Annulenylenes, annulynes, and annulenes.

A number of techniques have been found to generate annulynes. Some of the annulynes have been found to spontaneously dimerize to biannulenylenes and to form triannulenylenes. The reaction products, thermodynamics, and kinetic stabilities of the annulenylenes, annulynes, and their parent annulenes prove to be extremely dependent upon the number of pi electrons. In fact, the addition of an extra electron can trap some "fugitive" systems and render them sufficiently stable for spectroscopic study. Even the number of neutrons can perturb the conjugation and, presumably, the stability of annulenes that have internal protons.