Calculated potential-energy distributions and Cartesian displacements are used to determine the characters of planar vibrations of chlorinated benzenes in the 1600-300 cm-1 region. It has been assumed that hydrogen deformations occur in the 1200-1000 cm-1 region; however, the present work indicates that hydrogen deformations may occur between 1500-1100 cm-1 are are coupled, in varying degrees, with ring stretching and bending modes. The strongly infrared active bands in the 1100-1000 cm-1 region are ring modes with less than ∼50% coupling with CH deformation. Vibrations below 1000 cm-1 are shown to be highly substituent dependent. The CD deformations of the deuterated molecules are relatively pure and do not couple with the higher frequency ring modes as do the CH deformations. © 1965.
Scherer, J. R. (1965). Group vibrations of substituted benzenes-II. Planar CH deformations and ring stretching and bending modes of chlorinated benzenes. Spectrochimica Acta, 21(2), 321–339. https://doi.org/10.1016/0371-1951(65)80013-3