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Acta Crystallogr Sect E Struct Rep Online. 2010 March 1; 66(Pt 3): i17.
Published online 2010 February 13. doi:  10.1107/S1600536810005374
PMCID: PMC2983707

Aluminium cyclo­hexa­phosphate

Abstract

Single crystals of the title compound, Al2P6O18, were obtained by solid-state reaction. The monoclinic structure is isotypic with its CrIII, GaIII and RuIII analogues and is built up of six-membered phosphate ring anions, P6O18 6−, isolated from each other and further linked by isolated AlO6 octa­hedra by sharing corners. Each AlO6 octa­hedron is linked to four P6O18 6− rings. More accurately, two rings are linked through bidentate diphosphate groups attached in the cis-positions to the AlO6 octa­hedron. The other two rings are linked to the two remaining corners, also in cis-positions of the AlO6 octa­hedron.

Related literature

The title compound was first synthesized by Kanene et al. (1985 [triangle]) and its unit cell determined from Weissenberg photographs. Isotypic compounds have been reported: Ga2P6O18 (Chudinova et al., 1987 [triangle]); Cr2P6O18 (Bagieu-Beucher & Guitel, 1977 [triangle]) and Ru2P6O18 (Fukuoka et al., 1995 [triangle]). For a review of the crystal chemistry of cyclo­hexa­phosphates, see: Durif (1995 [triangle], 2005 [triangle]). For applications of aluminium phosphate, see: Vippola et al. (2000 [triangle]). For the structures of other cyclo­hexa­phosphates with the P6O18 6− anion, see: Averbuch-Pouchot & Durif (1991a [triangle],b [triangle],c [triangle]).

Experimental

Crystal data

  • Al2P6O18
  • M r = 527.79
  • Monoclinic, An external file that holds a picture, illustration, etc.
Object name is e-66-00i17-efi1.jpg
  • a = 6.0931 (2) Å
  • b = 15.0676 (4) Å
  • c = 8.2016 (3) Å
  • β = 105.166 (1)°
  • V = 726.75 (4) Å3
  • Z = 2
  • Mo Kα radiation
  • μ = 0.96 mm−1
  • T = 296 K
  • 0.16 × 0.07 × 0.06 mm

Data collection

  • Bruker APEXII CCD diffractometer
  • Absorption correction: multi-scan (SADABS; Bruker, 2008 [triangle]) T min = 0.860, T max = 0.945
  • 6548 measured reflections
  • 1674 independent reflections
  • 1398 reflections with I > 2σ(I)
  • R int = 0.035

Refinement

  • R[F 2 > 2σ(F 2)] = 0.032
  • wR(F 2) = 0.130
  • S = 1.16
  • 1674 reflections
  • 118 parameters
  • Δρmax = 0.56 e Å−3
  • Δρmin = −0.71 e Å−3

Data collection: APEX2 (Bruker, 2008 [triangle]); cell refinement: SAINT (Bruker, 2008 [triangle]); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 [triangle]); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 [triangle]); molecular graphics: CaRine (Boudias & Monceau, 1998 [triangle]) and ORTEP-3 (Farrugia, 1997 [triangle]); software used to prepare material for publication: SHELXTL.

Table 1
Selected geometric parameters (Å, °)

Supplementary Material

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536810005374/wm2303sup1.cif

Structure factors: contains datablocks I. DOI: 10.1107/S1600536810005374/wm2303Isup2.hkl

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

supplementary crystallographic information

Comment

Although the Al2P6018 cyclohexaphosphate is known since twenty five years (Kanene et al., 1985), its crystal structure has never been refined from single crystal X-ray diffraction data. This paper deals with this purpose.

The crystal structure of Al2P6018 is isotypic with Cr2P6O18 (Bagieu-Beucher & Guitel, 1977), Ga2P6O18 (Chudinova et al., 1987) and Ru2P6O18 (Fukuoka et al., 1995). It is built up of six-membered phosphate ring anions (P6O18)6- isolated from each others and further linked by AlO6 octahedra by sharing corners. These centrosymmetric ring anions (P6O18)6- are located around inversion centers at 0 0 1/2 and 0 1/2 0 (Fig. 1a). Their mean planes are parallel to either (121) or (121 ) planes (Fig. 1 b). Each AlO6 octahedron is linked to four P6O18 rings. More accurately, two rings are linked through bidentate diphosphate groups attached in cis-positions to the AlO6 octahedron. The two other rings are linked to the two remaining corners of the AlO6 octahedron (Fig. 2). Each (P6O18)6- ring anion is connected to eight AlO6 octahedra by corner-sharing. Four diphosphate groups of the ring anion including P(3)O4 and either P(1)O4 or P(2)O4 tetrahedra are bidentate whereas the P(1)O4—P(2)O4 couple does not bind in a bidentate fashion. This may be correlated with the value of the P(1)—O—P(2) angle (139.91 (16)°) which is greater than P(2)—O—P(3) (130.56 (16)°) and P(1)—O—P(3) (129.42 (16) °) ones and also to the P(1)—P(2) distance (2.9741 (12) Å) slightly greater than P(2)—P(3) = 2.8970 (11) Å and P(1)—P(3) = 2.8826 (12) Å ones.

