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The heteroatom in ether is oxygen.
nitrogen
An azahelicene is a heterohelicene with at least one nitrogen heteroatom.
An azoniahelicene is an azahelicene in which the nitrogen heteroatom carries a positive charge.
An atrane is any of a class of tricyclic cagelike heterocycles having a transannular dative bond between a nitrogen and another heteroatom.