| Summary: | 碩士 === 國立成功大學 === 化學系 === 104 === This work contains three parts. The first part, two series of heterometallic Ni－Ln dinuclear [NiIILnIII(L1)2(MeOH)3(H2O)Cl2]Cl (Ln = Gd (1), Tb (2), Dy (3), Ho (4), Er (5)) and [NiIILnIII(L1)2(MeOH)2(NO3)Cl2]·MeOH (Ln = Gd (7), Tb (8), Dy (9)) complexes have been synthesized by using a multidentate β-diketone ligand (L1), with Ni(II), Dy(III) metal ions. The structures of these compounds were determined by X-ray crystallography. Structural studies demonstrate that the metal centers in these complexes are bridged by two β-diketone ligands, leading to a [NiIILnIII(μ-O)2] core, and also show Ni ions in octahedral environment and lanthanide ions possessing a triangular dodecahedron geometry. Direct current (DC) magnetic susceptibility measurements reveal the presence of intramolecular ferromagnetic interactions in complexes 1·Gd4·Ho and 7·Gd9·Dy. However, intramolecular antiferromagnetic interactions exhibit in complex 5·Er. Alternating current (AC) magnetic susceptibility data indicate complexes 2·Tb5·Er and 9·Dy exhibiting slow relaxations of the magnetization. Moreover, the anisotropy energy of 3·Dy is the highest Ueff (322K) for all Ni-Ln complexes that have been found so far. Additionally, we discuss the tiny difference of the geometry between these two series of Ni-Ln complexes which may affect the magnetic behavior in different way. In the second part, a novel series of Ni-Ln tetranuclear [NiII2LnIII2(L2)2(OAc)6(H2O)4](ClO4)2·4H2O (Ln = Gd (10), Tb (11), Dy (12), Ho (13)) complexes have been obtained by using a Schiff based ligand (L2), with Ni(II), Dy(III) metal ions. The structures of these compounds were determined by X-ray crystallography. DC magnetic susceptibility measurements reveal the presence of ferromagnetic interactions between NiII and LnIII in complexes 10·Gd–13·Ho. AC magnetic susceptibility data indicate complexes 11·Tb–13·Ho exhibiting out-of-phase signals at low temperature because of the presence of strong quantum tunneling of magnetization (QTM) by the intermolecular and/or intramolecular interaction between lanthanide (III) ions. The third part, a series of defect-dicubane 3d-4f tetranuclear [NiII2LnIII2(L3)3(OAc)4(NO3)(MeO)2]·2MeOH·H2O (Ln = Y (14), Tb (15), Dy (16), Ho (17)) complexes have been synthesized by using another β-diketone multidentate ligand (L3), with Ni(II), Dy(III) metal ions. The structures of these compounds were determined by X-ray crystallography. DC magnetic susceptibility measurements reveal the presence of ferromagnetic interactions between NiII and LnIII in complexes 15·Tb and 16·Dy. However, intramolecular antiferromagnetic interactions exhibit in complex 17·Ho. AC magnetic susceptibility data indicate complexes 15·Tb–17·Ho exhibiting slow relaxation and QTM of the magnetization.
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