Question

Which of the following is the correct order of ligand field strength?

• A. CO<NH₃<en<C₂O₄²⁻<S²⁻
• B. S²⁻<C₂O₄²⁻<NH₃<en<CO
• C. NH₃<en<CO<S²⁻<C₂O₄²⁻
• D. S²⁻<NH₃<en<CO<C₂O₄²⁻

Hint:

Stronger field ligands induce greater crystal field splitting and favor low-spin complexes.

Answer 1

The Correct Option is B

Step 1: Ligand Field Strength Determination
Ligand field strength is determined by the spectrochemical series.
A higher ligand field strength results in increased d-orbital splitting in transition metal complexes.
Step 2: Spectrochemical Series Ranking \[{S}^{2-}<{C}_2{O}_4^{2-}<{NH}_3<{en}<{CO}\]Rationale:
Sulfide (S$^{2-}$) functions as a weak field ligand.
Oxalate (C$_2$O$_4^{2-}$), while stronger than S$^{2-}$, remains a weak field ligand.
Ammonia (NH$_3$) is classified as a moderate field ligand.
Ethylenediamine (en) exhibits greater strength than NH$_3$ due to the chelation effect.
Carbon monoxide (CO) is the strongest field ligand, causing the most significant crystal field splitting.