aromatic

https://doi.org/10.1351/goldbook.A00441
  1. In the traditional sense, 'having a chemistry typified by benzene'.
  2. A cyclically @C01267@ with a stability (due to @D01583@) significantly greater than that of a hypothetical localized structure (e.g. @K03373@) is said to possess aromatic character. If the structure is of higher energy (less @S05900@) than such a hypothetical classical structure, the molecular entity is 'antiaromatic'. The most widely used method for determining @A00442@ is the observation of diatropicity in the 1HNMR spectrum.
    See also:
    Hückel (4n + 2) rule
    ,
    Möbius aromaticity
  3. The terms aromatic and antiaromatic have been extended to describe the stabilization or destabilization of @T06468@ of @P04491@ The hypothetical reference structure is here less clearly defined, and use of the term is based on application of the @H02867@ and on consideration of the topology of orbital overlap in the @T06468@. Reactions of molecules in the @G02704@ involving antiaromatic transition states proceed, if at all, much less easily than those involving aromatic transition states.
Source:
PAC, 1994, 66, 1077.(Glossary of terms used in physical organic chemistry (IUPAC Recommendations 1994)) on page 1086 [Terms] [Paper]
See also:
PAC, 1995, 67, 1307.(Glossary of class names of organic compounds and reactivity intermediates based on structure (IUPAC Recommendations 1995)) on page 1319 [Terms] [Paper]