Formation constants of Mn(II), Cu(II), Co (II), Zn(II), Fe(II), Ni(II) and Pd(II) complexes of peonolphenylhydrazone

363-368Thermal and solution-stabilities of peonolphenylhydrazone chelates of Mn(II), Cu(II), Co(II), Zn(II), Fe(II), Ni(II) and Pd(II) have been measured. Thermodynamic parameters of complex formation and kinetic parameters of complex decomposition have also been evaluated. The solution stabilities determined pH-metrically in 75% dioxane-water, acetone-water and ethoxyethanol-water mixtures are in fair agreement with the Irving-Williams series of stability. The results obtained are compared with the data available in the literature for structurally similar ligand complexes. Amongst the solvents employed, acetonewater shows abnormal behaviour. The order of solution stabilities is found to be: Fe> Cu >Pd > Ni > Co> Zn > Mn while that for thermal stabilities, on the other hand, is: Mn > Ni> Pd > Cu > Fe