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I came across aza[9]-annulene, which is given to be aromatic. I can clearly see it follows Hückel's rule with 8 π-electrons in the ring and the lone pair of nitrogen.

azonine

But the thing that concerns me is the planarity of structure. I'm not convinced that this structure is planar with so much angle strain (and thus aromatic).

Can anyone please explain this to me?

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    $\begingroup$ There is a relevant article on Wikipedia regarding the molecule, azonine. $\endgroup$ – Nicolau Saker Neto Jan 2 at 5:37
  • $\begingroup$ @NicolauSakerNeto Thanks for the link. That surely answers my question to some extent. :) $\endgroup$ – Nex Jan 2 at 5:40
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    $\begingroup$ related: chemistry.stackexchange.com/q/51484/102629 $\endgroup$ – cngzz1 Jan 2 at 6:35
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    $\begingroup$ Please check the following link en.m.wikipedia.org/wiki/Azonine . It clearly states , this molecule is planar. $\endgroup$ – Chakravarthy Kalyan Jan 2 at 7:08
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    $\begingroup$ @Nex likely the non planar, 10 annulene counterpart is less strained. As far as a molecule do exist, there is not a clear border between stability or not. Also because strain is not the only parameter that affects the overall energy. Rather than compare different molecules you should compare the possible structures of the same molecule. If you would have molecular models at hand, you will certainly have to apply a force to close the azonine cycle while using localized double bonds, too. $\endgroup$ – Alchimista Jan 2 at 8:46

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