Question

Crystal field stabilization energy (CFSE) of $Mn\left[\right(H_{2}O{)}_6{]}^{+2}$ is:

• A. $-0.6{\Delta }_o$
• B. $-0.4{\Delta }_o$
• C. $0$
• D. $-0.8{\Delta }_o$

Answer 1

The correct option is C $0$

Given complex is $Mn\left[\right(H_{2}O{)}_6{]}^{+2}$
$\text{Configuration of}Mn:\left[Ar\right]3d^{5}4s^2$
$\text{Configuration of}Mn:\left[Ar\right]3d^{5}4s^0$
Since $H_{2}O$ is a weak field ligand, hence pairing would not take place.
$\Rightarrow M{n}^{+2}=t_{2g}^3{e}_g^2$
${\text{CFSE}}_{\text{octahedral}}=-0.4{\Delta }_o{n}_{t_{2g}}+0.6{\Delta }_o{n}_{e_g}$
$\Rightarrow {\text{CFSE}}_{\text{octahedral}}=-0.4{\Delta }_o\left(3\right)+0.6{\Delta }_o\left(2\right)$
$\Rightarrow {\text{CFSE}}_{\text{octahedral}}=-1.2{\Delta }_o+1.2{\Delta }_o=0$