MP2 study of cooperative effects between cation–π, anion–π and π–π interactions

In this manuscript we report high level ab initio calculations (RI-MP2(full)/6-31++G**) and experimental evidence that demonstrate that important non-additivity effects between three noteworthy non-covalent interactions that involve aromatic rings (benzene and hexafluorobenzene), i.e. cation–π, anion–π and π–π interactions, occur when the interactions coexist in the same complex. In some cases we have observed very high non-additivity energies (up to −20.3 kcal mol−1) that indicate that the cation–π and/or the anion–π have a strong influence on the π–π interaction and vice versa.