Crystallographic, thermal and spectroscopic characterization of the anhydrous thiourea- barbituric acid and thiourea-2-thiobarbituric acid co-crystals

Thiourea (Tu) crystallizes with barbituric acid (H₂ba) and 2-thiobarbituric (H₂tba) in the aqueous solution to yield co-crystals H₂ba∙Tu (1) and H₂tba∙Tu (2). Powder of 1 was also obtained from individual compounds via kneading with H₂O. The structure of compounds was solved by the X-ray single crystal diffraction technique. In 1–2, NH⋯O, NH⋯S, CH⋯S and CH⋯O hydrogen bonds form the different 3D nets. In structure 1, centrosymmetric dimers of H₂ba and Tu molecules are formed by two NH⋯O and NH⋯S hydrogen bonds, respectively. These dimers alternate in one-dimensional tapes. In compound 2, the same molecules are not bound by hydrogen bonds. Here, infinite chains are formed consisting of alternating molecules of H₂tba and Tu. In these chains, each of the molecules is connected to the other by two NH⋯S hydrogen bonds. The compounds have been characterized by powder XRD, TG-DSC, and FT-IR.