Which can form chelates?

Options

A. Ethylene diamine
B. Oxalate
C. Glycinate
D. Cyanide

Answer

To determine which ligands can form chelates, we need to analyze each ligand provided in the question. A chelating ligand is one that can form a ring-like structure with a metal ion by coordinating through multiple donor atoms.

### Step-by-Step Solution:

1. **Identify the Ligands**: The ligands given are:
- Ethylene diamine
- Oxalate
- Glycinate
- Cyanide

2. **Analyze Ethylene Diamine**:
- Structure: NH2CH2CH2NH2
- Ethylene diamine has two nitrogen atoms that can donate lone pairs to a metal ion.
- When ethylene diamine coordinates to a metal ion, it can form a ring structure.
- **Conclusion**: Ethylene diamine can form chelates.

3. **Analyze Oxalate**:
- Structure: COO-COO-
- Oxalate has two carboxylate groups that can donate electrons to a metal ion.
- This ligand can also form a ring structure when it coordinates to a metal ion.
- **Conclusion**: Oxalate can form chelates.

4. **Analyze Glycinate**:
- Structure: COO-CH2NH2
- Glycinate has both a carboxylate group and an amine group that can donate lone pairs to a metal ion.
- This ligand can also form a ring structure with a metal ion.
- **Conclusion**: Glycinate can form chelates.

5. **Analyze Cyanide**:
- Structure: CN-
- Cyanide has a nitrogen atom that can donate a lone pair to a metal ion.
- However, cyanide does not form a ring structure when it coordinates to a metal ion.
- **Conclusion**: Cyanide does not form chelates.

6. **Final Conclusion**:
- The ligands that can form chelates are:
- Ethylene diamine
- Oxalate
- Glycinate
- Therefore, the correct options are 1 (ethylene diamine), 2 (oxalate), and 3 (glycinate).

### Summary of Answers:
- Ethylene diamine: Forms chelates
- Oxalate: Forms chelates
- Glycinate: Forms chelates
- Cyanide: Does not form chelates