| Co-Investigator(Kenkyū-buntansha) |
OHBA Masaki Kyushu University, GRADUATE School of Science, Research Associate, 大学院・理学研究科, 助手 (00284480)
TAKAHASHI.KAZUHIRO Kyushu University, GRADUATE School of Science, Associate Professor, 大学院・理学研究科, 助教授 (00216706)
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| Research Abstract |
1. Bimetallic Magnetic Materials Extended by M-Cn-M' Linkages
1) 2-Dimencional bimetallic compounds [Ni(diamine)ィイD22ィエD2]ィイD22ィエD2 [Fe(Cn)ィイD26ィエD2] X have been prepared which have a square-sheet structure extended through FeィイD1IIIィエD1-CN-NiィイD1IIィエD1 linkages with Fe ions at the coiners and Ni ions at the edges. A ferromagnetic interaction operates within the sheet. The overall magnetic property is governed by the intersheet separation : a small intersheet separation (<10 Å) gives metamagnets owing to intersheet antiferromagnetic interaction whereas a large intersheet separation (>10 Å) provides ferromagnets. The intersheet separation can be controlled by the choice of counter ion and the hydration water.
2) 3-Dimencional bimetallic assemblies [Ni(L)ィイD22ィエD2]ィイD23ィエD2[FeィイD1IIィエD1(CN)ィイD26ィエD2]XィイD22ィエD2 (L=en, tn ; X=PFィイD26ィエD2ィイD1-ィエD1, CIOィイD24ィエD2ィイD1-ィエD1) have been prepared and structurally characterized. They have an isotropic cubic network with Fe ions at the corners and Ni
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ions on the edges.
Magnetic studies indicates a ferromagnetic interaction between the nearest Ni ions thorough the diamagnetic Fe ion.
3) A bimetallic assembly [(Mn)en]ィイD23ィエD2[Cr(CN)ィイD26ィエD2]ィイD22ィエD2 ・4HィイD22ィエD2O was obtained which has a defective cubane structure with three Cr atoms and four atoms at the seven corners and eight Cr-CN-Mn edges. Based on magnetization (FCM, ZFCM, RM) and hysteresis studies, it was fount to be a ferrimagnet showing magnetic ordering below 69 K. To the best of our knowledge, the Tc is the highest among the structurally characterized molecular-based magnets.
2. Magnetism of Dinuclear CuィイD1IIィエD1 Complexes Bridged by Diazine Ligands
Dinuclear CuィイD1IIィエD1 complexes of three polydantate diazine ligands, based on potentially bridge N-N single bond fragments, were studied. The magnetic interaction between the two CuィイD1IIィエD1 ions is markedly dependent upon the torsion angle between the two Cu chromophores with respect to the N-N bond. In general, a large distortion angle results in no spin-coupling and a small distortion causes a strong antiferromagnetic interaction.
3. New strategy for Magnetic Materials
A new bridging ligand having an oxamidate and a glyoxymate groups (HィイD24ィエD2L) was prepared. Its CuィイD1IIィエD1 complex [Cu(HL)]ィイD1-ィエD1 was synthesized in situ and reacted with a second MィイD1IIィエD1 ion to provide trinuclear CuィイD1IIィエD1-MィイD1IIィエD1-CuィイD1IIィエD1 complexes [M{Cu(HL)}ィイD22ィエD2(dmf)ィイD22ィエD2]/2dmf (M=Mn, Co, Ni, Zn) were obtained. The [Cu(HL)]ィイD1-ィエD1 entity form a planar {CuNィイD24ィエD2} chromophore with the hydrogen-bonded N-O-H-N-O chelate. Two {Cu(HL)ィイD22ィエD2ィイD1-ィエD1 molecules coordinate to the MィイD1IIィエD1 ion providing an octahedral geometry together with two dmf molecules. [Mn{Cu(Hl)}]ィイD22ィエD2(dmf)ィイD22ィエD2・2(dmf)ィイD22ィエD2}2dmf was reacted with MnィイD1IIィエD1 ion in the presence of KィイD1+ィエD1 and 18-crown-OィイD26ィエD2 to provide an ordered system exhibiting a spontaneous magnetization at 5.5 K. This work illustrates a stepwise synthesis of bimetallic magnets using a designed bridging ligand. Less
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