The far-infrared vapor phase spectra of some halosubstituted anilines

Abstract
Vapor phase far‐infrared spectra from 35 to 675 cm−1 of the nine ortho‐, meta‐, and para‐substituted fluoro‐, chloro‐, and bromoanilines obtained with an interferometer are reported. The vi=1, 2, and 3 levels of the amino group inversion vibration are established from the observed transitions, and the barriers to inversion are derived from these, using a simple double minimum harmonic well potential with a Gaussian barrier. Calculated barrier heights range between 385.9 cm−1 (2‐bromoaniline) and 599.9 cm−1 (4‐fluoroaniline). The following out‐of‐plane vibrations are also assigned: amino group wag, substituent wag, and ring deformation. The ντ±νi combinations lead to deduced frequencies for the torsional vibration ντ in a number of cases.