Electronic Spectra of Crystalline TCNQ Anion Radical Salts. II. Complex Salts

Abstract The present paper deals with crystalline TCNQ anion radical “complex” salts of (M+) 2- (TCNQ) 3 and M+ (TCNQ) 2 composed of the formally-neutral TCNQ and its anion radical TCNQ Their crystalline electronic spectra were measured in the range between 4. 0 and 30. 8 kK by diffuse reflectance and in the 0. 65–4. 0 kK range by transmittance. None of their spectra except those of the (2: 3) compounds were found to bear any resemblance to those in the simple salts. Although the spectra of the (2: 3) compounds are similar to those of the simple salts with low conductivities, the former exhibit an additional weak absorption in the range lower than 6 kK. The (1: 2) compounds with intermediate conductivities show a strong band around 3 kK, and those with high conductivities, around 2. 0–2. 5 kK. Their spectra are discussed on the basis of the interaction among unpaired electrons in connection with their electrical and magnetic properties. The difference in the interaction modes of the ion radicals between “simple” and “complex” salts is also speculated upon.