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  2. Antiaromaticity - Wikipedia

    en.wikipedia.org/wiki/Antiaromaticity

    Unlike aromatic compounds, which follow Hückel's rule ([4n+2] π electrons) [1] and are highly stable, antiaromatic compounds are highly unstable and highly reactive. To avoid the instability of antiaromaticity, molecules may change shape, becoming non-planar and therefore breaking some of the π interactions.

  3. Cyclobutadiene - Wikipedia

    en.wikipedia.org/wiki/Cyclobutadiene

    The compound is the prototypical antiaromatic hydrocarbon with 4 pi electrons (or π electrons). It is the smallest [n]-annulene ([4]-annulene).Its rectangular structure is the result of a pseudo [3] - (or second order) Jahn–Teller effect, which distorts the molecule and lowers its symmetry, converting the triplet to a singlet ground state. [4]

  4. Thiepine - Wikipedia

    en.wikipedia.org/wiki/Thiepine

    In organic chemistry, thiepine (or thiepin) is an unsaturated seven-membered heterocyclic compound, with six carbon atoms and one sulfur atom. The parent compound, C 6 H 6 S is unstable and is predicted to be antiaromatic.

  5. AP site - Wikipedia

    en.wikipedia.org/wiki/AP_site

    In biochemistry and molecular genetics, an AP site (apurinic/apyrimidinic site), also known as an abasic site, is a location in DNA (also in RNA but much less likely) that has neither a purine nor a pyrimidine base, either spontaneously or due to DNA damage. It has been estimated that under physiological conditions 10,000 apurinic sites and 500 ...

  6. Category:Antiaromatic compounds - Wikipedia

    en.wikipedia.org/.../Category:Antiaromatic_compounds

    Pages in category "Antiaromatic compounds" The following 13 pages are in this category, out of 13 total. This list may not reflect recent changes. ...

  7. Aromaticity - Wikipedia

    en.wikipedia.org/wiki/Aromaticity

    Two different resonance forms of benzene (top) combine to produce an average structure (bottom). In organic chemistry, aromaticity is a chemical property describing the way in which a conjugated ring of unsaturated bonds, lone pairs, or empty orbitals exhibits a stabilization stronger than would be expected from conjugation alone.

  8. Aromatic compound - Wikipedia

    en.wikipedia.org/wiki/Aromatic_compound

    Heteroarenes are aromatic compounds, where at least one methine or vinylene (-C= or -CH=CH-) group is replaced by a heteroatom: oxygen, nitrogen, or sulfur. [3] Examples of non-benzene compounds with aromatic properties are furan, a heterocyclic compound with a five-membered ring that includes a single oxygen atom, and pyridine, a heterocyclic compound with a six-membered ring containing one ...

  9. Cyclooctatetraene - Wikipedia

    en.wikipedia.org/wiki/Cyclooctatetraene

    Early studies demonstrated that COT did not display the chemistry of an aromatic compound. [7] Then, early electron diffraction experiments concluded that the C-C bond distances were identical. [ 8 ] However, X-ray diffraction data from H. S. Kaufman demonstrated cyclooctatetraene to adopt several conformations and to contain two distinct C–C ...