Benzene and water – different or similar?

Abstract

Considering the properties of water and benzene molecules, one can expect very different benzene/benzene and water/water interactions. Benzene does not have a dipole moment, while water does. Analysis of the data in the crystal structures in the Cambridge Structural Database (CSD) revealed the most frequent benzene/benzene and water/water geometries. The majority of the benzene/benzene interactions in the crystal structures in the CSD are stacking interactions with large horizontal displacements, and not geometries that are minima on benzene/benzene potential surface. A large number of the water/water contacts in the CSD are hydrogen bonds, 70% of all attractive water/water interactions. In addition, water/water contacts with two water forming antiparallel interactions are 20% of all attractive water/water contacts. In these contacts, the O-H bonds of water molecules are in antiparallel orientation. In benzene/benzene interactions at large horizontal displacements, two C-H bonds also are in the antiparallel orientation. This shows that although the two molecules are different, both of them form antiparallel interactions with a local O-H and C-H dipole moments.