JEE MainChemistryCoordination Compounds
Consider the following iron complexes: (P) [ Fe ( H ₂ O )₆ ]³⁺ (Q) [ FeCl ₄ ]²⁻ (R) [ Fe ( H ₂ O )₆ ]²⁺ (S) [ Fe ( en )₃ ]³⁺ The correct increasing order of the magnitude of their Crystal Field Stabilization Energies (CFSE) is :
Options
- A(P) (Q) (R) (S)
- B(Q) (R) (P) (S)
- C(P) (R) (Q) (S)
- D(Q) (R) (S) (P)
Correct answer
A. (P) (Q) (R) (S)
Step-by-step solution
To find the magnitude of CFSE, we determine the oxidation state, geometry, and electron configuration for each complex: (P) [ Fe ( H ₂ O )₆ ]³⁺ : Fe ³⁺ is a 3 d ^5 ion. H ₂ O is a weak field ligand, so the complex is high spin octahedral ( t _ 2 g ^3 e _ g ^2 ). CFSE = [3(-0.4) + 2(0.6)] _o = 0 . (Q) [ FeCl ₄ ]²⁻ : Fe ²⁺ is a 3 d ^6 ion. Cl ^- is a weak field ligand, and the coordination number is 4, so it is high spin tetrahedral ( e ^3 t ₂^3 ). CFSE = [3(-0.6) + 3(0.4)] _t = -0.6 _t . Since _t 4 9 _o , the magnit