A new polymorph of magnesium oxalate dihydrate

Abstract

In the asymmetric unit of the title compound, catena-poly[[diaquamagnesium(II)]-μ-oxalato], [Mg(C2O4)(H2O)2]n, there is one Mg atom in an octahedral coordination with site symmetry 222, a unique C atom of the oxalate anion lying on a twofold axis, an O atom of the anion in a general position and a water O atom at a site with imposed twofold rotation symmetry. The Mg2+ ions are ligated by water molecules and bridged by the anions to form chains that are held together by O—H...O hydrogen bonds. The structure of the title compound has already been reported in a different space group [Lagier, Pezerat & Dubernat (1969). Rev. Chim. Miner. 6, 1081–1093; Levy, Perrotey & Visser (1971). Bull. Soc. Chim. Fr. pp. 757–761].