Sodium samarium tetra­kis­(poly­phosphate), NaSm(PO3)4

Zhao, D.; Zhang, L.; Li, F.

doi:10.1107/S1600536810022543

inorganic compounds

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ISSN: 2056-9890

Volume 66| Part 7| July 2010| Page i53

doi:10.1107/S1600536810022543

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Sodium samarium tetrakis(polyphosphate), NaSm(PO₃)₄

Dan Zhao,^a ^* Lina Zhang ^a and Feifei Li ^a

^aDepartment of Physics and Chemistry, Henan Polytechnic University, Jiaozuo, Henan 454000, People's Republic of China
^*Correspondence e-mail: iamzd@hpu.edu.cn

(Received 2 June 2010; accepted 12 June 2010; online 23 June 2010)

NaSm(PO₃)₄ has been prepared by solid state reactions. It belongs to type II of the structural family of M^ILn^III(PO₃)₄ compounds (M^I = alkali metal and Ln^III = rare earth metal) and is composed of _∞(PO₃)_n]ⁿ⁻ polyphosphate chains with a repeating unit of four PO₄ tetrahedra. The chains extend parallel to [100] and share O atoms with irregular SmO₈ polyhedra, forming a three-dimensional framework which delimits tunnels occupied by Na⁺ cations in a distorted octahedral environment.

Related literature

The unit cell of NaSm(PO₃)₄, derived from X-ray powder data, was reported by Ferid et al. (1984 ). For classification of M^ILn^III(PO₃)₄ structures, see: Palkina et al. (1981 ); Durif (1995 ). Structures, properties and applications of other members of this family were discussed by Ettis et al. (2003 ); Parreu et al. (2007 ); Zhao et al. (2008 , 2010 ); Zhu et al. (2009 ).

Experimental

Crystal data

NaSm(PO₃)₄
M_r = 489.22
Monoclinic, P 2₁ /n
a = 7.1924 (13) Å
b = 13.091 (2) Å
c = 9.8480 (17) Å
β = 90.396 (10)°
V = 927.2 (3) Å³
Z = 4
Mo Kα radiation
μ = 7.14 mm⁻¹
T = 293 K
0.20 × 0.02 × 0.02 mm

Data collection

Rigaku Mercury70 CCD diffractometer
Absorption correction: multi-scan (ABSCOR; Higashi, 1995 ) T_min = 0.329, T_max = 0.870
7036 measured reflections
2111 independent reflections
1868 reflections with I > 2σ(I)
R_int = 0.041

Refinement

R[F² > 2σ(F²)] = 0.037
wR(F²) = 0.068
S = 1.15
2111 reflections
163 parameters
Δρ_max = 2.38 e Å⁻³
Δρ_min = −0.80 e Å⁻³

Table 1
Selected bond lengths (Å)

P1—O10	1.482 (4)
P1—O5	1.494 (4)
P1—O11	1.584 (4)
P1—O7	1.586 (4)
P2—O9	1.477 (4)
P2—O4	1.481 (4)
P2—O7ⁱ	1.574 (4)
P2—O6ⁱⁱ	1.598 (4)
P3—O1	1.482 (4)
P3—O12	1.486 (4)
P3—O6	1.591 (4)
P3—O3	1.596 (4)
P4—O8	1.479 (4)
P4—O2	1.487 (4)
P4—O11	1.594 (4)
P4—O3ⁱ	1.595 (4)
Symmetry codes: (i) -x+1, -y+1, -z+1; (ii) x+1, y, z.

Data collection: CrystalClear (Rigaku, 2004 ); cell refinement: CrystalClear; data reduction: CrystalClear; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ) and PLATON (Spek, 2009 ); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: DIAMOND (Brandenburg, 2004 ); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).

Supporting information

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536810022543/wm2360sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536810022543/wm2360Isup2.hkl

checkCIF report

Comment top

In recent years, alkali rare earth polyphosphates with general formula M^ILn^III(PO₃)₄ (M^I = alkali metal, Ln^III = rare earth metal) have been studied mainly due to their rich structural chemistry and interesting physical and chemical properties, such as high luminescence efficiency (Durif, 1995). The nomenclature of M^ILn^III(PO₃)₄ compounds has been proposed by Palkina et al. (1981) and is generally accepted today. Many compounds of this family have been reported, for example, LiLn(PO₃)₄ (Ln =Y, Sm, Dy) (Zhao et al., 2008, 2010), KGdP₄O₁₂ (Ettis et al., 2003), KNd(PO₃)₄ (Parreu et al., 2007) and CsEu(PO₃)₄ (Zhu et al., 2009). For the compound NaSm(PO₃)₄ only unit-cell parameters have been reported on basis of refined X-ray powder diffraction data (Ferid et al., 1984).

