The isotypic hydrogen phosphate and arsenate dihydrates M2HXO4·2H2O (M = Rb, Cs; X = P, As). Issue 1 (15th January 2014)

• Record Type: Journal Article
• Authors: Stöger, Berthold; Weil, Matthias
• Is Part Of: Acta crystallographica. Volume 70:Issue 1(2014:Jan.)
• Page Start: 7
• Page End: 11
• Publication Date: 2014-01-15
• Subjects: Crystallography -- Periodicals; Crystals -- Periodicals; 548.3
• DOI: 10.1107/S205322961303338X
• Languages: English
• ISSNs: 2053-2296

Abstract

<abstract abstract-type="main" xml:lang="en"> <title> <x xml:space="preserve">Abstract</x> </title> <p>The four isotypic alkaline metal monohydrogen arsenate(V) and phosphate(V) dihydrates <italic>M</italic><sub>2</sub>H<italic>X</italic>O<sub>4</sub>·2H<sub>2</sub>O (<italic>M</italic> = Rb, Cs; <italic>X</italic> = P, As) [namely dicaesium monohydrogen arsenate(V) dihydrate, Cs<sub>2</sub>HAsO<sub>4</sub>·2H<sub>2</sub>O, dicaesium monohydrogen phosphate(V) dihydrate, Cs<sub>2</sub>HPO<sub>4</sub>·2H<sub>2</sub>O, dirubidium monohydrogen arsenate(V) dihydrate, Rb<sub>2</sub>HAsO<sub>4</sub>·2H<sub>2</sub>O, and dirubidium monohydrogen phosphate(V) dihydrate, Rb<sub>2</sub>HPO<sub>4</sub>·2H<sub>2</sub>O] were synthesized by reaction of an aqueous H<sub>3</sub><italic>X</italic>O<sub>4</sub> solution with one equivalent of aqueous <italic>M</italic><sub>2</sub>CO<sub>3</sub>. Their crystal structures are made up of undulating chains extending along [001] of tetrahedral [<italic>X</italic>O<sub>3</sub>(OH)]<sup>−</sup> anions connected <italic>via</italic> strong O—H...O hydrogen bonds. These chains are in turn connected into a three‐dimensional network <italic>via</italic> medium‐strength hydrogen bonding involving the water molecules. Two crystallographically different <italic>M</italic><sup>+</sup> cations are located in channels running along [001] or in the free space of the [<italic>X</italic>O<sub>3</sub>(OH)]<sup>−</sup> chains, respectively. They are coordinated by eight and twelve O atoms forming irregular polyhedra. The structures possess pseudosymmetry. Due to the ordering of the protons in the [<italic>X</italic>O<sub>3</sub>(OH)]<sup>−</sup> chains in the actual structures, the symmetry is reduced from <italic>C</italic>2/<italic>c</italic> to <italic>P</italic>2<sub>1</sub>/<italic>c</italic>. Nevertheless, the deviation from <italic>C</italic>2/<italic>c</italic> symmetry is minute.</p> </abstract>