One-dimensional infinite chain structures of [Al2(OH)4(H2O)4]X2 (X = I, Br, Cl): an aggregate of Al2 species and a precursor of Al(OH)3
作者:Zhong Sun、Hui Wang、Ying Zhang、Jingshuang Li、Yang Zhao、Wuning Jiang、Li Wang
DOI:10.1039/c3dt50811k
日期:——
By a combination of the Rietveld full-profile fitting technique based on powder X-ray diffraction data and the single-crystal structure solving and refining method, one-dimensional infinite zigzag chain structures were observed in the structures of [Al2(OH)4(H2O)4]X2 (X = I, Br, Cl). These crystallize in the same monoclinic system and the same C2/c space group with different unit cell parameters from spontaneously hydrolyzed solutions of AlX3. Each chain is composed of a significant number of AlO6 octahedra that fall into two groups with reverse orientations and connect to each other by edge-sharing. Furthermore, the counterions intersperse among the chains forming strong van der Waals interactions. It was also discovered that each chain was an aggregate formed from the further hydrolysis of the Al2 species (Al2(OH)2(H2O)84+, a dimer formed by two octahedral Al(H2O)63+ monomers sharing an edge) and a building unit for constructing the infinite hexameric ring sheet in nordstrandite and gibbsite. These are three new structures, rarely solved from powder XRD data, of polyaluminum compounds, and they provide the first direct evidence of the aggregation processes of Al2 species and their subsequent evolution into an infinite zigzag chain as well as further evolution into an infinite hexameric ring layer as found in nordstrandite and gibbsite. Furthermore, they also represent the first three examples in which each polyaluminum species possesses a one-dimensional infinite chain structure formed by AlO6 octahedra via edge-sharing only.
结合基于粉末X射线衍射数据的Rietveld全轮廓拟合技术和单晶结构求解和细化方法,在[Al2(OH)4( H2O)4]X2 (X = I、Br、Cl)。这些结晶在相同的单斜晶系和相同的 C2/c 空间群中,具有不同的晶胞参数,来自 AlX3 的自发水解溶液。每条链均由大量 AlO6 八面体组成,这些八面体分为两组,方向相反,并通过共享边缘相互连接。此外,反离子散布在链之间,形成强烈的范德华相互作用。还发现每条链都是由 Al2 物种(Al2(OH)2(H2O)84+,由共享边缘的两个八面体 Al(H2O)63+ 单体形成的二聚体)和一个用于构建 Nordstrandite 和三水铝石无限六聚体环片的构建单元。这是聚铝化合物的三种新结构,很少从粉末 XRD 数据中解析出来,它们为 Al2 物质的聚集过程及其随后演化为无限之字形链以及进一步演化为无限六聚环提供了第一个直接证据。在 Nordstrandite 和三水铝矿中发现的层。此外,它们还代表了前三个例子,其中每种聚合铝物质都具有仅通过共享边缘由 AlO6 八面体形成的一维无限链结构。