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Redetermination of β-Ba(PO3)2

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

(Received 6 January 2014; accepted 7 January 2014; online 11 January 2014)

In comparison with the previous structure determination of the β-modification of barium catena-polyphosphate that was based on Weissenberg film data [Grenier et al. (1967[Grenier, J. C., Martin, C., Durif, A., Tranqui, D. & Guitel, J. C. (1967). Bull. Soc. Fr. Minéral. Cristallogr. 90, 24-31.]). Bull. Soc. Fr. Minéral. Cristallogr. 90, 24–31], the current CCD-data-based redetermination reveals all atoms with anisotropic displacement parameters, standard uncertainties for the atomic coordinates, and the determination of the absolute structure. Moreover, a much higher accuracy in terms of the bond-length distribution for the polyphosphate chain, with two shorter and two longer P—O distances, was achieved. The structure consists of polyphosphate chains extending parallel to [100] with a periodicity of two PO4 tetra­hedra. The Ba2+ cations are located between the chains and are surrounded by ten O atoms in the form of a distorted coordination polyhedron, with Ba—O distances ranging from 2.765 (3) to 3.143 (3) Å, also reflecting the higher precision of the current redetermination.

Related literature

For polymorphism of Ba(PO3)2, see: Grenier & Martin (1975[Grenier, J. C. & Martin, C. (1975). Bull. Soc. Fr. Minéral. Cristallogr. 98, 107-110.]). For the previous structure refinement of β-Ba(PO3)2, see: Grenier et al. (1967[Grenier, J. C., Martin, C., Durif, A., Tranqui, D. & Guitel, J. C. (1967). Bull. Soc. Fr. Minéral. Cristallogr. 90, 24-31.]). For the structure refinement of γ-Ba(PO3)2, see: Coing-Boyat et al. (1978[Coing-Boyat, J., Averbuch-Pouchot, M. T. & Guitel, J. C. (1978). Acta Cryst. B34, 2689-2692.]). For the crystal chemistry of condensed phosphates, see: Durif (1995[Durif, A. (1995). In Crystal Chemistry of Condensed Phosphates. New York: Plenum Press.]). For standardization of structure data, see: Gelato & Parthé (1987[Gelato, L. M. & Parthé, E. (1987). J. Appl. Cryst. 20, 139-143.]).

Experimental

Crystal data
  • Ba(PO3)2

  • Mr = 295.28

  • Orthorhombic, P 21 21 21

  • a = 4.4979 (2) Å

  • b = 8.3377 (4) Å

  • c = 13.3911 (6) Å

  • V = 502.19 (4) Å3

  • Z = 4

  • Mo Kα radiation

  • μ = 8.50 mm−1

  • T = 293 K

  • 0.15 × 0.08 × 0.05 mm

Data collection
  • Bruker SMART CCD diffractometer

  • Absorption correction: multi-scan (SADABS; Bruker, 2007[Bruker (2007). SMART, SAINT and SADABS. Bruker AXS Inc., Madison, Wisconsin, USA.]) Tmin = 0.362, Tmax = 0.676

  • 5836 measured reflections

  • 1587 independent reflections

  • 1560 reflections with I > 2σ(I)

  • Rint = 0.016

Refinement
  • R[F2 > 2σ(F2)] = 0.020

  • wR(F2) = 0.047

  • S = 1.13

  • 1587 reflections

  • 82 parameters

  • Δρmax = 1.09 e Å−3

  • Δρmin = −0.75 e Å−3

  • Absolute structure: Flack (1983[Flack, H. D. (1983). Acta Cryst. A39, 876-881.]), 624 Friedel pairs

  • Absolute structure parameter: 0.04 (2)

