Thermodynamic studies on metal complexes of Pb2+, Zn2+, Sr2+ and Mg2+ with 2-amino pyrimidine in water and water-acetonitrile binary solvent systems at 298.15 K, 308.15 K and 318.15 K by conductometric method

Stability constants are measured for complexes of Pb2+, Zn2+, Sr2+ and Mg2+ with 2-amino pyrimidine (AMPYM) in pure water and water-acetonitrile binary solvent systems at 298.15, 308.15 and 318.15 K by conductometric method. The results shows that the stoichiometry of the complexes of AMPYM with all investigated metal ions in all binary solvent systems is 1:2 [ML2]. The log Kf values of M2+-AMPYM complexes in H2O-ACN binary solvent systems decreases with increasing % of ACN and increased with the increase in percentage of water and also with increase in temperature. The value of formation constants obtained by spectrophotometry for the AMPYM with Pb2+, Zn2+, Sr2+ and Mg2+ at 298.15 K in pure water  are in good agreement with the values obtained by conductometry for AMPYM with all the investigated metal ions at 298.15 K. The ∆H0 and ∆S0 of the complexation reaction in the different H2O-ACN binary solvent systems were evaluated by the temperature dependence of the formation constants using a linear least square analysis according to van’t Hoff equation.