5-Isopropyl-5-methyl-2-sulfanylidene-imidazolidin-4-one.

In the title compound, C7H12N2OS, the 2-sulfanylideneimidazolidin-4-one moiety is nearly planar, with a maximum deviation of 0.054 (2) Å. In the crystal, a pair of N-H⋯O hydrogen bonds and a pair of N-H⋯S hydrogen bonds each form a centrosymmetric ring with an R 2 (2)(8) graph-set motif. The enanti-omeric R and S mol-ecules are alternately linked into a tape along [1-10] via these pairs of hydrogen bonds.

1-Acetyl-5-(4-fluoro-phen-yl)-2-sulfanyl-ideneimidazolidin-4-one.

In the title compound, C11H9FN2O2S, the 2-sulfanylideneimidazolidin-4-one moiety is essentially planar, with a maximum deviation of 0.0183 (14) Å. The mean plane of this moiety is approximately coplanar with the attached acetyl group and perpendicular to the benzene ring, making dihedral angles of 9.70 (14) and 86.70 (6)°, respectively. In the crystal, mol-ecules are linked by N-H⋯O hydrogen bonds between the amide NH and acetyl C=O groups, forming a C(6) chain along the a-axis direction.