Electronic structure of planar-quasicycled organic molecules with intramolecular hydrogen bond

Abstract

By means of the HF/6-311G(d,p) method, the electronic structure of the series of organic molecules, among which are malonaldehyde, acetylacetone, thiomalonaldehyde, the derivatives of aniline 2-XC 6 H 4 NH 2 , phenol 2-XC 6 H 4 OH, benzenethiol 2-XC 6 H 4 SH (X = CHO, COOH, COO -, NO, NO 2 , OH, OCH 3 , SH, SCH 3 , F, Cl, Br), 8-hydroxyquinoline, 8-mercaptoquinoline, tropolone, has been studied. The intramolecular hydrogen bond (IHB) has been established to lead to a local electron redistribution in quasicycle, and primarily to the electron density transfer between the direct IHB participants -from the hydrogen atom toward the proton-aceptor atom. On forming the IHB of the S-H···O type, the electron density in general decreases on the sulphohydryl hydrogen atom and increases on the sulphur atom.Keywords: intramolecular hydrogen bond, electronic structure, organic compounds with planar quasicycle, quantum chemical ab initio study, dipole moment.