A single heteroatom, for example, –Cl
; a heteroatom bearing one or more hydrogen atoms or other heteroatoms, for example, –NH2
; or a heteroatomic group attached to or containing a single carbon atom, for example, –CHO
, attached to a parent hydride.
Blue Book Guide, p. 13 (https://doi.org/10.1351/pac199971071327)