Testing the Conjugative Properties of Benzodithiophene and Benzotrithiophene in Charge Transfer Multi(ferrocenyl) Systems

The charge transfer properties of the mono-, di-, and tricationic derivatives of bis(ferrocenyl)benzodithiophene and tris- (ferrocenyl)benzotrithiophene were investigated. The cations were generated by chemical oxidation using ferrocenium(BF4) and acetylferrocenium(BF4) as the oxidative agents and monitored in the visible and NIR regions. By changing the supporting electrolyte from [nBu4N][PF6] to [nBu4][B(C6F5)4], we were able to selectively generate the monocationic species of bis- and triferrocenyl complexes. The redox and optical properties of the cationic derivatives were rationalized by an in-depth electrochemical and optical study. The comparison with the results previously obtained for the structurally related bis(ferrocenyl)-s-indacene and tris(ferrocenyl)-trindene allowed for the evaluation of the huge influence of thiolation on the metal−metal electronic coupling.