Was wondering why 1,3-cyclohexadiene only has three total resonance forms and not four. I have:
1,3-cyclohexadiene
![resonance :resonance:](https://www.chemicalforums.com/Smileys/classic/resonance.png)
1-anion, 2-cation, 3,4-ene
![resonance :resonance:](https://www.chemicalforums.com/Smileys/classic/resonance.png)
1-anion, 2,3-ene, 4-cation
![resonance :resonance:](https://www.chemicalforums.com/Smileys/classic/resonance.png)
1,2-ene, 3-anion, 4-cation
Sorry the notation is a little odd. Wasn't sure how to insert actual structures.
Thanks