Stability and Related Thermodynamics of Chelation of Fe(II), Co(II), Ni(II) and Cu(II) Metal Ions with Diacetyl-bis-(4-methoxybenzoylhydrazone)

Abstract

Chelate formation of Fe(II), Ni(II), Co(II) and Cu(II) with
diacetyl bis-(4-methoxybenzoylhydrazone) in water-dioxane (1 : 1)
at constant ionic strength (0.1 M KNO₃) and at three different
temperatures 20 ± 0.1 °c, 30 ± 0.1 °c and 40 ± 0.1 °c have been
studied potentiometrically. The proton-ligand and metal-ligand
stability constants were determined by Irving-Rossotti pH-metric
titration technique. Thermodynamic functions  ΔG, ΔH, ΔS and
ΔCp were evaluated by making the investigations at three  different
temperatures. The order of stability constant with respect to metal
ions followed the natural order.