“…Two pathways can be considered for the synthesis of long polymer chains: monomer ± oligomer and oligomer ± oligomer reactions. It is generally accepted that the former is predominant, and several experimental observations, such as the structural differences between polypyrrole and poly(bipyrrole) and the recent work of Barbarella et al [9] on the oligomerization of 3-(alkylsulfanyl)thiophenes, support this idea. However, it was also demonstrated that terpyrrole, bipyrrole, and pyrrole radical cations have similar lifetimes in acetonitrile [10] (rate constants for dimerization: 5 Â 10 8 , 1.2 Â 10 9 , and ca.…”