title: Antiferromagnetic Cu-Gd interactions through an oxime bridge.
abstract: The copper complex of a polydentate non-symmetrical Schiff base ligand [LCu]2, prepared by template synthesis, has been reacted with the series of lanthanide ions. This complex used as a ligand possesses two functions (phenol and oxime) able to coordinate the Ln ions and, according to the Ln ion, three types of complexes are obtained. From La to Eu, trinuclear [(LCu)2Ln(NO3)3] complexes with a double phenoxo-oximato bridge were isolated. From Gd to Ho, the complexes [(LCu)2Ln(NO3)3(H2O)] are still trinuclear, with a supplementary water molecule linked to the Ln ion but the Cu(II) and Ln(III) ions are only bridged by the oximato (N-O) pair, the phenoxo oxygen atom being hydrogen-bridged to the Ln-coordinated water molecule. Then, with heavier Ln ions, dinuclear [(LCu)Ln(NO3)3(H2O)2] complexes are characterized. The magnetic study demonstrates that the oximato bridge is responsible for the antiferromagnetic character of the Cu-Gd interaction, with JCuGd = -0.63 cm(-1) in [(LCu)2Gd(NO3)3(H2O)], in contrast to the ferromagnetic Cu-Gd interaction induced by the single oxygen atom phenoxo bridge.
authors.affiliation: Laboratoire de Chimie de Coordination du CNRS, 205, route de Narbonne, BP 44099, F-31077 Toulouse Cedex 4, France.
authors.forename: Jean-Pierre
authors.initials: JP
authors.lastname: Costes
authors.forename: Carine
authors.initials: C
authors.lastname: Duhayon
authors.forename: Sonia
authors.initials: S
authors.lastname: Mallet-Ladeira
authors.forename: Laure
authors.initials: L
authors.lastname: Vendier
authors.forename: Javier
authors.initials: J
authors.lastname: Garcia-Tojal
authors.forename: Luisa Lopez
authors.initials: LL
authors.lastname: Banet