Chemistry Reference
In-Depth Information
FIGURE 9.1.
Nonbonding natural orbitals of
o- 6a
,
m- 6a
,and
p- 6a
calculated at the (9,9)-
CASSCF/cc-pVTZ level of theory.
natural orbitals of
o-
, all three
orbitals have different symmetries corresponding to the molecular axes (orbitals
n
x
,
n
y
, and
n
z
), whereas in
o-
6a
,
m-
6a
, and
p-
6a
are shown in Figure 9.1 . In
p-
6a
6a
and
m-
6a
with lower symmetry the two in-plane orbitals
s
(C) have the same symmetry, and consequently the natural orbitals are
presented as linear combinations.
The electronic structure of the ground states and lowest lying excited states of
nitreno radicals
o-
(N) and
s
has been analyzed in detail by CASSCF and
MRMP2 calculations.
9
The occupation of the three nonbonding orbitals with three
electrons results in one quartet and five doublet states. One of these doublet states has
one electron in each nonbonding orbital, whereas the other four doublet states have
one orbital doubly occupied, one singly, and one not occupied. The former doublet
state can be thus described as open-shell doublet, whereas the others are closed-shell
doublets (of course, still containing one unpaired electron but not three as the open-
shell doublet and quartet states).
6a
,
m-
6a
, and
p-
6a
