In
the presence of H2O, (a weak ligand), 3d electrons do not pair up The
hybridisation is sp
3d
2 forming an outer orbital complex containing five unpaired
electrons, it is strongly paramagnetic 5 8 In the presence of NH3, the 3d electrons pair up leaving two d orbitals empty
to be involved in d
2sp
3 hybridisation forming inner orbital complex in case of [Co(NH3)6]
3+