Annulyne

[8]annulyne is known to exist but quickly dimerizes or trimerizes; the compound has been trapped as its radical anion and observed by EPR spectroscopy.

The NMR chemical shifts of two internal protons of the dianion were negative and attributed to an aromatic ring current.

The external proton next to the triple bond had a chemical shift of nearly 14, attributed to the positive charge of the potassium cation coordinated to it.

[4] They were unable to conceive a plausible mechanism and argued that based on the available spectroscopic data the products formed were in fact two linear 1,3-hexadien-5-yne isomers and not macrocycles.

[8] A dehydrobenzo[14]annulene was reported in 2001 by Boydston and Haley [9] Certain two-dimensional carbon networks containing a repeating dehydroannulene motif have been investigated for potential optoelectronics applications.