Syntheses, Crystal Structures And Magnetic Properties Of New Polynuclear Metal Complexes Containing Polydentate Hydroxy-rich Ligands

In recent twenty years, much interest has been focused on the polynuclear metal complexes of 3d,3d-4f or 4f because of their unique magnetic properties. With this in mind, we chose polydentate hydroxy-rich ligands reacting with MnⅡ/Ⅲor FeⅢor LnⅢions by self-assembly approach and obained thirty new complexes. They have been characterized by X-ray single crystal structure analysis, IR, element analysis and powder X-ray diffraction (XRD). The magnetic behaviors of twenty-eight complexes have been theoretically analyzed. And also the magneto-structure correlations of these complexes have been discussed. Among them:1. Two mixed-valence [Mn2ⅡMn2Ⅲ] cubane clusters, two tetranuclear ferric clusters and a one-dimensional polymer using 2,6-bis(hydroxymethyl)phenol as ligand have been obtained. Ac magnetic measurements suggest that the [Mn2ⅡMn2Ⅲ] cluster and 1D polymer behave as SMM and SCM, respectively.2. Three interesting wheel-shaped hexanuclear complexes have been obtained and the alkali ions are situated at the center of the hexagonal wheels and stabilize the three complexes. The magnetic behaviors of the three clusters indicates antiferromagnetic coupling between the iron (Ⅲ) centers and ferromagnetic coupling between the manganese (Ⅲ) centers.3. Fourteen mixed-valence Mn clusters and one heptanuclear Ferric cluster have been synthesized by using hydroxy-rich Schiff-base ligands. Among them, three [Mn5Ⅲ] cores and two [MnⅡMn4Ⅲ] cores are unprecedented in Mn clusters. Magnetic behaviors of those clusters have been characterized and the magneto-structure correlations of [Mn4] or [Mn5] systems have been studied.4. Five 2p-3d-4f nonanuclear clusters [Na2Mn6Ln] with novel structures have been obtained by using hydroxy-rich Schiff-base ligand, namely 2-[(2-hydroxyethyli mino)methyl]-6-methoxyphenol} (hmmpH2). It’s the second example of 2p-3d-4f cluster. The slow magnetic relaxation behavior is observed in cluster [Na2Mn6Tb], suggesting a single-molecule magnet.5. Two pure lanthanide tetranuclear clusters, namely [Yb4] and [Dy4] have been obtained by using pyridine-2,6-dimethanol as ligand. [Dy4] cluster possesses frequency-dependent magnetic behavior, indicating possible single-molecule magnet behavior.