Experimental and theoretical studies of the molecular structure of 4-(3-(1 H-imidazol-1-yl)propyl)-5- p-tolyl-2 H-1,2,4-triazol-3(4 H)-one

Abstract

The triazol–imidazol compound, 4-(3-(1 H-imidazol-1-yl)propyl)-5- p-tolyl-2 H-1,2,4-triazol-3(4 H)-one ( 3), (C 15H 17N 5O), was prepared and characterized by 1H NMR, 13C NMR, IR and single-crystal X-ray diffraction. By using the density functional theory (DFT) method with 6-31G(d) basis set, the molecular geometry, vibrational frequencies and gauge including atomic orbital (GIAO) 1H and 13C NMR chemical shift values of the title compound ( 3) in the ground state were calculated and compared with the experimental data. The calculated results are show that the optimized geometry can well reproduce the crystal structure. X-ray, FT-IR and NMR spectral results of the title compound ( 3) indicate that the compound exists as keto form. To determine most favorable conformation as theoretically, molecular energy profile of the title compound ( 3) were obtained as a function of the selected torsion angles T(N1 C8 C7 C6), T1 and T(C8 N1 C10 C11), T2, which is varied from −180° to +180° in every 10 by semi-empirical (PM3) calculations. In addition, DFT calculations of the title compound ( 3), molecular electrostatic potential and frontier molecular orbitals were performed at B3LYP/6-31G(d) level of theory.