Syntheses, Structures And Magnetic Properties Of Polynuclearity3d-4f Heterometallic Cluster Compounds

Research about clusters, especially polynuclearity3d-4f heterometallic clusters, is one of the most important topics in modern inorganic chemistry and solid state chemistry, because of their fascinating magnetic properties such as the slow relaxation of the magnetization and the magnetocaloric effect (MCE), which may have potential applications in information storage and ultra low-temperature refrigeration. Compared with a large number of reports about3d-4f clusters bearing single molecular magnets (SMMs) properties, the reports about similar single chain magnets (SCMs) and magnetic coolers are still rare. Here, oriented by the above mentioned functions, new3d-4f heterometallic clusters and cluster-based frameworks based on amino acids/formate ligands were investigated. Their syntheses, structures and magnetic properties were discussed.1. Two series of tetranuclearity [Ln2Co2] compounds based on trans-1,2-diamino cyclohexane-N,N,N’,N’-tetraacetic acid with rare structures, square clusters (1-3) with/m-O2bridged3d-4f-3d-4f arrangement and two μ3-OH-bridged "butterfly" clusters (4-7) with two "Ln+" ions as "body", were prepared. Their syntheses are mainly controlled by the radii of Ln3+ions and solvent. The magnetic interactions between the metal ions in the compounds were analysized.2. With glycine and iminodiacetate acid as mixed ligands, one undecanuclear face-shared dioctahedron cluster (8,[La2Ni9]) and six heptadecanuclear dual shell-like clusters (9-14,[Ln5Ni12]) were prepared. One similar heptadecanuclear dual shell-like cluster (15,[Gd5N12]) was also prepared with proline and N-carboxymethyl-L-proline acid as coligands. Magnetic investigations reveal that14and15([Gd5Ni12]) have a large magnetocaloric effect and could be used as potential ultra low-temperature molecular magnetic refrigerant materials.3. With formate as ligand, two linear (16,17) and three zigzag (18-20) ID coordination polymers were obtained. All of them are based on pyramidal [TbCu4] units. Chair-like [(H2O)2(ClO4)2]2-cluster was also observed in the linear compounds. Magnetic studies reveal that17and20show slow relaxation of the magnetization.4. With glycine and formate as mixed ligands, three ID undulating chain (21-23) and two3D (3,3)-connected pcu-h networks (24-25) based on [LnCu6] units were obtained under different pH values. When glycine was replaced by alanine. three (6,6)-connected pcu networks (26-28) based on [Ln6Cu24] units were prepared. Magnetic investigations reveal that26have a large magnetocaloric effect and the dimensions of the compounds may have little impact on their magnetocaloric effect.5. With D-penicillamine as ligand,3D3d-4d-4f coordination polymers based on [Ni6Ag8S12Cl] units with (3,3)-connected utg topology (29-31), and based on [Co2Ag3S6] units with (6,6)-connected pcu topology (32-34), were obtained. Properties studies reveal these compounds are chiral, rigid and thermostable.