Why Pentalene is non-aromatic?

It has chemical formula C8H6. It is antiaromatic, because it has 4n π electrons where n is any integer. The addition of two electrons removes the antiaromaticity; it becomes a planar 10π-electron aromatic species and is thus a bicyclic analogue of the cyclooctatetraene (COT) dianion C8H82−.

Is Cyclododecahexaene aromatic?

Cyclododecahexaene is non-aromatic due to the lack of planarity of the structure. On the other hand the dianion with 14 electrons is a Hückel aromat and more stable. Heating the radical ion solution to room temperature leads to loss of one equivalent of hydrogen and formation of the heptalene radical anion.

Why does cyclooctatetraene not show resonance?

Answer: Any angle strain from being planar is so quickly overtaken by the huge jump in stability that aromaticity brings that the molecule will twist to form an aromatic structure in a blink. If cyclooctatetraene were planar, it would be an antiaromatic compound according to Hückel’s rule, because it has 8 π-electrons.

Why is c8h8 not planar?

The reason cyclooctotetraene is non-planar is because its planar arrangement would be antiaromatic. It twists to avoid it, because antiaromatic compounds are unstable with respect to localisation of the π-electrons (see here: What is the justification for Hückel’s Rule?)

What is the aromaticity of Heptalene and pentalene?

The aromaticity of pentalene, heptalene and related bicyclic hydrocarbons 3411 The situation with regard to heptalene (II) is quite different. HMO calculations give 5 bonding, 1 non-bonding, and 6 anti-bonding MO’s for the 12 w-electrons, hence Hiickel heptalene does not possess a closed shell.

What does the formula C12H10 mean for Heptalene?

Heptalene is a polycyclic hydrocarbon with chemical formula C12H10, composed of two fused cycloheptatriene rings. It is an unstable, non-planar compound which is non-aromatic. The dianion, however, satisfies Hückel’s rule, is thermally stable, and is planar.

Which is a more stable hydrocarbon pentalene or azulene?

On the other hand, azulene is a stable 10-π-electron hydrocarbon that incorporates structural features of both pentalene and heptalene. Azulene is a stable blue crystalline solid that undergoes a number of typical aromatic substitution reactions.

What kind of hydrocarbon is Heptalene and what is its parent?

Heptalene is an ortho-fused bicyclic hydrocarbon and a mancude carbobicyclic parent. Copyright © 2002-2020 Wiley-VCH Verlag GmbH & Co. KGaA.