Dissertation

|3.3 NN-NHC-Ligand bbip: Toward Second Generation Catalysts|
Figure 92: ORTEP drawing of the solid state structures of Ru(ip) (left) and Ru(bip) (right). Ellipsoids
were drawn at the 70% probability level, counter ions, solvent molecules, and hydrogen atoms
except for the imidazole moieties were omitted for clarity.
and angles from the N,N’-chelating site and from the imidazole/carbene site will be discussed.
With respect to the phenanthroline coordination site, all complexes exhibit a number of
typical similarities which can be found in other ruthenium bipyridine/phenanthroline-type
complexes as well. The Ru-N1 and Ru-N2 bond distances vary in a narrow range between
2.055(4) Å and 2.067(5) Å. Even in the complex Ru(bbip) no significant influence on the
Ru-N distances was found although it bears a positively charged ligand. Furthermore, the
resulting N1-Ru-N2 angle varies insignificantly between 79.18(16)° and 80.15(17)° in all complexes
of this series. The coordination environment with respect to the nearby bond lengths and
angles remains unaffected by the changes at the imidazole part of the ligands. Thus, the
N1-C12 bond lengths and N2-C11 bond lengths vary between 1.363(7) Å and 1.385(7) Å and
the C11-C12 distances vary between 1.421(8) Å and 1.449(7) Å, respectively. In the N1-C12-C11
and the N2-C11-C12 bond angles only minor variations between 115.1(5)° and 117.4(5)° were
observed. Comparison of the N,N’-coordination site in series of ruthenium complexes and
in the respective pre-ligands revealed no or only very slight (not in every case significant)
changes in the corresponding distances and angles. The tendency goes toward more acute N1-C11-
C12 / N2-C12-C11 angles (e.g. ∠ ip
(N2,C12,C11)
= 117.0(2)° ≥ ∠Ru(ip)
(N2,C12,C11)
= 115.8(5)°), longer C12-N1 / C11-
N2 bond lengths (e.g. d ip
Ru(ip)
(N2-C11)
= 1.360(3) Å < d(N2-C11) = 1.385(5) Å) and shorter C11-C12 distances
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