Crystal structures and crystal chemical relationships of kröhnkite- and collinsite-type compounds Na2Me²⁺(XO₄)₂ · 2 H₂O (X = S, Me = Mn, Cd; and X = Se, Me = Mn, Co, Ni, Zn, Cd) and K₂Co(SeO₄)₂ · 2 H₂O

Author(s)

Manfred Wildner, Donka Stoilova

Abstract

The crystal structures of eight compounds with compositions A2Me2+(XO4)2 · 2H2O (A = Na, X = S, Me2+ = Mn, Cd; A = Na, X = Se, Me2+ = Mn, Co, Ni, Zn, Cd; and A = K, X = Se, Me2+ = Co) were investigated using single crystal X-ray CCD diffraction data. The Mn- and Cd-compounds crystallize in the monoclinic kröhnkite structure type [Na2Cu(SO4)2 · 2 H2O, space group P21/c], the Co-, Ni-, and Zn-selenates in the closely related triclinic structure type of collinsite [Ca2Mg(PO4)2 · 2 H2O, space group P1̅]. Both types are built up from infinite Me(XO4)2(H2O)2 chains, composed of MeO4(H2O)2 octahedra alternating with each two XO4 tetrahedra by sharing corners. A—O bonds and hydrogen bonds link the chains to layers and further on to the three-dimensional structures. The influence of the ionic radii of the various A, Me, and X cations on the distances between these structural units is discussed. Special attention is paid to polyhedral distortions as well as to individual peculiarities of the alkaline coordinations and the hydrogen bonding systems. Thus, the crystal chemical relationships between the two structure types as well as to isotypic copper compounds, which are characterized by the strong octahedral Jahn-Teller distortions, are elucidated.

Organisation(s)

Department of Mineralogy and Crystallography

External organisation(s)

Bulgarian Academy of Sciences (BAS)

Journal

Zeitschrift für Kristallographie : international journal for structural, physical, and chemical aspects of crystalline materials

Volume

218

Pages

201-209

No. of pages

9

ISSN

0044-2968

DOI

https://doi.org/10.1524/zkri.218.3.201.20751

Publication date

2003

Peer reviewed

Yes

Austrian Fields of Science 2012

1051 Geology, Mineralogy

Portal url

https://ucrisportal.univie.ac.at/en/publications/bb0ae771-91ae-487c-964c-2b23c081af1c