Question

The octahedral complex ion $[FeC{l}_6{]}^{3-}$ and $\left[Fe\right(CN{)}_6{]}^{3-}$ are both paramagnetic.

Select the correct statement :

The CFSE for________ .

• A. $[FeC{l}_6{]}^{3-}$ is zero.
• B. $\left[Fe\right(CN{)}_6{]}^{3-}$ is $-2{\Delta }_o$
• C. Both are correct
• D. None is correct

Answer 1

Answer: (C)

Both are correct

High spin complex $[FeC{l}_6{]}^{3-}$ has the d-configuration as $t_{2g}^3{e}_g^2$.

CFSE: 3(-0.4) + 2(0.6) = 0

High spin complex $\left[Fe\right(CN{)}_6{]}^{3-}$ has the d-configuration as $t_{2g}^5$

CFSE- 5(-0.4) = -2${\Delta }_o$

Therefore, option C is correct.