Physical Chemistry Heteroatomic Molecular Orbitals
ADVERTISEMENT
1
2Heteroatomic molecular
orbitals
Carbon monoxide
Heteroatomic molecular
orbitals
Physical Chemistry
Mix atomic orbitals
For discussion, treated
simplistically as one orbital
from each center
Lecture 25
Often close to correct
because a single orbital
Heteroatomic Diatomic Molecules
predominates
Must mix orbitals of
Similar energy
Same symmetry
Molecular orbital energies
Rough estimation by
diagram
Calculated with computer
simulations
Example: carbon monoxide
Example: carbon monoxide
Carbon monoxide
Hartree-Fock
Atomic orbitals
calculations give
1
20
.
58
hartree
2p
similar to 2p
C
O
2s
similar to 2s
relative energies of
C
O
*
Allows an energy diagram
states
2
11
.
32
hartree
similar to homonuclear
Calculated with
diatomics
3
. 1
55
hartree
Gaussian
Mixing occurs to create
bonding and antibonding
Not “correct”
*
4
. 0
79
hartree
states
energies, but gives
order of stability
Some mixing of 2s states
1
. 0
64
hartree
into the states from 2p
Gives a filling order
Some mixing of 2p states
for producing
5
. 0
54
hartree
into the states from 2s
configurations
Produces a filling order for
producing configurations
Determining configuration and
term of carbon monoxide
Example 2: hydrogen fluoride
When atoms are of different energies, one must be
Fill MOs in order
concerned with the relative energies and
Ground configuration
symmetries of orbitals
Orbitals of same symmetry and approximately similar
(1)
2
(2
*
)
2
(3)
2
(4
*
)
2
(1)
4
(5)
2
energy combine most effectively
Total angular momentum = 0
Can estimate approximate HF molecular orbitals
Total spin = 0
Energies calculated with Gaussian
Gives filling order of orbitals
Use term symbols as with
1
1
s
26
.
11
hartree
F
homonuclear diatomics
2
2
s
. 1
55
hartree
1
F
Note lack of indication of
3
C
2
p
1
s
. 0
71
hartree
0
F
H
inversion symmetry
1
2
p
2 ,
p
. 0
60
hartree
1
F
1
F
*
4
D
2
p
1
s
0
F
H
1
ADVERTISEMENT
0 votes
Related Articles
Related forms
Related Categories
Parent category: Education