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Asymmetric dinuclear lanthanide(III) complexes from the use of a ligand derived from 2-acetylpyridine and picolinoylhydrazide: synthetic, structural and magnetic studies

hal.structure.identifierDepartment of Chemistry
dc.contributor.authorMANIAKI, Diamantoula
hal.structure.identifierCentre de Recherche Paul Pascal [CRPP]
hal.structure.identifierInstitut de Chimie de la Matière Condensée de Bordeaux [ICMCB]
dc.contributor.authorPERLEPE, Panagiota
hal.structure.identifierDepartment of Chemistry
dc.contributor.authorPILICHOS, Evangelos
hal.structure.identifierInstitut de Ciencies Fotoniques [Castelldefels] [ICFO]
dc.contributor.authorCHRISTODOULOU, Sotirios
hal.structure.identifierCentre de Recherche Paul Pascal [CRPP]
dc.contributor.authorROUZIÈRES, Mathieu
hal.structure.identifierCentre de Recherche Paul Pascal [CRPP]
dc.contributor.authorDECHAMBENOIT, Pierre
hal.structure.identifierCentre de Recherche Paul Pascal [CRPP]
dc.contributor.authorCLÉRAC, Rodolphe
hal.structure.identifierFoundation for Research and Technology - Hellas [FORTH]
hal.structure.identifierDepartment of Chemistry
dc.contributor.authorPERLEPES, Spyros
dc.date.issued2020-07
dc.identifier.issn1420-3049
dc.description.abstractEnA family of four Ln(III) complexes has been synthesized with the general formula [Ln2(NO3)4(L)2(S)] (Ln = Gd, Tb, Er, and S = H2O; 1, 2 and 4, respectively/Ln = Dy, S = MeOH, complex 3), where HL is the flexible ditopic ligand N’-(1-(pyridin-2-yl)ethylidene)pyridine-2-carbohydrazide. The structures of isostructural MeOH/H2O solvates of these complexes were determined by single-crystal X-ray diffraction. The two LnIII ions are doubly bridged by the deprotonated oxygen atoms of two “head-to-head” 2.21011 (Harris notation) L¯ ligands, forming a central, nearly rhombic {LnIII2(μ-OR)2}4+ core. Two bidentate chelating nitrato groups complete a sphenocoronal 10-coordination at one metal ion, while two bidentate chelating nitrato groups and one solvent molecule (H2O or MeOH) complete a spherical capped square antiprismatic 9-coordination at the other. The structures are critically compared with those of other, previously reported metal complexes of HL or L¯. The IR spectra of 1–4 are discussed in terms of the coordination modes of the organic and inorganic ligands involved. The f-f transitions in the solid-state (diffuse reflectance) spectra of the Tb(III), Dy(III), and Er(III) complexes have been fully assigned in the UV/Vis and near-IR regions. Magnetic susceptibility studies in the 1.85–300 K range reveal the presence of weak, intramolecular GdIII∙∙∙GdIII antiferromagnetic exchange interactions in 1 [J/kB = −0.020(6) K based on the spin Hamiltonian Ĥ = −2J(ŜGd1∙ ŜGd2)] and probably weak antiferromagnetic LnIII∙∙∙LnIII exchange interactions in 2–4. Ac susceptibility measurements in zero dc field do not show frequency dependent out-of-phase signals, and this experimental fact is discussed for 3 in terms of the magnetic anisotropy axis for each DyIII center and the oblate electron density of this metal ion. Complexes 3 and 4 are Single-Molecule Magnets (SMMs) and this behavior is optimally observed under external dc fields of 600 and 1000 Oe, respectively. The magnetization relaxation pathways are discussed and a satisfactory fit of the temperature and field dependencies of the relaxation time τ was achieved considering a model that employs Raman, direct, and Orbach relaxation mechanisms.
dc.language.isoen
dc.publisherMDPI
dc.subject.enAsymmetric dinuclear lanthanide(III) complexes
dc.subject.enDysprosium(III) and erbium(III) single-molecule magnets
dc.subject.enMagnetic properties
dc.subject.enMetal complexes of N’-(1-(1-pyridin-2-yl)ethylidene)pyridine-2-carbohydrazide
dc.subject.enMagnetization relaxation pathways
dc.subject.enSingle-crystal X-ray structures
dc.subject.enasymmetric dinuclear lanthanide(III) complexes
dc.subject.endysprosium(III) and erbium(III) single-molecule magnets
dc.subject.enmagnetic properties
dc.subject.enmetal complexes of N'-(1-(1-pyridin- 2-yl)ethylidene)pyridine-2-carbohydrazide
dc.subject.enmagnetization relaxation pathways
dc.subject.ensingle-crystal X-ray structures
dc.title.enAsymmetric dinuclear lanthanide(III) complexes from the use of a ligand derived from 2-acetylpyridine and picolinoylhydrazide: synthetic, structural and magnetic studies
dc.typeArticle de revue
dc.identifier.doi10.3390/molecules25143153
dc.subject.halChimie/Matériaux
bordeaux.journalMolecules
bordeaux.page3153 ((23 p.)
bordeaux.volume25
bordeaux.issue14
bordeaux.peerReviewedoui
hal.identifierhal-02906220
hal.version1
hal.popularnon
hal.audienceInternationale
hal.origin.linkhttps://hal.archives-ouvertes.fr//hal-02906220v1
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