Dissertation

|3.2 Bisphenanthroline: A Suitable Molecular Bridge?|
exhibited three similar reduction potentials at E 1/2 (̂LL 1 ) ≈ -1.7 V, E 1/2 (̂LL 2 ) ≈ -2.0 V and E 1/2 (̂LL 3 ) ≈ -
2.3 V which were assigned to the three ligand centered reductions. The two reductions at
very negative potentials are quasi reversible and very similar for all three complexes but the
̂LL 1 -reduction waves (assigned to the phenphen-ligand based on comparison with data from
literature [131] ) differ within this series of complexes (see figure 74).
-2.0 -1.0 0 1.0
Fc/Fc +
current / a.u.
-2.0 -1.0 0 1.0
potential / V
Figure 74: Cyclovoltammograms of the ruthenium complexes with phenphen ligands, measured
in a 0.1 M solution of Bu 4 NPF 6 in dry acetonitrile under argon atmosphere, referenced vs. Fc/Fc + ,
E 1/2 = 0.00 V. Ru(phenphen) (—), Ru(phenphen)Ru (—), Ru(phenphen)Pt (—),.
In the case of Ru(phenphen) three fully reversible one-electron reduction waves were found but
no reduction of the free phenanthroline moiety.
Furthermore, in Ru(phenphen)Ru all redox potentials were assigned to two-electron reductions
of the equivalent sides of the molecule. Therefore, an irreversible two-electron ̂LL 1 -reduction
was found in the CV which may refer to a double bond formation or other side reaction
upon reduction. Interestingly, for the related compounds [{(bpy) 2 Ru} 2 (µ-phenphen)] and
[{(bpy) 2 Os} 2 (µ-phenphen)], no irreversible peaks were reported. [131]
The heteronuclear complex Ru(phenphen)Pt exhibits in the same region two (in combination
irreversible) one-electron waves at differing potentials which potentially correlate to the
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