Which of the following ligands may be flexidentate ?

Options

A. EDTA
B. `CO_(3)^(-2)`
C. `NO_(3)^(-)`
D. All of these

Answer

To determine which ligands may be flexidentate, we first need to understand what flexidentate ligands are. Flexidentate ligands are those that have more than two donor sites, allowing them to bind to a metal ion at multiple points.

### Step-by-Step Solution:

1. **Understanding Flexidentate Ligands**:
- Flexidentate ligands must have more than two donor sites. This means that the ligand can coordinate to a metal ion at multiple positions.

2. **Analyzing the Ligands**:
- We will analyze the ligands provided in the question to identify their donor sites.

3. **Example 1: EDTA (Ethylenediaminetetraacetic acid)**:
- Structure: EDTA has a structure that includes two nitrogen atoms and four carboxylate groups (–COO⁻).
- Donor Sites: The two nitrogen atoms contribute two donor sites, and the four carboxylate groups contribute four additional donor sites.
- Total: Therefore, EDTA has a total of 6 donor sites (2 from N and 4 from O).
- Conclusion: EDTA is a flexidentate ligand.

4. **Example 2: Carbonate Ion (CO₃²⁻)**:
- Structure: The carbonate ion has a central carbon atom double bonded to one oxygen atom and single bonded to two other oxygen atoms.
- Donor Sites: The two negatively charged oxygen atoms can act as donor sites.
- Total: Therefore, the carbonate ion has 2 donor sites.
- Conclusion: Carbonate is not a flexidentate ligand.

5. **Example 3: Nitrate Ion (NO₃⁻)**:
- Structure: The nitrate ion consists of a nitrogen atom bonded to three oxygen atoms, one of which is double bonded.
- Donor Sites: The two negatively charged oxygen atoms can act as donor sites.
- Total: Therefore, the nitrate ion also has 2 donor sites.
- Conclusion: Nitrate is not a flexidentate ligand.

6. **Final Conclusion**:
- Among the ligands analyzed, only EDTA qualifies as a flexidentate ligand due to its six donor sites. The carbonate and nitrate ions do not qualify as flexidentate ligands since they only have two donor sites each.

### Summary:
- **Flexidentate Ligand**: EDTA (6 donor sites)
- **Not Flexidentate**: Carbonate (2 donor sites), Nitrate (2 donor sites)