The Thermodynamics of Ion Association in Solution. II. Mixed Ion Association

Mixed ionic aggregates, such as the triple ion ABC, are more stable than would be predicted from elementary considerations of the stability of the triplet ions ABA and CBC. A similar stabilization of the mixed ion quadrupole ABCB, as compared to ABAB and CBCB, occur. For both mixed ion triplets and quadrupoles, entropy effects contribute R In 2 eu toward the total stabilization. The principal stabilization, however, arises from the polarization terms in the expression describing the potential energy of the systems. Agreement is found between theory and experimental results in benzene and acetic acid.