A B C
Z. Naturforsch. 2013, 68b, 1288 – 1294
doi:10.5560/ZNB.2013-3200
In Search of the True Structure of the Sodium Chromium Alum II: Crystal Growth and Structure of the Double Salt NaCr(SO4)2(H2O)6 · (CH3OH)0.6(2) · (H2O)1.5(5)
Luitgard Rees-Isele, Hans-Peter Winkler and Egbert Keller
Kristallographie, Institut für Geowissenschaften der Albert-Ludwigs-Universität Freiburg, Hermann-Herder-Str. 5, 79104 Freiburg, Germany
Reprint requests to Dr. Egbert Keller. Fax: 0049 761 6434. E-mail: egbert.keller@krist.uni-freiburg.de
Received July 23, 2013 / published online November 22, 2013
Attempts to crystallize the sodium chromium alum, NaCr(SO4)2(H2O)12, from water/methanol solutions at temperatures around 281 K yielded crystals of the title compound instead. Their monoclinic structure can be described as a centered rectangular array of linear {1}[Na(SO4)2]3− rods aligned parallel to [001] with vicinal rods held together by columns of isolated [Cr(H2O)6]3+ complexes. The structure forms channels parallel to [001] which are occupied by methanol and water molecules with atomic site occupancy factors of 1/5 and less. Various attempts to crystallize the compound or the sodium chromium alum from purely aqueous solutions remained unsuccessful.
Key words: Chromium Alums, Double Salt, Crystal Growth, Crystal Structure
Full-text PDF