Which of the following is the most stable species ?

Options

A.
B.
C.
D.

Explanation

To determine which of the given species is the most stable, we will analyze each structure based on their aromaticity. Aromatic compounds are generally more stable than non-aromatic and anti-aromatic compounds. Here are the steps to solve the problem:

### Step 1: Identify the Structures
We have four different species to analyze. We will denote them as Structure 1, Structure 2, Structure 3, and Structure 4.

### Step 2: Analyze Structure 1
- **Structure 1**: This structure is a cyclic compound with a ring and has a negative charge.
- **Aromaticity Check**: It has 6 π electrons (which fits the 4n + 2 rule, where n = 1), indicating that it is aromatic.
- **Conclusion**: Structure 1 is aromatic and therefore stable.

### Step 3: Analyze Structure 2
- **Structure 2**: This structure has a cyclic ring and a positive charge.
- **Aromaticity Check**: It has 4 π electrons (which fits the 4n rule, where n = 1), indicating that it is anti-aromatic.
- **Conclusion**: Structure 2 is anti-aromatic and therefore less stable.

### Step 4: Analyze Structure 3
- **Structure 3**: This structure has a cyclic ring with a negative charge and 7 carbons.
- **Aromaticity Check**: It has 8 π electrons (which does not fit either the 4n + 2 or 4n rule), indicating that it is also anti-aromatic.
- **Conclusion**: Structure 3 is anti-aromatic and therefore less stable.

### Step 5: Analyze Structure 4
- **Structure 4**: This structure is a cyclic compound with 3 carbons.
- **Aromaticity Check**: It has 4 π electrons, which indicates that it is anti-aromatic.
- **Conclusion**: Structure 4 is anti-aromatic and therefore less stable.

### Step 6: Compare Stability
- Based on the analysis:
- Structure 1 is aromatic (most stable).
- Structures 2, 3, and 4 are anti-aromatic (less stable).

### Final Conclusion
The most stable species among the given options is **Structure 1**, which is aromatic.

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