Design, Crystal Structures And Magnetic Properties Of 3D Micropore Transition Metal (Fe, Co And Mn) Compounds Based On Organphosphonic Ligands And Oxalate

Molecule-based magnets have been an active and popular research field due to their structural diversity, excellent magnetic properties, as well as complicated magnetio-structural relationship. The research trends of molecule-based magnets can be classified into the following these classes:(1) multifunctional magnetic materials, for example, porous magnetic materials, chiral magnetic materials, electrochemical magnetic materials; (2) molecule-based magnets existing higher critical temperature; (3) nanoscale molecular magnetic materials.In this thesis, we synthesized two analogous organophosphonic acids as two primary ligands and prepared eight complexes combined with the simple but suitable second ligand oxalic acid, as well as cyano as bridging ligand, of which seven are microporous materials. We study the influences of temperature, pH and solvent on the structures of complexes. The magnetic properties and magnetio-structural relationship of these compounds have been studied in detail.(1) H4pbp was used to react with different metal salts under solvothermal condition to obtain three micropore metal phosphonate coordination complexes with the general formulas of FeH2pbp·2H2O (1), CoH2pbp·2H2O (2) and MnH2pbp·2H2O (3). Then by using of the analogue organophosphonic acid H4bbp and an auxiliary ligand oxalate C2O42-, three novel three-dimensional micropore metal phosphonate coordination complexes with the general formulas of [Fe2pbp0.5(C2O4)1.5H2O]·2H2O (4), [Co2(H2pbp)o.5(C204)1.5H20]·2H20 (5) and [Co3(H2bbp)(C2O4)2]·2CH3OH·3H2O (6) have been successfully synthesized. Compounds 4 and 5 possess quite similar micropore crystal structures. Due to the selection of different major ligand H4bbp, complex 6 exhibits an entirely different 3D framework with slightly larger pore size. Magnetic characterization results show that compound 4 exhibits antiferromagnetic, and compounds 5 and 6 exhibit metamagnetic. This specific microporous structures have potential applications in adsorption and catalysis.(2) By using of K.3[Co(CN)6] as building block and the auxiliary ligand oxalic acid combined with the different organic templates, two interesting organic metal compounds Na[Co3(CN)6(C2O4)(H2O)2]·H2O (7) and [Co3(CN)6(C2O4)(H2O)]Cl·CH3OH·2H2O (8) were successfully synthesized. Compound 7 possesses 3D framework structures and compound 8 exhibits a 3D micropore structure. Compound 7 is antiferromagnetic, owning to the Com metal centers, and compound 8 presents diamagnetic. They can be used as precursors of battery materials due to their unique architecture.