Highly conducting 1:1 radical cation salts: (DMTSA)X with X=NO3 and BF4

(DMTSA)NO3 and -BF4 show high conductivity at room temperature, in spite of fully ionic salt of 1:1 stoichiometry with uniform segregated stack column structure. DMTSA denotes 2,3-dimethyltetraselenoanthracene. The NO3 salt is semiconducting below room temperature, and the BF4 salt is metallic above 220 K and semiconducting at lower temperatures. We found that their magnetic susceptibility is paramagnetic and independent of temperature from 300 K down to 10 K in common. The obtained magnetic property can not be attributed to conduction electrons but discussed in terms of Mott insulating state. Furthermore, high pressure experiment reveals that the NO3 salt is not semiconducting but rather semi-metallic, and more that the BFq salt shows a small conductive anomaly around 70 K and maintains metallic at low temperatures under the pressure of 0:5 GPa.