Chemistry Reference
In-Depth Information
d
2
d
3
d
4
d
5
d
1
+0.6
∆
o
-0.4
∆
o
d
6
d
7
d
8
d
9
d
10
+0.6
∆
o
-0.4
∆
o
Figure 3.19
Electron arrangements in the d orbitals in an octahedral field with maximum number of unpaired
electrons for the d
1
-d
10
systems.
only one option (assuming Hund's rule applies). However, for d
4
-d
7
, both low-spin and
high-spin options exist, as shown in Figure 3.21, the size of
o
influencing outcomes. This
is exemplified for d
6
in Figure 3.22. What is important about this model is that it can be
used to understand experimental observations (as any viable model should, of course). It
allows us to understand how the colour and magnetism of a complex can change even where
the central metal ion and its oxidation state is not altered, simply as a result of a changing
ligand environment perturbing the size of
o
- but more on that later.
E
+
∆
∆
high spin
E
tot
=
E
+ (
E
+
∆
)
= 2
E
+
∆
low spin
E
tot
= (2 x
E
) + P
= 2
E
+ P
E
Figure 3.20
Comparing the effects of spin pairing (right) versus separate orbital occupancy (left) for a simple (but
artificial) model of two nondegenerate orbitals containing two electrons.
