New conducting radical salts based upon Keggin-type polyoxometalates and perylene

Three new radical salts, Per(6)[PMo12O40].CH2Cl2 (1), Per(6)[PMo12O40].CH3CN (2), and Per(9)(NBu4)(4)[SiW12O40](2) (3) (Per = perylene), have been synthesised and their electrical and magnetic properties characterised. These three salts are diamagnetic and they behave as semiconductors with room temperature conductivities of 69, 3.6 and 0.85 S cm(-1). While salt 2 presents hole-type conduction and 3 exhibits electron-dominated electrical transport properties, salt 1 shows at 150 K an abrupt change in the thermal dependence of the electrical conductivity and the Seebeck coefficient suggesting a phase transition.