CRYSTAL STRUCTURES OF NEW DOUBLE HYDROGEN PHOSPHATES WITH ENORMOUS UNIT CELLS. N.Anisimova, A.Ilyukhin, and N.Chudinova, Institute of General and Inorganic Chemistry, Russian Academy of Science, Moscow 117907, Russia

Recently published [1] the direct method for the synthesis of cyclododecaphosphates (the biggest inorganic phosphate ring) includes the consistent thermal condensation of double cesium iron hydrogen monophosphate into cyclododecaphosphate Cs₃Fe₃P_l20₃₆. In the work [1] the previously unknown substance CsFeH₅(PO₄)₃ was firstly obtained and used as a starting material. The present work reports its crystal structure as well as the previously unknown structure of NaFe(H₂PO₄)₂HPO_{4[[dotaccent]]}H₂0. Unit cells of both compounds are characterized by the large dimensions unusual for other known inorganic hydrogen phosphates. The main structural elements of the structures of CsFeH₅(PO₄)₃ (R=0,029; Pna2₁, Z=12; a=27.18(1), b= 9.081(3), c=12.808(4) Å) and of NaFe(H₂PO₄)₂HPO₄H₂0 (R=0,036; Pbcn, Z=8; a=8.7291(7), b=12.4954(8), c= 18.944(1) Å) are the channels formed by PO₄-tetrahedra and FeO6-octahedra. Cs and Na atoms are placed inside the channels. Due to their specific structures both compounds are essential for the formation of new complex phosphate anions.

Acknowledgments: RFBR, DFG.

[1] U. Sckülke, N.Anisimova, and P.Neumann, Z.anorg.allg.chem., 1996, in print.