Which of the following options is correct when six ligands are approaching towards central metal ion along axis?

Options

A. Energy of `t_(2g)` set of d-orbitals increases and that of `e_g` set decreases as compared to that in free metal ion.
B. Energy of `t_(2g)` set of d-orbitals decreases and that of `e_g` set increases-as compared to that in free metal ion.
C. Energy of both sets of d-orbitals increases, equally as compared to that in free metal ion.
D. Energy of `e_g` set of d-orbitals increases more than `t_(2g)` set of d-orbitals, but the energy of both sets of d-orbitals increases as compared to that in free metal ion.

Answer

D

Explanation

When ligands approach along the axes in octahedral fields, the electrons present in the `e_g` set of d-orbitals `(d_(x^2 - y^2), d_(z^2))` faces more repulsion as compared to the electrons in,`t_(2g)` set `(d_(xy), d_(yz), d_(zx))` which point in between the axes. But repulsion is faced by electrons from both setofd-orbitals. Hence, the energy will increase for both sets of d-orbitals.