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  2. Cyclobutadiene - Wikipedia

    en.wikipedia.org/wiki/Cyclobutadiene

    Cyclobutadiene is an organic compound with the ... existence of two different 1,2-dideutero-1,3-cyclobutadiene ... π-system of 4 electrons is not aromatic.

  3. Antiaromaticity - Wikipedia

    en.wikipedia.org/wiki/Antiaromaticity

    This effect is of a smaller magnitude than the corresponding shifts in aromatic compounds. [8] Many aromatic and antiaromatic compounds (benzene and cyclobutadiene) are too small to have protons inside of the ring, where shielding and deshielding effects can be more diagnostically useful in determining if a compound is aromatic, antiaromatic ...

  4. Aromaticity - Wikipedia

    en.wikipedia.org/wiki/Aromaticity

    Whereas benzene is aromatic (6 electrons, from 3 double bonds), cyclobutadiene is not, since the number of π delocalized electrons is 4, which of course is a multiple of 4. The cyclobutadienide (2−) ion, however, is aromatic (6 electrons).

  5. Aromatic ring current - Wikipedia

    en.wikipedia.org/wiki/Aromatic_ring_current

    Values close to zero are non-aromatic, for example, borazine (Λ = −1.7) and cyclohexane (Λ = 1.1). Large positive values are antiaromatic, for example, cyclobutadiene (Λ = +18). Another measurable quantity is the chemical shift of lithium ions Li + in complexes of lithium with aromatic structures because lithium tends to bond as a π ...

  6. Homoaromaticity - Wikipedia

    en.wikipedia.org/wiki/Homoaromaticity

    Just as aromatic compounds exhibit exceptional stability, antiaromatic compounds, which deviate from Huckel's rule and contain a closed loop of 4n π electrons, are relatively unstable. The bridged bicyclo[3.2.1]octa-3,6-dien-2-yl cation contains only 4 π electrons, and is therefore "bishomoantiaromatic." A series of theoretical calculations ...

  7. Benzocyclobutadiene - Wikipedia

    en.wikipedia.org/wiki/Benzocyclobutadiene

    Benzocyclobutadiene is the simplest polycyclic hydrocarbon, being composed of an aromatic benzene ring fused to an anti-aromatic cyclobutadiene ring. It has chemical formula C 8 H 6 . Though the benzene ring is stabilized by aromaticity , the cyclobutadiene portion has a destabilizing effect.

  8. HuffPost Data

    projects.huffingtonpost.com

    Interactive maps, databases and real-time graphics from The Huffington Post

  9. Annulene - Wikipedia

    en.wikipedia.org/wiki/Annulene

    Using this form of nomenclature 1,3,5,7-cyclooctatetraene is [8]annulene and benzene is [6]annulene (and occasionally referred to as just 'annulene'). [ 2 ] [ 3 ] The discovery that [18]annulene possesses a number of key properties associated with other aromatic molecules was an important development in the understanding of aromaticity as a ...