Correlation between thermodynamic functions of metal complex. Formation and basicities of the iminodiacetate derivatives

The heat developed by addition of a metal nitrate solution to that of a neutralized complexing agent has been determined at 25 °C and I=0.1 (KNO3). By use of the known stability constants of the 1:1 complexes, it allows the calculation of the involved thermodynamic functions. The change of the free enthalpies of metal complex formation with substituted iminodiacetate derivatives of different basicities is correlated with that of the enthalpies of complex formation whereas the entropic term depends on the ligand size.