Theoretical study of the interplay between halogen bond and lithium–π interactions: Cooperative and diminutive effects

The interplay between halogen bonds and lithium–π interactions is investigated in the CF3X–NCLi–C2H4, CF3X–CNLi–C2H4 and CF3X–C2H4–LiCN (X = Cl,Br,I) complexes at the MP2/aug-cc-pVTZ level. Cooperative and diminutive effects are found when halogen and lithium–π bonds coexist in the same complex. These effects are studied in terms of structural and energetic properties of the complexes. The Bader’s theory of atoms in molecules is applied to characterize the interactions and to analyze their enhancement or attenuation depending upon the variation of charge density at critical points.