Ultraviolet and Visible Absorption Spectra of the Solid States of Aromatic Amine Complexes with Iodine

The ultraviolet and visible spectra of aromatic amine complexes with iodine in the crystalline state have been investigated by means of the KBr disk method or with a squashed powder between quartz plates. Part of the aniline (ANI) ions in the ANI-iodine system become positive, and the maximum of the spectrum band appears at 255 mμ. p-Phenylenediamine (p-PDA) and 1,5-naphthylenediamine (NDA) complexes with iodine possess the band maxima at the same position as those of ANI and α-naphthylamine. The ground states of these complexes seem to be dative states. In benzidine (BEN) and o-tolidine (TOL) from polyphenylenediamines, and iodine complex systems bathochromic shifts are observed. By estimating the ionization potential ID of these aromatic amines from the energies of the charge transfer transition, low values of ID, except for ANI, are obtained. The electrical resistivities of these specimens are in the order BEN