Ab initio calculations of of pyridine and its 2- and 3-chloroderivatives

Abstract

Ab initio calculations of the C5H5N, 2-. and 3-ClC5H4N molecules by the RHF method in the valence split 6-31G* basis set with full optimization of the geometry have been carried out. The alternation of the charges on the atoms of the pyridine ring and of the populations of their px-orbitals is in agreement with the noninductive through -the-field interaction of the geminal atoms. The35Cl NQR frequencies and the electric field gradient asymmetry parameters at the35Cl nuclei in 2- and 3-CIC5H4N were estimated using the populations of the valentp-orbitals of the Cl atoms and their components. The35Cl NQR frequency for the first compound is lower than that for the second one, mainly due to the higher pσ-electron population of its Cl atom.