NiII–LnIII complexes with o-vanillin as the main ligand: syntheses, structures, magnetic and magnetocaloric properties

Structural characterization of a new samarium-sodium heterometallic coordination polymer

Lanthanide-containing materials are of inter-est in the field of crystal engin-eering because of their unique properties and distinct structure types. In this context, a new samarium-sodium heterometallic coordination polymer, poly[tetra-kis-(μ2-2-formyl-6-meth-oxy-phenolato)samarium(III)sodium(I)], {[SmNa(C8H7O3)4]·solvent}n (Sm-1), was synthesized and crystallized via slow evaporation from a mixture of ethanol and aceto-nitrile. The compound features alternating SmIII and NaI ions, which are linked by ortho-vanillin (o-vanillin) ligands to form a mono-periodic chain-like coordination polymer. The chains propagate along the [001] direction. Residual electron density of disordered solvent mol-ecules in the void space could not be reasonably modeled, thus the SQUEEZE function was applied. The structural, vibrational, and optical properties are reported.

Formation of Defect-Dicubane-Type NiII 2LnIII 2 (Ln = Tb, Er) Clusters: Crystal Structures and Modeling of the Magnetic Properties

In the field of molecular nanoclusters, cubane and defect-dicubane, or butterfly structures, are typical examples of tetranuclear metal core architectures. In this work, a halogenated and anionic Schiff-base ligand (L^2-) is utilized as it is predisposed to chelate within a cluster core to both 3d and 4f metal ions, in different binding configurations (H₂L = 4-chloro-2-(2-hydroxy-3-methoxybenzyliden amino)phenol). The phenolate oxygen atoms of the deprotonated ligand can act in μ-O and μ₃-O bridging binding modes for the intramolecular assembly of metal ions. Based on that, two tetranuclear and isostructural compounds [Ni₂Tb₂(L)₄(NO₃)₂(DMF)₂]·2CH₃CN (1) and [Ni₂Er₂(L)₄(NO₃)₂(DMF)₂]·0.5CH₃CN (2) were synthesized and structurally characterized. Magnetic susceptibility and magnetization data indicate the occurrence of dominant intramolecular ferromagnetic interactions between the spin centers. Particular emphasis is given to the theoretical description of the magnetic behavior, taking into account the Ln-Ni and Ni-Ni coupling paths and the magnetic anisotropy of the Ln^III and Ni^II ions. The study is distinguished for its discussion of two distinct models, whereby model A relies on the uniaxial B ₂₀ Stevens term describing the lanthanide anisotropy and model B is based on point-charge model calculations. Importantly, the physical meaning of the obtained parameters for both models was critically scrutinized.

Hydroxido supported and differently networked octanuclear Ni6Ln2 [Ln = GdIII and DyIII] complexes: structural variation, magnetic properties and theoretical insights

Solvent derived hydroxido bridge driven Ni₆Ln₂ [Ln = Gd^III (1) and Dy^III (2)] coordination aggregates of two different types has been synthesized. Magnetic susceptibility study confirms field induced slow relaxation of magnetization for Ni₆Dy₂.

Coordination control of a semicarbazide Schiff base ligand for spontaneous aggregation of a Ni2Ln2 cubane family: influence of ligand arms and carboxylate bridges on the organization of the magnetic core

A new family of tetranuclear [Ni₂Ln₂O₄] cubane complexes has been assembled from carbazido ligand by altering the 4f ions without changing the core topology, which provided weak ferromagnetic and antiferromagnetic interactions.

Self-assembled octanuclear [Ni5Ln3] (Ln = Dy, Tb and Ho) complexes: synthesis, coordination induced ligand hydrolysis, structure and magnetism

Octanuclear NiII5LnIII3 complexes obtained with ligand H₂L show ferromagnetic interactions for Ni₅Dy₃ and Ni₅Tb₃ while antiferromagnetic interactions for Ni₅Ho₃.