UV-VISIBLE, IR, AND C-13 NMR-STUDIES ON CT COMPLEXES BETWEEN SOME THIOHYDANTOINS AND MOLECULAR DIIODINE

The reaction of some 5,5-dimethyl-2-thiohydantoin derivatives RNC(Me)2 CXNR'CS (X = O, S; R, R' = H, Me) with molecular diiodine has been stu died in CH2Cl2 solution by different spectroscopic techniques. The for mation constants (K) of the 1:1 molecular adducts and their thermodyna mic parameters have been measured by UV-visible spectroscopy. The resu lts allow us to point out the different donor properties of C(2) = S t hioketonic sulfur between the two series of compounds (X = O, S) and t he influence of N(1) and N(3) methylation on the K's. From the analysi s of the v(NH) frequencies, it has been possible to show hydrogen bond interactions between the NH's and the S-bonded iodine; this seems to be an important factor in determining the K values.