The donor sites of `(EDTA)^(4-)` are ?

Options

A. O atoms only
B. N atom only
C. Two N atoms and four O atoms
D. Three N atoms and three O atoms.

Answer

To determine the donor sites of the EDTA^4- ion, we will analyze its structure and identify the atoms that can donate lone pairs to a metal center.

### Step-by-Step Solution:

1. **Understand the Structure of EDTA**:
- EDTA stands for Ethylene Diamine Tetra Acetate. Its structure consists of two ethylene (–CH2–CH2–) groups connected to four acetate (–COO^-) groups.

2. **Identify the Atoms in EDTA**:
- The EDTA molecule contains:
- 2 Nitrogen (N) atoms from the ethylene diamine part.
- 4 Oxygen (O) atoms from the acetate groups.

3. **Determine the Donor Sites**:
- **Nitrogen Donor Sites**: Each nitrogen atom has a lone pair of electrons that can be donated to a metal ion. Therefore, the two nitrogen atoms contribute 2 donor sites.
- **Oxygen Donor Sites**: Each acetate group has one oxygen atom that carries a negative charge, which can also donate a lone pair to a metal ion. Thus, the four oxygen atoms contribute 4 donor sites.

4. **Count the Total Donor Sites**:
- Adding the donor sites together:
- Nitrogen donor sites: 2
- Oxygen donor sites: 4
- Total donor sites = 2 (from N) + 4 (from O) = 6 donor sites.

5. **Conclusion**:
- EDTA^4- is classified as a hexadentate ligand because it can coordinate to a metal ion through six donor atoms: 2 nitrogen atoms and 4 oxygen atoms.

### Final Answer:
The donor sites of EDTA^4- are 2 nitrogen atoms and 4 oxygen atoms, totaling 6 donor sites.

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