Give the number of ligand(s) in which donor atoms is only `N NH_(2)CH_(2)COO^(Θ)`, en, dinen, Py, `EDTA` ,ph .

Explanation

To solve the question regarding the number of ligands that have only nitrogen atoms as donor atoms, we will analyze each ligand provided in the question step by step.

### Step-by-Step Solution:

1. **Identify the Ligands**: The ligands given are:
- `NH2CH2COO^-`
- `en` (ethylene diamine)
- `dien` (diethylene triamine)
- `Py` (pyridine)
- `EDTA` (ethylenediaminetetraacetic acid)
- `ph` (orthophenanthroline)

2. **Analyze Each Ligand**:
- **NH2CH2COO^-**:
- Structure: NH2-CH2-COO^-
- Donor Atoms: This ligand has one nitrogen atom (NH2) and one oxygen atom (from COO^-).
- Conclusion: Not suitable since it has an oxygen donor atom.

- **en (Ethylene diamine)**:
- Structure: NH2-CH2-CH2-NH2
- Donor Atoms: This ligand has two nitrogen atoms (NH2).
- Conclusion: Suitable since it has only nitrogen donor atoms.

- **dien (Diethylene triamine)**:
- Structure: NH2-CH2-CH2-NH-CH2-CH2-NH2
- Donor Atoms: This ligand has three nitrogen atoms.
- Conclusion: Suitable since it has only nitrogen donor atoms.

- **Py (Pyridine)**:
- Structure: A six-membered aromatic ring with one nitrogen atom.
- Donor Atoms: This ligand has one nitrogen atom.
- Conclusion: Suitable since it has only nitrogen donor atoms.

- **EDTA (Ethylenediaminetetraacetic acid)**:
- Structure: Contains two nitrogen atoms and four oxygen atoms.
- Donor Atoms: This ligand has nitrogen and oxygen donor atoms.
- Conclusion: Not suitable since it has oxygen donor atoms.

- **ph (Orthophenanthroline)**:
- Structure: A compound with two nitrogen atoms in a fused ring system.
- Donor Atoms: This ligand has two nitrogen atoms.
- Conclusion: Suitable since it has only nitrogen donor atoms.

3. **Count the Suitable Ligands**:
- Suitable ligands: `en`, `dien`, `Py`, and `ph`.
- Total count: 4 ligands.

### Final Answer:
The number of ligands in which the donor atoms are only nitrogen is **4**.

---