Hückel's rule

Method of determining aromaticity in organic molecules

In organic chemistry, Hückel's rule predicts that a planar ring molecule will have aromatic properties if it has (4n + 2)π-electrons, where n is a non-negative integer. The quantum mechanical basis for its formulation was first worked out by physical chemist Erich Hückel in 1931. The succinct expression as the 4n + 2 rule has been attributed to W. v.

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