The Crystal Structure of LiZn2P3O10 8H2O

Abstract

The crystal structure of LiZn₂P₃O₁₀ 8H₂O has been determined from three-dimensional X-ray diffraction data collected on dicolet R3 four-circle diffractometer with CuK-radiation. In the region from 20 up to 110° 2016 independent reflections were obtained. Single crystals suitable for X-ray investigation were grown by slow evaporation from the 0.1 mol solution of the composition Li₅P₃O₁₀: Zn (NO₃)₂=1 : 1 at 278 K. The compound belongs to the triclinic space group P1 with cell parameters: a=10.305(1), b=10.505(1), c=8.671(1) Å, α=101.79(1), β=113.42(1), y=94.24(1)°, v=830.5 ų, δ_calc= =2.14 g/cm³, Z=2. The structure was solved by the heavy atom method. The positions of zinc atoms in the unit cell were determined from three-dimensional Patterson function. All other non-hydrogen atoms were located by successive Fourier synthesis. After the last refinement cycles using anisotropic thermal parameters the R value converged to R=0.042 and R_W =0.050. The bonding of the triphosphate group to the zinc atoms in this structure is bidentate. Zinc atoms have three crystallographically different positions. The tetrahedral coordination two of them is completed by oxygen atoms from triphosphate groups. The third one is octohedrally coordinated by four oxygen atoms from P₃O₁₀ ^5- groups and by two oxygens from water molecules. The tetrahedron of lithium ion is completed by water molecules only. Bond lengths and angles within P₃O₁₀ ^5- group are not fundamentally different from those found in similar chain anions. Zn-0 distances range between 1.938 and 2.141 Å while Li-O distances-between 1.939 and 1.969 Å.