Frequency assignments in the CsBr spectral region (650 to 285 cm−1) have been made from the spectra of 279 benzene derivatives. The Raman Spectra of 119 of these compounds were also used as aids in making the assignments. The assigned frequencies include several benzene-like ring-deformations and some vibrations that are either internal vibrations of the substituent group or involve the ring-substituent bond. A variation in frequency with symmetry or substitution type (ortho, meta, para, etc.) was found for the ring-deformations. Within a given substitution type certain of the ring-deformation vibrations were found to be sensitive to substituent effects. The assigned frequencies involving the substituent group can be classified as characteristic frequencies of benzene compounds with a particular substituent.
R. J. Jakobsen and F. F. Bentley, "Vibrational Spectra of Benzene Derivatives. II. Frequency Assignments in the CsBr Region," Appl. Spectrosc. 18, 88-92 (1964)