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首页> 外文期刊>Dalton transactions: An international journal of inorganic chemistry >On the formation of the Gd3Ru4Al12 versus the Y2Co3Ga9 type structure - M3Rh4Al12 (M = Ca, Eu) versus M2T3Al9 (M = Ca, Sr, Eu, Yb; T = Ir, Pt)
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On the formation of the Gd3Ru4Al12 versus the Y2Co3Ga9 type structure - M3Rh4Al12 (M = Ca, Eu) versus M2T3Al9 (M = Ca, Sr, Eu, Yb; T = Ir, Pt)

机译：在GD3RU4AL12的形成与Y2CO3GA9型结构 - M3RH4AL12（M = CA，EU）与M2T3AL9（M = CA，SR，EU，YB; T = IR，PT）相比

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摘要

The new Y2Co3Ga9 and Gd3Ru4Al12 type representatives M2T3Al9 (M = Ca, Sr, Eu; T = Ir, Pt) and M3Rh4Al12 (M = Ca, Eu) have been synthesized from the elements by heating the respective elemental compositions in sealed tantalum tubes. The samples were analysed by powder X-ray diffraction to check their purity. By applying different temperature treatments, their phase purity and crystallinity were enhanced. The crystal structures of Ca3Rh4Al12 and Eu3Rh4Al12 (hexagonal Gd3Ru4Al12 type, P6(3)/mmc) as well as Ca2Ir3Al9 and Ca2Pt3Al9 (orthorhombic Y2Co3Ga3 type, Cmcm) were refined from single-crystal X-ray diffraction data. All structures can be described based on distorted cube-like T@Al-8 units that are connected to form strands. Additionally, an Al-11 supertetrahedral building block can be identified within the structures. While the trigonal bipyramidal core of the cluster contains substantial bonding interactions in the case of the M3Rh4Al12 members, the connection via common edges in the case of the M2Ir3Al9 compounds seems to weaken these interactions. The differences in the bonding situation and the question why these different structure types are formed for the different transition metals has been targeted by quantum-chemical calculations. The calculated formation energy using three different reaction paths suggests that the stability of these phases is highly dependent on the side phases involved, even though Ca3T4Al12 phases are in general thermodynamically more favourable. According to the Bader analysis of the two polyanions, an improved covalent bonding can be observed in the [T4Al12](delta-) over the [T3Al9](delta-) framework.
机译：通过在密封钽管中加热相应的元素组合物，通过在密封钽管中加热相应的元素组合物，从元件中合成了新的Y2CO3GA9和GD3R4AL12型代表M2T3AL9（M = CA，SR，EU; T = IR，PT）和M3RH4AL12（M = CA，EU）。通过粉末X射线衍射分析样品以检查它们的纯度。通过施加不同的温度处理，增强了它们的相纯度和结晶度。通过单晶X射线衍射数据改进Ca3RH4Al12和Eu3RH4Al12（六方Gd3Ru4A112型，P6（3）/ MMC）以及Ca2ir3Al9和Ca2Po3GA3型，CMCM）的晶体结构。所有结构都可以基于扭曲的立方体样T @ Al-8单元来描述连接以形成股线。另外，可以在结构内识别Al-11超级去律构建块。虽然在M3RH4AL12成员的情况下，簇的三角形双核核心含有大量粘合相互作用，但在M2IR3A19化合物的情况下通过常见边缘的连接似乎削弱了这些相互作用。粘接情况的差异和质疑为什么以不同的过渡金属形成了这些不同的过渡金属的靶向是由量子化学计算的。使用三种不同反应路径的计算形成能量表明这些阶段的稳定性高度依赖于所涉及的侧相，即使CA3T4AL12阶段通常是热力学上更有利的。根据两个聚阳极的獾分析，可以在[T3AL9]（Delta-）框架上，在[T4AL12]（Delta-）中观察改进的共价键。

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