Interaction of iodine with some 5,5-dimethylimidazolidines with two chalcogen atoms at the 2- and 4-positions

Abstract

The title compounds react with molecular iodine in CH₂Cl₂ solution to form 1 : 1 adducts. The association constants (K) have been determined from the u.v.- visible spectra of several solutions with different amounts of reagents. Competition between the two chalcogen atoms to co-ordinate I₂ is discussed and the results indicate both that molecular iodine preferentially binds the atom at the 2-position and that the donor ability increases in the order O < S < Se. A good correlation is found between the K values and the CNDO/S charge densities of the donor atoms.