title: CsAl(H(2)AsO(4))(2)(HAsO(4)): a new monoclinic protonated arsenate with decorated kröhnkite-like chains.
abstract: The crystal structure of hydrothermally synthesized caesium aluminium bis[dihydrogen arsenate(V)] hydrogen arsenate(V), CsAl(H(2)AsO(4))(2)(HAsO(4)), was determined from single-crystal X-ray diffraction data collected at room temperature. The compound represents a new structure type that is characterized by decorated kröhnkite-like [100] chains of corner-sharing AlO(6) octahedra and AsO(4) tetrahedra. Ten-coordinated Cs atoms are situated between the chains, which are interconnected by five different hydrogen bonds [O...O = 2.569 (4)-2.978 (4) A]. All atoms are in general positions. CsAl(H(2)AsO(4))(2)(HAsO(4)) is very closely related to CsGa(H(1.5)AsO(4))(2)(H(2)AsO(4)) and isotypic CsCr(H(1.5)AsO(4))(2)(H(2)AsO(4)).
authors.affiliation: Universität Wien, Institut für Mineralogie und Kristallographie, Geozentrum, Althanstrasse 14, A-1090 Wien, Austria. karolina.schwendtner@univie.ac.at
authors.forename: Karolina
authors.initials: K
authors.lastname: Schwendtner
authors.forename: Uwe
authors.initials: U
authors.lastname: Kolitsch