Question

Give a reason for the following:

Mn⁺² compounds are more stable than Fe⁺² compounds.

Answer 1

Mn²⁺ = 1s² 2s² 2p⁶ 3s² 3p⁶ 3d⁵ (Half-filles d-orbital)

Fe²⁺ = 1s² 2s² 2p⁶ 3s² 3p⁶ 3d⁶ 

Mn²⁺ molecules are more stable because of their half-filled d-orbitals. Fe²⁺ complexes are less stable because they have six electrons in the 3d-orbital. Hence, they loose one electron to get stable 3d⁵ configuration.