Question

Among the following complexes the one which shows Zero crystal field stabilization energy (CFSE) is

• A. $\left[Mn\right(H_{2}O{)}_6{]}^{3+}$
• B. $\left[Fe\right(H_{2}O{)}_6{]}^{3+}$
• C. $\left[Co\right(H_{2}O{)}_6{]}^{2+}$
• D. $\left[Co\right(H_{2}O{)}_6{]}^{3+}$

Answer 1

The correct option is B

$\left[Fe\right(H_{2}O{)}_6{]}^{3+}$

$F{e}^{3+}$ has a $d^5$ configuration. Water is a weak field ligand, forcing a high spin complex. This is the only one that can have a 0 CFSE among the other 3+ species given here.