Dinuclear lanthanide(iii) complexes withschiff bases ligands derived from carbonohydrazide. Synthesis, spectroscopic studies and structural characterization
Résumé
The ligand N'-(2-hydroxy-3-methoxybenzylidene)nicotinohydrazide (H2L) was prepared by reaction of nicotinohydrazide with 2-hydroxy-3-methoxybenzaldehyde in a reflux ethanol solution. The lanthanides complexes were prepared by reaction of the ligand with the lanthanide nitrate. These complexes are well characterized by elemental analysis, IR, UV spectroscopies, conductance and room temperature magnetic moment measurement.The structure of the complexes was determined by single X-ray diffraction technic. Thecomplexes of Gd and Tb are isostructural and are formulated as {[Ln (HL)(H2O)2(NO3)]2.(NO3)2.(H2O)2}. Inthese structures, each Ln atom is nine coordinated. In the crystal of the dinuclear complex {[Eu2(HL)2(H2O)2(NO3)3].(NO3).(H2O)2} one Eu(III) center is nine-coordinated and the other one is tencoordinated. One nitrate anion acts in 2-coordination mode and as 2-mode Bridge between the two Eu (III) centers. In all the complexes, the ligand acts as bridge in tetradentate fashion. The nitrogen and the oxygen atoms of the hydrazino moietyare coordinated to one Ln (III) center and the oxygen atom of the methoxy group is coordinated the otherLn (III) center. The phenolate oxygen atom bridges the two Ln (III) centers. One nitrate group acts in bidentate manner to each Ln (III). Two nitrate groups remain uncoordinated. In both Gd and Tb dinuclear complexes the coordination polyhedral are best described as a tricapped trigonal prismfor each of the two centers.In the dinuclear complex of Eu, the polyhedron of the ten-coordinated Eu can be regarded as a 1333stacking patternwhile the polyhedron of the nine-coordinated Eu is best described as a monocapped square antiprism. The molecules are linked together in each case by multiple hydrogen bond interaction resulting in a three-dimensional network.
Domaines
Chimie de coordinationOrigine | Fichiers produits par l'(les) auteur(s) |
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