Question

Which one of the following is not an ambidentate ligand?

• A. \( \text{CN} \)
• B. \( \text{SCN}^- \)
• C. \( \text{SO}_4^{2-} \)
• D. \( \text{NO}_2^- \)

Hint:

Standard ambidentate ligands include \( \text{NO}_2^- \), \( \text{CN}^- \), \( \text{SCN}^- \), \( \text{OCN}^- \).

Answer 1

The Correct Option is C

Step 1: Definition:

Ambidentate ligands are monodentate ligands that contain more than one different donor atoms but coordinate through only one atom at a time. This leads to linkage isomerism.
Step 2: Evaluating Options:

- (A) \( \text{CN}^- \):
Can bond through Carbon (Cyano) or Nitrogen (Isocyano). Ambidentate. - (B) \( \text{SCN}^- \):
Can bond through Sulfur (Thiocyanato) or Nitrogen (Isothiocyanato). Ambidentate. - (D) \( \text{NO}_2^- \):
Can bond through Nitrogen (Nitro) or Oxygen (Nitrito). Ambidentate. - (C) \( \text{SO}_4^{2-} \):
The sulfate ion coordinates through Oxygen atoms. Although it has multiple oxygen atoms and can act as a monodentate, bidentate, or bridging ligand, it does not have two *chemically different* types of donor atoms (like C vs N, or S vs N) to be classified as ambidentate in the classical sense.
Step 3: Final Answer:

\( \text{SO}_4^{2-} \) is not an ambidentate ligand.