The cyclopentadienyl cation is a 5-membered cyclic carbocation containing two carbon-carbon double b — Hydrocarbons Chemistry Question

💡 Solution & Explanation

The cyclopentadienyl cation ($C_5H_5^+$) has a fully conjugated, planar ring system. The two double bonds contribute exactly 4 $\pi$ electrons to the system, while the empty $p$ -orbital of the carbocation contributes 0. Because it is cyclic, planar, fully conjugated, and contains exactly $4n$ $\pi$ electrons ($n=1$), it is strictly classified as anti-aromatic and highly unstable.