####2. Complete removal of both the axial ligands (along the -axis) from an octahedral complex leads to which of the following splitting patterns? (relative orbital energies not on scale).
(2019 Main, 12 April I)
(b)
(d)
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Solution:
- Complete removal of both the axial ligands (along the -axis) from an octahedral complex leads to the following splitting pattern.
The single electron in the orbital is being repelled by four ligands, while the electron in the orbital is only being repelled by two ligands. Thus, the energy of the increases relative to that of . A more stable arrangement arises when both the electrons pair up and occupy the lower energy orbital. This leaves the orbital empty.
Thus, four ligands can now approach along and directions without any difficulty as orbital is empty. However, ligands approaching along and directions meet very strong repulsive forces from filled orbitals. Thus, only four ligands succeed in bonding to the metal. A square planar complex is formed, the attempt to form an octahedral complex being unsuccessful.
