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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—HO 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].
For related literature, see: Basso et al. (1997 ); Caric (1959 ); Deyrieux et al. (1973 ); Echigo et al. (2005 ); Huang & Mak (1990 ); Lagier et al. (1969 ); Le Page (1987 ); Lethbridge et al. (2003 ); Levy et al. (1971 ); Neder et al. (1997 ); Schefer & Grube (1995 ); Tazzoli & Domeneghetti (1980 ); Vanhoyland, Bouree et al. (2001 ); Vanhoyland, Van Bael et al. (2001 ).
Data collection: Rigaku/AFC Diffractometer Control Software (Rigaku, 1994 ); cell refinement: Rigaku/AFC Diffractometer Control Software; data reduction: Rigaku/AFC Diffractometer Control Software; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ); molecular graphics: ATOMS (Dowty, 1999 ); software used to prepare material for publication: SHELXL97.
Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536808015870/pv2083sup1.cif
Structure factors: contains datablocks I. DOI: 10.1107/S1600536808015870/pv2083Isup2.hkl
This work was supported by the Funding Project for Academic Human Resources Development in Institutions of Higher Learning under the jurisdiction of Beijing Municipality.
β-Mg(C2O4).2H2O was first obtained from a hydrothermal reaction in an attempt to prepare novel hydrated borates. For the preparation of MgB6O10, a stoichiometric mixture of MgO and B2O3 was heated at 873 K for two weeks with several intermediate re-mixings and the resulting product was identified to be the pure phase of MgB6O10 based on the powder XRD analysis. A 0.300 g (3.376 mmol) sample of MgB6O10, 3 ml pyridine, 0.5 ml 14.5 M (65%) HNO3, and 0.5 ml H2O were sealed in an 15-ml Teflon-lined autoclave and subsequently heated at 453 K for one week, then cooled slowly to room temperature. The product consisted of colorless, block-like crystals with the largest having dimensions of 0.6 × 0.6 × 0.8 mm3 in pale yellow mother liquor. The final pH of the reaction system was about 1.0. The crystals were isolated in about 30% yield (based on Mg) by washing the reaction product with deionized water and anhydrous ethanol followed by drying with anhydrous acetone. X-ray structural analysis indicated that the formula of this compound may be Mg(C2O4).2H2O. It is unclear how the oxalate groups are formed.
Subsequently, a separate set of experiments was conducted, in which the starting materials were: 0.2718 g (6.7403 mmol) MgO, 0.8497 g (6.7400 mmol) H2(C2O4).2H2O, and 3 ml H2O, and the heating and isolation procedures were the same as those described above. The reaction resulted in pure colorless crystals. The powder XRD pattern of the ground crystals in this experiment was in good agreement with that calculated from the single-crystal data of Mg(C2O4).2H2O from the former experiment, confirming that the same phase had been obtained.
H-atom positions were located in a difference Fourier map and all associated parameters were refined freely.
