Syntheses, Structures And Characterization Of Coordination Polymers Based On Azole Ligands

In recent years, the research of molecular magnetic materials based oncoordination compounds have attracted considerable attention in the most fields. The azideion is able to effectively propagate the magnetic exchange as bridging ligands, and has richcoordination model, with the organic ligands work together to build a variety ofcoordination polymers.In this thesis, a series of complexes with1D,2D and3D structures were synthesizedby transition metal ions, isoxazolecarboxylic acid or pyridine derivatives and characterizedby single crystal X-ray analysis, elemental analyses, IR, and the part of them have alsobeen studied by variable-field magnetic measurements. This thesis based on the followingaspects:1.Coordination compounds with pyridyimidazoleThe pyridyimidazole can provide rich N source as organic ligand. In recent years,pyridine imidazole and its derivatives have been widely studied, but coordination mode hasseldom reported.(1)Three Co(II),Mn(II), Cu(II)coordination compounds (1-3) withN-(4-pyridylmethyl）imidazole (4-pyim) as auxiliary ligand and N3-as ligand weresynthesized and characterized. Single-crystal X-ray structural analysis revealed that twocoordination polymers (1and2) are isomorphous. the unique Co(II) resides at acrystallographic inversion center and exhibits a octahedral coordination geometry. Theadjacent Co(II) ions are connected by the4-pyim ligands to form a2D layer structure. Thelayers are further stacked in the ABAB mode to generate a entangled double-layer network.The thermal properties and electrochemical properties of compound1have also beenstudied. Compound3is simple1D structure and formed2D structure by hydrogen bonds.(2) Co(II) coordination compound4with N-(3-pyridylmethyl）imidazole (3-pyim)as auxiliary ligand and N3-as ligand was synthesized and characterized. Compound4iscomposed of double bridge connecting the adjacent Co (II) ion to form a one-dimensionalchain structure, the adjacent chains are connected into a two-dimensional layer structure by C-H…N hydrogen bonds.2. Coordination compound with isoxazolecarboxylic acidThe isoxazolecarboxylic acid (Iozcb), which contains both oxazolyl and carboxylate,has been explored widely because of the rich coordination polymer spot. But its magneticproperties research has not yet been deeply. Based on the above consideration, we studiedthe coordination chemistry and magnetism of Iozcb.Compound5with the Iozcb ligand or azide ion was synthesized, strutucrally andmagnetically characterized. The compound is2D coordination networks, which consists ofone dimensional chain with triple bridge (a carboxyl bridge, one oxygen bridge and a EOazide bridge) and double bridge (a carboxyl bridge and a EO azide bridge) alternatelytogether. Magnetic analysis shows that Cu(II) compoud transfer ferromagnetic interactionthough the triple bridges and double bridges.3. Coordination compound with pyridyltetrazoliumPyridyltetrazolium (pytz) have both asymmetric ligand of the tetrazolium group andthe pyridine group, which has been a hot area of research because of diversity ofcoordination way. So we use cyanopyridine, azide ion and metal ion directly to be obtainedcoordination polymer6by using the method of in-situ synthesis. And the complex is four-nuclear Co (II) unit based on ternary mixed bridging with azide-pyridine-tetrazolium toconstruct three-dimensional structure. Co1and Co4ions formed1D chain structure alongthe c direction respectively through organic ligand tetrazole ring on a μ2-1,4-nitrogenatom. And the adjacent chain constitutes the two-dimensional layer by μ3-1,1,3-N3bridging way, then the layer and layer form a three-dimensional structure through theauxiliary ligand directly. Magnetic analysis shows that the Co (II) ion have theantiferromagnetic interaction among the mixed bridges.