inorganic compounds\(\def\hfill{\hskip 5em}\def\hfil{\hskip 3em}\def\eqno#1{\hfil {#1}}\)

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ISSN: 2056-9890

Mg4Sb2O9 of the ilmenite structure type

aNational Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan
*Correspondence e-mail: MICHIUE.Yuichi@nims.go.jp

(Received 6 August 2008; accepted 1 September 2008; online 6 September 2008)

Single crystals of the title compound, tetra­magnesium dianti­monate(V), were obtained by the slow cooling method with K2CO3. The structure is isotypic with ilmenite, which is constructed by the alternate stacking of layers consisting of metal–oxygen coordination octa­hedra. In each layer, the octa­hedra are connected by sharing edges so as to make holes. One of the two non-equivalent metal sites is fully occupied by Mg (3 symmetry), while the second metal site (3 symmetry) is disordered and occupied by Mg and Sb with occupation factors of 1/3 and 2/3, respectively.

Related literature

For ilmenite structures, see: Wechsler & Prewitt (1984[Wechsler, B. A. & Prewitt, C. T. (1984). Am. Mineral. 69, 176-185.]) for FeTiO3 and Wechsler & Von Dreele (1989[Wechsler, B. A. & Von Dreele, R. B. (1989). Acta Cryst. B45, 542-549.]) for MgTiO3. For further phases in the MgO–Sb2O5 system, see: Kasper (1969[Kasper, H. (1969). Z. Kristallogr. 128, 72-84.]). For related literature, see: Becker & Coppens (1974[Becker, P. J. & Coppens, P. (1974). Acta Cryst. A30, 129-147.]); Blasse (1964[Blasse, G. (1964). Z. Anorg. Allg. Chem. 331, 44-50.]); Michiue (2007[Michiue, Y. (2007). J. Solid State Chem. 180, 1840-1845.]).

Experimental

Crystal data
  • Mg4O9Sb2

  • Mr = 484.7

  • Trigonal, [R \overline 3]

  • a = 5.1722 (11) Å

  • c = 14.028 (2) Å

  • V = 324.99 (11) Å3

  • Z = 2

  • Mo Kα radiation

  • μ = 8.73 mm−1

  • T = 295 K

  • 0.22 × 0.22 × 0.04 mm

Data collection
  • Rigaku AFC-7R diffractometer

  • Absorption correction: analytical (Tompa Analytical, Rigaku 2004[Rigaku (2004). CrystalStructure and Tompa Analytical. Rigaku Corporation, Tokyo, Japan.]) Tmin = 0.210, Tmax = 0.671

  • 2359 measured reflections

  • 773 independent reflections

  • 715 reflections with I > 2σ(I)

  • Rint = 0.046

  • 3 standard reflections every 200 reflections intensity decay: 4.6%

Refinement
  • R[F2 > 2σ(F2)] = 0.032

  • wR(F2) = 0.074

  • S = 1.55

  • 773 reflections

  • 17 parameters

  • Δρmax = 3.78 e Å−3

  • Δρmin = −3.64 e Å−3

Table 1
Selected bond lengths (Å), M = Mg, Sb

M1—O1 2.0527 (15)
M1—O1i 1.9928 (11)
M1—O1ii 2.0527 (19)
M1—O1iii 1.9928 (18)
M1—O1iv 2.0527 (12)
M1—O1v 1.9928 (17)
Mg2—O1 2.2091 (17)
Mg2—O1vi 2.0455 (17)
Symmetry codes: (i) [-x+{\script{2\over 3}}, -y+{\script{1\over 3}}, -z+{\script{1\over 3}}]; (ii) -y, x-y, z; (iii) [y-{\script{1\over 3}}, -x+y+{\script{1\over 3}}, -z+{\script{1\over 3}}]; (iv) -x+y, -x, z; (v) [x-y-{\script{1\over 3}}, x-{\script{2\over 3}}, -z+{\script{1\over 3}}]; (vi) [-x+{\script{1\over 3}}, -y-{\script{1\over 3}}, -z+{\script{2\over 3}}]; (vii) [y+{\script{1\over 3}}, -x+y+{\script{2\over 3}}, -z+{\script{2\over 3}}]; (viii) [x-y-{\script{2\over 3}}, x-{\script{1\over 3}}, -z+{\script{2\over 3}}].

