The molecular and supramolecular structures of the isomeric compounds 5,7-di­methoxy­imidazo­[1,2-c]­pyrimidine and 7-methoxy-1-methyl­imidazo­[1,2-a]­pyrimidin-5(1H)-one

The supramolecular structures of the isomeric compounds 5,7-di­methoxy­imidazo­[1,2-c]­pyrimidine, C₈H₉N₃O₂, (I), and 7-methoxy-1-methyl­imidazo­[1,2-a]­pyrimidin-5(1H)-one, C₈H₉N₃O₂, (II), are determined by weak C-H...N and C-H...O hydrogen bonds in (I), which generate alternating linked centrosymmetric R₂²(8) and R₂²(10) rings that form a ribbon running parallel to the c axis, and by C-H...O bonds in (II), which link the mol­ecules into sheets comprising centro­symmetric R₂²(10) and R₄⁴(22) rings.

2-Benzyl­amino-6-benzyl­oxy­pyrimidin-4(3H)-one: hydrogen-bonded chains of rings linked into sheets by a [pi]-[pi]-stacking interaction

The title compound, C₁₈H₁₇N₃O₂, crystallizes with Z' = 2 in space group P2₁/c, and the two independent mol­ecules are approximate, but not exact, mirror images. The molecular-electronic structure is strongly polarized, and the mol­ecules are linked by paired N-H...O hydrogen bonds [H...O = 2.00-2.23 Å, N...O = 2.798 (3)-2.992 (3) Å and N-H...O = 145-151°] into two independent C(4)C(6)[R₂¹(6)] chains of rings, which are linked into sheets by a single aromatic [pi]-[pi]-stacking interaction.