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 pyridin e molecule, for further use in the metal complexes study. During the refine ment procedure, the results of semiempirical (MNDO) and ab initio (4-31G*) calculations were taken into account. Approximate normal coordinate analysi s was performed on the basis of different theoretical calculations. Theoret ical results predict significant mixing of the ring and CH modes. Neverthel ess, there is qualitative agreement between normal mode assignments made up on quantum chemical calculations, force field refinement results and result s based on earlier experimental information. Calculation of the IR intensit ies serves as an additional check of the force field quality. The interpret ation of the IR intensities and contribution of various parts of the molecu le to the total IR spectra is given. (C) 1999 Elsevier Science B.V. All rig hts reserved.