Effect Of Solvents On Stability Constants of Fe(II) and Ni(II) Transition Metal Ions Chelates With Some Substituted Pyrazoles

Abstract

The reaction of Fe(II) and Ni (II) metal ions with L1 : 3 (2’- chlorophenyl) - 4- benzoyl - 5 (2-hydroxy phenyl) pyrazole, L2: 3 (2’-chlorophenyl) - 4- pyridoyl -5 (2-hydroxy phenyl) pyrazole , L3: 3 (2’-aminophenyl)- 4-pyridoyl - 5 (2- hydroxyl phenyl) pyrazole and L4: 3 (4’-chlorophenyl) -4-Benzoyl -5(2-hydroxy-phyenyl) pyrazole, at 0.1M ionic strength at 28 ± 0.10C in 70% ethanol -water mixture and 70% dioxane-water mixture have been studied pH-metrically. The data obtained were used to estimate the values of proton-ligand (pK) and metal-ligand (logK) stability constants in different solvents. It is observed that the pK and logK values in 70% dioxane-water mixture are greater than in 70% ethanol -water mixture. Fe(II) and Ni(II) metal ions formed 1:1 and 1:2 complexes with all the ligands in both solvent medium.