The pH titration method was used to measure the protonation constants of PnAO [2,2'-(1,3-propyldiamine)-bis(2-methyl-3-butanone oxime)], and the stability constants of binary and ternary complexes. The heats of protonation and of complex formation were measured by calorimetry. The results showed that some linear free energy relationships (LEER) exists between the protonation constants of 5-R-Phen (R = Me, Cl, NO2) and the stability constants of Cu(II)-PnAO-RPhen ternary system. Also found was the existence of linear enthalpy relanationships (LER) in ternary system. The substituent effect is discussed.

Key words: STABILITY CONSTANT, COPPER COMPLEX, FORMATION HEAT, CALORIMETRY, SUBSTITUENT EFFECT, COORDINATION REACTION, PROTONATION CONSTANT