Theoretical study of the vibrational spectra of 2-chloropyridine metal complexes.: I.: Calculation and analysis of the IR spectrum of 2-chloropyridine

The force field and the electrooptical parameters of 2-chloropyridine were determined by the refinement of the corresponding parameters of the pyridine molecule, for further use in the metal complexes study. During the refinement procedure, the results of semiempirical (MNDO) and ab initio (4-31G*) calculations were taken into account. Approximate normal coordinate analysis was performed on the basis of different theoretical calculations. Theoretical results predict significant mixing of the ring and CH modes. Nevertheless, there is qualitative agreement between normal mode assignments made upon quantum chemical calculations, force field refinement results and results based on earlier experimental information. Calculation of the IR intensities serves as an additional check of the force field quality. The interpretation of the IR intensities and contribution of various parts of the molecule to the total IR spectra is given. (C) 1999 Elsevier Science B.V. All rights reserved.