The electrochemistry of [1.1]metallocenophanes: a cyclic voltammetry study of homo-binuclear and hetero-binuclear systems

The redox chemistry of ferrocene is well known: oxidation to the ferrocenium ion is a highly reversible one-electron step. Several studies on ruthenocene have led to conflicting results, but it is now clear that an electrochemically irreversible two-electron oxidation at comparatively high potential is involved. For [1.1]ferrocenophane, two reversible one-electron oxidations are known to exist, which indicate the absence of significant cooperative interactions between the two ferrocene units of this homo-binuclear compound. For the analogous hetero-binuclear iron/ruthenium system we find a ferrocenecentered reversible one-electron oxidation and a ruthenocene-centered irreversible two-electron oxidation, showing the independence of the two different metallocenes in this system. In contrast to this finding, the two ruthenocenes in [1.1]ruthenocenophane appear to interact strongly: this compound shows a quasi-reversible two-electron oxidation at an unusually low potential. The electronic structure of the d ication of [1.1]ruthenocenophane is uncertain, but independent evidence indicates a mixed valence species with one ruthenocene and one ruthenocene dication. © 1982.