Abstract:The optical absorption spectra have been measured of alkali metal reduced solutions of triphenylene in 2-methyltetrahydrofuran from -155 to +75°. Several ion pairs have been observed. A linear correlation between frequency of absorption and reciprocal of catioh radius has been demonstrated for both solvated and contact ion pairs. The low-temperature spectra show a clear equilibrium between two types of ion pairs at high radical concentrations. lts thermodynamic parameters have been measured for sodium, potassium, and rubidium triphenylene solutions. At low-radical concentration dissociation occurs into free ions. The dissociation enthalpy and entropy have been determined. The high-temperature spectra show a gradual increase in frequency as the temperature is increased. This shift has been interpreted as due to an equilibrium between solvated and contact ion pairs. For potassium, rubidium, and cesium triphenylene solutions the thermodynamic constants characterizing the latter equilibrium have been calculated.

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