title: A new polymorph of magnesium oxalate dihydrate.
abstract: In the asymmetric unit of the title compound, catena-poly[[diaqua-magnesium(II)]-μ-oxalato], [Mg(C(2)O(4))(H(2)O)(2)](n), there is one Mg atom in an octa-hedral 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 Mg(2+) ions are ligated by water mol-ecules 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].
authors.forename: Xue-An
authors.initials: XA
authors.lastname: Chen
authors.forename: Fang-Ping
authors.initials: FP
authors.lastname: Song
authors.forename: Xin-An
authors.initials: XA
authors.lastname: Chang
authors.forename: He-Gui
authors.initials: HG
authors.lastname: Zang
authors.forename: Wei-Qiang
authors.initials: WQ
authors.lastname: Xiao