The Prominent Enhancing Effect of the Cation-π Interaction on the Halogen-Hydride Halogen Bond in M1⋅⋅⋅C6H5X⋅⋅⋅HM2

We designed M1⋅⋅⋅C6H5X⋅⋅⋅HM2 (M1=Li+, Na+; X=Cl, Br; M2=Li, Na, BeH, MgH) complexes to enhance halogen–hydride halogen bonding with a cation–π interaction. The interaction strength has been estimated mainly in terms of the binding distance and the interaction energy. The results show that halogen–hydride halogen bonding is strengthened greatly by a cation–π interaction. The interaction energy in the triads is two to six times as much as that in the dyads. The largest interaction energy is −8.31 kcal mol−1 for the halogen bond in the Li+⋅⋅⋅C6H5Br⋅⋅⋅HNa complex. The nature of the cation, the halogen donor, and the metal hydride influence the nature of the halogen bond. The enhancement effect of Li+ on the halogen bond is larger than that of Na+. The halogen bond in the Cl donor has a greater enhancement than that in the Br one. The metal hydride imposes its effect in the order HBeH