The structures of six symmetrically 4,6-disubstituted 2-aminopyrimidines, four of them containing a 5-nitroso substituent, have been determined. The nitroso compounds, in particular, exhibit polarized molecular–electronic structures leading to extensive charge-assisted hydrogen bonding. The intermolecular interactions observed include hard hydrogen bonds of N—H...N and N—H...O types together with O—H...O and O—H...N types in 2-amino-4,6-bis(2-hydroxyethylamino)-5-nitrosopyrimidine; soft hydrogen bonds of the C—H...O type in both 2-amino-4,6-bis(morpholino)-5-nitrosopyrimidine (3) and 2-amino-4,6-bis(benzylamino)-5-nitrosopyrimidine (4), and of the C—H...π(arene) type in both 2-amino-4,6-bis(piperidino)pyrimidine (1) and 2-amino-5-nitroso-4,6-bis(3-pyridylmethoxy)pyrimidine (5); and aromatic π...π stacking interactions in 2-amino-5-nitroso-4,6-bis(3-pyridylmethoxy)pyrimidine. The supramolecular structures formed by the hard hydrogen bonds are finite, zero-dimensional in (1), one-dimensional in 2-amino-4,6-bis(3-pyridylmethoxy)pyrimidine (2), two-dimensional in both (3) and (4), and three-dimensional in both (5) and 2-amino-4,6-bis(2-hydroxyethylamino)-5-nitrosopyrimidine.