Standard thermodynamic parameters G, H and S for several series of coordination reactions between mixed ligand complexes of Cd(II) and single entering groups in aqueous solution at T = 298.15 K and constant ionic strength µ = 1 for KNO 3 were inspected for the occurrence of enthalpy-entropy and free energy relationships. Both the series of reactions between constant substratum and variable ligands (Sub + L (i) = Sub-L (i) ; i = variable) and the series of reactions between variable Cd(II) complex substrata and constant entering ligand (Sub (i) + L = Sub (i) -L; i = variable) disclose linear compensative H -S interplay ( H = H res + τ S). The parameters ( H res and τ ) of the linear relationships do not discriminate within the coordination levels of the reacting substrata.
The series Sub
3 is distinguished from the other series for more a favourable H res .
The series of reactions Sub (i) + L = Sub (i) -L (i = variable) shows a non-linear dependence of the substratum-to-ligand affinities on the overall thermodynamic stability of the reacting substrata. The exponential relationship Y = A + B exp(C X ) is proposed for describing the dependencies. The general interpretation of the parameters A, B and C are given.