Low spin complex of d^6 -cation in an octahedral field will have...

(\text{C.F.S.E. }=(-0.4 x+0.6 y) \Delta_o+z P) where (\mathrm{x}=) number of electrons occupying (\mathrm{t}_{2 g}) orbital $y=$ number of electrons occupying $e_g$ orbital $z=$ number of pairs of electrons For low spin (\mathrm{d}^6) complex electronic configuration $$\begin{aligned} & =t_{2 g}^6 e_g^0 \text{ or } t_{2 g}^{2,2,2} e_g^0 \\ & \therefore \quad x=6, y=0, z=3 \\ & \text{ C.F.S.E. }=(-0.4 \times 6+0 \times 0.6) \Delta_o+3 P \\ & =\frac{-12}{5} \Delta_o+3 P \end{aligned}$$)$