Crystal Structure and Computational Study of 5-Ethyl-4-(4-Methoxyphenethyl)-4,5-Dihydro-3H-1,2,4-Triazol-3-One and 4-(4-Methoxyphenethyl)-5-Propyl-4,5-Dihydro-3H-1,2,4-Triazol-3-One

Molecular structures of compounds 5-ethyl-4-(4-methoxyphenethyl)-4,5-dihydro-3H-1,2,4-triazol-3-one, (C13H17N3O2) (I) and 4-(4-methoxyphenethyl)-5-propyl-4,5-dihydro-3H-1,2,4-triazol-3-one, (C14H19N3O2) (II) were studied by single crystal X-ray diffraction. Molecular compound I crystallizes in the monoclinic space group P21 with Z = 2, while molecular compound II crystallizes in the monoclinic space group P21/c with Z = 4. The molecular geometries of the compounds I and II were optimized using computational quantum mechanical methods: the density functional theory and the Hartree–Fock approximation. Theoretical values of bond lengths, bond angles, and torsion angles were obtained using the BL3YP functional and the 6-31G+(d) basis. The results show that theoretical values are consistent with experimental values.