A Polymer with Two Different Redox Centers in the π-Conjugated Main Chain: Alternate Combinations of Ferrocene and Dithiafulvene

A redox-active alternating π-conjugated copolymer of ferrocene with dithiafulvene was synthesized by cycloaddition polymerization of aldothioketene derived from 1,1‘-bis(trimethylsilylethynyl)ferrocene ( 1 ). The obtained polymer ( 2 ) was soluble in common organic solvents such as THF, CH 2 Cl 2, CHCl 3, DMF, and DMSO. The structure of 2 was confirmed by IR, 1 H NMR, and 13 C NMR spectra compared with those of 2,6-bis(ferrocenyl)-1,4-dithiafulvene as a model compound ( 3 ). The cyclic voltammogram of 3 showed three oxidation peaks, which were originated from the two ferrocene units and the dithiafulvene unit. The polymer 2 showed only single-broad oxidation peak at 0.58 V vs Ag/Ag + . This result was caused by an effective interaction between two different donors in 2 . Compounds 2 and 3 did not undergo oxidative dimerization to form extended tetrathiafulvalene during cyclic voltammetry. The polymer 2 formed a soluble charge-transfer (CT) complex with TCNQ in DMSO. The ratio of the dithiafulvene unit in 2 to TCNQ in the complex was 1:1, confirmed by 1 H NMR. The electrical conductivity of 2 was 3.6 × 10 -3 S/cm after I 2 doping.