Question

In the following complex ion, explain the type of hybridisation, shape and magnetic property:

[Fe(H₂O)₆]²⁺

(At. Nos.: Fe = 26)

Answer 1

The electronic configuration of Fe is [Ar] 4s² 3d⁶. After the electronic configuration loses two electrons. H₂O is a weak field ligand, meaning it does not cause the pairing of electrons in the metal ion. Therefore, in this complex, Fe²⁺ will have its electrons arranged with unpaired electrons in the d-orbitals.

The complex has sp³d² hybridisation due to the coordination number of 6. This leads to an octahedral shape. Since H₂O is a weak field ligand, it does not cause electron pairing, so the Fe²⁺ complex has unpaired electrons. Therefore, [Fe(H₂O)]²⁺ is paramagnetic.