Molecular Conductors with Effectively Half‐Filled Electronic States Based on Tetrathiafulvalene Derivatives Condensed with a 2‐Isopropylidene‐1,3‐dithiole Ring

Abstract

The electron donor 2‐isopropylidene‐1,3‐dithiolo[4,5‐d]‐4,5‐ethylenediselenotetrathiafulvalene (3) provides two new molecular conductors, (3)2[M(CN)2] (M = Ag and Au). These salts crystallize in the triclinic P$\bar {1}$ space group. The donor sheet structure of these salts is the so‐called β‐type molecular array, in which the donor molecules form a head‐to‐tail dimer. The formation of considerable dimerization and the 2:1 donor–anion ratio result in an effectively half‐filled electronic nature. These salts show metallic conducting behavior from room temperature. The metallic conducting behavior of (3)2[Ag(CN)2] was retained down to 8 K; however, the resistivity of (3)2[Au(CN)2] increased at around 50 K. The magnetic susceptibility of (3)2[Au(CN)2] suggests that the strength of the electron correlation for this salt is enhanced below 50 K.