INFRARED INTENSITIES AS A QUANTITATIVE MEASURE OF INTRAMOLECULAR INTERACTION .7. NU13 BAND NEAR 1500-CM-1 IN MONOSUBSTITUTED AND PARA-DISUBSTITUTED BENZENES

The integrated intensity is reported for the 1500-cm-1 band for many monosubstituted and para-disubstituted benzenes. The values in monosubstituted benzenes are linearly related to σR0 but the accuracy of this identity is lower than with the 1600-cm-1 intensities previously reported. The values obtained suggest the polarization C--H+ in the aromatic C-H bonds. The values obtained for the para-disubstituted benzenes can be explained in terms of the intensities of the corresponding monosubstituted compounds and give further evidence for the participation of d orbitals in bonding halogen atoms to the aromatic nucleus.