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Volume 69 
Part 5 
Page i29  
May 2013  

Received 18 April 2013
Accepted 19 April 2013
Online 24 April 2013

Key indicators
Single-crystal X-ray study
T = 296 K
Mean [sigma](As-O) = 0.004 Å
H completeness 0%
Disorder in main residue
R = 0.029
wR = 0.058
Data-to-parameter ratio = 19.1
Details
Open access

Mg6.75(OH)3(H0.166AsO4)3(HAsO4), a member of the M1-xM'6(OH)3(H2x/3AsO4)3(HAsO4) family (M,M' = Co; Ni)

aInstitute for Chemical Technologies and Analytics, Division of Structural Chemistry, Vienna University of Technology, Getreidemarkt 9/164-SC, A-1060 Vienna, Austria
Correspondence e-mail: mweil@mail.zserv.tuwien.ac.at

In the structure of the title compound, magnesium hydroxide hydrogenarsenate (6.75/3/4), two different Mg2+ ions, one located on a site with symmetry 3m. (occupancy 3/4) and one on a general position, as well as two different AsO3(OH) tetrahedra (symmetry .m. with partial occupancy for the H atom for one, and symmetry 3m. with full occupancy for the H atom for the other) and one OH- ion (site symmetry .m.) are present. Both Mg2+ ions are octahedrally surrounded by O atoms. The MgO6 octahedra belonging to the partially occupied Mg2+ sites share faces, forming chains along [001]. The other type of MgO6 octahedra share corners and faces under formation of strands parallel to [001] whereby individual strands are linked through common corner atoms. The two types of AsO3(OH) tetrahedra interlink the strands and the chains, building up a three-dimensional framework resembling that of the mineral dumortierite. The OH groups were assigned on basis of bond-valence calculations and crystal chemical considerations.

Related literature

For the isotypic Co and Ni members of the M1-xM'6(OH)3(H2x/3AsO4)3(HAsO4) series, see: Hughes et al. (2003[Hughes, R. W., Gerrard, L. A., Price, D. J. & Weller, M. T. (2003). Inorg. Chem. 42, 4160-4164.]). For other reaction products obtained under the given or similar hydrothermal conditions, see: Weil (2004a[Weil, M. (2004a). Acta Cryst. E60, i25-i27.],b[Weil, M. (2004b). Z. Naturforsch. Teil B, 59, 859-864.]). For the crystal structure of dumortierite, see: Alexander et al. (1986[Alexander, V. D., Griffen, D. T. & Martin, T. J. (1986). Am. Mineral. 71, 786-794.]). The bond-valence method has been described by Brown (2002[Brown, I. D. (2002). In The Chemical Bond in Inorganic Chemistry: The Bond Valence Model. Oxford University Press.]).

Experimental

Crystal data
  • Mg6.75(OH)3(H0.166AsO4)3(HAsO4)

  • Mr = 772.31

  • Hexagonal, P 63 m c

  • a = 12.7651 (3) Å

  • c = 5.0844 (1) Å

  • V = 717.49 (3) Å3

  • Z = 2

  • Mo K[alpha] radiation

  • [mu] = 9.65 mm-1

  • T = 296 K

  • 0.30 × 0.02 × 0.02 mm

Data collection
  • Bruker APEXII CCD diffractometer

  • Absorption correction: multi-scan (SADABS; Bruker, 2008[Bruker (2008). APEX2, SAINT and SADABS. Bruker AXS Inc., Madison, Wisconsin, USA.]) Tmin = 0.160, Tmax = 0.830

  • 21473 measured reflections

  • 1144 independent reflections

  • 1066 reflections with I > 2[sigma](I)

  • Rint = 0.051

Refinement
  • R[F2 > 2[sigma](F2)] = 0.029

  • wR(F2) = 0.058

  • S = 1.21

  • 1144 reflections

  • 60 parameters

  • 1 restraint

  • H-atom parameters not refined

  • [Delta][rho]max = 1.31 e Å-3

  • [Delta][rho]min = -2.16 e Å-3

  • Absolute structure: Flack (1983[Flack, H. D. (1983). Acta Cryst. A39, 876-881.]), 446 Friedel pairs

  • Flack parameter: 0.022 (16)

Table 1
Selected bond lengths (Å)

Mg1-O1i 2.100 (5)
Mg1-O1ii 2.102 (5)
Mg1-Mg1iii 2.5422 (1)
Mg2-O2 2.018 (3)
Mg2-O2iv 2.029 (3)
Mg2-O5 2.036 (3)
Mg2-O3v 2.053 (2)
Mg2-O4 2.139 (3)
Mg2-O4ii 2.225 (3)
As1-O2 1.678 (2)
As1-O1 1.687 (4)
As1-O3 1.696 (3)
As2-O5 1.644 (3)
As2-O6ii 1.710 (8)
Symmetry codes: (i) x-1, y-1, z; (ii) [-x+1, -y+1, z+{\script{1\over 2}}]; (iii) [-x, -y, z+{\script{1\over 2}}]; (iv) [y, x, z+{\script{1\over 2}}]; (v) [x-y+1, x, z-{\script{1\over 2}}].

Data collection: APEX2 (Bruker, 2008[Bruker (2008). APEX2, SAINT and SADABS. Bruker AXS Inc., Madison, Wisconsin, USA.]); cell refinement: SAINT (Bruker, 2008[Bruker (2008). APEX2, SAINT and SADABS. Bruker AXS Inc., Madison, Wisconsin, USA.]); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]); molecular graphics: ATOMS for Windows (Dowty, 2006[Dowty, E. (2006). ATOMS for Windows. Shape Software, Kingsport, Tennessee, USA.]); software used to prepare material for publication: publCIF (Westrip, 2010[Westrip, S. P. (2010). J. Appl. Cryst. 43, 920-925.]).


Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: VN2069 ).


Acknowledgements

The X-ray centre of the Vienna University of Technology is acknowledged for financial support and for providing access to the single-crystal diffractometer.

References

Alexander, V. D., Griffen, D. T. & Martin, T. J. (1986). Am. Mineral. 71, 786-794.  [ChemPort]
Brown, I. D. (2002). In The Chemical Bond in Inorganic Chemistry: The Bond Valence Model. Oxford University Press.
Bruker (2008). APEX2, SAINT and SADABS. Bruker AXS Inc., Madison, Wisconsin, USA.
Dowty, E. (2006). ATOMS for Windows. Shape Software, Kingsport, Tennessee, USA.
Flack, H. D. (1983). Acta Cryst. A39, 876-881.  [CrossRef] [details]
Hughes, R. W., Gerrard, L. A., Price, D. J. & Weller, M. T. (2003). Inorg. Chem. 42, 4160-4164.  [ISI] [CrossRef] [PubMed] [ChemPort]
Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.  [CrossRef] [ChemPort] [details]
Weil, M. (2004a). Acta Cryst. E60, i25-i27.  [CrossRef] [ChemPort] [details]
Weil, M. (2004b). Z. Naturforsch. Teil B, 59, 859-864.  [ChemPort]
Westrip, S. P. (2010). J. Appl. Cryst. 43, 920-925.  [ISI] [CrossRef] [ChemPort] [details]


Acta Cryst (2013). E69, i29  [ doi:10.1107/S1600536813010714 ]

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