Vibrational analysis of substituted anisoles. I-Vibrational spectra and normal coordinate analysis of some fluoro and chloro compounds

The Raman spectra of 4-fluoroanisole, 2,3,5,6-tetrafluoro-, pentafluoro-, 2,3,6-trichloro-, 2,3,4-trichloro- and 3,5-dichloro-anisole were recorded in the region 4000–10 cm−1 and their infrared spectra as mulls were measured in the range 4000–200 cm−1. The Fourier transform far-infrared spectra of the same samples in the region 600–20 cm−1 were also obtained. A normal coordinate analysis was made for the in-plane vibrations of these molecules using a 50-parameter modified valence force field. The force constants were refined using an overlay least-squares technique. Unambiguous vibrational assignments were made using the potential energy distributions and eigenvectors.