The spectral manifestations of hydrogen bonding on the ν(NH) and 2γ (HNH) absorption bands of 2,5-, 3,4- and 3,5-dichloroaniline and 2,4,6-trichloroaniline in association with CH3CN, C4H8O2, (CH3)2NOCH, (CH3)2SO and (CH3)2N3PO were studied. The NH⋯Cl intramolecular hydrogen bond has been shown to be present in 2,5-dichloroaniline and 2,4,6-trichloroaniline. In the framework of the RNH2 model for free molecules of chloro-substituted aniline we have calculated the normal vibration forms and frequencies, (νs(NH) and νas(NH)), the force constants (K(NH)), the valence angles (γ(HNH)), and the electro-optical parameters (∂μ/∂q and ∂μ/∂q′). For 1:1 complexes and for free 2,5-dichloroaniline molecules, the electro-optical parameters were calculated with account being taken of the mechanical and electro-optical nonequivalence of NH bonds. The position of the chlorine atom in the aromatic ring of free molecules influences the value of the valence angle (γ(HNH)) and the electro-optical parameters (∂μ/ ∂q). The ∂μ/∂q′ parameter of free molecular dichloro-substituted aniline does not depend on the position of the chlorine atoms. In 1:1 hydrogen bonded complexes a considerable increase in the parameters ∂μ/∂q1 and ∂μ1/∂q2 is observed; however, the ∂μ2/∂q2 value of the free NH group remains virtually unchanged. © 1990.
