A monocyclic array of orbitals in which there is a single
out-of-phase overlap (or, more generally, an odd number of
out-of-phase overlaps) reveals the opposite pattern of
aromatic character to Hückel systems; with
electrons it is stabilized (aromatic), whereas with
it is destabilized (antiaromatic). In the
excited state
Möbius π-electron systems are stabilized, and
systems are destabilized. No examples of ground-state
Möbius π-electron systems are known, but the concept has been applied to
transition states of
pericyclic reactions
[
See: aromatic].
The name is derived from the topological analogy of such an
arrangement of orbitals to a Möbius strip.
Source:
PAC, 1994, 66, 1077
(Glossary of terms used in physical organic chemistry (IUPAC Recommendations 1994))
on page 1141
Cite as:
IUPAC. Compendium of Chemical Terminology, 2nd ed. (the "Gold Book"). Compiled by
A. D. McNaught and A. Wilkinson. Blackwell Scientific Publications, Oxford (1997).
XML on-line corrected version: http://goldbook.iupac.org (2006-) created by M. Nic,
J. Jirat, B. Kosata; updates compiled by A. Jenkins. ISBN 0-9678550-9-8.
https://doi.org/10.1351/goldbook.
rule
