Quantitative crystal structure analysis of 1,3,4-thiadiazole derivatives

Abstract

A series of four biologically active 2-benzamido-5-(4-fluoro-3-phenoxyphenyl)-1,3,4-thiadiazoles derivatives have been synthesized and their crystal structures have been studied with systematic variations in the functional group at the para position of the benzamido ring. The molecular geometry of all these compounds is found to be L-shaped and their molecular conformation is found to be stabilized via S⋯O and F⋯C (lp⋯π) contacts. The lattice energies of these crystal structures have been calculated by PIXEL. Detailed quantitative analysis of the crystal packing have been performed with calculation of the interaction energies of the extracted molecular pairs from the crystal packing using PIXEL and these are further supported with inputs from high level DFT + Disp quantum mechanical calculations. The isostructurality present in the crystal packing has been investigated using XPAC. The Hirshfeld surfaces and consequently the fingerprint analysis have been performed to study the nature of interactions and their quantitative contributions towards the crystal packing. The electrostatic potential has been mapped over the Hirshfeld surface to explore the electrostatic complementarity which exists in the crystal packing. It is found that the weak interactions, such as C–H⋯OC/O–C, C–H⋯π, C–H⋯F, lp⋯π, π⋯π are significant contributors in the stabilization of the crystal packing in addition to the presence of strong N–H⋯N hydrogen bonds. It was observed that they are not only responsible for the alteration in the crystal structures, but their presence does provide extra stabilization in the absence of any structural change.