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Ludmila S. Ivashkevich, Kirill A. Selevich, Anatoly I. Lesnikovich, Anatoly F. Selevich, Alexander S. Lyakhov

Two isostructural manganese (III) diphosphates, acid α-MnHP₂O₇ and double MnLiP₂O₇: crystal structure determination from X-ray powder diffraction data

Keywords: Diphosphates, Powder diffraction structure analysis, X-ray diffraction

Ab initio crystal structure determination of the α form of MnHP₂O₇ and Rietveld refinement of the MnLiP₂O₇ structure were performed using powder X-ray diffraction data. The final structures have been obtained using soft restraints on interatomic bond lengths and bond angles for the diphosphate group. The two compounds were found to be to a great extent isostructural. They crystallize in the monoclinic space group P2₁, Z = 2, a = 6.7547(6), b = 8.3160(7), c = 4.8769(5) Å, β = 113.1791(18)°, R_p = 0.0283, R_wp = 0.0390, R _Bragg = 0.0930, R_F = 0.0869 for α-MnHP 2₂O₇, and a = 7.0018(5), b = 8.1616(6), c = 4.7267(4)Å, β = 109.404(3)°, R_p = 0.0307, R_wp = 0.0423, R_Bragg = 0.0960, R_F = 0.0861 for MnLiP₂O₇. In both compounds, diphosphate groups adopt nearly eclipsed configuration. Their structures present three-dimensional networks, which have tunnels including the lithium cations or hydrogen atoms. The behaviour of the crystalline forms of MnHP₂O₇ in H/Li exchange reactions is discussed, vs. their structural aspects.

Zeitschrift für Kristallographie, Oldenbourg Wissenschaftsverlag

Print ISSN: 0044-2968
Volume: 221, 02/2006
Pages: 115 - 121

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