ABSOLUTE INTENSITIES OF C-H OUT-OF-PLANE COMBINATION BANDS FOR BENZENE DERIVATIVES IN CS2 SOLUTION

Infrared absolute intensities of the CH out-of-plane binary combination bands were measured for benzene and various methyl- and chlorobenzenes in CS2 solution by using Ramsay's direct integration method, and these intensities were calculated by introducing several dipole moment parameters which can be written in terms of the second derivatives of the dipole moment with respect to the CH out-of-plane deformation. By taking [ ∂2μ(C-H+) ∂θ2]0 = -1.37D, the band intensities calculated were in fairly good agreement with those observed. In the case of chlorobenzenes, it was found that an induced moment of about 10 per cent should be added on a CH bond as a result of the ortho-effect caused by its nearest neighboring CCl bond. © 1968.