Determine the oxidation state of iron in the complex ion [Fe(en)${}_3$]${}^{2+}$ where en = 1,10-ethylenediamine (neutral ligand).

Step-by-step solution

1. Write the charge balance equation: oxidation state of Fe + 3×(charge of en) = overall charge
2. Since en is neutral, charge of Fe + 0 = +2
3. Thus oxidation state of Fe = +2.

Concept tested: Oxidation state determination

Published 7 October 2026 · How this solution was prepared and checked