ROMP Synthesis and Redox Properties of Polycationic Metallopolymers Containing the Electron-Reservoir Complex [Fe(η5-C5H5)(η6-C6Me6)][PF6]

Electron-reservoir metallopolymers in which these nanomaterials are robust in at least two oxidation states are being actively investigated in view of applications as stable electron-transfer reagents. Here living ring-opening metathesis polymerization (ROMP) and diblock copolymerization of norbornene derivatives are conducted in which the cationic organoiron complex [FeCp(eta(6)-C6Me6)][PF6] (Cp = eta(5)-C5H4R) is covalently attached to the norbornene motif with a short trimethylene amido linker or a longer linker containing also the triethylene glycol (TEG) unit. Solubility constraints involved with the shorter linker require that the ROMP reaction be conducted in dimethylformamide (DMF), whereas the solubilizing longer linker conveniently allows carrying out the ROMP reaction in dichloromethane (DCM). Cyclic voltammetry (CV) of all these metallopolymers shows the full reversibility of the Fe-II -> Fe-I reduction wave at -1.35 V vs decamethylferrocene, [FeCp*(2)], and the numbers of monomer units found using the Bard-Anson method by CV are close to the monomer/catalyst ratio used in the ROMP reaction.