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.

Di­benzyl­ammonium hydrogen maleate and a redetermination at 120 K of bis­(di­benzyl­amino)­methane

In di­benzyl­ammonium hydrogen maleate [or di­benzyl­am­monium (2Z)-3-carb­oxy­prop-2-enoate], C₁₄H₁₆N⁺·C₄H₃O₄^-, (I), the anion contains a fairly short and nearly linear O-H...O hydrogen bond, with an O...·O distance of 2.4603 (16) Å, but with the H atom clearly offset from the mid-point of the O...O vector. The counter-ions in (I) are linked by two N-H...O hydrogen bonds to form C₂²(6) chains and these chains are weakly linked into sheets by a C-H...O hydrogen bond. Bis(di­benzyl­amino)­methane, C₂₉H₃₀N₂, (II), crystallizes with two independent mol­ecules lying across twofold rotation axes in the space group C2/c, and the mol­ecules are conformationally chiral; there are no direction-specific inter­molecular inter­actions in the crystal structure of (II).