title: The diphyllosilicate Rb2(VO)2[Si8O19].
abstract: Dirubidium divanadyl phyllooctasilicate, Rb(2)(VO)(2)[Si(8)O(19)], is the first known anhydrous diphyllosilicate containing V(IV). The structure consists of silicate double layers which are separated by [V(2)O(8)](8-) dimers and is related to that of the compounds A(2)Cu(2)[Si(8)O(19)] (A = Rb or Cs), although the title compound crystallizes in a noncentrosymmetric orthorhombic space group. The silicate double layers contain four tetrahedrally coordinated Si sites in general positions and 12 O sites, nine in general positions and the other three on mirror planes. The vanadyl dimers have two square-pyramidally coordinated V sites (site symmetry m). There are two different 10- and 12-fold coordinated Rb sites with site symmetry m, one of which is a split position located between the dimers in the interlayer space, while the other is in a channel within the silicate layer.
authors.affiliation: Institut für Kristallographie der RWTH Aachen, Jägerstrasse 17-19, 52066 Aachen, Germany. prinz@xtal.rwth-aachen.de
authors.forename: Sebastian
authors.initials: S
authors.lastname: Prinz
authors.forename: Karine M
authors.initials: KM
authors.lastname: Sparta
authors.forename: Georg
authors.initials: G
authors.lastname: Roth