Normal coordinate analyses of three isomeric acetylpyridines and acetophenone

Abstract

Normal coordinate analyses for 2-, 3- and 4-acetylpyridine and acetophenone were carried out employing a systematic procedure based on a modified valence force field that is comparable to those used previously for different aromatic molecules. The general valence force fields (GVFF) were determined using a set of 41 parameters (25 planar and 16 non-planar) for the above compounds to compare the observed wavenumbers with the calculated values satisfactorily with an average error of 7.0 cm−1 (0.82%) for in-plane and 9.2 cm−1 (1.60%) for out-of-plane modes. On the basis of the calculated potential energy distribution, certain revisions of the previous assignments were made. The decomposition of the normal mode wavenumbers into those related to different internal coordinates is discussed. Copyright © 2000 John Wiley & Sons, Ltd.