A survey of the internal symmetry of the (P6O18)6- ring anions shows that most of them are centrosymmetric with P—P—P angles spreading from 87.8° to 142.8° (Averbuch-Pouchot & Durif, 1991a), i.e. with large deviations from the ideal value of 120°. When the (P6O18)6- ring anion has internal 1 symmetry, it is built up of three independent P atoms and hence there are three characteristic αi = P—P—P angles in the ring (α1 = P1—P2—P3, α2 = P2—P3—P1, α3 = P3—P1—P2). When taking the δ = Σi|120-αi| parameter as a rough measure of the ring distorsion, Al2P6O18 exhibits the third lowest δ = 15.28° value after its homologous congeners Ru2P6O18 (δ = 13.78°) and Cr2P6O18 (δ = 14.39°). It should be noted that the characteristic P—P—P angles for both isotypic Ga2P6O18 and Fe2P6O18 structures have not been reported. The highest δ values calculated from data for other cyclohexaphosphates reported up to date are related to Cu2(NH4)2P6O18.8H2O (δ = 65.98°) (Averbuch-Pouchot & Durif, 1991b) and Ag4Li2P6O18.2H2O (δ = 67.29°) (Averbuch-Pouchot & Durif, 1991c).

For applications of aluminium phosphate, see: Vippola et al. (2000). For general reviews on the crystal chemistry of cyclohexaphosphates, see: Durif (1995) and Durif (2005).

Experimental

Single crystals of the title compound have been obtained by reacting Al2O3 with (NH4)H2PO4 in an alumina boat. A mixture of these reagents in the molar ratio 1:6 was used for the synthesis. The mixture was first heated at 473 K for 24 h. Afterwards the temperature was successively raised to 573 K for 12 h, then to 673 K for 12 additional hours and finally to 923 K. After a heating period of 48 h at this temperature, the sample was cooled to room temperature by switching the furnace off. Translucent rhombs of Al2P6O18 were extracted from the batch.

Refinement

The highest residual peak in the final difference Fourier map was located 0.47 Å from atom O7 and the deepest hole was located 1.12 Å from atom P3.

Figures

Fig. 1.
(a) ORTEP-3 view of the centrosymmetric (P6O18)6- ring anion. Displacement ellipsoids are drawn at the 50% probability level. Symmetry codes: (iii) 2 - x, 1/2 + y, 1/2 - z; (iv) 1 - x, 1 - y, -z; (v) 2 - x, 1 - y, 1 - z; (vi) x, 1 + y, z; (vii) 1 + x, ...
Fig. 2.
Partial projection showing the connection between the (P6O18)6- ring anion and the AlO6 octahedra.

Crystal data

Al2P6O18F(000) = 520
Mr = 527.79Dx = 2.412 Mg m3
Monoclinic, P21/cMo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybcCell parameters from 2041 reflections
a = 6.0931 (2) Åθ = 3.5–27.5°
b = 15.0676 (4) ŵ = 0.96 mm1
c = 8.2016 (3) ÅT = 296 K
β = 105.166 (1)°Rhombic, colourless
V = 726.75 (4) Å30.16 × 0.07 × 0.06 mm
Z = 2

Data collection

Bruker APEXII CCD diffractometer1674 independent reflections
Radiation source: fine-focus sealed tube1398 reflections with I > 2σ(I)
graphiteRint = 0.035
Detector resolution: 8.3333 pixels mm-1θmax = 27.5°, θmin = 2.7°
[var phi] and ω scansh = −7→7
Absorption correction: multi-scan (SADABS; Bruker, 2008)k = −11→19
Tmin = 0.860, Tmax = 0.945l = −10→10
6548 measured reflections

Refinement

Refinement on F20 restraints
Least-squares matrix: fullPrimary atom site location: structure-invariant direct methods
R[F2 > 2σ(F2)] = 0.032Secondary atom site location: difference Fourier map
wR(F2) = 0.130w = 1/[σ2(Fo2) + (0.0787P)2 + 0.2264P] where P = (Fo2 + 2Fc2)/3
S = 1.16(Δ/σ)max < 0.001
1674 reflectionsΔρmax = 0.56 e Å3
118 parametersΔρmin = −0.71 e Å3

Special details

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 > 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)

xyzUiso*/Ueq
P10.70149 (15)0.33738 (5)0.01706 (11)0.0049 (2)
P20.64525 (14)0.04431 (5)0.21869 (11)0.0050 (2)
P30.08497 (14)0.11301 (5)−0.20937 (11)0.0054 (2)
Al0.61549 (17)0.13831 (6)−0.12313 (13)0.0046 (3)
O10.3051 (4)0.15855 (15)−0.1454 (3)0.0082 (5)
O2−0.0766 (4)0.11484 (16)−0.1026 (3)0.0090 (5)
O30.6755 (4)0.25850 (15)−0.0920 (3)0.0078 (5)
O40.6653 (4)0.12162 (15)0.1117 (3)0.0076 (5)
O50.5656 (4)0.34555 (16)0.1415 (3)0.0084 (5)
O60.4448 (4)−0.01495 (15)0.1608 (3)0.0073 (5)
O70.6509 (5)0.42395 (15)−0.0967 (3)0.0109 (5)
O80.8737 (4)−0.01227 (15)0.2539 (3)0.0110 (5)
O90.9653 (4)0.34779 (16)0.1085 (3)0.0107 (5)

