Molecular structure and vibrational and chemical shift assignments of 5-(2-Hydroxyphenyl)-4-(p-tolyl)-2,4-dihydro-1,2,4-triazole-3-thione by DFT and ab initio HF calculations

Abstract

The molecular geometry, vibrational frequencies, gauge including atomic orbital (GIAO) (1)H and (13)C chemical shift values and several thermodynamic parameters of 5-(2-Hydroxyphenyl)-4-(p-tolyl)-2,4-dihydro-1,2,4-triazole-3-thione in the ground state have been calculated by using the Hartree-Fock (HF) and density functional method (DFT/B3LYP) with 6-31G(d), 6-31 + G(d,p) and LANL2DZ basis sets. The results of the optimized molecular structure are presented and compared with the experimental X-ray diffraction. The computed vibrational frequencies are used to determine the types of molecular motions associated with each of the experimental bands observed. Also, calculated (1)H chemical shift values compared with the experimental ones. The data of the title compound display significant molecular structure and IR, NMR analysis provide the basis for future design of efficient materials having the of 1,2,4-triazole core.

DFT Calculations on the Molecular Structure, Vibrational and Chemical Shift Assignments of 4-Allyl-2-(morpholin-4-ylmethyl)-5-(pyridin-4-yl)-2,4-Dihydro-3H-1,2,4-Triazole-3-Thione

“…This is attributed to delocalization between the lone pair on N(1) and the C(1)=S(1) double bond. These results for the C(1)=S(1) double bond are similar to our previous calculations [32]. To understand this phenomenon in the context of a molecular orbital picture, we examined the molecular HOMOs (the π donor ) and molecular LUMOs (the π acceptor ) that were generated by Gaussian 03 W. B3LYP/6-31G(d) generated the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) for the title compound and this is shown in Fig.…”

“…This statement is supported by our previous work [32]. These bond lengths are 1.3006(15), 1.3526(15), 1.3711(14) and 1.3734(15) Å [7], respectively.…”

“…Moreover, we took into account the important bonds that consist of O(1)-C(5), O(1)-C(6) and C(1)=S(1) for the title compound bond lengths, and these bond lengths are 1.413(2), 1.419(2) and 1.6676(12) Å, respectively [7]. In previous work, the C-S bond distance for 1,3,4-thidiazole, thiophene and 1,2,4-triazole rings were found to be 1.720-1.820, 1.740-1.782 and 1.665-1.709 Å [32][33][34]. In our work, the O(1)-C(5), O(1)-C(6) and C(1)=S(1) bond distances were calculated to be 1.439, 1.440 and 1.684 Å using the BLYP/6-31G(d) method, and 1.421, 1.422 and 1.674 Å using the B3LYP/6-31G(d) method and the data are listed in Table 1.…”

“…16 107.81 C(10)-N(5)-C (11) 116.20 (14) at 1504 cm −1 [38], 1622 cm −1 [39] and 1614 cm −1 [7] while they are at 1599-1668 cm −1 at the B3LYP level [32] and 1508 cm −1 at the B3LYP/6-311G(d,p) level [38]. We calculated that these modes are at 1533 cm −1 at the BLYP/6-31G(d) level and 1556 cm −1 at the B3LYP/6-31G(d) level.…”

Experimental and ab initio Computational Studies on Dimethyl-(4-{4-{3-methyl-3-phenyl-cyclobutyl)-thiazol-2-yl]-hydrazonomethyl}-phenyl)-amine

“…23 A number of papers have recently appeared in the literature concerning the calculation of vibrational assignments by quantum-chemistry methods. [24][25][26][27][28] These papers indicate that geometry optimization is a crucial factor in an accurate determination of computed vibrational frequencies. Moreover, it is known that the density functional theory (DFT) adequately takes into account electron correlation contributions, which are especially important in systems containing extensive electron conjugation and/or electron lone pairs.…”