Crystal structures and Hirshfeld surface analyses of 2-[(4,6-di­amino­pyrimidin-2-yl)sulfan­yl]-N-(pyridin-2-yl)acetamide and 2-[(4,6-di­amino­pyrimidin-2-yl)sulfan­yl]-N-(pyrazin-2-yl)acetamide

In the title compounds, C(11)H(12)N(6)OS (I) and C(10)H(11)N(7)OS (II), the di­amino­pyrimidine ring makes dihedral angles of 71.10 (9)° with the pyridine ring in (I) and 62.93 (15)° with the pyrazine ring in (II). The ethanamine group, –CH(2)–C(=O)–NH– lies in the plane of the pyridine and pyrazine rings in compounds (I) and (II), respectively. In both compounds, there is an intra­molecular N—H⋯N hydrogen bond forming an S(7) ring motif and a short C—H⋯O inter­action forming an S(6) loop. In the crystals of both compounds, mol­ecules are linked by pairs of N—H⋯N hydrogen bonds, forming inversion dimers with R (2) (2)(8) ring motifs. In (I), the dimers are linked by N—H⋯O and N—H⋯N hydrogen bonds, forming layers parallel to (1[Image: see text] [Image: see text]). The layers are linked by offset π–π inter­actions [inter­centroid distance = 3.777 (1) Å], forming a three-dimensional supra­molecular structure. In (II), the dimers are linked by N—H⋯O, N—H⋯N and C—H⋯O hydrogen bonds, also forming a three-dimensional supra­molecular structure.