In the diamagnetic
octahedral 
complex,
[Co(NH3)6]
3+, the cobalt ion
is in +3 oxidation state
and has the electronic
configuration 3d
6 The
hybridisation scheme is as
shown in diagram Orbitals of Co ion
3+
sp d
3
2
3+
hybridised
orbitals of Co
[CoF ]
(outer orbital or
high spin complex)
6
3–
Six pairs of electrons
from six F ions
–
3d
4s
4p
sp d
3
3 hybrid
4d
3d
3d
Six pairs of electrons, one from each NH3 molecule, occupy the six
hybrid orbitals Thus, the complex has octahedral geometry and is
diamagnetic because of the absence of unpaired electron