Chemistry Reference
In-Depth Information
Tab. 2.1
Selected bond lengths and angles for
4a-c
.
4a
4b
4c
Bond lengths (Å)
Pd-N1
2.032(7)
Pd-N1
2.034(3)
Pd-N1
2.200(6)
Pd-N1
a)
Pd-N2
2.022(4)
Pd-N2
2.030(5)
Pd-Cl1
2.205(5)
Pd-Cl1
2.2833(15)
Pd-Cl1
2.271(2)
Pd-Cl1
a)
Pd-Cl2
2.2984(12)
Pd-Cl2
2.236(2)
N1-C3
1.484(8)
N1-C10
1.460(6)
N1-C11
1.445(9)
N2-C30
1.457(5)
N2-C41
1.412(9)
C1-C1
a)
1.482(10)
C1-C2
1.507(6)
C1-C2
1.460(10)
C1-C2
1.532(9)
C1-C3
1.482(6)
C1-C3
1.465(10)
C2-C4
1.480(7)
C2-C4
1.492(9)
C1-N1
1.300(8)
C1-N1
1.287(6)
C1-N1
1.276(8)
C2-N2
1.289(6)
C2-N2
1.280(9)
Bond angles (
)
N1-Pd -N1
a)
78.9(4)
N1-Pd-N2
78.98(15)
N1-Pd-N2
79.7(2)
N1-Pd-Cl1
98.0(3)
N1-Pd-Cl1
174.23(10)
N1-Pd-Cl1
95.41(17)
N1-Pd-Cl1
a)
176.9(3)
N1-Pd-Cl2
174.4(8)
N1-Pd-Cl2
164.4(2)
N1a-Pd-Cl1
98.0(3)?
N2-Pd-Cl1
174.23(10)
N2-Pd-Cl1
165.7(2)
N2-Pd-Cl2
95.9(3)
N2-Pd-Cl2
164.4(2)
Cl1-Pd-Cl1
a)
85.2(4)
Cl1-Pd-Cl2
89.26(5)
Cl1-Pd-Cl2
92.41(9)
a)
Symmetry transformations used to generate equivalent atoms in
4a
: (a) -
x
+2,-
y
,
z
.
(Fig. 2.7) is introduced to give a more quantitative description of the influence of
the 2,6-diphenyl substituents.
The planes A, B, and C (A
, respectively) as well as the corresponding
plane vectors were calculated by least-squares methods using the relevant X-ray
data. The angle
,B
,C
describes the
level of distortion of the “terphenyl wings” and is given as the angle between the
plane vectors
E
A
and
E
A
;
is defined as that between the vectors
X
1
and
X
2
;
is a measure of the staggered arrangement of the phe-
nyl planes B and C within one “terphenyl wing” and is defined as the angle be-
tween the plane vectors
E
B
and
E
C
.
for the terphenyl complex
4a
indicat-
ing the lack of sufficient distortion, as expected. The value of
is 7.5
by introduction of the 4-methoxy groups in
4b
, and the structure begins to reduce
the steric influence of the para-groups by adopting a distorted conformation in
the crystalline state. If the steric demand of the 2,6-diphenyl substituents is en-
larged by exchanging the 4-methoxy groups with
tert
-butyl fragments (
4c
),
increases to 27.8
is in-
creased to 51.4
and the structure finally adopts a distinct chiral,
C
2
-symmetric ge-
ometry (Fig. 2.6,
4c
; Fig. 2.8). The two substituents pointing to the metal center
push the chloride atoms down (or up, respectively), so that the Pd(II) atom is forced
to give up its favored square-planar coordination. The steric bulk of the rear pointing
2-(4-
tert
-butyl)phenyl groups also affects the methyl substituents of the backbone,
which additionally forces the metallacycle to adopt its chiral conformation.
Search WWH ::
Custom Search