Synthesis and Properties of New Bridged Tetrathiafulvalenes

The condensation reaction of dithiole phosphonium Perchlorates 17 and 18a–c with 2-ethylselenodithiolium tetrafluoroborate 16 in the presence of triethylamine was employed for the high-yield synthesis of four new donors 7a–c, 9 of the tetrathiafulvalene series. The carbomethoxy groups of 7a–c were removed by basic hydrolysis followed by decarboxylation to give 8a–c. Electrochemical studies for seven new TTFs were carried out. An unusual effect resulting in an decrease of the first oxidation potential was observed for 7b. Some properties of the starting 4-mercapto-5-carbomethoxy-1,3-dithiole-2-thione (10) are reported.