Crystal Research and Technology
Cryst. Res. Technol. 42, 98 (2007) - Abstract -

Synthesis and crystal structure of hexaaquamagnesium hydrogen phosphododecatungstate tetrahydrate [Mg(H2O)6][HPW12O40].4H2O

A. Kremenovic, D. Poleti*, N. Ghermani***, L. Karanovic, U. B. Mioč**, Z. Nedic**, and A. Spasojevic-de Biré***

Department of Crystallography, Faculty of Mining and Geology, University of Belgrade, Đušina 7, 11000 Belgrade, Serbia and Montenegro
*Faculty of Technology and Metallurgy, University of Belgrade, Karnegijeva 4, 11000 Belgrade, Serbia and Montenegro
**Faculty of Physical Chemistry, University of Belgrade, P.O. Box 137, 11001 Belgrade, Serbia and Montenegro
***SPMS, UMR 8580 CNRS Ecole Centrale Paris, 1 Grande Voie des Vignes, 92295 Châtenay-Malabry, France

Keywords polyoxometalates, tungsten, magnesium, solid-state structures
PACS 61.10.Nz, 61.50.-f, 61.66.Fn, 61.68.+n
DOI 10.1002/crat.200610778

Crystals suitable for X-ray structure analysis were obtained after the slow evaporation of the reaction mixture containing equimolar quantities of magnesium chloride and dodecatungstophosphoric acid aqueous solution insuring pH of the solution between 1.0 and 1.2. This simple synthetic route yielded stability of Keggin anion and high quality [Mg(H2O)6][HPW12O40].4H2O single crystals. The obtained compound belong to the group of heteropoly compounds and its structure is composed of Keggin [PW12O40]3– anions, [Mg(H2O)6]2+ cations and lattice water molecules. Zigzag arrangement of Keggin anions along c-axis creates irregular channels occupied by [Mg(H2O)6]2+ cations and lattice H2O molecules. The calculation of the total potential solvent area indicated the presence of 4.1 H2O lattice molecules per formula unit, which is in agreement with the here presented structural model. The position of one lattice water molecule is well defined, while each of three other molecules is statistically distributed over two locations. Hydrogen bonds involve all coordinated and lattice H2O molecules, as well as some oxygens from the Keggin anion.




The full text of this paper in pdf-Format:

If you have come directly to this page, click this symbol to go to the CRT homepage.