Question

Write the electronic configuration for d$^4$ ion if \( \Delta_0 < P \) on the basis of crystal field theory.

Hint:

In weak field ligands (\( \Delta_0 < P \)), electrons occupy the higher energy \( e_g \) orbitals after filling the lower-energy \( t_{2g} \) orbitals.

Answer 1

For a d$^4$ ion, if \( \Delta_0 < P \) (weak field ligand), the electronic configuration will be as follows:
- The four electrons will be placed in the \( e_g \) and \( t_{2g} \) orbitals, but due to the weak field, electrons will occupy the \( t_{2g} \) orbitals first and then move to the \( e_g \) orbitals.
- The configuration will be \( t_{2g}^3 e_g^1 \), meaning three electrons in the lower-energy \( t_{2g} \) orbitals and one in the higher-energy \( e_g \) orbital.

Step 1: In weak field complexes, electrons are spread out in the available orbitals to minimize pairing.


Step 2: The \( t_{2g} \) orbitals are filled first, and the \( e_g \) orbitals are filled next.