Functionalised polyferrocene complexes: synthesis and mixed-valency properties

Abstract

We have synthesised three types of hexamers bearing 6 or 12 electro-active groups by a cyclotrimerisation reaction of symmetric alkynes. Two types of electro-active groups were added to the ferrocene, being introduced either before (case of Rubipy) or after (case of BDT) cyclotrimerisation. While the characterisation of compounds with the BDT functionalisation can be carried out by NMR due to the complete symmetry of these molecules, complexes bearing the Rubipy fragment are obtained as mixtures of diastereoisomers and were characterised using electrospray or FAB mass spectrometric techniques. Alkynes and hexamers functionalised by the BDT group (1 and 2) gave interesting spectrochemical properties. Indeed, in the case of molecules bearing a double bond between the ferrocene and the phenyl core (1b and 2b), two mono-electronic oxidation waves are observed in the CVs, corresponding to the successive oxidation of two ferrocenes. In the case of 2b an intervalence band is observed in NIR region.