Table 1
Comparison of the P—O bond lengths (Å) of the two related PO4 tetra­hedra in the current and the previous (Grenier et al., 1967[Grenier, J. C., Martin, C., Durif, A., Tranqui, D. & Guitel, J. C. (1967). Bull. Soc. Fr. Minéral. Cristallogr. 90, 24-31.]) refinement of β-Ba(PO3)2

current refinement previous refinement
P1—O3 1.475 (2)viii P2—O6 1.427
P1—O1 1.480 (2)viii P2—O5 1.540
P1—O6 1.607 (2)ix P2—O2 1.590
P1—O4 1.625 (2)viii P2—O1 1.652
P2—O2 1.481 (2) P1—O3 1.476
P2—O5 1.486 (2)vii P1—O4 1.540
P2—O6 1.604 (3)vi P1—O2 1.559
P2—O4 1.607 (3)vi P1—O1 1.621
Symmetry codes: (vi) −x + [{1\over 2}], −y, z + [{1\over 2}]; (vii) x − [{1\over 2}], −y + [{1\over 2}], −z + 1; (viii) −x, y + [{1\over 2}], −z + [{1\over 2}]; (ix) −x + 1, y + [{1\over 2}], −z + [{1\over 2}]; (x) x − 1, y, z.

Data collection: SMART (Bruker, 2007[Bruker (2007). SMART, SAINT and SADABS. Bruker AXS Inc., Madison, Wisconsin, USA.]); cell refinement: SAINT (Bruker, 2007[Bruker (2007). SMART, 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 (Dowty, 2006[Dowty, E. (2006). ATOMS. 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.]).

Supporting information


Comment top

Polymorphism of Ba(PO3)2 with three modifications has been reported by Grenier & Martin (1975): The stable β-form transforms to the high-temperature α-form at 1058 K, and the γ-form transforms at 978 K to the β-form. Structure determinations were carried out for the γ-form (Coing-Boyat et al., 1978) and for the β-form (Grenier et al., 1967). The crystal structure of α-Ba(PO3)2 is yet unknown. Comparative discussions of the structural set-up of the β- and γ-form of Ba(PO3)2 and of other divalent long-chain polyphosphates were given by Durif (1995).

During experiments intended to isolate crystals of α-Ba(PO3)2 by quenching the reaction product from the re-crystallized melt at temperatures above the indicated transition point, high-quality crystals of β-Ba(PO3)2 were obtained instead. Since the first structure refinement of this modification was based on Weissenberg film data and converged with a relatively high residual R = 0.1, with atoms refined only with isotropic displacement factors and without indication of standard uncertainties for the fractional atomic coordinates, a re-refinement of the structure with modern CCD-based data seemed appropriate. The results of this re-refinement are reported here, confirming in principle the results of Grenier et al. (1967), however, achieving bond lengths and angles with much higher accuracy and precision, as exemplified by a comparison of the P—O bond length (Table 1).

The catena-polyphosphate chain has a periodicity of two PO4 tetrahedra and extends parallel to [100] (Fig. 1). In comparison with the previous structure refinement (Grenier et al., 1967), the determined bond lengths of the present refinement are in much better agreement with the usually observed bond length distribution in such long-chain polyphosphates (Durif, 1995), with two shorter and two longer P—O distances, each with similar values (Table 1).

The Ba2+ cation is located between the chains and is surrounded by ten oxygen atoms in an irregular coordination sphere with Ba—O distances in the range from 2.765 (3) to 3.143 (3) Å (Fig. 2).

Related literature top

For polymorphism of Ba(PO3)2, see: Grenier & Martin (1975). For the previous structure refinement of β-Ba(PO3)2, see: Grenier et al. (1967). For the structure refinement of γ-Ba(PO3)2, see: Coing-Boyat et al. (1978). For the crystal chemistry of condensed phosphates, see: Durif (1995). For standardization of structure data, see: Gelato & Parthé (1987).

Experimental top

Stoichiometric amounts of BaCO3 and (NH4)2HPO4 (molar ratio 1:2) with a 3% excess of the phosphate precursor were finely ground, heated in a platinum crucible to 1173 K and slowly cooled to 1073 K at a rate of 2 K h-1. Then the crucible was quenched in a cold water bath. Colourless fragments of the title compound were cut from the clear, transparent reaction product.

Refinement top

In contrast to the previous structure refinement (Grenier et al., 1967) with a = 4.510 (2), b = 13.44 (2) c = 8.36 (5) Å, the reduced cell setting was chosen for the current refinement. Structure data were finally standardized with STRUCTURE-TIDY (Gelato & Parthé, 1987). The highest and lowest remaining electron densities are located 0.75 Å from Ba and 1.19 Å from O6, respectively.

