高核稀土-氧簇Ln_(19)的组装、结构与磁性研究

Assembly, Structure and Magnetic Properties of High-Nuclearity Lanthanide-Oxo Cluster Ln_(19)

因其奇特的物理和化学性质,高核稀土-氧簇已经成为配位化学中极其活跃的领域之一并受到广泛关注。然而,由于稀土离子具有较高的配位数和多变的配位几何构型,高核稀土-氧簇的合成及组装仍极具挑战性。采用螯合配体1,2-环己二胺四乙酸(2,2′,2″,2′″-(Cyclohexane-1,2-diylbis(azanetriyl))tetraacetic acid, H4CDTA)控制稀土离子水解,得到了两个零维盘状结构的高核稀土-氧簇Ln_(19)(Ln=Dy为化合物1, Ln=Tb为化合物2)。在相同条件下,采用乙二胺四乙酸二钠盐(Disodium edetate dihydrate, Na2H2EDTA)控制稀土离子水解,得到两个以Ln_(19)为构筑基元的一维链状化合物3(Ln=Dy)和4(Ln=Tb),以及两个以Ln_(19)为构筑基元的三维框架化合物5(Ln=Dy)和6(Ln=Tb)。结果表明,通过改变螯合配体的空间位阻可以实现以高核稀土-氧簇为节点的多维配位聚合物的可控组装。磁性研究表明,化合物1~6均表现出弱的反铁磁相互作用。

High-nuclearity lanthanide clusters have become one of the most active fields in coordination chemistry and attracted extensive attention because of their unique physical and chemical properties. However, the synthesis and assembly of high-nuclearity lanthanide-oxo clusters remain the large challenge due to the high coordination number and variable coordination geometry of lanthanide ions. In this work, two zero-dimensional disk-shaped high-nuclearity lanthanide-oxo clusters Ln_(19)(Ln=Dy for compound 1 and Ln=Tb for compound 2) were obtained by using 2,2′,2″,2′″-(Cyclohexane-1,2-diylbis(azanetriyl))tetraacetic acid, H4CDTA) as chelating ligand to control the hydrolysis of Ln3+ ion. Replacing H4CDTA with disodium edetate dihydrate(Na2H2EDTA), two one-dimensional chain-like compounds 3(Ln=Dy) and 4(Ln=Tb) and two three-dimensional framework compounds 5(Ln=Dy) and 6(Ln=Tb) with Ln_(19) as the nodes were obtained. The results indicated that the controlled assembly of multi-dimensional polymers with high-nuclearity lanthanide-oxo cluster as nodes can be achieved by changing the steric hindrance groups. Magnetic studies showed that compounds 1~6 exhibited weak antiferromagnetic interactions.