Potentiometric and spectrophotometric studies of copper(II) complexes of some ligands in aqueous and nonaqueous solution

Stoichiometry and equilibrium study of copper-ligands including mercaptobenzoxazole (MBO), 4-propyl 2-thiouracyl (PTU), methyl-2-pyridylketone oxime (MPKO), phenyl-2-pyridylketone oxime (PPKO), 4,6-dihydroxy-2-mercaptopyrimidine (DHMP), N,N'-phenylene bis(salicylaldimine) (PBS) and 1,2-bis(2-hydroxyphenyl)naphtaldiimine (BHNPDI) were conducted in aqueous and nonaqueous solution by potentiometry and spectrophotometry. Stability constants of the complexes are determined at 25 1 degrees C and 0.1 or 0.05 M ionic strength in water or acetonitrile solvents. Oximes ligand protonation constants and copper-ligands complexes' stability and hydrolysis constants were calculated using the BEST program in aqueous solution. The stability constants of copper-ligands complexes were calculated using the KINFIT program in acetonitrile solution. The results of these two methods are made self-consistent, then rationalized assuming an equilibrium model including the species, ML, MLH, MLOH and ML2 (where the charges of the species have been ignored for the sake of simplicity) (L = MBO, PTU, MPKO, PPKO, DHMP, BHNPDI and PBS).