical foundation for designing high performance FLPs.