Cs2Cr4O13: a new structure type among alkali tetrachromates.
Dicaesium tetrachromium(VI) tridecaoxide, Cs(2)Cr(4)O(13), contains finite [Cr(4)O(13)](2-) anions composed of four corner-linked CrO(4) tetrahedra. These anions are linked by Cs(+) cations whose Cs-O bond lengths range between 3.015 (2) and approximately 3.7 A. Although Cs(2)Cr(4)O(13) is not isotypic with its NH(4), K or Rb analogs, the [Cr(4)O(13)](2-) anions in all these compounds exhibit a similar zigzag-like geometry.
Kolitsch
Uwe
U
Universität Wien, Institut für Mineralogie und Kristallographie, Geozentrum, Althanstrasse 14, A-1090 Wien, Austria. uwe.kolitsch@univie.ac.at