Which of the following is not a resonance structure of the other?

Options

A.
B.
C.
D.

Answer

To determine which of the given options is not a resonance structure of the others, we need to analyze each structure and see how they relate to each other through resonance. Resonance structures are different ways of drawing the same molecule that show the delocalization of electrons.

### Step-by-Step Solution:

1. **Identify the Structures**: First, we need to look at the provided options (let's label them as A, B, C, and D) and identify the key features of each structure, such as charges, bonds, and atom connectivity.

2. **Check for Electron Delocalization**: For each structure, check if the electrons can be delocalized. This means looking for double bonds that can shift to adjacent atoms or lone pairs that can form double bonds.

3. **Draw Resonance Structures**:
- For **Structure A**: If it has a negative charge, we can move the electrons to create a new structure by shifting the double bond.
- For **Structure B**: Similarly, we can check if we can move electrons from a double bond or lone pair to create a new structure.
- For **Structure C**: Repeat the process of checking for possible electron shifts.
- For **Structure D**: Analyze this structure as well.

4. **Compare the Structures**: After drawing the resonance structures for A, B, and C, compare them to see if they can be interconverted through the movement of electrons.

5. **Identify the Outlier**: The structure that cannot be converted into the others through resonance will be the answer. In this case, it was determined that **Structure D** does not resonate with the others.

### Conclusion:
The structure that is not a resonance structure of the others is **Option D**.