Solution and molecular modeling studies on some bivalent metal complexes of higher analogues of biologically active 1,3-diaryl-4,5,6-pyrimidinetrione-2-thioxo-5-oxime

Thermodynamic proton-ligand stability constants of 1,3-diethylphenyl-4,5,6- pyrimidinetrione-2-thioxo-5-oxime (and the thermodynamic metal ligand stab ility constants) with some bivalent metal ions were determined by potentiom etric measurements in 75% (v/v) aqueous-dioxan medium at different temperat ures ranging from 25 degrees C to 35 degrees C. The acidity and stability c onstants vary according to the kind of substitution at the 1- and 3- positi ons of the pyrimidine ring. The order of stability constants is UO22+> CU2> Ni2+> Co2+> Zn2+> Cd2+> Mn2+> Mg2+. The values of S-min(chi (2)) have als o been calculated. The thermodynamic functions for the stepwise complexatio n processes are calculated at 25 +/-0.5 degreesC. Molecular modeling studie s have also been carried out on the ligand and complexes, the results of wh ich corroborate the experimental findings.