LINEAR THERMODYNAMIC FUNCTION RELATIONSHIPS IN COORDINATION CHEMISTRY- CALORIMETRIC STUDY ON NICKEL(II), COBALT(II), ZINC(II) N-(P-SUBSTITUTED PHENYL) IMINODIACETIC ACID BINARY-SYSTEMS AND NICKEL(II), COBALT(II), ZINC(II) NITRILOTRIACETIC ACID N-(P-SUBSTITUTED PHENYL)IMINODIACETIC ACID TERNARY-SYSTEMS

The heats of protonation of N-(p-substituted phenyl)iminodiacetic acid s (B, R-phenyl-N(CH2COOH)(2), RPhIDA: R Is CH3O, CH3, H, Cl) and nitri lotriacetic aad (A, N(CH2COOH)(3), NTA) and the heats of formation of the M(II)-B and M(II)-A binary systems (M is Ni, Co, Zn), and of the M (II)-A-B ternary systems have been determined at 25.0 +/- 0.2 degrees C, I = 0.1 mol dm(-3) (NaClO4) in aqueous solution using an improved m odel RD-1 automatic conduction calorimeter. The entropies of protonati on and of formation for these binary and ternary systems have been cal culated from their free energies. The results show that both linear en thalpy relationships (LERs) and linear entropy relationships (LSRs) ex ist between the heat (and entropy) of protonation of B and the heat (a nd entropy) of formation of bath binary and ternary complex compounds. It is noted that the heats of protonation of RPhIDA and the heat of f ormation for their metal complexes are all positive, i.e. endothermic, and a hypothetical structure of the polyring for the hydrated ligands B has been suggested to interpret the experimental results.