ISSN:
1600-5759
Source:
Crystallography Journals Online : IUCR Backfile Archive 1948-2001
Topics:
Chemistry and Pharmacology
,
Geosciences
,
Physics
Notes:
The title compound, calcium oxide–dialuminium trioxide–calcium dibromide–calcium dichloride hydrate (3/1/0.5/0.5/10), also formulated as Ca2Al(OH)6Br0.478Cl0.522·2H2O (dicalcium aluminium hydroxide hemibromide hemichloride dihydrate), is a double-layered hydroxide which belongs to the solid solution Ca2Al(OH)6BrxCl1−x·2H2O, where x can vary from 0 to 1. Chloride and bromide anions of the negatively charged interlayer [Br0.5Cl0.5·2H2O]− share statistically the same crystallographic site. Al3+ and Ca2+ cations are coordinated by six and seven O atoms, respectively. All water molecules are bonded to Ca2+ cations and assume the seventh coordination position. Anions in the interlayer are surrounded by ten H atoms. Br− and Cl− are therefore connected to the main layer by ten hydrogen bonds, six of 2.74 (2) Å and four of 2.52 (5) Å, where the donors are hydroxyl groups and water molecules, respectively. Like the chloride equivalent, the title compound is a 6R polytype with trigonal space group R\overline 3c and lattice parameters a = 5.7537 (4) Å and c = 48.108 (4) Å.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1107/S0108270100014025
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