Chemistry - Coordination Chemistry Question with Solution | TestHub

$[Ni(N{H}_3{)}_4]S{O}_4$ is the only complex that does not follow Sidgwick's EAN rule.

For $[Fe(CO{)}_5]$:

$EAN=26-0+10=36$ (Follows)

For $K_2[PtC{l}_6]$:

$EAN=78-4+12=86$ (Follows)

For $[Fe(N{H}_3{)}_6]C{l}_2$:

$EAN=26-2+12=36$ (Follows)

For $[Ni(N{H}_3{)}_4]S{O}_4$:

$EAN=28-2+8=34$ (Does not follow)

In $[Ni(N{H}_3{)}_4{]}^{2+}$, $N{i}^{2+}$ has a $3d^8$ configuration with 2 unpaired electrons ($n=2$) in its tetrahedral geometry.

Therefore, the sum of the magnetic moments is $\mu =\sqrt{2(2+2)}=\sqrt{8}=2.82BM$.