Dissertation

|3.4 Outlook, Exploratory Investigations and Perspectives|
Figure 120: Solid state molecular structures of eip (left) and edip (right). Ellipsoids were drawn at
the 50% and 70% probability level respectively. Compare table 16 on page 171 for selected bond
lengths and angles.
Furthermore, similar chemical behaviors and good structural relationships exist between eip and
bip, and between edip and bbip respectively, therefore, the same numbering scheme was applied
to all ligands for convenience reasons (see chapter 3.3.3 on page 118).
With respect to bip, no significant changes in distances and angles of the ip-skeleton were
observed in eip. Only the C1-N1-C12 angle of the phenanthroline sphere is slightly increased in
bip, which might be an effect of the coordinated solvent water in the latter (∠ bip
C1,N1,C12 = 118.38(15)°
> ∠ eip
C1,N1,C12 = 117.6(2)°).
Furthermore, eip exhibits the same asymmetry of bond lengths and angles in the imidazole ring
of the imidazophenanthroline backbone as observed in bip, which is a result of the partial double
bond character between C13 and N4 and of the asymmetric substitution. Therefore, eip exhibits
a significantly shortened C13-N4 bond in comparison to the C13-N3 bond (d eip
C13-N3 = 1.361(3) Å
> d eip
C13-N4
= 1.314(4) Å). An other effect is that the opposing angles of the imidazole moiety at
C5/C6 and N3/N4 differ significantly (∠ eip
eip
C13,N3,C5
= 105.9(2)° > ∠C13,N4,C6 = 103.7(2)° and even more:
∠ eip
eip
N3,C5,C6
= 105.3(2)° < ∠N4,C6,C5 = 111.1(2)°), which was also observed in bip. The opposing sides of
the phenanthroline sphere show no asymmetry which supports the picture of a phenanthroline
sphere which is independent of the variable imidazole moiety.
The imidazolum salt edip is best compared to the imidazolium salt bbip. Although edip exhibits
an asymmetric substitution pattern, a highly symmetric ip-skeleton with respect to bond distances
and angles was found. The only difference exists between the opposing angles around C5 and C6
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