Chemistry Reference
In-Depth Information
Table 5.2
Equilibrium bond distances and electric properties (au) of a few polar
molecules
ea
0
2
ea
0
3
a
0
3
Molecule
R
e
=
a
0
m
1
=
ea
m
2
=
m
3
=
a=
OC
2.132
0.044
1.47
3.46
13.08
NH
3
1.913
0.579
2.45
2.462
14.56
H
2
O
1.836
0
:
726
0
:
06
ð
2
:
19
Þ
1
:
98
ð
4
:
25
Þ
9.51
FH
1.733
0.704
1.71
2.50
5.60
ClH
2.409
0.4
2.8
17.75
LiH
3.015
2
:
294
3
:
097
6
:
326
28.31
H
2
1.40
0.44
5.43
N
2
2.074
1.04
11.74
O
2
2.282
0
:
30
10.59
F
2
2.71
0.536
9.31
CO
2
2.192
3.18
17.51
C
2
H
2
6.213
4.03
21.21
Figure 5.2
HOMO/LUMO (left) and electrostatic (right) descriptions of the origin of
the H-bonded structure of
ð
HF
Þ
2
The shapes of some H-bonded dimers resulting from electrostatic
calculations involving permanent multipole moments
5
up to R
6
are
shown in Table 5.3, where angles refer to the coordinate system of
Figure 5.3. Apart from the
Þ
2
dimer, a substantial agreement is
found between theoretical predictions and experiment.
ð
NH
3
5
The R
6
term of the expanded electrostatic energy involves interaction between dipole-hex-
adecapole
ð
l
¼
1
;
l
0
¼
4
Þ
,
hexadecapole-dipole
ð
l
¼
4
;
l
0
¼
1
Þ
,
quadrupole-octupole
ð
l
¼
2
;
l
0
¼
3
Þ
and octupole-quadrupole
ð
l
¼
3
;
l
0
¼
2
Þ
moments.
