BETS-Based Molecular Conductors with Tetrahedral Anions TlCl_4~-,MnBr_4~(2-),CoCl_4~(2-) (BETS=Bis (ethylenedithio) tetraselenafulvalene)

摘要

Molecular conductors on te basis of bis (ethylenedithio) tetraselenafulvalene (BETS) with tetrahedral anions TlCl_4~-,MnBr_4~(2-) were synthesized and studied by X-ray diffraction analysis.The salts under study exhibit various conducting properties:kappa-(BETS)_2TlCl_4 (I) is a superconductor with T_c=2.5 K,delta-(BETS)_4MnBr_4·2C_2H_5OH(II) is a metal up to approx =30K.while (BETS)_2CoCl_4 (III) is a dielectric.Salt I has kappa-packing of the donor molecules,salt II has delta-packing,whereas salt III has no conducting layers.These structural differences are mainly the reasons for different ocnducting properties of compounds I-III.