Subject: There is...
Author:
Posted on: 2019-08-19 10:14:00 UTC

... but it's paywalled.

The abstract says that Characterization of cyclo[18]carbon by high-resolution atomic force microscopy revealed a polyynic structure with defined positions of alternating triple and single bonds, so I think they're basing their characterisation solely on the AFM. Looking at the pictures, you can definitely see the differing electron density around the ring, with nine 'large' nodes and nine 'small' ones. If you don't know what you're looking at, it looks more like a 9-carbon ring, but comparing the image of the precursor shows that 'large blob means atom' doesn't stand up.

Now that you say it, it does seem like the double-bond-equivalent pi orbitals should interact. Is it possible that the shape of the structure, which is very strained, is preventing it? I don't know; organic chemistry isn't my field, and the Wikipedia Aromaticity page doesn't feature the word 'triple' at all. I'd love to hear any more thoughts you have!

For of course, all knowledge will rebound to the glory of the Binder. All hail!

hS, Herald of the Binder

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