[Co(NH3)6]3+ is an inner orbital complex.
In inner orbital complexes, the d-electrons of the central metal ion preferentially participate in bonding before the s-electrons. This results in the pairing of electrons in the lower energy (inner) d-orbitals before populating the higher energy (outer) d-orbitals.
For [Co(NH3)6]3+, cobalt (Co) has the electronic configuration [Ar] 3d^7 4s^2 in its neutral state. In the complex, it loses three electrons to form Co^3+, resulting in the electronic configuration [Ar] 3d^6.
In this case, the six ammonia (NH3) ligands (which are weak field ligands) form coordinate bonds with the central cobalt ion. Due to the nature of these ligands and the high spin state of the Co^3+ ion, the complex is likely to be a high spin complex.
In inner orbital complexes, the electrons fill the lower energy d-orbitals (inner d-orbitals) before the higher energy ones (outer d-orbitals). Therefore, the six ammonia ligands primarily interact with the inner d-orbitals of the cobalt ion.
Thus, [Co(NH3)6]3+ is an inner orbital complex, where the bonding primarily occurs through the inner d-orbitals of the central cobalt ion.
