Theoretical ab initio study of substituted benzene trimer: Interplay between hydrogen bonding and π-π interactions

The interplay between two important noncovalent interactions involving aromatic rings is studied by means of ab initio calculations (RI-MP2/aug-cc-pVTZ//RI-MP2/aug-cc-pVDZ level of theory). We demonstrate that synergetic effects are present in complexes where hydrogen bonding interactions and π-π interactions coexist and that these effects are transmitted through the space to a third aromatic ring. The π-π interaction is influenced by the presence/absence of hydrogen bonding interactions that are established in a third π-system far from the stacking interaction. These synergetic effects have been studied using energetic and geometric criteria and the Bader's theory of “atoms in molecules”.