Three ethyl 5-amino-1-aryl-1H-imidazole-4-carboxylates: hydrogen-bonded supra­molecular structures in one, two and three dimensions

The mol­ecules of ethyl 5-amino-1-(4-cyano­phen­yl)-1H-imidazole-4-carboxyl­ate, C₁₃H₁₂N₄O₂, are linked into a chain of alternating R²₂(10) and R⁴₄(34) rings by a combination of N-H...N and C-H...N hydrogen bonds. In ethyl 5-amino-1-(4-chloro­phen­yl)-1H-imidazole-4-carboxyl­ate, C₁₂H₁₂ClN₃O₂, where the ethyl group is disordered over two sets of sites, a combination of N-H...O, N-H...N, C-H...N and C-H...[pi](arene) hydrogen bonds links the mol­ecules into complex sheets. Two inter­molecular hydrogen bonds, one each of N-H...N and C-H...O types, link the mol­ecules of ethyl 5-amino-1-(2,6-difluoro­phen­yl)-1H-imidazole-4-carboxyl­ate, C₁₂H₁₁F₂N₃O₂, into a continuous three-dimensional framework structure.

π-Stacked dimers in 6-meth­oxy-3,3-dimethyl-3H-benzo[f]chromene, and centrosymmetric dimers containing C—H...π(arene) hydrogen bonds in racemic 3-bromo-2,2,6,6-tetra­methyl-3,4-dihydro-2H,6H-1,5-dioxa­triphenyl­ene

The title compounds, namely 6-meth­oxy-3,3-dimethyl-3H-benzo[f]chromene, C₁₆H₁₆O₂, (III), and racemic 3-bromo-2,2,6,6-tetra­methyl-3,4-dihydro-2H,6H-1,5-dioxatriphenyl­ene, C₂₀H₂₁BrO₂, (IV), were both synthesized in one-step regioselective Wittig reactions from substituted 1,2-naphthoquinones. The new ring in both compounds adopts a screw-boat conformation. A single π–π stacking inter­action links the mol­ecules of (III) into centrosymmetric dimeric aggregates, and a single C—H...π(arene) hydrogen bond links the mol­ecules of (IV) into centrosymmetric dimers.