A three-dimensional hydrogen-bonded framework in 2-amino-6-(N-methylanilino)pyrimidin-4(3H)-one and a ribbon of fused hydrogen-bonded rings in 2-amino-6-(N-methylanilino)-5-nitropyrimidin-4(3H)-one.

The molecular dimensions of both 2-amino-6-(N-methylanilino)pyrimidin-4(3H)-one, C11H12N4O, (I), and 2-amino-6-(N-methylanilino)-5-nitropyrimidin-4(3H)-one, C11H11N5O3, (II), are consistent with considerable polarization of the molecular-electronic structures. The molecules of (I) are linked into a three-dimensional framework by a combination of one N-H...N hydrogen bond, two independent N-H...O hydrogen bonds and one C-H...pi(arene) hydrogen bond. The molecules of (II) are linked into ribbons containing three types of edge-fused ring by the combination of two independent three-centre N-H...(O)2 hydrogen bonds.