Studies on the crystal structure and electronic states of TCNQ radical anion salts

There have been considerable interests on the syntheses, crystal structures, electronic structures, and physical properties of the radical anion salts of 7,7,8,8-tetracyanoquinodimethane (TCNQ). The counter cation exchange of TCNQ radical anion salt provides various stable charge-transfer complexes. In this report, we focus on the crystal structures and electronic states of TCNQ radical anion salt having a counter cation of Me₄N⁺. This salt contains neutral TCNQ and TCNQ radical anions in the ratio 1:2. In this crystal, two TCNQ radical anions form π-dimer structure with intermolecular antiferromagnetic interaction. We would like to report the temperature dependence of the crystal structure and the electronic state of this charge transfer salt. The results of variable temperature X-ray crystallographic analyses and ESR spectra will be discussed.