Structure description top

Polymorphism of Ba(PO3)2 with three modifications has been reported by Grenier & Martin (1975): The stable β-form transforms to the high-temperature α-form at 1058 K, and the γ-form transforms at 978 K to the β-form. Structure determinations were carried out for the γ-form (Coing-Boyat et al., 1978) and for the β-form (Grenier et al., 1967). The crystal structure of α-Ba(PO3)2 is yet unknown. Comparative discussions of the structural set-up of the β- and γ-form of Ba(PO3)2 and of other divalent long-chain polyphosphates were given by Durif (1995).

During experiments intended to isolate crystals of α-Ba(PO3)2 by quenching the reaction product from the re-crystallized melt at temperatures above the indicated transition point, high-quality crystals of β-Ba(PO3)2 were obtained instead. Since the first structure refinement of this modification was based on Weissenberg film data and converged with a relatively high residual R = 0.1, with atoms refined only with isotropic displacement factors and without indication of standard uncertainties for the fractional atomic coordinates, a re-refinement of the structure with modern CCD-based data seemed appropriate. The results of this re-refinement are reported here, confirming in principle the results of Grenier et al. (1967), however, achieving bond lengths and angles with much higher accuracy and precision, as exemplified by a comparison of the P—O bond length (Table 1).

The catena-polyphosphate chain has a periodicity of two PO4 tetrahedra and extends parallel to [100] (Fig. 1). In comparison with the previous structure refinement (Grenier et al., 1967), the determined bond lengths of the present refinement are in much better agreement with the usually observed bond length distribution in such long-chain polyphosphates (Durif, 1995), with two shorter and two longer P—O distances, each with similar values (Table 1).

The Ba2+ cation is located between the chains and is surrounded by ten oxygen atoms in an irregular coordination sphere with Ba—O distances in the range from 2.765 (3) to 3.143 (3) Å (Fig. 2).

For polymorphism of Ba(PO3)2, see: Grenier & Martin (1975). For the previous structure refinement of β-Ba(PO3)2, see: Grenier et al. (1967). For the structure refinement of γ-Ba(PO3)2, see: Coing-Boyat et al. (1978). For the crystal chemistry of condensed phosphates, see: Durif (1995). For standardization of structure data, see: Gelato & Parthé (1987).

Computing details top

Data collection: SMART (Bruker, 2007); cell refinement: SAINT (Bruker, 2007); data reduction: SAINT (Bruker, 2007); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ATOMS (Dowty, 2006); software used to prepare material for publication: publCIF (Westrip, 2010).

