5,5′-Methylenebis[6-amino-3-methyl-2-methylsulfanylpyrimidin-4(3H)-one]:an unusual molecular geometry within a hydrogen-bonded molecular ribbon

The molecules of the title compound, C13H18N6O2S2, lie across twofold rotation axes in the space group C2/c. Although the pyrimidine ring is effectively planar, the bridging methylene C atom is displaced from the plane of the pyrimidine ring by 0.213 (2) angstrom, while the C-C-C angle at the bridging C atom is 120.3 (2)degrees. The molecule contains two symmetry-related N-H center dot center dot center dot O hydrogen bonds, generating S(8) motifs, and intermoecular N-H center dot center dot center dot O hydrogen bonds link the molecules into a ribbon of edge-fused rings.