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 Cs3Fe3Pl2036. 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)2HPO4[[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.