Chemistry Reference
In-Depth Information
uckel theory, we put b sh ¼ b s h ¼ b , a parameter
characteristic of the N
If, in the spirit of H
H bond, the coefficients become after dividing
by b 2 :
<
24 b 2 cos 2 v ð
cos 2
A
¼
2
Þ
24 b 2 sin2 v ð
cos 2
B
¼
2
Þ
8
<
9
=
3 b 2 1
4 sin 2 v
h
i
2
2
2
cos 4 v ða p a h Þ
6 b 2
C
¼
4
ða b a h Þ
þ
2 ð
sin2
þ
þ
:
;
:
2
4 sin2 v cos 2 v ½ða p a h Þ
6 b 2
D
¼
þ
2
2
6 b 2
¼ð
sin2
½ða p
a h Þ
þ
:
E
ð
2
:
242
Þ
As before, we now examine the following two particular cases.
(i) For v ¼
0 (no hybridization), a b a h ¼ a p
a h , coefficients B, D, E
72 b 2
24 b 2 , and Equation (2.241) gives:
vanish, A
¼
;
C
¼
8
<
1
p Y g ¼
74
3x 2
¼
1
;
x
¼
cos
g ¼
54
:
ð
2
:
243
Þ
p
p Y
2
:
2
3
1
90
p
p Y
sin
g ¼
sin u ¼
sin u ¼
2 u ¼
as it must be.
(ii) If we put:
a b a h ¼ a p a h ¼
0
ð
2
:
244
Þ
(which is tantamount to assuming nonpolar bonds) dividing through-
out by 6 b 2 , the coefficients will depend only on v , becoming:
<
4 cos 2 v ð
cos 2
A
¼
2
Þ
cos 2
B
¼
4 sin 2 v ð
2
Þ
2
8 sin 2 v
4 cos 4 v
ð
2
:
245
Þ
C
¼ð
sin 2
þ
:
4 sin 2 v cos 2 v
D
¼
2
E
¼ð
sin 2
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