Three new acid M⁺ arsenates and phosphates with multiply protonated As/PO₄ groups

Author(s)

Karolina Schwendtner, Uwe Kolitsch

Abstract

The crystal structures of caesium dihydrogen arsenate(V) bis[trihydrogen arsenate(V)], Cs(H2AsO4)(H3AsO4)2, ammonium dihydrogen arsenate(V) trihydrogen arsenate(V), NH4(H2AsO4)(H3AsO4), and dilithium bis(dihydrogen phosphate), Li2(H2PO4)2, were solved from single-crystal X-ray diffraction data. NH4(H2AsO4)(H3AsO4), which was hydrothermally synthesized (T = 493 K), is homeotypic with Rb(H2AsO4)(H3AsO4), while Cs- (H2AsO4)(H3AsO4)2 crystallizes in a novel structure type and Li2(H2PO4)2 represents a new polymorph of this composition. The Cs and Li compounds grew at room temperature from highly acidic aqueous solutions. Li2(H2PO4)2 forms a three-dimensional (3D) framework of PO4 tetrahedra sharing corners with Li2O6 dimers built of edge-sharing LiO4 groups, which is reinforced by hydrogen bonds. The two arsenate compounds are characterized by a 3D network of AsO4 groups that are connected solely via multiple strong hydrogen bonds. A statistical evaluation of the As-O bond lengths in singly, doubly and triply protonated AsO4 groups gave average values of 1.70 (2) A ° for 199 As-OH bonds, 1.728 (19) A ° for As-OH bonds in HAsO4 groups, 1.714 (12) A ° for As-OH bonds in H2AsO4 groups and 1.694 (16) A ° for As-OH bonds in H3AsO4 groups, and a grand mean value of 1.667 (18) A ° for As-O bonds to nonprotonated O atoms.

Organisation(s)

Department of Mineralogy and Crystallography

External organisation(s)

Technische Universität Wien, Naturhistorisches Museum Wien (NHM)

Journal

Acta Crystallographica. Section C: Structural Chemistry

Volume

C75

Pages

1134-1141

No. of pages

8

ISSN

2053-2296

DOI

https://doi.org/10.1107/S2053229619008489

Publication date

08-2019

Peer reviewed

Yes

Austrian Fields of Science 2012

104011 Materials chemistry, 105113 Crystallography

Keywords

ASJC Scopus subject areas

Condensed Matter Physics, Materials Chemistry, Inorganic Chemistry, Physical and Theoretical Chemistry

Portal url

https://ucrisportal.univie.ac.at/en/publications/282bfd95-d12b-42c4-ae6d-a6dd9b0ce691