THERMODYNAMIC RELATIONSHIPS OF COMPLEX-FORMATION .5. ISOEQUILIBRIUM RELATIONSHIPS IN SOFT-SOFT INTERACTIONS IN HARD SOLVENTS

The inspection of the DELTA-H-DELTA-S patterns for reactions between Ag(I) complex substrata and various entering ligands discloses linear interplay between the two parameters. The actual DELTA-H (DELTA-S) values demonstrate that soft-hard interactions can produce favourable enthalpy changes coupled to unfavourable entropy changes, and confirm that soft-soft interactions can yield unfavourable enthalpy changes coupled to favourable entropy changes. These results, together with the already published enthalpy-entropy interplays, which show negative values of both DELTA-H and DELTA-S for hard-hard interactions in aqueous solution, demonstrate that in this solvent soft-soft (hard-hard) interactions do not necessarily produce DELTA-H < 0 (DELTA-H > 0) coupled to DELTA-S < 0 (DELTA-S > 0) because their values also descend from the role of the solvent molecules in the specific reaction. The coordinated solvent produces a sort of 'shielding' or 'levelling' of the acceptor and donor abilities.