Data collection: MSC/AFC Diffractometer Control Software (Molecular Structure Corporation, 1994[Molecular Structure Corporation (1994). MSC/AFC Diffractometer Control Software. MSC, The Woodlands, Texas, USA.]); cell refinement: MSC/AFC Diffractometer Control Software; data reduction: CrystalStructure (Rigaku, 2004[Rigaku (2004). CrystalStructure and Tompa Analytical. Rigaku Corporation, Tokyo, Japan.]); method used to solve structure: structure of the present compound is isotypic with ilmenite; program(s) used to refine structure: JANA2000 (Petříček et al., 2000[Petříček, V., Dušek, M. & Palatinus, L. (2000). JANA2000. Institute of Physics, Prague, Czech Republic.]); molecular graphics: ATOMS (Dowty, 2005[Dowty, E. (2005). ATOMS. Shape Software, Kingsport, Tennessee, USA.]); software used to prepare material for publication: JANA2000.

Supporting information


Comment top

A pronounced resemblance of X-ray diffraction patterns for Mg4Sb2O9 and the ilmenite MgTiO3 was pointed out by Blasse (1964). In general, ilmenite structure is represented by A2+B4+O3, that is including equal amounts of divalent and tetravalent cations such as FeTiO3 and MgTiO3. Although the chemical composition Mg4Sb2O9 is away from that of the typical ilmenite structure, the present analysis has confirmed that the structure of Mg4Sb2O9 is deduced from the ilmenite MgTiO3 by replacing the Ti4+ ions statistically by 1/3 Mg2+ and 2/3 Sb5+, as was supposed by Blasse (1964).

The structure is constructed by the alternate stacking of atomic layers along c as shown in Fig. 1. Each of the two nonequivalent metal sites is octahedrally coordinated by six oxygen ions. Two types of layers consisting of edge-shared octahedra are seen in the structure, both of which have holes as illustrated in Fig. 2.

Related literature top

For ilmenite structures, see: Wechsler et al. (1984) for FeTiO3 and Wechsler et al. (1989) for MgTiO3. For further phases in the MgO–Sb2O5 system, see: Kasper (1969).

For related literature, see: Becker & Coppens (1974); Blasse (1964); Michiue (2007); Rigaku (2004).

Experimental top

Single crystals of the title compound were obtained unintentionally as the product of a synthesis of K-hollandite by the slow cooling method with excess K2CO3 (Michiue, 2007).

Refinement top

Partial substitution of Sb for Mg at the Mg2 site was checked by refining the occupation factors of Mg and Sb at the site. In the refinement the full occupation at all the metal and oxygen sites was assumed and the charge neutrality of the whole crystal was kept by imposing constraint conditions. The possibility of the existence of Sb ions at the Mg2 site was excluded because the occupation factor of Sb at the site was slightly negative, -0.001, and that of Mg was 1.001 after the refinement. Thus, it was concluded that Sb ions are only at the Mg1/Sb1 site.

Computing details top

Data collection: MSC/AFC Diffractometer Control Software (Molecular Structure Corporation, 1994); cell refinement: MSC/AFC Diffractometer Control Software (Molecular Structure Corporation, 1994); data reduction: Crystal Structure (Rigaku, 2004); program(s) used to solve structure: structure of the present compound is isotypic with ilmenite; program(s) used to refine structure: (JANA2000; Petříček et al., 2000); molecular graphics: ATOMS (Dowty, 2005); software used to prepare material for publication: (JANA2000; Petříček et al., 2000).

