The change of ground state configuration of the cobalt(II) is very evident,
comparing the spectrum (a) with (b), and indicates that the coordination of pyridine
increases the weight of the (xz)
2 (xy)
2 (yz)
2 (z
2 ) configuration. Consequently, the
electron transfer from Co(II) to O 2 becomes easier.
5.6 Chemical Message
From the above discussion, it appears that the responsibility of the easy electron
transfer from the Co(II) to oxygen lies in the location of the unpaired electron along
the z-axis. However, also the (xz)
2 (xy)
2 (yz)(z
2 )
2 configuration assists this interaction
through overlap of the d xz,yz with the p* orbitals. When oxygen is removed, the
unpaired electron reversibly returns onto the cobalt.
Wavelength/nm
Absorption
16.66
10
g/kK
6.66
5
600
(a)
(b)
(c)
(d)
(e)
1000
1500
2500
Fig. 5.6 Diffuse reflectance
spectra reported in nm and in
kK (cm
−1 Â 1000) of
a planar CoAcacen and
b pentacoordinated CoAcacen
py [5–8]
92
5 The Symmetry Properties Describe the Electronic Structure …
comparing the spectrum (a) with (b), and indicates that the coordination of pyridine
increases the weight of the (xz)
2 (xy)
2 (yz)
2 (z
2 ) configuration. Consequently, the
electron transfer from Co(II) to O 2 becomes easier.
5.6 Chemical Message
From the above discussion, it appears that the responsibility of the easy electron
transfer from the Co(II) to oxygen lies in the location of the unpaired electron along
the z-axis. However, also the (xz)
2 (xy)
2 (yz)(z
2 )
2 configuration assists this interaction
through overlap of the d xz,yz with the p* orbitals. When oxygen is removed, the
unpaired electron reversibly returns onto the cobalt.
Wavelength/nm
Absorption
16.66
10
g/kK
6.66
5
600
(a)
(b)
(c)
(d)
(e)
1000
1500
2500
Fig. 5.6 Diffuse reflectance
spectra reported in nm and in
kK (cm
−1 Â 1000) of
a planar CoAcacen and
b pentacoordinated CoAcacen
py [5–8]
92
5 The Symmetry Properties Describe the Electronic Structure …