Stacking interactions between hydrogen-bridged and aromatic rings: study of crystal structures and quantum chemical calculations

Geometric analysis of data from Cambridge Structural Database (CSD) reveals that contacts between planar hydrogen-bridged rings and C6-aromatic rings are mostly parallel stacked geometries. High-level quantum chemical calculations show that their interaction energies are comparable with interactions between two hydrogen-bridged rings. Namely, the interaction energy, at the CCSD(T)/CBS level, of the most stable geometry is -4.38 kcal mol-1, which is comparable with that of interaction between two hydrogen-bridged rings (-4.89 kcal mol-1) and significantly stronger than that of stacking between two benzene rings (-2.73 kcal mol-1).