Calorimetric determination of the heats of formation of competitive ternary mixed-ligand complex compounds. Copper(II)-12-(2′-hydroxy-benzyl)-1,4,7,10-tetraazacyclotridecane-11,13-dione-α-aminoacids and 5-substituted phenanthrolines systems

Abstract

The heats of protonation of 12-(2′-hydroxy-benzyl)-1,4,7,10-tetraazacyclotridecane-11,13-dione (HTADO) have been determined in aqueous solution at 25 ± 0.1°C and I = 0.1 mol dm −3 KNO 3 by conduction calorimetry. The heats of formation of the binary complex compound of this ligand with Cu(II) and the ternary complex compounds of this ligand with Cu(II)-5-substituted phenanthrolines have also been determined under identical conditions. By utilizing the calorimetric data, the heats of formation of the ternary complex compounds Cu(II)-α-aminoacids-HTADO have been evaluated through “overall calculation”. Some linear enthalpy relationships have been found between the heats of protonation of the ligands and the heats of formation of the ternary complex compounds.