Which of the following is a tridentate ligand?

Options

A. `NO_(2)^(Θ)`
B. Oxalate ion
C. Glycinate ion
D. Dien

Answer

To determine which of the following is a tridentate ligand, we need to understand what a tridentate ligand is. A tridentate ligand is a type of ligand that has three donor atoms, each capable of donating a lone pair of electrons to a metal center in a coordination compound.

### Step-by-Step Solution:

1. **Define Tridentate Ligand**:
- A tridentate ligand is one that has three donor atoms, which can each donate a pair of electrons to a metal ion.

2. **Examine the Options**:
- We will analyze each of the given options to identify how many donor sites they possess.

3. **Option 1: NO2- (Nitrite Ion)**:
- The structure of NO2- shows that it has two potential donor sites: one from nitrogen and one from oxygen. However, it is ambidentate, meaning only one site is active at a time.
- **Conclusion**: NO2- is a monodentate ligand.

4. **Option 2: Oxalate Ion (C2O4^2-)**:
- The oxalate ion has two oxygen atoms that can donate lone pairs, thus it has two donor sites.
- **Conclusion**: Oxalate is a bidentate ligand.

5. **Option 3: Glycinate Ion**:
- The glycinate ion has one nitrogen atom and one oxygen atom that can donate lone pairs. Therefore, it has two donor sites.
- **Conclusion**: Glycinate is also a bidentate ligand.

6. **Option 4: Diethylene Triamine (dien)**:
- Diethylene triamine has three nitrogen atoms, each capable of donating a lone pair of electrons.
- **Conclusion**: Diethylene triamine is a tridentate ligand.

7. **Final Answer**:
- The correct option that represents a tridentate ligand is **Diethylene Triamine (dien)**.

### Summary:
- **Tridentate Ligand**: A ligand with three donor atoms.
- **Identified Ligands**:
- NO2-: Monodentate
- Oxalate: Bidentate
- Glycinate: Bidentate
- Diethylene Triamine: Tridentate

Thus, the answer is **Diethylene Triamine (dien)**.