Single Two-Electron Transfers and Successive One-Electron Transfers in Biferrocenyl-Indacene Isomers

Novel biferrocenyl complexes of s- and as- dihydroindacenes have been prepared and the charge transfer properties of their mono - and dicationic derivatives, selectively generated by one-electron and two-electron oxidation, have been investigated. Mixed-valence cations are generated by chemical oxidation using acetylferricinium as an oxidant agent and monitored in the visible, IR, and near-IR regions. The IT bands in the near-IR spectra are rationalized in the framework of Marcus-Hush theory. The rigid and planar indacene platform bonded to two terminal redox groups displays a redox chemistry that can be switched from single two-electron transfers to two successive one-electron transfers by changing the supporting electrolyte from nBu4NPF6 to nBU4NB(C6F6)4