Question

What is the decreasing order of field strength of given ligands? (A) S\(^{2-}\)
(B) Ethylenediamine
(C) NCS\(^{-}\)
(D) CN\(^{-}\)

• A. (A), (C), (B), (D)
• B. (A), (B), (C), (D)
• C. (B), (C), (D), (A)
• D. (D), (C), (B), (A)

Hint:

Strong field ligands like CN\(^{-}\) and ethylene diamine can cause a significant splitting of d-orbital energies, whereas weaker field ligands like S\(^{2-}\) have lesser effect.

Answer 1

The Correct Option is D

Step 1: Understanding field strength of ligands.
Field strength of ligands is a measure of their ability to split the d-orbital energies of a metal ion. The order of field strength can be determined based on the ligand's ability to donate electrons.
Step 2: Analyzing the ligands.
- S\(^{2-}\): This is a strong field ligand due to the high charge density.
- Ethylene diamine: A bidentate ligand that is a moderate field ligand.
- NCS\(^{-}\): A weaker ligand compared to ethylenediamine.
- CN\(^{-}\): A very strong field ligand with a high charge density and good electron-donating ability.
Step 3: Conclusion.
The decreasing order of field strength is:
(1) CN\(^{-}\) (strongest)
(2) NCS\(^{-}\)
(3) Ethylenediamine
(4) S\(^{2-}\) (weakest)
Final Answer: \[ \boxed{\text{The correct answer is (4) (D), (C), (B), (A).}} \]