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.