Which of the following cyclic, planar, and fully conjugated species are classified as anti-aromatic? — Aromatic Hydrocarbons Chemistry Question

💡 Solution & Explanation

Anti-aromatic compounds are cyclic, planar, and fully conjugated systems that contain exactly $4n \pi$ electrons, making them highly unstable. Cyclobutadiene has $4\pi$ electrons ($n=1$). The cyclopentadienyl cation has $4\pi$ electrons ($n=1$). The cycloheptatrienyl cation has $6\pi$ electrons (aromatic). Benzene has $6\pi$ electrons (aromatic).