Question

If ${\Delta }_{\circ }$ > P (P = pairing energy; ${\Delta }_{\circ }$ change in energy of octahedral complexes), the correct electronic configuration for $d^4$ system will be

• A. $t_{2g}^4{}^0{e}_g$
• B. $t_{2g}^3{}^0{e}_g$
• C. $t_{2g}^0{}^4{e}_g$
• D. $t_{2g}^2{}^2{e}_g$

Answer 1

The correct option is A

$t_{2g}^4{}^0{e}_g$

${\Delta }_{\circ }$ > P implies that the difference between $e_g$ and $t_{2g}$ is so large that the electrons would get paired at the lower energy level before the electrons populate the higher level. If pairing energy is less, then electrons cannot resist themselves from being paired up.