Which of the following acts as a nucleophile?

Options

A. `CH_3 NH_2`
B. `overset(+)CH_3`
C. `AlCl_3`
D. `CH_3 MgBr`.

Explanation

To determine which of the given options acts as a nucleophile, we need to understand what a nucleophile is and identify the characteristics of nucleophiles.

### Step-by-Step Solution:

1. **Define Nucleophile**: A nucleophile is an electron-rich species that donates an electron pair to an electrophile (electron-deficient species) during a chemical reaction. Nucleophiles can be negatively charged ions (anions) or neutral molecules that have a lone pair of electrons.

2. **Identify Characteristics of Nucleophiles**:
- Nucleophiles are typically characterized by the presence of lone pairs of electrons.
- They can be anions (like OH⁻, CN⁻, etc.) or neutral molecules with a complete octet and a lone pair (like H2O, NH3, etc.).

3. **Analyze the Given Options**:
- Look at each option provided in the question and check if they fit the definition of a nucleophile.
- For example, if the options include:
- CH3NH2 (methylamine): This is a neutral molecule with a lone pair on nitrogen, making it a nucleophile.
- AlCl3 (aluminum chloride): This is an electron-deficient species and acts as an electrophile, not a nucleophile.
- CH3MgBr (Grignard reagent): This contains a carbanion (R⁻) which is a strong nucleophile.
- H2O (water): This is a neutral molecule with lone pairs on oxygen, making it a nucleophile.

4. **Conclusion**: Based on the analysis, the species that act as nucleophiles among the given options are CH3NH2 and CH3MgBr.

### Final Answer:
The nucleophiles from the options are:
- CH3NH2 (methylamine)
- CH3MgBr (Grignard reagent)