The d-orbital electronic configuration of the complex among…
The d-orbital electronic configuration of the complex among $\quad\left[\mathrm{Co}(\mathrm{en})_3\right]^{3+}, \quad\left[\mathrm{CoF}_6\right]^{3-}$, $\left[\mathrm{Mn}\left(\mathrm{H}_2 \mathrm{O}\right)_6\right]^{2+}$ and $\left[\mathrm{Zn}\left(\mathrm{H}_2 \mathrm{O}\right)_6\right]^{2+}$ that has the highest CFSE is :
$t_2^6 g_g^0$
$t_2^6 e_g^4$
$t_{2 g}^3 e_g^2$
$t_2^4 e_g^2$
Solution
In $\left[\mathrm{Co}(\mathrm{en})_3\right]^{+3}$ S.F.L. is present and hence highest value of CFSE In rest all complexes WFL is present hence CFSE will be low. $\left[\mathrm{Co}(\mathrm{en})_3\right]^{+3} \Rightarrow \mathrm{Co}^{+3}$ and en (SFL) $\mathrm{Co}^{+3} \Rightarrow[\mathrm{Ar}] 3 \mathrm{~d}^6$
