What is the CFSE of the d7 electronic configuration in the presence of a strong field ligand?

CFSE of the d7 Electronic Configuration

The spherically symmetrical electrostatic field of the ligands alters the energies of the orbitals, resulting in a net increase in energy. The energy of the "d" orbitals has increased, but they are still degenerate or have similar energy. 

If a complex will be a low spin or high spin, we can find it by the magnitude of CFSE. The energy of the 't2g' orbitals is reduced by. 4Δ₀ and the energy of 'e' is increased by .6Δ₀ each.

• Strong field ligands typically result in more splitting and high CFSE.
• When this occurs, the electrons couple up in the lower orbitals set because the Pairing energy P is unable to defeat the CFSE.
• There are a fewlone electrons when the electrons pair up, making the complex a low spin.
• The d7 electronic configuration in strong field ligands presence is shown below:

The CFSE = difference of energy between the two orbitals sets = lower set energy - higher set energy

= (.4 × 6) - (1 × .6) = 2.4 - .6 = 1.8Δ₀

Therefore, the CFSE of the d7 electronic configuration in strong field ligand presence is 1.8Δ₀.

Summary:

What is the CFSE of the d7 electronic configuration in the presence of a strong field ligand? (A) 1.2 Δ₀ (B) 0.8 Δ₀ (C) 0.4 Δ₀ (D) 1.8 Δ₀

The CFSE of the d7 electronic configuration in the presence of a strong field ligand is 1.8Δ₀. The CFT treats ligands as the point charges and increases their degeneracy since d-orbitals are easily broken.