The formation constants of the competitive ternary mixed-ligand complex compounds Cu(II)-N-acetylglycine-a-amino acids were determine by pH method at 25?in the presence of 0.1 mol/dm3 NaClO4. The a-amino acids used were L-proline, D,L-a-aminoisobutyric acid, L-isoleucine, L-valine, glycine, L-serine, L-threonine. Linear free energy relationships exist between the stability of the ternary mixed ligand complex compounds and the base strengths of the a-amino acids and with the stability of the parent binary complex compounds as well. The relevant correlation expressions are as follows: log b111 = 6.79 + 0.391pK2, r = 0.980; log b111 = 0.931 + 1.176 log b101, r = 0.999; log b111 = 2.06 + 0.565 log b102, r = 0.997, where b111 is the overall stability constant of the ternary complex compounds, b101 and b102 are the overall stability constants of the parent binary complex compounds, pk2 is the dissociation constant of the amino acid.

Key words: AMINO ACID, STABILITY, DATA HANDLING, COMPUTATIONAL METHOD, TERNARY SYSTEM, COPPER COMPLEX, TERNARY COMPLEX, GLYCINE, DISSOCIATION EQUILIBRIUM, ACID-BASE EQUILIBRIUM