Question

The intense blue colour of prussian blue salts arises from which one of the following?

• A. d-d transition
• B. Inter valence electron transfer
• C. Ligand to metal charge transfer
• D. Metal to ligand charge transfer

Answer 1

The correct option is B Inter valence electron transfer

Option (C) is correct. The intense blue colour of Prussian blue salts arises from inter valence electron transfer between $Fe\left(II\right)$ and $Fe\left(III\right)$ present in the compound.

Prussian blue differ in the oxidation states of iron inside and outside of the coordination sphere of the compound which leads to the change in colour.