Synthesis of TSF Donors Substituted with the meso-Dimethylethylenedithio Group: Structures and Conducting Properties of (meso-DM-BETS)2X (X− = PF6− and AsF6−)

Abstract Synthesis and X-ray structure analysis of TSF-based donors substituted with the meso-dimethylethylenedithio group (meso-DM-EDT-TSF and meso-DM-BETS) were successfully performed. The donor molecules in (meso-DM-BETS)2X (X− = PF6− and AsF6−) formed a dimerized face-to-face π-stack, and the packing pattern could be classified as β-type. A tight-binding band calculation suggested that the meso-DM-BETS salts have a two-dimensional Fermi surface with a wide bandwidth. Both salts exhibited metallic conductivities down to low temperatures with σr.t. = 45–46 S cm−1.