Alkali Metal Ion Templated Transition Metal Formate Framework Materials: Synthesis, Crystal Structures, Ion Migration, and Magnetism
Alkali Metal Ion Templated Transition Metal Formate Framework Materials: Synthesis, Crystal Structures, Ion Migration, and Magnetism
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DOI：
10.1021/ic501152j
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发表时间：
2014-10-06
影响因子：
4.6
通讯作者：
Iversen, Bo Brummerstedt
中科院分区：
文献类型：
--
作者：
Eikeland, Espen;Lock, Nina;Iversen, Bo Brummerstedt
采用温和溶液化学方法合成了Na[Mn(HCOO)(3)]、K[Mn(HCOO)(3)]、Na-2[Cu-3(HCOO)(8)]和K-2[Cu-5(HCOO)(12)]四种具有阴离子框架的过渡金属甲酸酯配位聚合物。化合物的多温单晶（100-300 K）和粉末x射线衍射研究表明，化合物的结构有很大的多样性，从立方手性Na-Mn甲酸酯到三斜性Na-Cu甲酸酯。结构的多样性是由过渡金属的性质、碱金属离子模板和甲酸基团的多功能性引起的，甲酸基团除了通过单个氧原子进行金属桥接外，还通过三种不同的O-C-O桥接模式（syn-syn, syn-anti, anti-anti）提供金属金属配位。这两种锰（II）化合物都含有单核的八面体配位基团，但在两种结构中，锰八面体之间的三维连通性有很大不同。相比之下，这两种铜骨架分别由双核和单核部分（Na-Cu甲酸）和三核和单核部分（K-Cu甲酸）组成。化合物的原晶电子密度分析表明K- mn和K- cu中的一维K+离子电导率，并将所提出的钾离子迁移性质与已知Na+和K+离子导体的类似分析结果进行了比较。K-Mn和Na-Mn作为正极材料进行了测试，但由于电导率低或结构崩溃，导致可逆性差。用振动样品磁强法研究了化合物的磁性能，用热重分析和差热分析测定了化合物的热稳定性。尽管结构不同，但含有相同过渡金属的金属甲酸酯具有相似的磁性能和热分解途径，即过渡金属的性质控制着化合物的性质。
Four transition metal formate coordination polymers with anionic frameworks, namely, Na[Mn(HCOO)(3)], K[Mn(HCOO)(3)], Na-2[Cu-3(HCOO)(8)], and K-2[Cu-5(HCOO)(12)], were synthesized using a mild solution chemistry approach. Multitemperature single-crystal (100-300 K) and powder Xray diffraction studies of the compounds reveal structures of large diversity ranging from cubic chiral Na-Mn formate to triclinic Na-Cu formate. The structural variety is caused by the nature of the transition metals, the alkali metal ion templation, and the versatility of the formate group, which offers metal metal coordination through three different O-C-O bridging modes (syn-syn, syn-anti, anti-anti) in addition to metal metal bridging via a single oxygen atom. The two manganese(II) compounds contain mononuclear, octahedrally coordinated moieties, but the three-dimensional connectivity between the manganese octahedra is very different in the two structures. The two copper frameworks, in contrast, consist of binuclear and mononuclear moieties (Na-Cu formate) and trinuclear and mononuclear moieties (K-Cu formate), respectively. Procrystal electron density analysis of the compounds indicates one-dimensional K+-ion conductivity in K-Mn and K-Cu, and the nature of the proposed potassium ion migration is compared with results from similar analysis on known Na+ and K+ ion conductors. K-Mn and Na-Mn were tested as cathode materials, but this resulted in poor reversibility due to low conductivity or structural collapse. The magnetic properties of the compounds were studied by vibrating sample magnetometric measurements, and their thermal stabilities were determined by thermogravimetric analysis and differential thermal analysis. Despite structural differences, the metal formates that contain the same transition metal have similar magnetic properties and thermal decomposition pathways, that is, the nature of the transition metal controls the compound properties.