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

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


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)°, Rp = 0.0283, Rwp = 0.0390, RBragg = 0.0930, RF = 0.0869 for α-MnHP 22O7, and a = 7.0018(5), b = 8.1616(6), c = 4.7267(4)Å, β = 109.404(3)°, Rp = 0.0307, Rwp = 0.0423, RBragg = 0.0960, RF = 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.

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Zeitschrift für Kristallographie – Crystalline Materials offers a place for researchers to present results of their crystallographic studies. The journal includes theoretical as well as experimental research. It publishes Original Papers, Letters and Review Articles in manifold areas of crystallography.