A chain of [pi]-stacked mol­ecules in 4-(2-chloro­phenyl)­pyrrolo­[1,2-a]quinoxaline and a hydrogen-bonded sheet in (4RS)-4-(1,3-1,3-benzo­dioxol-6-yl)-4,5-di­hydro­pyrrolo­[1,2-a]quinoxaline

In the mol­ecule of 4-(2-chloro­phenyl)­pyrrolo­[1,2-a]­quinoxa­line, C₁₇H₁₁ClN₂, (I), the bond lengths are consistent with electron delocalization in the two outer rings of the fused tricyclic system, with a localized double bond in the central ring. The mol­ecules of (I) are linked into chains by a [pi]-[pi] stacking inter­action. In (4RS)-4-(1,3-benzo­dioxol-6-yl)-4,5-di­­hydro­pyrrolo­[1,2-a]­quinoxaline, C₁₈H₁₄N₂O₂, (II), the central ring of the fused tricyclic system adopts a conformation inter­mediate between screw-boat and half-chair forms. A combination of N-H...O and C-H...[pi](arene) hydrogen bonds links the mol­ecules of (II) into a sheet. Comparisons are made with related compounds.