Synthesis and electrochemistry of novel heteronuclear Fe-Ru bi- and quatermetallocenes, conjugatively connected by ethene and thiophene bridges

(all-E)-2,5-Bis[2-[1′-[2-(1′,2,2′,3,3′,4,4′,5-octamethylferrocenyl)ethenyl]ruthenocenyl]ethenyl]thiophene was synthesized by Wittig olefinations. The X-ray structure of the intermediate (E)-2-(1′-formylruthenocenyl)ethenyl-1′,2,2′,3,3′,4,4′,5-octamethylferrocene is reported. The cyclic voltammogram of this quatermetallocene exhibits completely unusual redox properties. In contrast to most ruthenocene-containing compounds, a reversible two-electron transfer is observed at a significantly lower potential than found usually for ruthenocenes that can be attributed unambiguously to the independent oxidation/reduction of the two ruthenocene moieties.