Question

The spin only magnetic moment value (in B.M.) of the complex $[FeC{l}_6{]}^{4-}$ is:

• A. $3.9\text{B.M.}$
• B. $4.9\text{B.M.}$
• C. $5.9\text{B.M.}$
• D. $2.9\text{B.M.}$

Answer 1

The correct option is B $4.9\text{B.M.}$

In $[FeC{l}_6{]}^{4-}$, the $C{l}^{-}$ ion is a weak field ligand. The structure of $[FeC{l}_6{]}^{4-}$ is octahedral with $s{p}^3{d}^2$ hybridsation.


The number of unpaired electrons $=4$
The magnetic moment is $=\sqrt{n(n+2)}\text{Where, n= number of unpaired electrons}=\sqrt{4\times (4+2)}=\sqrt{24}=4.9\text{B.M.}$