Understanding the effect of substitution on the formation of S..F chalcogen bond

In this study, we have investigated the effect of substitution on the formation of S …F non-covalent interactions in XHS …FCH₃ complexes (X =-H, -F, -Cl, -OH, -OCH₃, -NH₂, -NHCH₃, -NO₂, -CN) at MP2/aug-cc-pVDZ level of theory. The formation of S …F chalcogen bonds was observed in all the cases, except for X = -H. The binding energy of the S …F non-covalent interactions is strongly dependent on the nature of the substituent groups. The energy decomposition analysis revealed that electrostatic and exchange energy component are the dominant contributors towards the stability of these interactions. The topological analysis established the presence of the S …F chalcogen bond due to the presence of a bond critical point exclusively between sulphur and fluorine atoms representing a closed-shell interaction. The natural bond orbital analysis shows that the stability of the interaction comes from a charge transfer from F(lp) to s*(S-X) orbital transition. [Figure not available: see fulltext.]