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A revision is presented of the restrained Rietveld analysis of the crystal structure of magnesium perchlorate tetrahydrate, Mg(ClO4)2·4H2O, recently published by Robertson & Bish [(2010), Acta Cryst. B66, 579-584]. The actual symmetry of the material is shown to be C2/m. The corrected structure model is refined by the derivative difference method [Solovyov (2004). J. Appl. Cryst. 37, 743-749], anisotropically for all non-H atoms and isotropically for two independent H atoms without restraints.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S0108768111054371/kd5057sup1.cif
Contains datablock I

rtv

Rietveld powder data file (CIF format) https://doi.org/10.1107/S0108768111054371/kd5057sup2.rtv
Contains datablock profile

txt

Text file https://doi.org/10.1107/S0108768111054371/kd5057sup3.txt
DDM parameter file

txt

Text file https://doi.org/10.1107/S0108768111054371/kd5057sup4.txt
DDM data file

pdf

Portable Document Format (PDF) file https://doi.org/10.1107/S0108768111054371/kd5057sup5.pdf
Extra tables and ellipsoid plot

Computing details top

Program(s) used to refine structure: DDM.

(I) top
Crystal data top
Cl2H8MgO12V = 504.46 (3) Å3
Mr = 295.26Z = 2
Monoclinic, C2/mDx = 1.945 Mg m3
Hall symbol: -C 2YCu Kα radiation, λ = 1.5406, 1.5444 Å
a = 11.4802 (2) ÅT = 348 K
b = 8.0016 (4) Åwhite
c = 5.9363 (2) Åflat_sheet, 10 × 14 mm
β = 112.3169 (8)°
Data collection top
Specimen mounting: Ni-Cr plated copper front-loaded sample mountScan method: step
Data collection mode: reflection2θmin = 10.000°, 2θmax = 85.000°, 2θstep = 0.017°
Refinement top
Least-squares matrix: full4417 data points
Rwp = 0.05576 parameters
Rexp = 0.0160 restraints
RBragg = 0.011(Δ/σ)max = 0.005
R(F) = 0.020
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
Cl0.2974 (2)0.000000.3935 (5)0.0373
Mg0.000000.000000.000000.0255
O10.1627 (3)0.000000.3207 (6)0.0461
O20.3321 (2)0.1458 (3)0.3056 (6)0.1046
O30.3507 (3)0.000000.6526 (8)0.0696
O40.000000.2513 (5)0.000000.0566
O50.1013 (4)0.000000.2218 (9)0.0567
H10.036 (5)0.312 (4)0.121 (6)0.095 (15)*
H20.124 (2)0.099 (4)0.222 (6)0.079 (17)*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Cl0.023 (2)0.042 (2)0.046 (3)0.00000.0127 (19)0.0000
Mg0.025 (2)0.037 (3)0.018 (3)0.00000.0116 (19)0.0000
O10.014 (4)0.099 (4)0.021 (4)0.00000.001 (3)0.0000
O20.102 (4)0.091 (2)0.138 (4)0.033 (2)0.064 (3)0.040 (2)
O30.049 (5)0.092 (4)0.036 (4)0.00000.021 (3)0.0000
O40.078 (6)0.033 (5)0.047 (4)0.00000.010 (5)0.0000
O50.054 (4)0.090 (6)0.045 (3)0.00000.041 (2)0.0000
Geometric parameters (Å, º) top
Cl—O11.440 (4)Mg—O42.011 (4)
Cl—O21.397 (4)Mg—O52.061 (6)
Cl—O31.423 (5)O4—H10.83 (3)
Mg—O12.100 (3)O5—H20.83 (3)
O1—Cl—O2108.34 (15)O1—Mg—O5ii93.22 (14)
O1—Cl—O3107.2 (3)Mg—O4—H1126 (2)
O2—Cl—O2i113.3 (4)H1—O4—H1ii109 (4)
O2—Cl—O3109.72 (17)Mg—O5—H2104 (3)
O1—Mg—O586.78 (14)H2—O5—H2i144 (4)
Symmetry codes: (i) x, y, z; (ii) x, y, z.
 

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