A C-13 NMR study of 3,5,5-trimethyl-4-oxo-imidazolidine-2-thione and 3,5,5-trimethylimidazolidine-2,4- dithione complexes with molecular diiodine.

The C-13 NMR spectra of C.T. complexes between donors containing a thioamido group and diiodine are reported. The rapid exchange of donor between the free and the adduct state makes the variation in the position of the resonance depend on the ratio of these two species. Data are comparatively examined with those of the related molecules: 5,5-dimethyl-4-oxoimidazolidine-2-thione and 5,5-dimethylimidazolidine-2,4-dithione. The influence of diiodine on the C-13 chemical shifts shows that I2 affects C(2) more than C(4) and confirms that, in the two compounds with two C=S groups, the interaction of I2 takes place with the sulphur bonded to C(2)