antiaromatic

antiaromatic

[‚an·tē‚ar·ə′mad·ik]
(chemistry)
A cyclic compound with delocalized electrons that does not obey Hückel's rule, and is much less stable than similar nonaromatic compounds.
References in periodicals archive ?
They're classified as antiaromatic molecules, which chemical theory predicts will be extremely reactive--in contrast to aromatics, such as benzene, which have unusually stable structures.
The cyclopentadienyl cation is a common textbook example of an antiaromatic molecule, a molecule so electronically unstable and, therefore, extremely reactive that it should not exist for any length of time.