A new stable organic metal in the well known family of radical cation α-salts: α-(BETS)2TlHg(SeCN)4. Synthesis, structure and properties

The stable organic metalα-(BETS)2TlHg(SeCN)4 has been obtained by means of electrochemical oxidation of bis(ethylenedithio)tetraselenafulvalene (BETS) in 1,1,2-trichloroethane (TCE) with the addition of absolute ethanol in the presence of an electrolyte consisting of 18-crown-6, TlSeCN and Hg(SeCN)2 . The salt is isostructural with the ET-based salt with the same anion and ET and BETS salts with KHg(SCN)4 as well. The number of the side-by-side Se‥Se, Se‥S and S‥S contacts in each radical cation layer was twice that in comparison with the corresponding ET salt. Reflectivity spectra and magnetoresistance were studied. The Shubnikov–de Haas effect and angular oscillations of the magnetoresistance were observed. Optical and transport properties of α-(BETS)2TlHg(SeCN)4 were compared with those of the analogous ET salt.