Deciphering the Importance of Weak CH…O and CH…π Interactions in S-Propyl (E)-2-(1,1-Dioxido-2-Propylbenzo[d]Isothiazol-3(2H)-ylidene)-1-Propylhydrazine-1-Carbothioate: An Experimental and Theoretical Approach

Abstract

The title compound, C₁₇H₂₅N₃O₃S₂, hereafter 1, has been prepared and fully characterized by FTIR, ¹H NMR and ¹³C NMR. Its crystal structure was determined by single-crystal X-ray diffraction. The crystal packing is stabilized by weak CH···O and CH···π interactions. The CLP-Pixel method was used to quantify the energetically significant molecular dimers. The intermolecular contacts were identified and quantified using Hirshfeld surfaces (HS) and the corresponding fingerprint plots. The main contributions to the HS of 1 come from HH, OH/HO and CH/HC contacts, which cover about 93% of the total HS surface. The enrichment ratios showed that the favorable contacts accountable for the crystal packing are consistent with their contributions to the HS. Interaction region indicator (IRI) analysis was used to visualize the location and type of intermolecular contacts, allowing identify the CH···O contacts as van der Waals interactions. To visualize the 3D topology of interactions in the crystal structure, interaction energy values were used to construct energy framework diagrams, which showed that the dispersion energy dominates over other interaction energies, as expected for crystal packing governed by weak interactions. Finally, a combination of MEP surface, QTAIM and NCIplot analysis energetically confirmed the existence of CH···O and O···O dichalcogen interactions.