Dissertation

|3.1 Brominated Phenanthrolines - A Gate to new Bridging Ligands|
was used to remove the educt and recrystallization from chloroform/dichloromethane gave pure
monosubstituted product in 70% yield.
In addition to 1 H-NMR and 13 C-NMR spectroscopy as well as mass spectrometry was used
for the characterization of the products. Especially the loss of the signals, referring to the
protons in 5- and 6-position in 1 H-NMR spectroscopy were good indicators for the completed
transformation. Furthermore, it was as well possible to obtain suitable crystals of both compounds
by recrystallization from chloroform to perform X-ray diffraction experiments. The obtained
molecular structures are depicted in figure 39.
Figure 39: ORTEP representation of the molecular structures of 5-bromo-1,10-phenanthroline
and 5,6-dibromo-1,10-phenanthroline coordinated to the solvent chloroform via hydrogen bonds.
Ellipsoids were drawn at 50% probability level (see table 3 for selected bond lengths and angles).
Both phenanthroline derivatives crystallize in the monoclinic crystal system with the space group
P2(1)/n. An alternating orientation of the phenanthrolines and π-stacking effects of the planar
aromatic systems were prominent in the crystal lattice (“π − π” in table 3, example depicted
in figure 40). Furthermore, via hydrogen bonds coordinated solvent chloroform was found in
the N,N’-coordination site with H-N-distances in the region of d(H1Cl-N) = [2.312 - 2.493 Å].
A significant influence of the bromination on the phenanthroline skeleton was not observed by
comparison of the bond lengths and angles (see table 3 on page 62).
After the successful synthesis, it was important to focus on other phenanthroline derivatives such
as bathophenanthroline or 2,9-dimethyl-1,10-phenanthroline to explore this type of reaction with
a broadened palette of possible substrates for future applications.
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