| Abstract
| - The electrochemical polymerization of 3,4-difluoropyrrole (DFP) has been examined bycyclic voltammetry (CV) as a function of scan rate and solvent. The polymerization is facilein dichloroethane, leading to a stable electroactive film. In contrast, the correspondingpolymerization in acetonitrile occurs only with difficulty. Poly(3,4-difluoropyrrole) (PDFP)exhibits a high redox potential (+0.90 V vs Ag/AgCl), a particularly high doping level (ca.55%), and a rather good conductivity (up to 0.1 S·cm-1), in comparison to other polyhalopyrroles. Meanwhile, the lifetime of the DFP radical cation, as determined by fast scan CVexperiments, is about 1 ms. This lifetime is substantially longer than that of other pyrrolederivatives under identical experimental conditions. Theoretical calculations are in agreementwith experiment in showing that the DFP radical cation is a powerful oxidant in comparisonto pyrrole radical cation. However, these computational studies indicate that the net chargeand spin distributions are similar for the cation radicals of DFP and pyrrole itself. To interpretthese results, we propose that the introduction of fluorine substituents could be responsiblefor a lower polarizability of the cation radical, leading to a higher activation barrier fordimerization of DFP in comparison to pyrrole and other halopyrroles.
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