Structures and properties of new organic molecule-based metals, (D)2 brc2 h4 so3 [d = bedt-ttf and bets]

Abstract

An organic anion, 2-bromoethanesulfonate (BrC2 H4 SO3− ), provides one bis(ethylenedithio) tetrathiafulvalene (BEDT-TTF) and two bis(ethylenedithio)tetraselenafulvalene (BETS) salts, the compositions of which are β”-β”-(BEDT-TTF)2 BrC2 H4 SO3 (1), β”-β”-(BETS)2 BrC2 H4 SO3 (2), and θ-(BETS)2 BrC2 H4 SO3 (3), respectively. Compound 1 shows a metal–insulator transition at around 70 K. Compound 2 is isomorphous to 1, and 3 is polymorphic with 2. Compounds 2 and 3 show metallic behavior at least down to 4.2 K. The pressure dependence of the electrical resistivity of 1 is also reported.