Chemistry Reference
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with the resonance energy
D
E
¼
E
ð
2K
þ
3D
Þ
E
ð
K
Þ¼ð
2
:
6055
1
:
5
Þ
K
¼
1
:
1K
ð
9
:
127
Þ
which is the largest seen so far for benzene.
For the coefficients of the resonant structures, we have from the
homogeneous system
5
2
x
6
3x
þ
9
c
K
¼
0
c
D
¼
:
4321c
K
for x
¼
2
:
6055
ð
9
:
128
Þ
Assuming orthogonality between the structures, we obtain the
normalization factor for the
Y
in (9.121):
hYjYi¼
2c
K
þ
3c
D
¼
1
)
N
¼ð
2c
K
þ
3c
D
Þ
1
=
2
ð
9
:
129
Þ
Figure 9.10 Percentage relativeweights of VB canonical structures in conjugated and
aromatic hydrocarbons
