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(BF<sub>4</sub>) and acetylferrocenium­(BF<sub>4</sub>) as the oxidative agents and monitored in the visible and NIR regions. By changing the supporting electrolyte from [<i>n</i>Bu<sub>4</sub>N]­[PF<sub>6</sub>] to [<i>n</i>Bu<sub>4</sub>]­[B­(C<sub>6</sub>F<sub>5</sub>)<sub>4</sub>], 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)-<i>s</i>-indacene and tris­(ferrocenyl)-trindene allowed for the evaluation of the huge influence of thiolation on the metal–metal electronic coupling.