In the title pyrimidine-2,4-dione derivative, C14H16N2O2S, the dihedral angle between the six-membered rings is 77.81 (10)°. The mol-ecule is twisted about the Cp-S (p = pyrimidine) bond, with a C-S-C-N torsion angle of -59.01 (17)°. An intramolecular C-H⋯S hydrogen bond generates an S(5) ring motif. In the crystal, bifurcated acceptor N-H⋯O and C-H⋯O hydrogen bonds generate inversion-related dimers incorporating R 2 (1)(9) and R 2 (2)(8) loops. These dimers are connected into a chain extending along the a-axis direction by a second pair of inversion-related N-H⋯O hydrogen bonds, forming another R 2 (2)(8) loop. The crystal structure is further stabilized by weak inter-molecular C-H⋯π inter-actions, generating a three-dimensional network.
In the mol-ecule of the title compound, C7H9ClN2O2, the conformation is determined by intra-molecular C-H⋯O and C-H⋯Cl hydrogen bonds, which generate S(6) and S(5) ring motifs. The isopropyl group is almost perpendicular to the pyrimidine ring with torsion angles of -70.8 (3) and 56.0 (3)°. In the crystal, two inversion-related mol-ecules are linked via a pair of N-H⋯O hydrogen bonds into R 2 (2)(8) dimers; these dimers are connected into chains extending along the bc plane via an additional N-H⋯O hydrogen bond and weaker C-H⋯O hydrogen bonds. The crystal structure is further stabilized by a weak π-π inter-action [3.6465 (10) Å] between adjacent pyrimidine-dione rings arranged in a head-to-tail fashion, producing a three-dimensional network.