Question

Explain why \( [\text{Fe(CN)_6]^{3-} \) is an inner orbital complex, whereas \( [\text{Fe(H}_2\text{O)}_6]^{3+} \) is an outer orbital complex.}

Hint:

- Inner orbital complexes involve \( d^2sp^3 \) hybridization with strong ligands. - Outer orbital complexes involve \( sp^3d^2 \) hybridization with weak ligands.

Answer 1

Step 1: Electronic Configuration of Fe\(^{3+}\) \[ \text{Fe}^{3+} = 3d^5 \] Step 2: Effect of Ligands on Hybridization - \( CN^- \) is a strong field ligand, causing electron pairing and leading to \( d^2sp^3 \) hybridization (inner orbital complex). - \( H_2O \) is a weak field ligand, preventing electron pairing and leading to \( sp^3d^2 \) hybridization (outer orbital complex).