CsGa(H_1.5AsO₄)₂(H₂AsO ₄) and isotypic CsCr(H_1.5AsO₄) ₂(H₂AsO₄): Decorated kröhnkite-like chains in two unusual hydrogen arsenates

Author(s)

Karolina Schwendtner, Uwe Kolitsch

Abstract

Hydrothermally synthesized caesium gallium(III) hydrogen arsenate(V), CsGa(H1.5AsO4)2(H2AsO4), (I), and isotypic caesium chromium(III) hydrogen arsenate(V), CsCr(H 1.5AsO4)2(H2AsO4), (II), represent a new structure type and stoichiometry among MI-M III hydrogen arsenates. The crystal structure, determined from single-crystal X-ray diffraction data, is based on an infinite octahedral-tetrahedral chain and can be described as a decorated kröhnkite-like chain. The chains extend parallel to [100] and are separated by tencoordinated Cs atoms. The hydrogen-bonding scheme comprises one very short symmetry-restricted hydrogen bond, with O⋯O distances of 2.519 (4) and 2.508 (4) Å in (I) and (II), respectively, and two further medium-strong hydrogen bonds, all of which reinforce the connections between adjacent chains. The average Ga-O and Cr-O bond lengths are 1.973 (15) and 1.980 (13) A, respectively, and the average As-O bond lengths in the two protonated arsenate groups lie within a very narrow range [1.690 (18)-1.69 (3) Å]. The Cs atom is located on a centre of inversion, while the MIII and As2 atoms lie on twofold axes. Relationships to CaBa2(HPO 4)2(H2PO4)2 and other compounds containing decorated kröhnkite-type or kröhnkite-like chains are discussed. © 2005 International Union of Crystallography. © 2005 International Union of Crystallography.

Organisation(s)

Department of Mineralogy and Crystallography

Journal

Acta Crystallographica. Section C: Crystal Structure Communications

Volume

61

ISSN

0108-2701

DOI

https://doi.org/10.1107/S0108270105023243

Publication date

2005

Peer reviewed

Yes

Austrian Fields of Science 2012

1051 Geology, Mineralogy

Portal url

https://ucrisportal.univie.ac.at/en/publications/0207441d-b621-4324-8edd-ab1f9cd81e34