215.

What can be inferred from the magnetic moment values of the following complex species?

Example	Magnetic Moment (BM)
K4[Mn(CN)6]	2.2
[Fe(H2O)6]2+	5.3
K3 [Mn Cl4]	5.9

(i) K₄[Mn(CN)₆]

For in transition metals, the magnetic moment is calculated from the spin-only formula. Therefore,

$\sqrt{\mathrm{n}(\mathrm{n}+2)} = 2.2$

We can see from the above calculation that the given value is closest to n = 1. Also, in this complex, Mn is in the +2 oxidation state. This means that Mn has 5 electrons in the d-orbital.

Hence, we can say that CN - is a strong field ligand that causes the pairing of electrons.

(ii) [Fe(H2O)6]²⁺

$\sqrt{\mathrm{n}(\mathrm{n}+2)} = 5.3$

We can see from the above calculation that the given value is closest to n = 4. Also, in this complex, Fe is in the +2 oxidation state. This means that Fe has 6 electrons in the d-orbital.

Hence, we can say that H2O is a weak field ligand and does not cause the pairing of electrons.

(iii) K2[MnCl4]

$\sqrt{\mathrm{n}(\mathrm{n}+2)} = 5.9$

We can see from the above calculation that the given value is closest to n = 5. Also, in this complex, Mn is in the +2 oxidation state. This means that Mn has 5 electrons in the d-orbital.

Hence, we can say that Cl - is a weak field ligand and does not cause the pairing of electrons.