Crystallographic and Theoretical Investigation on the Nature and Characteristics of Type i C=S···S=C Interactions

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.