Crystallographic and Theoretical Investigation on the Nature and Characteristics of Type I C═S···S═C Interactions

Abstract

In this study, we have performed an extensive crystallographic and theoretical analysis to explore the nature and characteristics of C═S···S═C interactions. A Cambridge Structural Database study revealed the abundance of C═S···S═C interactions wherein more than 70% of the crystal structures can be categorized as Type I chalcogen–chalcogen interactions. The binding energies for these contacts range in magnitudes from +2.02 kcal/mol (highly destabilized) to −1.67 kcal/mol (stabilized). Ab initio studies on (X2CS)2 models systems where X = −H, −NH2, −OH, −F, −Cl reveals that C═S···S═C are governed by the presence of negative σ-holes for X = −NH2, −OH, while the presence of a positive electrostatic region on sulfur is observed for the halogen substituted complexes. These interactions are of dispersive nature with electrostatics contributing to the destabilization in some cases.