Two cycloalkanespiro-5-(2-thiohydantoins): Synthesis, spectral and structural characterization

The presented study deals with the structural and spectral properties of two derivatives of 2-thiohydantoin employing experimental and theoretical methods. The crystal structures of two novel cycloalkanespiro-5-(2-thiohydantoins) are described and compared with the available data on their dithio- and dioxo-analogues. For cyclopentanespiro-5-(2-thiohydantoin) – compound 1, two independent molecules are present in the asymmetric unit in contrast to its dithio-analogue. Cyclohexanespiro-5-(2-thiohydantoin) – compound 2, crystallizes as a monohydrate similarly to the dioxo-analogue. The cyclopentane rings in 1 adopt envelope conformation, while the cyclohexane ring in 2 adopts chair conformation. Although that the molecules of 1 and 2 possess same proton donor and acceptor groups, the presence of the crystallization water in 2 leads to different hydrogen bonding types and patterns. In compound 1 NH⋯O and NH⋯S intermolecular hydrogen bonds are formed, while the intermolecular hydrogen bonds in compound 2 are of OH⋯O, OH⋯N and NH⋯S types. rformance of quantum chemical methods, HF and DFT, to predict the molecular structure of the studied compounds, 1 and 2, and their dithio- and dioxo-analogues is assessed in comparison with available crystallographic data. Detailed analyses of the vibrational frequencies and the 13C NMR shifts are performed with regard to the effect of the sulphur atom on the structural and spectroscopic properties of the studied hydantoin derivatives.