Relevance of weak intermolecular forces on the supramolecular structure of free or DMSO solvated 5-(4-X-benzylidene)rhodanines (X = F, Cl, Br, I)

Abstract The rhodanines of the title (Xp-Rhod, X = F, Cl, Br, I) were synthesized and characterized in solid state and in solution. The crystal structures of the four compounds show different supramolecular organizations. In the F-, Cl- and Br-derivatives, a R 2 2 ( 8 ) (CSNH) 2 ring forms via N H⋯S hydrogen bonds between two neighbouring molecules to give dimers. The I-derivative is also dimeric, but exhibits R 2 2 ( 8 ) (CONH) 2 rings. The two type of dimers are associated in a variety of structures through hydrogen bonding, π-stacking, C H⋯π interactions and halogen bonding. These interactions were analysed from a crystallographic point of view and their relative relevance was explored using DFT calculations. The effect produced on all these interactions by the incorporation of DMSO molecules to the lattice was analysed by comparing the crystal structures of Xp-Rhod compounds and those of corresponding Xp-Rhod⋅DMSO solvates.