Synthesis and some properties of binuclear ruthenocene derivatives bridged by both ethene and thiophene derivatives

Binuclear ruthenocenes bridged by ethenes and thiophene derivatives, Rc–CHdouble bond; length as m-dashCH–Z–Rc and Rc∗–CHdouble bond; length as m-dashCH–Z–CHdouble bond; length as m-dashCH–Rc∗ (Z = thiophene, thieno[3,2-b]thiophene, and 2,2′-bithiophene; Rc = ruthenocenyl, R∗ = 1′,2′,3′,4′,5′-pentamethylruthenocenyl) were prepared. These complexes showed a one-step two-electron redox wave in the cyclic voltammograms, in contrast to the benzenoid-bridged dinuclear ruthenocenes. The chemical oxidation of the Rc–CHdouble bond; length as m-dashCH–Z–Rc complexes gave no stable oxidized species. The two-electron oxidized species of the Rc∗–CHdouble bond; length as m-dashCH–Z–CHdouble bond; length as m-dashCH–Rc∗ complexes were comparably stable and contained a fulvene-complex type structure.