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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.
Hückel's rule is not valid for many compounds containing more than one ring. For example, pyrene and trans-bicalicene contain 16 conjugated electrons (8 bonds), and coronene contains 24 conjugated electrons (12 bonds). Both of these polycyclic molecules are aromatic, even though they fail the 4n + 2 rule. Indeed, Hückel's rule can only be ...
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]
It is antiaromatic, because it has 4n π electrons where n is any integer. For this reason it dimerizes even at temperatures as low as −100 °C. [3] [4] The derivative 1,3,5-tri-tert-butylpentalene was synthesized in 1973. [5] Because of the tert-butyl substituents this compound is thermally stable.
In contrast to the rarity of Möbius aromatic ground state molecular systems, there are many examples of pericyclic transition states that exhibit Möbius aromaticity. The classification of a pericyclic transition state as either Möbius or Hückel topology determines whether 4N or 4N + 2 electrons are required to make the transition state aromatic or antiaromatic, and therefore, allowed or ...
King Charles' team reportedly refreshed the royal family's website after a digital glitch.. On Jan. 22, the royal family's Royal.UK website featured what was apparently an accidental heading on ...
Pages in category "Antiaromatic compounds" The following 13 pages are in this category, out of 13 total. This list may not reflect recent changes. ...
BEIJING/SHANGHAI (Reuters) -China's BYD on Monday started offering advanced autonomous driving features on most of its models including ones priced as low as $9,555, far undercutting competitors ...