HIGH-MOLECULAR-WEIGHT POLY(FERROCENEDIYL SILANES) - SYNTHESIS AND ELECTROCHEMISTRY OF [-(C5H4)FE(C5H4)SIR2-]N, R = ME, ET, N-BU, N-HEX

High molecular weight poly(dialkylsilane-ferrocenediyls) of general formula [-(C5H4)Fe(C5H4)SiR2-]n, R = methyl, ethyl, butyl, and hexyl) were synthesized by thermal polymerization of the corresponding [1]-(dialkylsilyl)ferrocenophane. The polymers are stable up to 450-500-degrees-C and with the smaller alkyl groups, e.g., methyl and butyl, the polymers are predominantly crystalline in the solid state. The voltammograms of these polymers in Et4NBF4/dichloromethane show two reversible redox peaks for the stepwise oxidation of the polymer where half of the ferrocene centers on the polymer chain (possibly alternating) are oxidized in the first reaction and the remaining in the second reaction. Both oxidation states of the polymers are stable to the electrochemical conditions. The redox potentials of both reactions are affected by the size of the alkyl group. Although, these polymers are soluble in dichloromethane, they deposit on the electrode surface and influence the shape of the voltammograms by affecting the diffusion of the electrolyte ions to the electrode. The polymers were chemically oxidized with anhydrous FeCl3. Two equivalents of FeCl3/(ferrocene) are required to fully oxidize the polymers.