Figures top
[Figure 1] Fig. 1. The projection of Mg4Sb2O9 along [110].
[Figure 2] Fig. 2. Layers with holes consisting of (a) Mg2O6 octahedra extending around z = 0 and (b) (Mg1/Sb1)O6 octahedra around z = 1/6 in Mg4Sb2O9.
tetramagnesium diantimonate top
Crystal data top
Mg4O9Sb2Dx = 4.952 Mg m3
Mr = 484.7Mo Kα radiation, λ = 0.71069 Å
Trigonal, R3Cell parameters from 20 reflections
Hall symbol: -R 3θ = 9.3–13.5°
a = 5.1722 (11) ŵ = 8.73 mm1
c = 14.028 (2) ÅT = 295 K
V = 324.99 (11) Å3Plate, colorless
Z = 20.22 × 0.22 × 0.04 mm
F(000) = 444
Data collection top
Rigaku AFC-7R
diffractometer
715 reflections with I > 2σ(I)
Radiation source: rotating-anode X-ray tubeRint = 0.047
Graphite monochromatorθmax = 50.1°, θmin = 4.4°
ω/2θ scansh = 1111
Absorption correction: analytical
(Tompa Analytical, Rigaku 2004)
k = 1111
Tmin = 0.210, Tmax = 0.671l = 030
2359 measured reflections3 standard reflections every 200 reflections
773 independent reflections intensity decay: 4.6%
Refinement top
Refinement on F2Primary atom site location: isomorphous structure methods
Least-squares matrix: fullWeighting scheme based on measured s.u.'s w = 1/(σ2(I) + 0.0009I2)
R[F2 > 2σ(F2)] = 0.032(Δ/σ)max = 0.0004
wR(F2) = 0.075Δρmax = 3.78 e Å3
S = 1.55Δρmin = 3.64 e Å3
773 reflectionsExtinction correction: B-C type 1 Lorentzian isotropic (Becker & Coppens, 1974)
17 parametersExtinction coefficient: 0.071 (3)
0 restraints
Crystal data top
Mg4O9Sb2Z = 2
Mr = 484.7Mo Kα radiation
Trigonal, R3µ = 8.73 mm1
a = 5.1722 (11) ÅT = 295 K
c = 14.028 (2) Å0.22 × 0.22 × 0.04 mm
V = 324.99 (11) Å3
Data collection top
Rigaku AFC-7R
diffractometer
715 reflections with I > 2σ(I)
Absorption correction: analytical
(Tompa Analytical, Rigaku 2004)
Rint = 0.047
Tmin = 0.210, Tmax = 0.6713 standard reflections every 200 reflections
2359 measured reflections intensity decay: 4.6%
773 independent reflections
Refinement top
R[F2 > 2σ(F2)] = 0.03217 parameters
wR(F2) = 0.0750 restraints
S = 1.55Δρmax = 3.78 e Å3
773 reflectionsΔρmin = 3.64 e Å3
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/UeqOcc. (<1)
Mg1000.152618 (14)0.00628 (7)0.3333
M1000.152618 (14)0.00628 (7)0.6667
Mg2000.35806 (10)0.0098 (2)
O10.3091 (3)0.0125 (3)0.24710 (7)0.0078 (3)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Mg10.00711 (10)0.00711 (10)0.00461 (10)0.00356 (5)00
M10.00711 (10)0.00711 (10)0.00461 (10)0.00356 (5)00
Mg20.0080 (3)0.0080 (3)0.0133 (4)0.00401 (13)00
O10.0097 (4)0.0073 (4)0.0069 (3)0.0047 (3)0.0010 (3)0.0011 (2)
Geometric parameters (Å, º) top
M1—O12.0527 (15)Mg2—O12.2091 (17)
M1—O1i1.9928 (11)Mg2—O1vi2.0455 (17)
M1—O1ii2.0527 (19)Mg2—O1ii2.209 (2)
M1—O1iii1.9928 (18)Mg2—O1vii2.0455 (14)
M1—O1iv2.0527 (12)Mg2—O1iv2.2091 (15)
M1—O1v1.9928 (17)Mg2—O1viii2.046 (2)
O1—M1—O1i83.77 (5)O1—Mg2—O1vi87.88 (6)
O1—M1—O1ii82.80 (6)O1—Mg2—O1ii75.84 (7)
O1—M1—O1iii166.22 (6)O1—Mg2—O1vii89.32 (5)
O1—M1—O1iv82.80 (6)O1—Mg2—O1iv75.84 (7)
O1—M1—O1v92.43 (7)O1—Mg2—O1viii160.12 (8)
O1i—M1—O183.77 (5)O1vi—Mg2—O187.88 (6)
O1i—M1—O1ii92.43 (5)O1vi—Mg2—O1ii160.12 (8)
O1i—M1—O1iii99.93 (6)O1vi—Mg2—O1vii103.48 (8)
O1i—M1—O1iv166.22 (6)O1vi—Mg2—O1iv89.32 (6)
O1i—M1—O1v99.93 (6)O1vi—Mg2—O1viii103.48 (7)
O1ii—M1—O182.80 (6)O1ii—Mg2—O175.84 (7)
O1ii—M1—O1i92.43 (5)O1ii—Mg2—O1vi160.12 (8)
O1ii—M1—O1iii83.77 (7)O1ii—Mg2—O1vii87.88 (6)
O1ii—M1—O1iv82.80 (6)O1ii—Mg2—O1iv75.84 (7)
O1ii—M1—O1v166.22 (5)O1ii—Mg2—O1viii89.32 (6)
O1iii—M1—O1166.22 (6)O1vii—Mg2—O189.32 (5)
O1iii—M1—O1i99.93 (6)O1vii—Mg2—O1vi103.48 (8)
O1iii—M1—O1ii83.77 (7)O1vii—Mg2—O1ii87.88 (6)
O1iii—M1—O1iv92.43 (7)O1vii—Mg2—O1iv160.12 (8)
O1iii—M1—O1v99.93 (8)O1vii—Mg2—O1viii103.48 (7)
O1iv—M1—O182.80 (6)O1iv—Mg2—O175.84 (7)
O1iv—M1—O1i166.22 (6)O1iv—Mg2—O1vi89.32 (6)
O1iv—M1—O1ii82.80 (6)O1iv—Mg2—O1ii75.84 (7)
O1iv—M1—O1iii92.43 (7)O1iv—Mg2—O1vii160.12 (8)
O1iv—M1—O1v83.77 (6)O1iv—Mg2—O1viii87.88 (6)
O1v—M1—O192.43 (7)O1viii—Mg2—O1160.12 (8)
O1v—M1—O1i99.93 (6)O1viii—Mg2—O1vi103.48 (7)
O1v—M1—O1ii166.22 (5)O1viii—Mg2—O1ii89.32 (6)
O1v—M1—O1iii99.93 (8)O1viii—Mg2—O1vii103.48 (7)
O1v—M1—O1iv83.77 (6)O1viii—Mg2—O1iv87.88 (6)
Symmetry codes: (i) x+2/3, y+1/3, z+1/3; (ii) y, xy, z; (iii) y1/3, x+y+1/3, z+1/3; (iv) x+y, x, z; (v) xy1/3, x2/3, z+1/3; (vi) x+1/3, y1/3, z+2/3; (vii) y+1/3, x+y+2/3, z+2/3; (viii) xy2/3, x1/3, z+2/3.

