ELECTRICAL AND MAGNETIC-PROPERTIES OF THE NEW CONDUCTORS - (TMDTP)(2)ASF6 AND (TMDOP)(2)ASF6

From the donor molecules tetramethyldithiapyrene (TMDTP) and the oxyge n analogue tetramethyldioxapyrene (TMDOP), single crystals with compos ition (TMDTP)(2)AsF6 and (TMDOP)(2)AsF6 were prepared by electrocrysta llization. In spite of the similar donor molecule structure and the sa me stoichiometry they exhibit quite different properties. (TMDTP)(2)As F6 has metallic-like properties at high temperature (sigma(RT)approxim ate to 1 S/cm, S(RT)approximate to 20 mu V/K, chi(Pauli,RT) = 3.8x10(- 4) emu/mol) with a metal-insulator transition at ca. 75 K, while the r esistance of (TMDOP)(2)AsF6 shows an activated behaviour, in agreement with charge localization suggested by the thermopower results (S(RT)a pproximate to 48 mu V/K).