Electrical properties of one-dimentional Pt complexes and TCNQ salts are discussed in connection with the exciton mechanism of high temperature superconductivity proposed by Little.
Bis (dimethylglyoximato) Pt (II) (Pt(DMG)2) and its related complexes exhibit a remarkable decrease in electrical resistance at high pressures. The least resistivity and the activation energy observed for Pt(DMG)2 are 10-1Ωcm and 0.005eV, respectively. These low values are tentatively attributed to the effect of hyperconjugation of methyl substituent on the electronic polarizability in the ligand.
Magnitudes of electrical conductivities of TCNQ salts depend strongly on the nature of the cation. LeBlanc has suggested that the electronic polarizability of the cation is a more important determinant of the variation in conductivities. However, Torrance et al have showed that Coulomb interaction are strong in all TCNQ salts and that there is no evidence for excitonic screening. From the crystal and electronic structures, and electrical behavior at high pressure for TCNQ salts, we believe that the excitonic screening is not dominant for electrical properties of TCNQ salts.