Figures top
[Figure 1] Fig. 1. The crystal structure of β-Ba(PO3)2 in a projection approximately along [100]. Ba2+ cations are shown in blue, PO4 tetrahedra in red with O atoms in white. Displacement ellipsoids are drawn at the 90% probability level. For clarity, no Ba—O bonds are shown.
[Figure 2] Fig. 2. The irregular BaO10 coordination polyhedron in the structure of β-Ba(PO3)2. Displacement ellipsoids are drawn at the 90% probability level. [Symmetry codes: (i) -x + 1/2, -y, z - 1/2; (ii) -x + 1, y - 1/2, -z + 1/2; (iii) x + 1/2, -y + 1/2, -z + 1; (iv) x + 1, y, z; (v) -x, y - 1/2, -z + 1/2; (vi) -x + 1/2, -y, z + 1/2; (vii) x - 1/2, -y + 1/2, -z + 1.]
Barium catena-polyphosphate top
Crystal data top
Ba(PO3)2F(000) = 536
Mr = 295.28Dx = 3.905 Mg m3
Orthorhombic, P212121Mo Kα radiation, λ = 0.71073 Å
Hall symbol: P 2ac 2abCell parameters from 4713 reflections
a = 4.4979 (2) Åθ = 2.4–31.0°
b = 8.3377 (4) ŵ = 8.50 mm1
c = 13.3911 (6) ÅT = 293 K
V = 502.19 (4) Å3Fragment, colourless
Z = 40.15 × 0.08 × 0.05 mm
Data collection top
Bruker SMART CCD
diffractometer
1587 independent reflections
Radiation source: fine-focus sealed tube1560 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.016
ω scanθmax = 31.0°, θmin = 2.9°
Absorption correction: multi-scan
(SADABS; Bruker, 2007)
h = 66
Tmin = 0.362, Tmax = 0.676k = 1211
5836 measured reflectionsl = 1919
Refinement top
Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.020 w = 1/[σ2(Fo2) + (0.0223P)2 + 0.9553P]
where P = (Fo2 + 2Fc2)/3
wR(F2) = 0.047(Δ/σ)max = 0.001
S = 1.13Δρmax = 1.09 e Å3
1587 reflectionsΔρmin = 0.75 e Å3
82 parametersAbsolute structure: Flack (1983), 624 Friedel pairs
0 restraintsAbsolute structure parameter: 0.04 (2)
Crystal data top
Ba(PO3)2V = 502.19 (4) Å3
Mr = 295.28Z = 4
Orthorhombic, P212121Mo Kα radiation
a = 4.4979 (2) ŵ = 8.50 mm1
b = 8.3377 (4) ÅT = 293 K
c = 13.3911 (6) Å0.15 × 0.08 × 0.05 mm
Data collection top
Bruker SMART CCD
diffractometer
1587 independent reflections
Absorption correction: multi-scan
(SADABS; Bruker, 2007)
1560 reflections with I > 2σ(I)
Tmin = 0.362, Tmax = 0.676Rint = 0.016
5836 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0200 restraints
wR(F2) = 0.047Δρmax = 1.09 e Å3
S = 1.13Δρmin = 0.75 e Å3
1587 reflectionsAbsolute structure: Flack (1983), 624 Friedel pairs
82 parametersAbsolute structure parameter: 0.04 (2)
Special details top

Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s 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 > σ(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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
Ba0.49023 (4)0.05203 (2)0.375501 (12)0.01202 (6)
P10.03622 (19)0.67382 (10)0.34674 (6)0.00958 (15)
P20.04126 (18)0.03118 (10)0.60393 (6)0.01002 (15)
O10.0024 (8)0.1293 (3)0.25946 (16)0.0142 (4)
O20.0272 (6)0.1222 (3)0.69880 (17)0.0153 (4)
O30.0307 (6)0.3369 (3)0.11686 (17)0.0149 (4)
O40.1343 (5)0.0429 (3)0.08393 (18)0.0116 (4)
O50.4603 (6)0.3816 (3)0.48895 (17)0.0142 (5)
O60.6315 (5)0.1360 (3)0.11585 (19)0.0131 (4)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Ba0.01116 (8)0.01345 (9)0.01147 (8)0.00007 (7)0.00044 (8)0.00042 (6)
P10.0082 (3)0.0093 (3)0.0113 (3)0.0002 (3)0.0007 (3)0.0001 (3)
P20.0087 (3)0.0103 (3)0.0111 (3)0.0000 (3)0.0001 (3)0.0008 (3)
O10.0152 (9)0.0156 (10)0.0118 (9)0.0018 (12)0.0002 (11)0.0016 (8)
O20.0163 (11)0.0151 (10)0.0145 (10)0.0008 (11)0.0010 (10)0.0037 (8)
O30.0167 (11)0.0110 (10)0.0171 (10)0.0020 (10)0.0019 (12)0.0017 (8)
O40.0076 (9)0.0135 (11)0.0137 (11)0.0021 (9)0.0010 (8)0.0047 (9)
O50.0156 (13)0.0129 (10)0.0140 (10)0.0012 (10)0.0022 (10)0.0041 (8)
O60.0072 (9)0.0118 (10)0.0203 (12)0.0004 (8)0.0031 (9)0.0014 (10)
Geometric parameters (Å, º) top
Ba—O12.765 (3)Ba—O53.143 (3)
Ba—O2i2.778 (2)P1—O3viii1.475 (2)
Ba—O3ii2.806 (2)P1—O1viii1.480 (2)
Ba—O5iii2.841 (3)P1—O6ix1.607 (2)
Ba—O1iv2.852 (3)P1—O4viii1.625 (2)
Ba—O2iii2.897 (2)P2—O21.481 (2)
Ba—O3v2.952 (2)P2—O5vii1.486 (2)
Ba—O4vi2.955 (2)P2—O6vi1.604 (3)
Ba—O5vii3.047 (3)P2—O4vi1.607 (3)
O1—Ba—O2i67.71 (8)O3ii—Ba—O5125.05 (7)
O1—Ba—O3ii141.17 (7)O5iii—Ba—O563.43 (6)
O2i—Ba—O3ii73.64 (7)O1iv—Ba—O595.77 (7)
O1—Ba—O5iii154.74 (7)O2iii—Ba—O549.37 (6)
O2i—Ba—O5iii131.84 (8)O3v—Ba—O5118.72 (7)
O3ii—Ba—O5iii61.94 (7)O4vi—Ba—O576.68 (7)
O1—Ba—O1iv106.39 (7)O5vii—Ba—O561.30 (6)
O2i—Ba—O1iv71.14 (7)O3viii—P1—O1viii121.65 (14)
O3ii—Ba—O1iv62.86 (7)O3viii—P1—O6ix105.50 (14)
O5iii—Ba—O1iv72.72 (7)O1viii—P1—O6ix111.06 (17)
O1—Ba—O2iii68.54 (8)O3viii—P1—O4viii109.50 (15)
O2i—Ba—O2iii101.50 (3)O1viii—P1—O4viii108.97 (15)
O3ii—Ba—O2iii124.60 (7)O6ix—P1—O4viii97.43 (13)
O5iii—Ba—O2iii89.67 (7)O2—P2—O5vii117.17 (15)
O1iv—Ba—O2iii63.57 (7)O2—P2—O6vi109.83 (14)
O1—Ba—O3v62.04 (7)O5vii—P2—O6vi112.95 (15)
O2i—Ba—O3v71.91 (7)O2—P2—O4vi112.26 (15)
O3ii—Ba—O3v102.70 (7)O5vii—P2—O4vi105.74 (15)
O5iii—Ba—O3v133.37 (7)O6vi—P2—O4vi97.02 (13)
O1iv—Ba—O3v142.84 (6)P1v—O1—Ba133.76 (18)
O2iii—Ba—O3v128.82 (7)P1v—O1—Bax119.03 (18)
O1—Ba—O4vi116.29 (7)Ba—O1—Bax106.39 (7)
O2i—Ba—O4vi131.24 (7)P2—O2—Bavi117.64 (13)
O3ii—Ba—O4vi86.55 (7)P2—O2—Bavii100.85 (12)
O5iii—Ba—O4vi65.78 (7)Bavi—O2—Bavii141.37 (9)
O1iv—Ba—O4vi136.74 (7)P1v—O3—Baix137.20 (14)
O2iii—Ba—O4vi125.91 (7)P1v—O3—Baviii112.75 (13)
O3v—Ba—O4vi69.76 (7)Baix—O3—Baviii102.70 (7)
O1—Ba—O5vii70.83 (6)P2i—O4—P1v126.27 (15)
O2i—Ba—O5vii125.48 (8)P2i—O4—Bai103.09 (11)
O3ii—Ba—O5vii134.05 (7)P1v—O4—Bai129.06 (12)
O5iii—Ba—O5vii99.57 (7)P2iii—O5—Bavii128.45 (15)
O1iv—Ba—O5vii156.26 (7)P2iii—O5—Baiii102.60 (13)
O2iii—Ba—O5vii94.54 (7)Bavii—O5—Baiii99.57 (7)
O3v—Ba—O5vii57.92 (7)P2iii—O5—Ba90.73 (11)
O4vi—Ba—O5vii48.51 (6)Bavii—O5—Ba120.73 (9)
O1—Ba—O591.95 (7)Baiii—O5—Ba114.41 (9)
O2i—Ba—O5150.21 (7)P2i—O6—P1ii130.68 (17)
Symmetry codes: (i) x+1/2, y, z1/2; (ii) x+1, y1/2, z+1/2; (iii) x+1/2, y+1/2, z+1; (iv) x+1, y, z; (v) x, y1/2, z+1/2; (vi) x+1/2, y, z+1/2; (vii) x1/2, y+1/2, z+1; (viii) x, y+1/2, z+1/2; (ix) x+1, y+1/2, z+1/2; (x) x1, y, z.

