# ULTRAVIOLET SPECTRA OF CATION RADICALS OF p-PHENYLENE-DIAMINE AND ITS ANALOGUES. DIMERIZATION OF THE RADICALS IN SOLUTIONS AND SOLIDS

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 Title: ULTRAVIOLET SPECTRA OF CATION RADICALS OF p-PHENYLENE-DIAMINE AND ITS ANALOGUES. DIMERIZATION OF THE RADICALS IN SOLUTIONS AND SOLIDS Creators: Suzuki, Keisuke; Yamada, Haruka; Ooshika, Yuzuru Issue Date: 1966 Publisher: Ohio State University Abstract: Dimerization of radicals in Wurster's blue solution has been suggested by Hausser and Murrell. In this report, we shall report investigations of electronic spectra of cation radicals of p-phenylenediamine (I), dimethyl-p-phenylenediamine (II), tetramethyl-p-phenylenediamine (III), benzidine (IV), and tetramethyl-benzidine (V) in solutions and solids at various temperatures. Solution of I gives 3 absorption bands at 21, 26 and 31 (in units $10^{3} cm^{-1}$) at room temperature, 4 bands at 17 (C band), 26, 27 (X band) and 36 at low temperatures, and a mixture of the former and the latter in an intermediate temperature range. Intensity data at various temperatures can be analyzed by a dimer (low T) $\rightleftarrows$ monomer (high T) equilibrium model. Spectra of II and III are qualitatively similar to those of I except that each of the corresponding bands shifts towards the red by increased methyl substitutions. For the low temperature spectra of III, the ratio of intensity of C band to that of $R'$ band is smaller than those in I and II, which may be accounted for by decreased perturbation by the weaker dimerization. Spectra of IV and V differ from those of I, II and III. Their temperature dependence can also be explained by the dimerization model. Heats of dimerization by the above spectra are between 11 (for IV) and 5 kcal $mole^{-1}$ (for IV). Solid spectra of I and II show that the radicals dimerize in the solids even at room temperature. For the III solid, the spectra show that weak dimerization occurs below the transition point. The dimerization below the transition point was also confirmed by infrared spectroscopic study. Description: Author Institution: Faculty of Science, Kwansei Gakuin University URI: http://hdl.handle.net/1811/14988 Other Identifiers: 1966-D-10