A new tetrathiafulvalene–diamide cation salt with [Cu2Br4]2− anions

The title salt, bis2,3‐bis(aminocarbonyl)‐8,9‐bis(methylsulfanyl)tetrathiafulvalenium] di‐μ‐bromido‐bisbromidocopper(II)], (C₁₀H₁₀N₂O₂S₆)₂Cu₂Br₄], contains 2,3‐bis(aminocarbonyl)‐8,9‐bis(methylsulfanyl)tetrathiafulvalenium radical cations, DMT‐TTF(CONH₂)₂]^·+, and Cu₂Br₄]^2? anions. The cations are associated across centres of inversion in a head‐to‐tail fashion via short face‐to‐face S...S stacking (TTF moiety). These dimers are further assembled into a one‐dimensional chain structure via interdimer double S...S contacts involving the methylsulfanyl groups. The one‐dimensional chains give rise to a two‐dimensional structure through intermolecular double N—H...O hydrogen bonds involving the amide group. The Cu₂Br₄]^2? anions, which straddle centres of inversion, are located between the cation layers. Electron paramagnetic resonance measurements show a radical signal, indicating that the two TTF^·+ radicals are not completely coupled in the dimer.