Synthesis and electrochemical properties of 1,1′-bis(benzo-1,3-dithiol-2-ylidene)ferrocene derivatives as novel electron donor compounds

A number of 1,1′-bis(benzo-1,3-dithiol-2-ylidene)ferrocene derivatives 7a–b and 12–14 based on the strong electron donating ability of 1,3-dithiole and ferrocene moieties were synthesized as new π-donors. The structure and physical properties of these compounds were characterized both by experimental techniques and spectral analysis. These new classes of donor compounds were obtained in very high yields based on modification of the Wittig–Horner reaction and the 1,3-dithiole rings were separated by conjugated spacers including aryl–ferrocenyl–aryl. The electrochemical properties of the new compounds have been studied in comparison to DB-TTF 4 analogues, and the parent ferrocene donor by cyclic voltammetry (CV), using Pt electrode as the working electrode in CH2Cl2 solutions at room temperature. Three subsequent oxidation processes are observed as three oxidation waves associated only with two reduction processes. Polycrystalline samples of 14a–b are conducting σrt14a=0.2 S cm−1 and σrt14b=4.8×10−4 S cm−1) respectively, while compounds 15 and 16 were found essentially as insulator (σrt<10−10 S cm−1).