Experimental details

Crystal data
Chemical formulaBa(PO3)2
Mr295.28
Crystal system, space groupOrthorhombic, P212121
Temperature (K)293
a, b, c (Å)4.4979 (2), 8.3377 (4), 13.3911 (6)
V3)502.19 (4)
Z4
Radiation typeMo Kα
µ (mm1)8.50
Crystal size (mm)0.15 × 0.08 × 0.05
Data collection
DiffractometerBruker SMART CCD
Absorption correctionMulti-scan
(SADABS; Bruker, 2007)
Tmin, Tmax0.362, 0.676
No. of measured, independent and
observed [I > 2σ(I)] reflections
5836, 1587, 1560
Rint0.016
(sin θ/λ)max1)0.724
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.020, 0.047, 1.13
No. of reflections1587
No. of parameters82
Δρmax, Δρmin (e Å3)1.09, 0.75
Absolute structureFlack (1983), 624 Friedel pairs
Absolute structure parameter0.04 (2)

Computer programs: SMART (Bruker, 2007), SAINT (Bruker, 2007), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), ATOMS (Dowty, 2006), publCIF (Westrip, 2010).

Comparison of the P—O bond lengths (Å) of the two related PO4 tetrahedra in the current and the previous (Grenier et al., 1967) refinement of β-Ba(PO3)2 top
current refinementprevious refinement
P1—O3 1.475 (2)viiiP2—O6 1.427
P1—O1 1.480 (2)viiiP2—O5 1.540
P1—O6 1.607 (2)ixP2—O2 1.590
P1—O4 1.625 (2)viiiP2—O1 1.652
P2—O2 1.481 (2)P1—O3 1.476
P2—O5 1.486 (2)viiP1—O4 1.540
P2—O6 1.604 (3)viP1—O2 1.559
P2—O4 1.607 (3)viP1—O1 1.621
Symmetry codes: (vi) -x+1/2, -y, z+1/2; (vii) x-1/2, -y+1/2, -z+1; (viii) -x, y+1/2, -z+1/2; (ix) -x+1, y+1/2, -z+1/2; (x) x-1, y, z.
 

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

First citationBruker (2007). SMART, SAINT and SADABS. Bruker AXS Inc., Madison, Wisconsin, USA.  Google Scholar
First citationCoing-Boyat, J., Averbuch-Pouchot, M. T. & Guitel, J. C. (1978). Acta Cryst. B34, 2689–2692.  CrossRef CAS IUCr Journals Web of Science Google Scholar
First citationDowty, E. (2006). ATOMS. Shape Software, Kingsport, Tennessee, USA.  Google Scholar
First citationDurif, A. (1995). In Crystal Chemistry of Condensed Phosphates. New York: Plenum Press.  Google Scholar
First citationFlack, H. D. (1983). Acta Cryst. A39, 876–881.  CrossRef CAS Web of Science IUCr Journals Google Scholar
First citationGelato, L. M. & Parthé, E. (1987). J. Appl. Cryst. 20, 139–143.  CrossRef Web of Science IUCr Journals Google Scholar
First citationGrenier, J. C. & Martin, C. (1975). Bull. Soc. Fr. Minéral. Cristallogr. 98, 107–110.  CAS Google Scholar
First citationGrenier, J. C., Martin, C., Durif, A., Tranqui, D. & Guitel, J. C. (1967). Bull. Soc. Fr. Minéral. Cristallogr. 90, 24–31.  CAS Google Scholar
First citationSheldrick, G. M. (2008). Acta Cryst. A64, 112–122.  Web of Science CrossRef CAS IUCr Journals Google Scholar
First citationWestrip, S. P. (2010). J. Appl. Cryst. 43, 920–925.  Web of Science CrossRef CAS IUCr Journals Google Scholar

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