Redetermination of kovdorskite, Mg(2)PO(4)(OH)·3H(2)O.

Shaunna M Morrison,Hexiong Yang,Robert T Downs

doi:10.1107/s1600536812000256

Shaunna M Morrison, Hexiong Yang + Show 1 more

Open Access

https://doi.org/10.1107/s1600536812000256

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Abstract

The crystal structure of kovdorskite, ideally Mg2PO4(OH)·3H2O (dimagnesium phosphate hydroxide trihydrate), was reported previously with isotropic displacement paramaters only and without H-atom positions [Ovchinnikov et al. (1980 ▶). Dokl. Akad. Nauk SSSR. 255, 351–354]. In this study, the kovdorskite structure is redetermined based on single-crystal X-ray diffraction data from a sample from the type locality, the Kovdor massif, Kola Peninsula, Russia, with anisotropic displacement parameters for all non-H atoms, with all H-atom located and with higher precision. Moreover, inconsistencies of the previously published structural data with respect to reported and calculated X-ray powder patterns are also discussed. The structure of kovdorskite contains a set of four edge-sharing MgO6 octahedra interconnected by PO4 tetrahedra and O—H⋯O hydrogen bonds, forming columns and channels parallel to [001]. The hydrogen-bonding system in kovdorskite is formed through the water molecules, with the OH− ions contributing little, if any, to the system, as indicated by the long H⋯A distances (>2.50 Å) to the nearest O atoms. The hydrogen-bond lengths determined from the structure refinement agree well with Raman spectroscopic data.

Highlights

The crystal structure of kovdorskite, ideally Mg2PO4(OH)3H2O, was reported previously with isotropic displacement paramaters only and without H-atom positions [Ovchinnikov et al (1980)
The structure of kovdorskite contains a set of four edge-sharing MgO6 octahedra interconnected by PO4 tetrahedra and O—H O hydrogen bonds, forming columns and channels parallel to [001]
The hydrogen-bonding system in kovdorskite is formed through the water molecules, with the OH ions contributing little, if any, to the system, as indicated by the long H A distances (>2.50 Å) to the nearest O atoms

Summary

Crystal data

The crystal structure of kovdorskite, ideally Mg2PO4(OH)3H2O (dimagnesium phosphate hydroxide trihydrate), was reported previously with isotropic displacement paramaters only and without H-atom positions [Ovchinnikov et al (1980). The kovdorskite structure is redetermined based on single-crystal. The structure of kovdorskite contains a set of four edge-sharing MgO6 octahedra interconnected by PO4 tetrahedra and O—H O hydrogen bonds, forming columns and channels parallel to [001]. The hydrogen-bonding system in kovdorskite is formed through the water molecules, with the OH ions contributing little, if any, to the system, as indicated by the long H A distances (>2.50 Å) to the nearest O atoms. The hydrogen-bond lengths determined from the structure refinement agree well with Raman spectroscopic data.

Data collection

Special details