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Penta‐Ammoniates of Aluminium Halides: The Crystal Structures of AlX 3 ·5NH 3 with X =Cl, Br, I
Author(s) -
Jacobs Herbert,
Schröder Felix O.
Publication year - 2002
Publication title -
zeitschrift für anorganische und allgemeine chemie
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.354
H-Index - 66
eISSN - 1521-3749
pISSN - 0044-2313
DOI - 10.1002/1521-3749(200206)628:5<951::aid-zaac951>3.0.co;2-o
Subject(s) - iodide , bromide , chemistry , halide , octahedron , crystallography , chloride , crystal structure , bromine , inorganic chemistry , organic chemistry
Colourless crystals grow in the colder part of a glass ampoule when AlX 3 ·5NH 3 with X = Cl, Br, I is heated for 3—6 d to 330 °C (Cl), 350 °C (Br) and 400 °C (I), respectively. The chloride forms hexagonal prisms while the bromide and iodide were obtained as a bunch of lancet‐like crystals. The chloride and bromide crystallize isotypic whereas the iodide has an own structure type. All three are related to the motif of the K 2 PtCl 6 type. So the formula of the ammoniates may be written as X 2 [Al(NH 3 ) 5 X] ≙ [Al(NH 3 ) 5 X]X 2 . The compounds are characterized by the following crystallographic data AlCl 3 ·5NH 3 : Pnma, Z = 4, a = 13.405 (1)Å, b = 10.458 (1)Å, c = 6.740 (2)Å AlBr 3 ·5NH 3 : Pnma, Z = 4, a = 13.808 (2)Å, b = 10.827 (1)Å, c = 6.938 (1)Å AlI 3 ·5NH 3 : Cmcm, Z = 4, a = 9.106 (2)Å, b = 11.370 (2)Å, c = 11.470 (2)Å For the chloride and the bromide the structure determinations were successful including hydrogen positions. All three compounds contain octahedral molecular cations [Al(NH 3 ) 5 X] 2+ located in distorted cubes formed by the remaining 2X — ions. The orientation of the octahedra to each other is clearly different for those with X = Cl, Br in comparison to the one with X = I.