The protonation constants of N,N'-bis(p-substituted phenyl)ethylenediamines and the formation constants of their complexes with Cu(II) and Ni(II) were determine by pH-titrn. at 25?and ionic strength 0.1 (NaClO4) in mixed solvents [50 vol.% aqueous dioxane and 70 vol.% aqueous EtOH]. The results showed that linear relations exist between ligand constants and the corresponding Hammett constants, the stability factor and the Hammett constants, the formation constants of the complexes and the ligand protonation constants This is further evidences for the existence of linear free energy relationships in coordination chem.

Key words: HYDROCARBON WITH TWO PHENYLS P, STABILITY, COMPLEX COMPOUNDS, COPPER ION, NICKEL ION, ACID-BASE EQUILIBRIUM, LINEAR FREE ENERGY RELATIONSHIP, ETHANEDIAMINE P, LIGANDS