Crystal structure of CsLnFe(CN)(6)center dot 5H(2)O (Ln = Ce, Pr, Nd), CsCeFe(CN)(6)center dot 4H(2)O, and TlTmRu(CN)(6)center dot 3H(2)O

We have investigated the crystal structures of CsLnFe(CN)(6)(.)nH(2)O (Ln = lanthanide, n = 4,5), as well as TITm-Ru(CN)(6)(.)3H(2)O. These phases can be thought of as derivatives of LnFe(CN)(6)(.)4H(2)O, where, simultaneousl y, an alkali ion (or Tl+) is introduced while the valence of Fe is reduced from Fe3+ to Fe2+. A new arrangement of the structural units is observed in the CsLnFe(CN)(6)(.)-5H(2)O, where the coordination of the Ln-ion is chang ed to a bisdisphenoid. The resulting LnN(5)O(3) units alternate with Fe(CN) (6) units to form an overall rocksalt-type ralted lattice that accommodates the alkali ions in interstitial sites. Due to the arrangement of the water molecules, a layer structure results. (C) 2000 Editions scientifiques et m edicales Elsevier SAS. All rights reserved.