Chemistry Reference
In-Depth Information
Ar
Ar
t
-Bu
t
-Bu
N
41a
:Ar=
N
41c
:Ar=
N
N
N
N
41b
:Ar=
41a
41c
Fig. 11
Structures and ORTEP drawings of 4,5-diheteroarylphenanthrenes
41a-c
[
44
]. Reprinted
with permission from [
44
]. Copyright (2010) Royal Society of Chemistry
twists (Scheme
8
). While there are many examples of ruthenium terpyridine
complexes with liner and planar structures [
45
], such molecules with helical
architecture are rare.
The close proximity of the acridine and acridan moieties in
45
provides the
opportunity to generate
46
possessing a bridging hydrogen atom (C-H
...
C
+
)
between the methylacridan and methylacridinium groups (Fig.
12
)[
46
]. The
X-ray structure of
46
shows an unsymmetrical bridge with a distance of 1.08
˚
for the localized C-H bond and a distance of 2.51
˚
for H
...
C
+
. The distance
between the two carbon atoms is 3.14
˚
. The C4-C4a-C4b-C5 torsional angle is
29.7
. The activation barrier for the hydride shift, determined by variable-
temperature NMR studies, is 12.4 kcal/mol at 5
C.
