CRYSTAL-STRUCTURE AND ELECTRONIC-PROPERTIES OF (2,6-DMBTN)3(CLO4)2

Crystal structure, conductivity, and magnetic properties of the monoclinic cation radical salt 2,6-dimethoxy-3,6-bis(methylthio)naphthalene-perchlorate [(2,6-DMbTN)3(ClO4)2] are presented. The trimerization of the 2,6-DMbTN stack causes the salt to be semiconducting, sigma (300 K) almost-equal-to 0.5 S cm-1, with a band gap of 0.5 eV. The susceptibility is quite low 0.02 spins/complex at 300 K, above 200 K the susceptibility originates from the thermal excitation of triplet spin excitons of the Wannier type from an antiferromagnetically coupled ground state with J = 0.11 eV. The electrical and magnetic properties below roughly 200 K are governed by deep defect levels in the band gap. The unusually narrow ESR linewidth for a sulphur containing ion-radical salt, 0.8 x 10(-4) T at 300 K, implies that the electron structure is "one-dimensional" and/or the spin density on the sulphur atoms is low.