Acta Cryst. (2005). E61, m1920-m1922  [ doi:10.1107/S1600536805027406 ]

Bis[hexaquamagnesium(II)] pyrazine-2,3,5,6-tetracarboxylate tetrahydrate

M. Gryz, W. Starosta and J. Leciejewicz

Abstract: The unit cell of the title compound, [Mg(H₂O)₆]₂(C₈N₂O₈)·4H₂O, contains two hexaquamagnesium(II) cations, one fully deprotonated pyrazine-2,3,5,6-tetracarboxylate [(2,3,5,6-PZTC)^4-] anion with its geometrical centre situated at the inversion centre and four solvent water molecules. The magnesium(II) ion is surrounded by six water molecules with their O atoms located at the apices of a fairly regular octahedron. Mg-O bond distances range from 2.036 (1) to 2.113 (1) Å (mean value 2.065 Å). The carboxylate groups are inclined to the pyrazine ring by 22.8 (1)and 99.1 (1)°. A three-dimensional network of hydrogen bonds is built up between the coordinated water molecules and the carboxylate O atoms.

Online 7 September 2005

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