Chemistry - Coordination Chemistry Question with Solution | TestHub

Question Explanation: Stability of coordination compounds based on charge and size. Concept: Factors affecting the stability of complexes.

Solution: The stability (formation constant) of a coordination complex depends on the charge density of the central metal ion. Charge density $\propto \frac{\text{ Charge }}{\text{ Radius }}$ Since Charge: ${\mathrm{Fe}}^{3+}>{\mathrm{Fe}}^{2+}$ and Size: ${\mathrm{Fe}}^{3+}<{\mathrm{Fe}}^{2+}$

This higher charge-to-size ratio leads to a stronger electrostatic attraction for the ${\mathrm{CN}}^{-}$ligands, making ${\left[\mathrm{Fe}(\mathrm{CN}{)}_6\right]}^{3-}$ more stable than ${\left[\mathrm{Fe}(\mathrm{CN}{)}_6\right]}^{4-}$. Final Answer: Option (A)