Abstract

The reaction of dimethylthio- (1) and ethylenedithio-tetrathiafulvalenothioquinone-1,3-dithiolemethides (2) with CuCl₂ afforded the corresponding CuCl₄ salts, (1)₂·CuCl₄ and (2)₃·CuCl₄. For (1)₂·CuCl₄ the 1 molecules are stacked to form a one-dimensional column, and in each column the neighboring 1 molecules are dimerized. On the other hand, the 2 molecules in (2)₃·CuCl₄ are stacked one-dimensionally in a triad unit. The CuCl₄ ions intervene between the 1- or 2-stacked columns in each case. The electrical resistivities (ρ) for single crystals of (1)₂·CuCl₄ and (2)₃·CuCl₄ were 3 × 10⁴ and 0.6 Ω cm at room temperature, respectively. The ρ value of (2)₃·CuCl₄ increased continuously on cooling, and its activation energy was 0.15 eV, which became gradually smaller with increasing applied pressure. For (1)₂·CuCl₄ the Cu(II) spins on the CuCl₄ ions were only present whilst (2)₃·CuCl₄ involved both conducting π electrons on the 2-stacked column and localized Cu(II) spins on the CuCl₄ ions which did not interact with each other between 300 and ca. 170 K, but below ca. 170 K the conducting π electrons disappeared, presumably as a result of interaction with the localized d spins.