Unsymmetrical bis-Schiff bases derived from ethylenediamine, dehydroacetic acid and another aldehyde/ketone and the preparation and characterisation of their copper(II) and nickel(II) complexes

Partial displacement of the symmetrical bis-Schiff bases (1)–(4) of ethylenediamine and salicyladehyde, o-hydroxyacetophenone, acetylacetone or benzoylacetone by dehydroacetic acid have led to the formation and isolation of the unsymmetrical bis-Schiff base ligands (6)–(9). Attempted partial displacements of the symmetrical bis-Schiff base (5) of dehydroacetic acid or (1)–(4) by each of the other four carbonyl compounds have been unsuccessful. The Ni(II) and Cu(II) complexes of (6)–(9) have been prepared and characterized.