One-dimensional infinite chain structures of [Al sub(2)(OH) sub(4)(H sub(2)O) sub(4)]X sub(2) (X = I, Br, Cl): an aggregate of Al sub(2) species and a precursor of Al(OH) sub(3)

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 [Al sub(2)(OH) sub(4)(H sub(2)O) sub(4)]X sub(2) (X...

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Bibliographic Details
Published in:Dalton transactions : an international journal of inorganic chemistry 2013-08, Vol.42 (36), p.12956-12964
Main Authors: Sun, Zhong, Wang, Hui, Zhang, Ying, Li, Jingshuang, Zhao, Yang, Jiang, Wuning, Wang, Li
Format: Article
Language:English
Subjects:
Aggregates
Aluminum base alloys
Bayer process
Biological evolution
Chains
Construction
Fittings
Unit cell
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Summary: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 [Al sub(2)(OH) sub(4)(H sub(2)O) sub(4)]X sub(2) (X = I, Br, Cl). These crystallize in the same monoclinic system and the same C2/cspace group with different unit cell parameters from spontaneously hydrolyzed solutions of AlX sub(3). Each chain is composed of a significant number of AlO sub(6) 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 Al sub(2) species (Al sub(2)(OH) sub(2)(H sub(2)O) sub(8) super(4+), a dimer formed by two octahedral Al(H sub(2)O) sub(6) super( 3+) 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 Al sub(2) 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 AlO sub(6) octahedra viaedge-sharing only.
ISSN:1477-9226
1477-9234
DOI:10.1039/c3dt50811k