Which of the following is not an ambidntate ligand ?

Options

A. `CN^(-)`
B. `NO_(2)^(-)`
C. `SCN^(-)`
D. `NH_(3)`

Answer

To determine which of the following is not an ambidentate ligand, we first need to understand the definition of ambidentate ligands. Ambidentate ligands are those that can bind to a metal center through two different atoms, each of which has a lone pair of electrons that can be donated to the metal.

Let's analyze the given ligands:

1. **CN⁻ (Cyanide)**: This ligand can coordinate to a metal through the carbon atom or the nitrogen atom. Therefore, it is an ambidentate ligand.

2. **NO₂⁻ (Nitrite)**: This ligand can also coordinate through either the nitrogen atom or one of the oxygen atoms. Hence, it is also an ambidentate ligand.

3. **SCN⁻ (Thiocyanate)**: This ligand can bind through the sulfur atom or the nitrogen atom, making it ambidentate as well.

4. **NH₃ (Ammonia)**: This ligand has a lone pair on the nitrogen atom but can only coordinate through that single atom. It does not have another atom to coordinate with, so it is not an ambidentate ligand.

Based on this analysis, the ligand that is not ambidentate is **NH₃**.

### Final Answer:
**NH₃ (Ammonia) is not an ambidentate ligand.**

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