Novel TTF vinylogues affording stable cation radicals

Novel TTF vinylogues with extended π-conjugation have been synthesized using an oxidative dimerization reaction of 1, 4-dithiafulvenes. The cation radicals of the derivatives with o-substituted phenyl groups are thermodynamically stable where the aryl units are twisted and the TTF vinylogue skeleton is planar. Some compounds afforded cation radical salts upon electrochemical oxidation. X-ray structure analyses revealed unusual crystal structures.