Theoretical investigations on the enhancing effect of the cation–π interaction on the halogen bond in the M∙∙∙HCCX∙∙∙NH3 (M = Li+, Na+, Cu+, Ag+, Au+; X = Cl, Br) complexes

Abstract

The M∙∙∙HCCX∙∙∙NH₃ (M = Li⁺, Na⁺, Cu⁺, Ag⁺, Au⁺; X = Cl, Br) complexes were designed to study the influence of cation-π interaction on the X∙∙∙N halogen bonds under M05-2X/aug-cc-pVDZ(PP) level. In comparison with the HCCX∙∙∙NH₃ complexes, the bond distances of the halogen bonds have decreased, and the interaction energies become more negative. The results show that the X∙∙∙N halogen bonds have been strengthened by the cation-π interactions. For different cations, the enhancing effect is more intensive in the order of Au⁺ > Cu⁺ > Ag⁺ > Li⁺ > Na⁺, which indicates that transition metal cations can enhance the halogen bond in a stronger manner. Molecular electrostatic potential and second-order perturbation stabilization energy were calculated to deepen the discussion. In addition, atoms in molecules analysis was performed and the electron density shift was studied.

How Do Distance and Solvent Affect Halogen Bonding Involving Negatively Charged Donors?

“…Moreover, the total interaction energy has a similar magnitude to the dispersion term . Recently, the additive and synergistic effects between halogen bonding and other noncovalent interactions, ,− such as cation···π, S···N, anion···π, and hydrogen-bonding interactions, were also studied.…”