Hydrogen bonding abilities and self-association of thiazolidin-and imidazolidin-2-ones and 2-selenones

The hydrogen bonding abilities of iV-methylimidazolidin-2-one and -2-selone and thiazolidin-2-one and -2-selenone have been studied by ir spectroscopy at 25° in carbon tetrachloride solutions, using dimethyl sulphoxide and 4-chlorophenol as proton acceptor (K_A) and proton donor (K_B), respectively. The results are compared with those previously reported for N-methylimidazolidine-2-thione and thiazolidine-2-thione. The K_A values increase in each series in the order O < S < Se and Kg in the reverse order. The and K_B values are discussed in terms of the substituent in ring. The self-association constants (K_D) are dependent on both K_A and K_B, although K_A seems to be much more important.