Halogen bonding in the antibacterial 1,2,4-triazole-3-thione derivative - Spectroscopic properties, crystal structure and conformational analysis

The molecular structure of 4-(4-bromophenyl)-5-(3-chlorophenyl)-2,4-dihydro-3H-1,2,4-triazole-3-thione (TP-4) has been determined by the X-ray diffraction experiment and compared to the geometry calculated in the ground state by using HF and DFT methods. The compound crystallizes in the triclinic P-1 space group. To explain the observed rotational disorder of meta-chloro-substituted aromatic ring the conformational analysis was performed for TP-4 and the molecular energy profile has been obtained. The vibrational frequencies in the solid state were recorded and compared to the calculated in the ground state. The molecular electrostatic potential isosurfaces (MEPS) were calculated to confirm the role of halogen bonds in stabilizing the crystal structure. (C) 2014 Elsevier B.V. All rights reserved.