Pimobendan B from powder diffraction data

The title mol­ecule, C(19)H(18)N(4)O(2) {systematic name: (RS)-6-[2-(4-meth­oxy­phen­yl)-1H-benzimidazol-5-yl]-5-methyl-4,5-di­hydro­pyridazin-3(2H)-one}, adopts an extended conformation. The dihedral angles between the central benzimidazole ring sytem and the pendant meth­oxy­phenyl and pyridazinone residues are 1.41 (18) and 9.7 (3)°, respectively. In the crystal, N—H⋯N hydrogen bonds link the imadazole groups into [001] chains, and pairs of N—H⋯O hydrogen bonds link the pyridazinone groups into dimers. Together, these generate a two-dimensional supra­molecular structure parallel to (010). The layers are linked by C—H⋯π inter­actions.