Yôichi Iida

Abstract The present paper deals with crystalline TCNQ, anion radical “simple” salts of M+ TCNQ\divdot, where M+ represents a diamagnetic counter cation. Their crystalline electronic spectra were measured in the range between 4.0 and 30.8 kK by means of diffuse reflectance. The crystalline spectra thus obtained were quite different from that of the TCNQ, radical anion monomer and exhibited a broad and intense low-energy band around 9 kK in the low-conductivity compounds and at 4.3 kK in the high-conductivity compound. These bands were ascribed to inter-radical charge-transfer in the solid state. The crystalline spectra were found to be closely correlated to their unusual electrical and magnetic properties. It was concluded that these physical properties were based on a unique TCNQ molecular arrangement in groups of several or an infinite number of face-to-face molecular systems.

Abstract The present paper deals with crystalline TCNQ anion radical “complex” salts of (M+)2-(TCNQ)3\ewdot\ewdot and M+(TCNQ)2\ewdot composed of the formally-neutral TCNQ and its anion radical TCNQ\ewdot 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.

Abstract The cation radical salts of phenothiazine bromide, phenothiazine bisulfate monohydrate, and phenothiazine picrate were prepared. The absorption spectra in a dilute hydrochloric acid solution and the solid-state spectra of the salts were examined. The solid-state spectra showed a strong charge-transfer band and blue-shifts of the high-energy bands, unlike the absorption spectra in solution. The magnetic susceptibilities of these salts were measured at room temperature. They were found to be diamagnetic, with values almost corresponding to those of the diamagnetic contribution of the salts, except for that of the picrate. These spectroscopic and magnetic properties were discussed on the basis of the charge-transfer interaction between the phenothiazine cation radicals. The properties of the usual phenothiazine-picric acid charge-transfer complex and the holoquinoid phenothiazine perchlorate were investigated in association with those of the cation radical salts.