Bismuth heterocycles

Bismole is a theoretical heterocyclic organic compound, a five-membered ring with the formula C4H4BiH. 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.

Bismabenzene () is the parent representative of a group of organobismuth compounds that are related to benzene with a carbon atom replaced by a bismuth atom. Bismabenzene itself has been synthesised but not isolated because it is too reactive, tending to instead dimerize in a Diels-Alder addition.