LANTHANIDE COMPOUNDS WITH PARTICULAR MAGNETIC-PROPERTIES

Compartmental, potentially hepta- and hexa-dentate Schiff bases (H-4-L), have been obtained by the reaction of 3-formylsalicylic acid or 2,3-dihydroxybenzaldehyde with the polyamines NH2-(CH2)2-X-(CH2)2-NH2 (X = NH, S, CH3-(CH2)11-) or NH2-R-NH2 (R = -(CH2)2-; -C(CH3)2-CH2-, -CH2-C(CH3)2-CH2-), respectively. Heptadentate ligands, which contain an inner N2XO2 and an outer O2O2 coordination chamber, form homo- and heterodinuclear lanthanide(III) complexes Ln2(L)(X)2.nH2O (X = Cl-, NO3-; n = 3-8). The hexadentate ligands have a smaller N2O2 inner compartment, capable of securing a d-transition but not a f metal ion, and the same O2O2 outer chamber. Consequently, mononuclear, M(H2L) heterodinuclear MLn(H-2-L)(NO3)3 and heterotetranuclear [MLn(L)(NO3)(S)]2 COMPlexes have been prepared. The properties of the complexes are discussed focusing the attention on the magnetic data. Digadolinium(III) complexes show an antiferromagnetic behaviour, while heteropolynuclear complexes containing copper(II) and gadolinium(III) show ferromagnetic interactions.