ELECTROCHEMICAL POLYMERIZATION OF THE TETRATHIENYL DERIVATIVES OF THECARBON GROUP ELEMENTS

The electropolymerization of four tetrathienyl compounds of the carbon group elements (T(4)M, where M = Si, Ge, Sn or Pb) was studied on ind ium tin oxide electrodes in three organic solvents with low water cont ent (acetonitrile, propylene carbonate and nitrobenzene). Only poorly conducting deposits were obtained in acetonitrile, but polymerization in propylene carbonate yielded partially electroactive films. The best polymers were formed in nitrobenzene, but none of the tetrathienyls t ested produced polythiophene films superior to those prepared using th iophene as the monomer with the same experimental conditions. The poly merization mechanism of the thienylmetals is different from that of pu rely organic thiophene derivatives, as the oxidation produces neutral thiophene radicals in the former case, instead of radical cations. The results suggest that the reactive neutral thiophene radical can abstr act a hydrogen atom from solvents such as acetonitrile, explaining the apparent contradiction in the polymerization efficiency of tetrathien yls and thiophene in this solvent.