Gaussian calculations of novel 3-(methyl/ethyl/n-propyl)-4-[3-ethoxy-4-(4-methoxybenzoxy)-benzylidenamino]-4,5-dihydro-1H-1,2,4-triazol-5-ones

In this study, three new 3-alkyl-4-[3-ethoxy-4-(4-methoxybenzoxy)-benzylidenamino)-4,5-dihydro-1H-1,2,4triazol- 5-ones (3a-c) were synthesized by the reaction of 3-alkyl-4-amino-4,5-dihydro-1H-1,2,4-triazol-5-ones (1a-c) with 3-ethoxy-4-(4-methoxybenzoxy)-benzaldehyde (2), which was synthesized by the reaction of 3-ethoxy-4-hydroxybenzaldehyde with 4-methoxybenzoyl chloride by using triethylamine. The compounds synthesized were characterized by IR, H-1-NMR, C-13-NMR and UV spectral data. These compounds were optimized by using the B3LYP/6-31G(d, p) and HF/6-31G(d, p) basis sets. H-1 and C-13-NMR isotropic shift values were calculated by the method of GIAO using the program package Gaussian G09W. Experimental and theoretical values were inserted into the grafic according to equation of delta exp=a+b. delta calc. IR absorption frequencies of analysed molecules were calculated by two methods. The experimental and theoretical values were compared and found by regression analysis that are accurate. Furthermore, geometric properties (bond angles, bond lengths and dihedral angles), thermodynamic parameters, electronic properties (total energy, dipole moment), the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO), Mulliken atomic charges of compounds 3a-c have been investigated by using Gaussian G09W program. The structural data of these compounds have been calculated by using 6-31G(d, p) basis set with density functional method (DFT/B3LYP) and Hartree-Fock method (HF).