Among the following which are ambidentate ligands?
(a) `NO_(2)^(-)` (b) `NO_(3)^(-)` (c) `EDTA^(+)`
(d) `C_(2)O_(4)^(2+)` (e) `SCN^(-)` (f) `H_(2)NCH_(2)CH_(2)NH_(2)`

Options

A. (a) and (b)
B. (c) and (d)
C. (a) and (f)
D. (a) and (e)

Explanation

To determine which of the given ligands are ambidentate ligands, we need to analyze each option based on their ability to bind to a metal center through different atoms. Ambidentate ligands can coordinate to a metal through two different atoms.

### Step-by-Step Solution:

1. **Understanding Ambidentate Ligands**:
- Ambidentate ligands are those that can bind to a metal through two different atoms. This means they have two potential donor atoms that can form coordinate bonds with the metal.

2. **Analyzing Each Option**:
- **(a) `NO2^(-)`**:
- The nitrite ion (`NO2^(-)`) can bind through either the nitrogen atom or one of the oxygen atoms. Therefore, it is an ambidentate ligand.
- **(b) `NO3^(-)`**:
- The nitrate ion (`NO3^(-)`) primarily binds through the nitrogen atom and does not have an alternative binding site. Thus, it is not ambidentate.
- **(c) `EDTA^(+)`**:
- EDTA (ethylenediaminetetraacetic acid) binds through multiple sites, but all are through nitrogen and oxygen atoms in a fixed manner. It does not have two different atoms that can bind to the metal in an ambidentate manner. Therefore, it is not ambidentate.
- **(d) `C2O4^(2-)`**:
- The oxalate ion (`C2O4^(2-)`) can only bind through its two oxygen atoms, making it a bidentate ligand but not ambidentate.
- **(e) `SCN^(-)`**:
- The thiocyanate ion (`SCN^(-)`) can bind through either the sulfur atom or the nitrogen atom. Hence, it is an ambidentate ligand.
- **(f) `H2NCH2CH2NH2`**:
- Ethylenediamine (en) binds through its two nitrogen atoms only and does not have alternative binding sites. Thus, it is not ambidentate.

3. **Conclusion**:
- The ambidentate ligands among the given options are **(a) `NO2^(-)`** and **(e) `SCN^(-)`**.

### Final Answer:
The ambidentate ligands are **(a) `NO2^(-)` and (e) `SCN^(-)`**.

---