Crystal structure and physical properties of (EDS-TTF) 2FeBr 4

Abstract

Crystal structure, transport and magnetic properties of (EDS-TTF) 2FeBr 4 (EDS-TTF: ethylenediselenotetrathiafulvalene) are reported. Between one-dimensional columns of donors and quasi square-lattices of FeBr 4 anions, close Br⋯Se van der Waals contacts and CH⋯Br type hydrogen bonds are observed. This salt shows high room-temperature conductivity and metal–insulator transition at ca. 250 K ( σ RT=400 S cm −1, E A=380 K). The magnetic susceptibility obeys the Curie–Weiss law ( C=4.58 emu K mol −1, Θ=−0.9 K) without showing any magnetic transition down to 1.8 K. The weak π–d interaction can be due to the small contribution of Se 4p orbitals to the HOMO of EDS-TTF.