A comparison of the energetic and topological properties of weak interactions in molecular organic crystals

Abstract

Several molecular organic crystals [tetraphenylphosphonium squarate, bianthrone, and bis(benzophenone) azine] have been analyzed topologically following a multipole refinement of each compound. This has resulted in the complete characterization of all the weak interactions present in these systems (C-H···O, C-H···C, and C-Hδ+···δ+H-C). Correlations have been found to exist between the energetic and topological properties for each type of interaction. The coexistence of the three types of interactions provides a unique opportunity to examine their energetic differences and similarities. This examination can also be used to help understand the complex nature of C-Hδ+···δ+H-C type interactions, in particular those characterized as H–H bonds. All this leads to a better understanding of the role H–H bonds play in molecular organic crystals compared with other weak interactions such as hydrogen bonds and van der Waals interactions.Key words: energetics, multipole refinement, H–H bonds, hydrogen bonds.