Thiophene-functionalized TTF pi-electron donors as potential precursors to conducting polymers and organic metals: Synthesis, properties, structure, and electropolymerization studies

The synthesis and physical properties of a series of novel thiophene-subustituted TTF electron donors (6a-d) are described. The cyclic voltammograms of 6a-d exhibited two reversible one-electron redox waves, characteristic of TTF derivatives. Electropolymerization studies on compound 6a in nitrobenzene indicate that no polymer formed on the working electrode, but a blue-colored intermediate was observed diffusing away from the electrode. In addition, the single-crystal X-ray structure of compound 6d indicates that the central five-membered C3S2 rings are buckled and the ethylenedithiolo fragment adopts a twisted chair conformation. The pendant thiophene moieties are highly flexible, and short intermolecular interactions of 3.49 Angstrom (S ... S) and 3.45 Angstrom (S ... C) exist in the unit cell, resulting in the formation of a chain structure along the c-axis. ethylenedithiolo fragment adopts a twisted chair conformation.