K. Kawabata et al., HIGHLY CONDUCTING 1 1 RADICAL-CATION SALTS - (DMTSA)X WITH X=NO3 AND BF4/, Molecular crystals and liquid crystals science and technology. Section A, Molecular crystals and liquid crystals, 296, 1997, pp. 197-204
(DMTSA)NO3 and -BF4 show high conductivity at room temperature, in spi
te of fully ionic salt of 1:1 stoichiometry with uniform segregated st
ack column structure. DMTSA denotes 2,3-dimethyltetraselenoanthracene.
The NO3 salt is semiconducting below room temperature, and the BF4 sa
lt is metallic above 220 K and semiconducting at lower temperatures. W
e found that their magnetic susceptibility is paramagnetic and indepen
dent of temperature from 300 K down to 10 K in common. The obtained ma
gnetic property can not be attributed to conduction electrons but disc
ussed in terms of Mott insulating state. Furthermore, high pressure ex
periment reveals that the NO3 salt is not semiconducting but rather se
mi-metallic, and more that the BFq salt shows a small conductive anoma
ly around 70 K and maintains metallic at low temperatures under the pr
essure of 0:5 GPa.