2-Propylamino Phenyl]-1,3,4 X-Ray and DFT-Calculated Structures

Abstract

2-Propylamino-5-[4-(2-hydroxy-3,5-dichlorobenzylideneamino) phenyl]-1,3,4-thiadiazole, formulated as C<inf>18</inf>H<inf>16</inf>Cl<inf>2</inf>N<inf>4</inf>OS (I), was synthesized. The crystal and molecular structure of (I) have been determined by 1H-NMR, IR, and X-ray single crystal diffraction. The compound (I) crystallizes in the monoclinic, space group P2(1)/c with unit cell parameters a = 9.0576(2) Å, b = 24. 3382(8) Å, c = 9. 0585(2) Å, M<inf>r</inf> = 407.31, V = 1851. 13(9) Å3, Z = 4, R<inf>1</inf> = 0.036, and wR<inf>2</inf> = 0. 096. Molecular geometry from X-ray experiment of (I) in the ground state has been compared using the density functional method (B3LYP) with 6-31G(d) basis set. To determine conformational flexibility, molecular energy profile of (I) was obtained by semi-empirical (PM3) calculations with respect to selected degree of torsional freedom, which was varied from -180° to +180° in steps of 10°. The results are indicative that the Schiff base, which contains a thiadiazole ring, prefers to be in E-configuration. In addition, molecular electrostatic potential, frontier molecular orbitals, and natural bond orbitals analysis were performed by the B3LYP/6-31G(d) method. © Springer Science+Business Media, LLC 2009.