Synthesis and crystal structure analysis of 2-(4-fluorobenzyl)-6-phenylimidazo[2,1-b][1,3,4]thiadiazole and its chlorophenyl derivative

Preparations of 2-(4-fluorobenzyl)-6-phenylimidazo[2,1-b][1,3,4]thiadiazole (3a) and its chlorophenyl derivative (3b) are described. Preliminary analysis was done spectroscopically by means of 1H NMR, 13C NMR spectra, mass spectra and elemental analyses. Further the structures were confirmed by X-ray crystal structure analyses. The compound (3a) has crystallized in a triclinic P-1 space group with three independent molecules in the asymmetric unit, while the compound (3b) belongs to P21/c space group with one molecule in the asymmetric unit. The molecule (3b) differs from molecule (3a) by the presence of chlorine substituent. Additionally, the imidazo-thiadiazole entity is as usual planar. Intramolecular C–H⋯N hydrogen bonding between the imidazole and the phenyl ring of the molecule can be observed in (3a) & (3b). The molecules of (3a) are linked into two dimensional supramolecular hexagonal hydrogen bonded network sustained by C–H⋯F interaction, while those of (3b) are linked by bifurcated C–H⋯N interactions. Further, the molecular packing of both the compounds is stabilized by π–π stacking interactions between the benzene and imidazo-thiadiazole ring systems.