Wikipedia
Bismole
Bismole is a theoretical heterocyclic organic compound, a five-membered ring with the formula C H BiH. It is classified as a metallole. It can be viewed as a structural analog of pyrrole, with bismuth replacing the nitrogen atom of pyrrole. The unsubstituted compound has not been isolated due to the high energy of the Bi-H bond. Substituted derivatives, which have been synthesized, are called bismoles.