Sulfuric acid-mediated synthesis of 2,5-disubstituted 1,3,4-thiadiazole via intramolecular cyclization reaction from dithioesters: An approach to crystal structure prediction, DFT studies and Hirshfeld surface analysis

Abstract

There is an immense need to discover novel methods that would make diversely functionalized molecules available through atom-economical and environmentally friendly reactions that minimize the use of organic solvents. An efficient and facile synthesis of 2, 5-disubstituted 1, 3, 4-thiadiazoles via intramolecular cyclization from dithioesters and benzoic acid in presence of H2SO4 has been developed using dithioesters. The synthesized compound was characterized and confirmed by NMR analysis and single-crystal X-ray diffraction studies. The geometry (bond lengths and bond angles), and molecular properties were estimated by means of the density functional theory (DFT) at B3LYP/6–31 G level of theory with no symmetry constraints. Frontier molecular orbital (HOMO and LUMO) was drawn using the optimized structures which elucidates the charge transfer collaboration and chemical stability of the compound. Good correlation coefficients were found (R2 = 0.9629 and 0.9176,) between the experimental bond length and bond angles and theoretical values. The Hirshfeld surface (HS) analysis showed that oxygen and nitrogen atoms of the 5 h compound may act as H-bond acceptors, some H-bonds contacts are expected to be shown as red spots on the HS of the molecule.