A new dissymmetrical double Schiff base Cu(II) mononuclear complex: Cu(HLt) (1), where H₃Lt is N-3-carboxylsalicylidene-N'-salicylidene-1,3-propylenediamine) and its two heterotrinuclear complexes: [(CuLt)₂Ni]•2.5H₂O (2) and [(CuLt)₂Mn]•5H₂O (3) have been synthesized and characterized by means of elemental analyses, IR and electronic spectra. The crystal structure of the complex 3 was determined by X-ray analysis. Each dissymmetrical cell unit of the complex 3 contains one heterotrinuclear neutral molecule, in which the central Mn^2＋ ion is located at the site of O₆ with a distorted octahedral geometry and two terminal Cu^2＋ ions are located at the 4-coordination site of N₂O₂. The magnetic properties of the two heterotrinuclear complexes have been determined in the temperature range 5～300 K, indicating that the interaction between the central M^2＋ ion and the outer Cu^2＋ ions is antiferromagnetic. The exchange integrals are equal to －57.7 cm^－1 for 2 and －28.5 cm^－1 for 3.

Key words: dissymmetrical double Schiff base, heterotrinuclear complex, crystal structure, magnetic property