Second update on compounds with kröhnkite-type chains
- Author(s)
- Uwe Kolitsch, Michel Fleck
- Abstract
The crystal structures of five new synthetic double salt dihydrates have been determined from single-crystal X-ray diffraction data. The following three selenate(VI), sulphate(VI) and chromate(VI) compounds all contain krošhnkite-[Na2Cu(SO4)2 ž 2 H 2O]-type infinite tetrahedral-octahedral chains: K 2Zn(SeO4)2 ž 2 H2O (a = 5.571(1), b = 6.586(1), c = 7.458(2) A°, a = 111.14(3), ß = 96.35(3), ? = 106.15(3)°, V = 238.26(8) A°3, R(F) = 0.037, space group P1, no. 2, Z = 1), K2Co(SO4) 2 ž 2 H2O (a = 5.327(1), b = 6.566(1), c = 7.256(2) A°, a = 110.74(3), ß = 95.00(3), ? = 107.02(3)°, V = 221.72(8) A°3, R(F) = 0.037, space group P1, no. 2, Z = 1), Rb2Cd(CrO4)2 ž 2 H2O (a = 6.852(1), b = 7.706(2), c = 11.362(2) A°, a = 73.07(3), ß = 75.11(3), ? = 69.63(3)°, V = 529.88(18) A°3, R(F) = 0.026, space group P1, no. 2, Z = 2). The crystal structures of the two remaining compounds, the isotypic dichromates K2Co(Cr 2O7)2 ž 2 H2O and Cs 2Cd(Cr2O7)2 ž 2 H 2O (a = 6.801(1)/7.368(1), b = 7.723(1)/8.051(2), c = 7.814(1)/ 8.047(2) A°, a = 89.23(3)/88.68(3), ß = 81.05(3)/81.12(3), ? = 64.39(3)/63.81(3)°, V = 364.93(14)/422.66(16) A°3, R(F) = 0.022/0.025, space group P1, no. 2, Z = 1) are closely related to those of krošhnkite-type compounds; the structure contains Cr2O 7 groups assuming the same bridging role that XO4 groups have in krošhnkite-type oxysalts. Both dichromates are isotypic with their K-Zn- and K-Cd-analogues although the hydrogen bonding scheme in Cs 2Cd(Cr2O7)2 ž 2 H 2O is completely different. The atomic arrangements of the five new compounds are described and unusual features are pointed out. Structural relations with other krošhnkite-type and -like minerals and compounds are discussed with respect to our previously proposed classification (Fleck et al., 2002; Fleck and Kolitsch, 2003). The compound Rb2Cd(CrO 4)2 ž 2 H2O represents both the first krošhnkite-type rubidium compound and the first chromate with structure type D. Cs2Cd(Cr2O7)2 ž 2 H 2O is the first caesium compound known to contain krošhnkite-like chains. Œ by Oldenbourg Wissenschaftsverlag, Mušnchen.
- Organisation(s)
- Department of Mineralogy and Crystallography
- Journal
- Zeitschrift für Kristallographie : international journal for structural, physical, and chemical aspects of crystalline materials
- Volume
- 220
- Pages
- 31-41
- No. of pages
- 11
- ISSN
- 0044-2968
- Publication date
- 2005
- Peer reviewed
- Yes
- Austrian Fields of Science 2012
- 105113 Crystallography, 104006 Solid state chemistry, 1051 Geology, Mineralogy
- Portal url
- https://ucrisportal.univie.ac.at/en/publications/a79dfac0-76f1-4dd6-8f05-d38c6ea73e86