Question

The spin-only magnetic moments of $\left[Fe\right(N{H}_3{)}_6{]}^{3+}$ and $[Fe{F}_6{]}^{3-}$ in BM are respectively:

• A. $1.73$ and $1.73$
• B. $5.92$ and $1.73$
• C. $1.73$ and $5.92$
• D. $5.92$ and $5.92$

Answer 1

Answer: (C)

$1.73$ and $5.92$

As $N{H}_3$ is a strong field it will pair up the electrons while $F^{-}$ is a weak field ligand, it will not pair up the electrons. Hence, spin only magnetic moments are 1.73 and 5.92 BM respectively.

Magnetic moment, $\mu =\sqrt{n(n+2)}$, where $n=$ number of unpaired electrons.

Hence option $C$ is correct.