What will be the electronic configuration of d5 in terms of t2g and eg in an octahedral field when Δo<P, where P is the energy required for pairing of electrons in a single orbital?

Correct Answer: t2g3 eg2
When the field splitting is less than the pairing energy, the energy gap between the two sets of d orbitals is small. This allows the electrons to occupy the higher energy orbitals once the lower orbitals are singly occupied. Thus, the configuration will be t2g3 eg2, with one electron in each orbital.