#### Question

Amongst the following, the most stable complex is

**(i)** [Fe(H_{2}O)_{6}]^{3+}

**(ii)** [Fe(NH_{3})_{6}]^{3+}

**(iii)** [Fe(C_{2}O_{4})_{3}]^{3−}

**(iv)** [FeCl_{6}]^{3−}

#### Solution 1

We know that the stability of a complex increases by chelation. Therefore, the most stable complex is [Fe(C_{2}O_{4})_{3}]^{3−}.

Then

#### Solution 2

In each of the given complex, Fe is in + 3 oxidation state. As C_{2}0_{4}^{2-}is didentate chelating ligand, it forms chelate rings and hence (iii) out of complexes given above is the most stable complex.

Is there an error in this question or solution?

Solution Amongst the Following, the Most Stable Complex is Concept: Importance and Applications of Coordination Compounds.