Electron transfer in ferrocene-containing π-conjugated polymers

We describe here our recent research on n-conjutgated organometallic polymers containing ferrocenyl groups. Internuclear electronic interactions through the pi-conjugated spacer display unique redox and optical properties. The dependence of the redox properties on the number of ferrocene moieties in oligo(1,1 '-ferrocenylene)s were analyzed by the neigh boring-site interaction model. The electronic structure in the mixed-valence states of biferrocene and terferrocene were estimated using the infrared (IR) spectra. Intervalence-transfer (IT) bands in the mixed-valence states of oligo(1,1 '-ferrocenylene)s were rationalized by taking into account the change in neighboring-site interaction by photo-electron transfer. Near-IR photoconductivity was found for the charge transfer complex of oligo- and poly-(1-1 '-ferrocenylene)s with tetracycanoethylene (TCNE). Redox and optical properties of azo-bridged ferrocene oligomers and a polymer was also analyazed based on the neighboring-site interaction model. Metallacyclization reaction of para-bis(ferrocenylethynyl)benzene with CpCo(PPh3)(2) affforded a ferrocene-containing cyclobutadienecobalt polymer, of which redox property indicates strong intra-unit and weak inter-unit interactions.