Synthesis of oligomeric 2,5-thienylenes; their u.v. spectra and oxidation potentials

Oligomeric 2,5-thienylenes and 3-methyl-2,5-thienylenes have been synthesized by NiCl2(dppp)(dppp = Ph2PCH2CH2CH2PPh2) coupling of Grignard compounds with the appropriate bromothiophene; u.v. spectra and oxidation potentials of the oligomers are dicussed in terms of coplanarity of the oligomeric species.