Local Restricted Metal Building Block Controlling The Synthesis Of Molecule-based Magnetic Materials With Expected Structures

Since Wickman found the first example of molecule-based magnets in 1967, molecule-based magnets which built of magnetically active metal complexes or organic radicals have been intensively studied due to various magnetic properties. Among them, cyano-bridged metal coordination polymers have attracted interest because [M(CN)x]n- are good building blocks for bimetallic assemblies. Cyanides prefer to form linear linkages between two metal centers to stabilise a variety of transition metal centers in different oxidation states and efficiently transmit spin density information. Most of these complexes combined with [CoIII(CN)x]n- prefer to show paramagnetic property because of the diamagnetic CoIII. In our researches, the complexes combined with [CoIII(CN)x]n- show interesting magnetic properties.In general, if we just change the metal ions and keep the other reaction conditions unchanged, we will get a series of complexes which are isostructural. However, when we used flexible tridentate ligand N,N-Bis(3-aminopropyl)methylamine(medpt) to coordinate with the metal ions, we found that the coordination modes of the metal ions also changed, and the strucrures for complexes are totally different. In this way, we can obtain the molecule-based magnets with expected structures.In this work, we first prepared four compounds Ni3(medpt)3[Co(CN)6]2·5H2O(1),Co3(medpt)3[Co(CN)6]2·2H2O(2),Cu2(medpt)[Co(CN)6](3). Compounds 1 and 2 exhibit a 3D framework, while 3 displays a 2D structrue. There exist ferromagnetic interactions at low temperacture in 1, and 2 shows antiferromagnetic interactions between metal ions. 3 exhibits spin-flop phenomenon.Meanwhile, we use Fe(CN)63- to react with phenanthroline(L1) and 4-picolinic acid(L2), respectively, and then Fe(CN)6[Cu(L1)2(H2O)2]2?4H2O(4) and Mn3(L2)[Fe(CN)6]2(H2O)6?4H2O(5) were obtained and characterized. Complexe 4 shows a trinuclear cluster, while 5 is a 3D porous structure. Magnetic measurements demonstrate that compound 5 exhibits ferromagnetic interactions.