annulene

Annulenes are completely conjugated monocyclic hydrocarbons. They have the general formula C_nH_n (when n is an even number) or C_nH_n+1 (when n is an odd number). The IUPAC naming conventions are that annulenes with 7 or more carbon atoms are named as [n]annulene, where n is the number of carbon atoms in their ring, though sometimes the smaller annulenes are referred to using the same notation, and benzene is sometimes referred to simply as annulene.