title: Synthesis and characterization of heterodinuclear Ln(3+)-Fe3+ and Ln(3+)-Co3+ complexes, bridged by cyanide ligand (Ln3+ = lanthanide ions). Nature of the magnetic interaction in the Ln(3+)-Fe3+ complexes.
abstract: The reaction of Ln(NO3)3.aq with K3[Fe(CN)6] or K3[Co(CN)6] in N,N'-dimethylformamide (DMF) led to 25 heterodinuclear [Ln(DMF)4(H2O)3(mu-CN)Fe(CN)5].nH2O and [Ln(DMF)4(H2O)3(mu-CN)Co(CN)5].nH2O complexes (with Ln = all the lanthanide(III) ions, except promethium and lutetium). Five complexes (Pr(3+)-Fe3+), (Tm(3+)-Fe3+), (Ce(3+)-Co3+), (Sm(3+)-Co3+), and (Yb(3+)-Co3+) have been structurally characterized; they crystallize in the equivalent monoclinic space groups P21/c or P21/n. Structural studies of these two families show that they are isomorphous. This relationship in conjunction with the diamagnetism of the Co3+ allows an approximation to the nature of coupling between the iron(III) and the lanthanide(III) ions in the [Ln(DMF)4(H2O)3(mu-CN)Fe(CN)5].nH2O complexes. The Ln(3+)-Fe3+ interaction is antiferromagnetic for Ln = Ce, Nd, Gd, and Dy and ferromagnetic for Ln = Tb, Ho, and Tm. For Ln = Pr, Eu, Er, Sm, and Yb, there is no sign of any significant interaction. The isotropic nature of Gd3+ helps to evaluate the value of the exchange interaction.
authors.affiliation: Departament de Química Inorgànica, Universitat de Barcelona, Martí i Franqués 1-11,08028 Barcelona, Spain.
authors.forename: Albert
authors.initials: A
authors.lastname: Figuerola
authors.forename: Carmen
authors.initials: C
authors.lastname: Diaz
authors.forename: Joan
authors.initials: J
authors.lastname: Ribas
authors.forename: Vassilis
authors.initials: V
authors.lastname: Tangoulis
authors.forename: Jaume
authors.initials: J
authors.lastname: Granell
authors.forename: Francesc
authors.initials: F
authors.lastname: Lloret
authors.forename: José
authors.initials: J
authors.lastname: Mahía
authors.forename: Miguel
authors.initials: M
authors.lastname: Maestro