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 |
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Authors: | Figuerola Albert Diaz Carmen Ribas Joan Tangoulis Vassilis Granell Jaume Lloret Francesc Mahía José Maestro Miguel |
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Institution: | Departament de Química Inorgànica, Universitat de Barcelona, Martí i Franqués 1-11,08028 Barcelona, Spain. |
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Abstract: | The reaction of Ln(NO3)3.aq with K3Fe(CN)6] or K3Co(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. |
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