Syntheses and Crystal Structures of ET and BETS Salts Containing Bis(dithiosquarato)metalate Anions

Abstract

Abstract A series of cation radical salts of bis(ethylenedithio)tetrathiafulvalene (ET) and bis(ethylenedithio)tetraselenafulvalene (BETS) as donors and bis(dithiosquarato)metalate ([M(dts)2]n−) as anions were synthesized. The electrical resistivities of most of these salts ((BETS)2[Pd(dts)2] (1), (BETS)2[Pd(dts)2]·2(1,1,2,2-TCE) (2) (1,1,2,2-TCE = 1,1,2,2-tetrachloroethane), (BETS)[Au(dts)2] (4), (ET)2[Pd(dts)2] (5), (ET)2[Pt(dts)2] (6), and (ET)[Au(dts)2] (7)) were semiconductive. However, one of the BETS salts with [Pd(dts)2], whose donor : anion ratio was 5 : 1. (BETS)x[Pd(dts)2] (x ≈ 5.0) (3), showed a metallic behavior down to 4 K. Although the crystal structure of these semiconducting salts was a kind of mixed stacks, many short contacts within the sum of the van der Waals radii were seen between chalcogens of the donors, and between chalcogens of the donor and anion. In addition, four terminal oxygen atoms of bis(dithiosquarato)metalate anion had C–H···O hydrogen bonds with terminal ethylene groups of ET and BETS, which was one of the factors determining the conformation of the terminal ethylene groups in these crystals.