Experimental details

Crystal data
Chemical formulaMg4O9Sb2
Mr484.7
Crystal system, space groupTrigonal, R3
Temperature (K)295
a, c (Å)5.1722 (11), 14.028 (2)
V3)324.99 (11)
Z2
Radiation typeMo Kα
µ (mm1)8.73
Crystal size (mm)0.22 × 0.22 × 0.04
Data collection
DiffractometerRigaku AFC-7R
diffractometer
Absorption correctionAnalytical
(Tompa Analytical, Rigaku 2004)
Tmin, Tmax0.210, 0.671
No. of measured, independent and
observed [I > 2σ(I)] reflections
2359, 773, 715
Rint0.047
(sin θ/λ)max1)1.080
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.032, 0.075, 1.55
No. of reflections773
No. of parameters17
Δρmax, Δρmin (e Å3)3.78, 3.64

Computer programs: MSC/AFC Diffractometer Control Software (Molecular Structure Corporation, 1994), Crystal Structure (Rigaku, 2004), structure of the present compound is isotypic with ilmenite, (JANA2000; Petříček et al., 2000), ATOMS (Dowty, 2005).

Selected bond lengths (Å) top
M1—O12.0527 (15)Mg2—O12.2091 (17)
M1—O1i1.9928 (11)Mg2—O1vi2.0455 (17)
M1—O1ii2.0527 (19)Mg2—O1ii2.209 (2)
M1—O1iii1.9928 (18)Mg2—O1vii2.0455 (14)
M1—O1iv2.0527 (12)Mg2—O1iv2.2091 (15)
M1—O1v1.9928 (17)Mg2—O1viii2.046 (2)
Symmetry codes: (i) x+2/3, y+1/3, z+1/3; (ii) y, xy, z; (iii) y1/3, x+y+1/3, z+1/3; (iv) x+y, x, z; (v) xy1/3, x2/3, z+1/3; (vi) x+1/3, y1/3, z+2/3; (vii) y+1/3, x+y+2/3, z+2/3; (viii) xy2/3, x1/3, z+2/3.
 

References

First citationBecker, P. J. & Coppens, P. (1974). Acta Cryst. A30, 129–147.  CrossRef IUCr Journals Web of Science Google Scholar
First citationBlasse, G. (1964). Z. Anorg. Allg. Chem. 331, 44–50.  CrossRef CAS Web of Science Google Scholar
First citationDowty, E. (2005). ATOMS. Shape Software, Kingsport, Tennessee, USA.  Google Scholar
First citationKasper, H. (1969). Z. Kristallogr. 128, 72–84.  CrossRef Google Scholar
First citationMichiue, Y. (2007). J. Solid State Chem. 180, 1840–1845.  Web of Science CrossRef CAS Google Scholar
First citationMolecular Structure Corporation (1994). MSC/AFC Diffractometer Control Software. MSC, The Woodlands, Texas, USA.  Google Scholar
First citationPetříček, V., Dušek, M. & Palatinus, L. (2000). JANA2000. Institute of Physics, Prague, Czech Republic.  Google Scholar
First citationRigaku (2004). CrystalStructure and Tompa Analytical. Rigaku Corporation, Tokyo, Japan.  Google Scholar
First citationWechsler, B. A. & Von Dreele, R. B. (1989). Acta Cryst. B45, 542–549.  CrossRef CAS Web of Science IUCr Journals Google Scholar
First citationWechsler, B. A. & Prewitt, C. T. (1984). Am. Mineral. 69, 176–185.  CAS Google Scholar

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ISSN: 2056-9890
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