Crystal Structure, Computational Study and Hirshfeld Surface Analysis of 4-(4-Methoxyphenethyl)-5-(p-tolyl)-2,4-Dihydro-3H-1,2,4-Triazol-3-One, C18H19N3O2

The title compound, 4-(4-methoxyphenethyl)-5-(p-tolyl)-2,4-dihydro-3H-1,2,4-triazol-3-one (C18H19N3O2), was characterized by single crystal X-ray diffraction. In order to compare the experimental and theoretical compatibility, the DFT and HF modeling technique was also used. When the theoretical and experimental results are compared, it is seen that the geometric parameters from both investigation techniques are quite compatible. X-ray diffraction (XRD) analysis shows that the structure has crystallized in the orthorhombic space group Pna2(1). The planes of the triazole and benzyl rings in the molecule make dihedral angles of 46.14(1)(omicron) (C1-C6) and 43.89(1)(omicron) (C12-C17). The molecules in the asymmetric unit are linked by intermolecular N-H center dot center dot center dot O hydrogen bonds, forming a three-dimensional network. Frontier molecular orbital (FMO) analysis was performed to describe intramolecular interactions. For the molecule the energy difference between the lowest unoccupied molecular orbital (LUMO) and highest occupied molecular orbital (HOMO) was calculated as - 4.95 eV. Potential energy surface (PES) analysis was performed by a semi-empirical method to determine the stable states of molecular structure and to compare them with XRD geometry. In order to determine the thermodynamic properties of the molecular structure enthalpy, heat capacity and entropy values were calculated for selected temperature values