Crystal Structures of 1,3-Bis[thioxo-thiazolinyl]-/1,3-[oxo/thioxo-thiazolinyl] Aromatic Atropisomers with Two C(Aryl)−N(Heterocycle) Chiral Axes: An X-ray and DFT Analysis of Dispersion and Weak Chalcogen Interactions Governing Supramolecular Ordering

The crystal packing of five atropisomers with two C(aryl)-N(heterocyle) chiral axes, namely, four 1,3-bis[thioxo-thiazolinyl]- and one 1,3-[oxo/thioxo-thiazolinyl] aromatic compounds, was investigated by single-crystal X-ray diffraction. The aim is to establish the relevance of S···S/S···O chalcogen interactions and S···H weak hydrogen bonds in the crystalline network. The high number of alkyl substituents, together with hindered rotation about the C−N bonds, suggests that dispersion is the primary contributor to crystal cohesion. However, even weak, highly directional contacts such as C−H···S and S···S could be emphasized as significant forces in the crystalline supramolecular network. Chalcogen S···S/OC synthon was identified as a pattern along the series of compounds, and replacing S···SC with S···OC confirmed the propensity of these chalcogen interactions, CO being a stronger nucleophile. DFT, NBO, and QTAIM methods were used to define the type and features of the S···S/S···O interactions even at distances 10% beyond the sum of the Bondi van der Waals radii (ΣvdW). SAPT analysis revealed dispersion-driven interactions even when σ-hole interactions were geometrically within the chalcogen bond definition.