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

Golovnev, Nicolay N.; Molokeev, Maxim S.; Sterkhova, Irina V.; Lesnikov, Maxim K. Source: JOURNAL OF MOLECULAR STRUCTURE, 1176 865-870; 10.1016/j.molstruc.2018.09.035 JAN 2019

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 12, 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.