Synthesis, Structures And Managnetic Properties Of Nano Molecular Magnets Containing Mn~Ⅲ And Polynuclear Coordination Compounds

Nowadays, the subjects of nano-molecule magnets (SMMs and SCMs) and multifunctional magnetic materials have become hot topic of research at the frontier between chemistry and physics. In this thesis, salicylaldoxime-based MnⅢcomplexes and other polynuclear complexes with azide, carboxylic acid and dicyanamide bridge ligands have been prepared. All of them were characterized by X-ray single crystal structure analysis, IR, and element analysis. The magnetic behaviors of twenty two complexes have been theoretically analyzed. And also the magneto-structural correlations of these complexes have been discussed. Among them:1 Four [MnⅢ6(μ3-O)2]14+ and two [MnⅢ3(μ3-O)]7+ clusters incorporating salicylaldoxime and its derivatives ligands have been obtained, in which one complex shows rare ferromagnetic Mn…n interactions in [MnⅢ3] triangles. Frequency-dependent out-of-phase (χm") signals suggest three complexes are single-molecule magnets (SMMs).2 The four 1D chainlike complexes with [MnⅢ3(μ3-O2-)] unit bearing salicylaldoxime ligand were synthesized. Among them, three complexes show antiferromagnetic exchange SCMs behaviors and one features unusual ferromagnetic interactions when the trinuclear units are linked by end-to-end azido bridges. All complexes show clear slow magnetic relaxation behaviors at low temperature. One rare SCM is obtained by using [MnⅢ6(μ3-O)2]14+ cluster as unit bridged by dicyanamide.3 Seven magnetic complexes with helical or porous structures bridged by carboxylate were prepared by hydrothermal method.4 A tetranuclear CuⅡand two ferromagnetic dinuclear CoⅡand NiⅡcomplexes with end-on azide were synthesized and structurally characterized. Seven CuⅡcomplexes with mixed azide-carboxylate bridges were prepared and their structures of the resulting complexes were greatly influenced by substitutional groups of coligands.