Modulation of intramolecular electronic coupling in 2,6-diferrocenylanthracene via a Diels—Alder reaction with TCNE

2-ferrocenylanthracene and 2,6-diferrocenylanthraccnc have been prepared by a Bachmann- Gomberg reaction between the bis(diazonium) derivative of anthraquinone and ferrocene, followed by a reduction with aluminium cyclohexanolate. These two compounds give Diels-Alder adduces with tetracyanoethylene. The comparative study of intervalence electron transfer between reduced and oxidized ferrocene sites has been performed for 2,6-diferrocenylanthracene and its adduct. In the latter, the electronic interaction (Vab) decreases, but does not vanish, despite the loss of conjugated character. An orbital interpretation of the weakness of this effect is proposed.