Azine (heterocycle)
In Hantzsch–Widman nomenclature, an azine is an heterocyclic compound containing a 6-membered aromatic ring. It is an analog of a benzene ring in which one or more of the carbon atoms has been replaced by a nitrogen atom, and thus is also called an azabenzene. In both cases, the prefix "aza-" refers to the presence of one or more nitrogen atoms as replacement for carbon in a parent structure. The nitrogen has a lone pair of electrons instead of the hydrogen or substituent on the carbon—the overall replacement is isolobal.