Strong Negative Synergism of Ion Pair Extinction Coefficients in Chloroform–Acetone and Methylene Dichloride–Acetone Mixtures

The heteroselective preferential solvation of the iodides of N-heterocyclic aromatic cations in acetone–chloroalkane (chloroform and dichloromethane) binary mixtures results in not only a shift in the maxima of outer-sphere charge transfer absorption bands but also a considerable decrease in the molar extinction coefficients of ion pairs.