Which one of the following ion is aromatic ?

Options

A.
B.
C.
D.

Answer

To determine which of the given ions is aromatic, we will follow the criteria set by Huckel's rule. Aromatic compounds must satisfy three main conditions:

1. **Planarity**: The molecule must be planar.
2. **Cyclic Structure**: The molecule must be cyclic and contain a ring.
3. **Conjugation and Pi Electrons**: The molecule must have a total of \(4n + 2\) pi electrons, where \(n\) is a non-negative integer (0, 1, 2, ...).

Let's analyze the given ions step by step:

### Step 1: Identify the Structure
- Look at the structure of each ion provided in the options. Identify if they are cyclic and planar.

### Step 2: Check Hybridization
- For each carbon in the ring, check the hybridization. Aromatic compounds require that each carbon in the ring be sp² hybridized. This means each carbon should form three sigma bonds and have one unhybridized p orbital for pi bonding.

### Step 3: Count Pi Electrons
- Count the number of pi electrons in the structure. Remember that pi electrons come from double bonds and lone pairs that can participate in resonance.

### Step 4: Apply Huckel's Rule
- Check if the total number of pi electrons fits the formula \(4n + 2\). If it does, the ion is aromatic.

### Example Analysis
Let's analyze a hypothetical ion:

1. **Structure**: Assume we have a cyclic ion with a ring structure.
2. **Hybridization**: Check if all carbons in the ring are sp² hybridized.
3. **Pi Electrons**: Count the pi electrons. For example, if there are 6 pi electrons, we can set \(n = 1\) in \(4n + 2\) which gives us \(4(1) + 2 = 6\).
4. **Conclusion**: If all conditions are satisfied, this ion is aromatic.

### Final Decision
Based on the analysis of all provided ions, select the one that meets all three criteria of aromaticity.