What distinct physical property inherently differentiates planar, anti-aromatic compounds (such as c — Hydrocarbons Chemistry Question
Question
What distinct physical property inherently differentiates planar, anti-aromatic compounds (such as cyclobutadiene) from structurally similar planar aromatic compounds?
💡 Solution & Explanation
Molecular orbital theory indicates that planar, fully conjugated cyclic systems with $4n$ $\pi$ electrons (anti-aromatic) possess degenerate non-bonding molecular orbitals. According to Hund's rule, these orbitals are singly occupied, leaving the molecule with unpaired electrons. This intrinsic diradical character makes anti-aromatic compounds highly reactive and distinctly paramagnetic, unlike stable, diamagnetic aromatic compounds.