An infrared spectroscopic investigation on N-methyl-1,3-thiazolidine-2-thione and -2-selone

An infrared investigation cm N-methyl-1,3-thiazolidine-2-thione and -2-selone in the range 4000-200 cm^?1 is reported. The v CS and v CSe vibrations give contributions to the absorptions around 1000 cm^?1 and below 600 cm^?1. The assignments are supported by comparison of their ir spectra with those of S- and Se-methiodides. The π-bond orders of the thio- and seleno-ketonic links in these compounds are higher than those found for 1,3-imidazolidine-2-thione and -2-selone.