Question

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

K₂[MnCl₄] 5.9

Answer 1

Magnetic moment () is given as.

For value n = 1, .

For value n = 2, .

For value n = 3, .

For value n = 4, .

For value n = 5, .

(i) K₄[Mn(CN)₆]

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

We can see from the above calculation that the given value is closest to. 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⁺

We can see from the above calculation that the given value is closest to. 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]

We can see from the above calculation that the given value is closest to. 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.