Atomic displacement parameters (Å2)

U11U22U33U12U13U23
P10.0052 (5)0.0050 (4)0.0042 (5)−0.0007 (3)0.0008 (3)0.0001 (3)
P20.0060 (5)0.0041 (4)0.0050 (5)−0.0003 (3)0.0014 (3)−0.0009 (3)
P30.0036 (5)0.0058 (4)0.0069 (5)0.0007 (3)0.0015 (3)0.0002 (3)
Al0.0034 (5)0.0055 (5)0.0052 (5)−0.0006 (4)0.0015 (4)−0.0003 (3)
O10.0045 (12)0.0065 (12)0.0136 (13)−0.0012 (9)0.0025 (10)−0.0021 (9)
O20.0050 (12)0.0127 (12)0.0094 (13)−0.0002 (9)0.0024 (10)0.0014 (10)
O30.0110 (13)0.0045 (11)0.0077 (12)−0.0028 (9)0.0020 (10)−0.0015 (9)
O40.0119 (13)0.0059 (11)0.0053 (12)−0.0022 (9)0.0025 (10)−0.0007 (9)
O50.0066 (13)0.0132 (12)0.0057 (12)0.0000 (9)0.0020 (10)0.0003 (9)
O60.0060 (12)0.0063 (12)0.0098 (12)0.0002 (9)0.0025 (10)−0.0012 (9)
O70.0221 (15)0.0059 (12)0.0053 (12)0.0033 (9)0.0045 (11)0.0022 (9)
O80.0061 (12)0.0073 (12)0.0175 (14)−0.0004 (9)−0.0007 (10)−0.0038 (9)
O90.0052 (13)0.0186 (13)0.0084 (13)−0.0021 (10)0.0019 (10)−0.0062 (10)

Geometric parameters (Å, °)

P1—O31.471 (2)Al—O31.852 (2)
P1—O51.478 (2)Al—O2iv1.873 (3)
P1—O71.587 (2)Al—O11.877 (3)
P1—O91.594 (3)Al—O41.887 (3)
P2—O41.482 (2)Al—O5v1.889 (3)
P2—O61.487 (2)Al—O6iii1.904 (2)
P2—O7i1.579 (2)O2—Alvi1.873 (3)
P2—O81.593 (2)O5—Ali1.889 (3)
P3—O11.476 (2)O6—Aliii1.904 (2)
P3—O21.479 (3)O7—P2v1.579 (2)
P3—O9ii1.594 (2)O8—P3iii1.597 (2)
P3—O8iii1.597 (2)O9—P3vii1.594 (3)
O3—P1—O5119.77 (14)O3—Al—O490.93 (11)
O3—P1—O7109.47 (14)O2iv—Al—O489.61 (11)
O5—P1—O7106.27 (14)O1—Al—O490.56 (12)
O3—P1—O9107.50 (14)O3—Al—O5v89.33 (11)
O5—P1—O9110.17 (14)O2iv—Al—O5v90.32 (11)
O7—P1—O9102.27 (14)O1—Al—O5v89.50 (11)
O4—P2—O6118.09 (14)O4—Al—O5v179.74 (12)
O4—P2—O7i110.17 (13)O3—Al—O6iii178.54 (12)
O6—P2—O7i107.36 (14)O2iv—Al—O6iii88.66 (11)
O4—P2—O8108.93 (14)O1—Al—O6iii89.77 (11)
O6—P2—O8110.01 (13)O4—Al—O6iii90.46 (11)
O7i—P2—O8100.91 (14)O5v—Al—O6iii89.29 (11)
O1—P3—O2117.68 (15)P3—O1—Al139.30 (16)
O1—P3—O9ii108.14 (14)P3—O2—Alvi139.15 (17)
O2—P3—O9ii109.62 (14)P1—O3—Al149.33 (16)
O1—P3—O8iii109.89 (14)P2—O4—Al133.84 (15)
O2—P3—O8iii108.82 (14)P1—O5—Ali138.32 (16)
O9ii—P3—O8iii101.47 (14)P2—O6—Aliii138.20 (15)
O3—Al—O2iv90.88 (11)P2v—O7—P1139.91 (16)
O3—Al—O190.69 (11)P2—O8—P3iii130.56 (16)
O2iv—Al—O1178.43 (11)P1—O9—P3vii129.42 (16)

Symmetry codes: (i) x, −y+1/2, z+1/2; (ii) x−1, −y+1/2, z−1/2; (iii) −x+1, −y, −z; (iv) x+1, y, z; (v) x, −y+1/2, z−1/2; (vi) x−1, y, z; (vii) x+1, −y+1/2, z+1/2.

Footnotes

Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: WM2303).

References

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