|[Mg(C2O4)(H2O)2]||F000 = 608|
|Mr = 148.36||Dx = 1.870 Mg m−3|
|Orthorhombic, Fddd||Mo Kα radiation λ = 0.71073 Å|
|Hall symbol: -F 2uv 2vw||Cell parameters from 25 reflections|
|a = 5.3940 (11) Å||θ = 13.0–19.6º|
|b = 12.691 (3) Å||µ = 0.29 mm−1|
|c = 15.399 (3) Å||T = 290 K|
|V = 1054.1 (4) Å3||Block, colourless|
|Z = 8||0.30 × 0.20 × 0.15 mm|
|Rigaku AFC-7R diffractometer||Rint = 0.054|
|Radiation source: fine-focus sealed tube||θmax = 32.5º|
|Monochromator: graphite||θmin = 4.2º|
|T = 290 K||h = 0→8|
|2θ/ω scans||k = 0→19|
|Absorption correction: ψ scan(Kopfmann & Huber, 1968)||l = 0→23|
|Tmin = 0.915, Tmax = 0.962||3 standard reflections|
|1110 measured reflections||every 150 reflections|
|483 independent reflections||intensity decay: 1.1%|
|321 reflections with I > 2σ(I)|
|Refinement on F2||Secondary atom site location: difference Fourier map|
|Least-squares matrix: full||Hydrogen site location: difference Fourier map|
|R[F2 > 2σ(F2)] = 0.034||All H-atom parameters refined|
|wR(F2) = 0.110||w = 1/[σ2(Fo2) + (0.0683P)2] where P = (Fo2 + 2Fc2)/3|
|S = 0.97||(Δ/σ)max < 0.001|
|483 reflections||Δρmax = 0.89 e Å−3|
|27 parameters||Δρmin = −0.48 e Å−3|
|Primary atom site location: structure-invariant direct methods||Extinction correction: none|
|Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes.|
|Refinement. Refinement of F2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F2, conventional R-factors R are based on F, with F set to zero for negative F2. The threshold expression of F2 > 2sigma(F2) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F2 are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger.|
|C1||0.8750||0.3750||0.32406 (10)||0.0153 (3)|
|O1||0.66783 (15)||0.37630 (11)||0.28779 (5)||0.0202 (3)|
|O2||0.3750||0.53689 (11)||0.3750||0.0343 (4)|
|H2||0.399 (6)||0.578 (2)||0.3335 (16)||0.050 (7)*|
|Mg1||0.0117 (4)||0.0237 (4)||0.0136 (4)||0.000||0.000||0.000|
|C1||0.0149 (6)||0.0199 (6)||0.0110 (6)||−0.0001 (8)||0.000||0.000|
|O1||0.0145 (4)||0.0342 (5)||0.0120 (4)||0.0012 (4)||−0.0014 (3)||−0.0018 (4)|
|O2||0.0631 (11)||0.0228 (7)||0.0169 (6)||0.000||0.0086 (10)||0.000|
|Mg1—O2i||2.0546 (15)||Mg1—O1||2.0734 (9)|
|Mg1—O2||2.0546 (15)||C1—O1||1.2494 (11)|
|Mg1—O1i||2.0734 (9)||C1—O1iv||1.2494 (11)|
|Mg1—O1ii||2.0734 (9)||C1—C1v||1.569 (3)|
|Mg1—O1iii||2.0734 (9)||O2—H2||0.84 (3)|
|O2i—Mg1—O1i||89.55 (4)||O2—Mg1—O1||89.55 (4)|
|O2—Mg1—O1i||90.45 (4)||O1i—Mg1—O1||99.26 (5)|
|O2i—Mg1—O1ii||89.55 (4)||O1ii—Mg1—O1||80.75 (5)|
|O2—Mg1—O1ii||90.45 (4)||O1iii—Mg1—O1||179.09 (8)|
|O1i—Mg1—O1ii||179.09 (7)||O1—C1—O1iv||126.89 (14)|
|O2i—Mg1—O1iii||90.45 (4)||O1—C1—C1v||116.56 (7)|
|O2—Mg1—O1iii||89.55 (4)||O1iv—C1—C1v||116.56 (7)|
|O1i—Mg1—O1iii||80.75 (5)||C1—O1—Mg1||113.06 (8)|
|O1ii—Mg1—O1iii||99.26 (5)||Mg1—O2—H2||128.7 (19)|
Symmetry codes: (i) −x+3/4, −y+3/4, z; (ii) x, −y+3/4, −z+3/4; (iii) −x+3/4, y, −z+3/4; (iv) −x+7/4, −y+3/4, z; (v) −x+7/4, y, −z+3/4.
|O2—H2···O1vi||0.84 (3)||1.97 (2)||2.761 (1)||158 (2)|
Symmetry codes: (vi) x−1/4, y+1/4, −z+1/2.
Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: PV2083).