In [CO(NH3)6]3+ , oxidation state of CO = +3 Electronic configuration = 3d6
In presence of NH3 , 3d electrons pair up leaving two d-orbitais empty. Hence, the hybridisation is d2p2 forming an inner orbital complex. In [Ni(NH3)6]2+.
Oxidation state = +2, Electronic Configuration = 3d8. In the presence of NH3 , 3d electrons do not pair up. The hybridisation involved is , s3d2 and it forms an outer orbital complex.