The structure of NaSm(PO₃)₄ is characterized by a three-dimensional framework built up of irregular SmO₈ polyhedra linked with polyphosphate chains via Sm–O–P bridges, as show in Fig. 2. The undulated [(PO₃)_n]ⁿ^- chains have a repeating unit of four corner-sharing PO₄ tetrahedra and extend parallel to the a-axis. Furthermore, the framework delimits tunnels in which the Na⁺ ions are located. They are 6-coordinated by O atoms with Na—O distances ranging from 2.386 (5)—2.741 (5) Å in a distorted octahedral arrangement.

Related literature top

The unit cell of NaSm(PO₃)₄, derived from X-ray powder data, was reported by Ferid et al. (1984). For classification of M^ILn^III(PO₃)₄ structures, see: Palkina et al. (1981); Durif (1995). Structures, properties and applications of other members of this family were discussed by Ettis et al. (2003); Parreu et al. (2007); Zhao et al. (2008, 2010); Zhu et al. (2009).

Experimental top

The finely ground reagents Na₂CO₃, Sm₂O₃, and NH₄H₂PO₄ were mixed in a molar ratio of Na: Sm: P = 7: 1: 10, placed in a Pt crucible, and heated at 673 K for 4 h. The mixture was re-ground and heated at 1173 K for 20 h, then cooled to 673 K at a rate of 4 K h^-1, and finally quenched to room temperature. A few yellow crystals of the title compound with prismatic shape were obtained.

Computing details top

Data collection: CrystalClear (Rigaku, 2004); cell refinement: CrystalClear (Rigaku, 2004); data reduction: CrystalClear (Rigaku, 2004); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008) and PLATON (Spek, 2009); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: DIAMOND (Brandenburg, 2004); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).

Figures top

	Fig. 1. Asymmetric unit of the structure of NaSm(PO₃)₄ with the atom labelling scheme. The displacement ellipsoids are drawn at the 50% probability level.
	Fig. 2. View of the crystal structure of NaSm(PO₃)₄ in a projection down [010].

Sodium samarium tetrakis(polyphosphate) top

Crystal data top

NaSm(PO₃)₄	F(000) = 916
M_r = 489.22	D_x = 3.504 Mg m⁻³
Monoclinic, P2₁/n	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2yn	Cell parameters from 2180 reflections
a = 7.1924 (13) Å	θ = 2.1–27.5°
b = 13.091 (2) Å	µ = 7.14 mm⁻¹
c = 9.8480 (17) Å	T = 293 K
β = 90.396 (10)°	Prism, yellow
V = 927.2 (3) Å³	0.20 × 0.02 × 0.02 mm
Z = 4

Data collection top

Rigaku Mercury70 CCD diffractometer	2111 independent reflections
Radiation source: fine-focus sealed tube	1868 reflections with I > 2σ(I)
Rigaku Graphite Monochromator DIFFRACTOMETER TYPE monochromator	R_int = 0.041
Detector resolution: 14.6306 pixels mm^-1	θ_max = 27.5°, θ_min = 2.6°
ω scans	h = −9→9
Absorption correction: multi-scan (ABSCOR; Higashi, 1995)	k = −15→17
T_min = 0.329, T_max = 0.870	l = −12→12
7036 measured reflections

Refinement top

Refinement on F²	0 restraints
Least-squares matrix: full	Primary atom site location: structure-invariant direct methods
R[F² > 2σ(F²)] = 0.037	Secondary atom site location: difference Fourier map
wR(F²) = 0.068	w = 1/[σ²(F_o²) + (0.0639P)²] where P = (F_o² + 2F_c²)/3
S = 1.15	(Δ/σ)_max < 0.001
2111 reflections	Δρ_max = 2.38 e Å⁻³
163 parameters	Δρ_min = −0.80 e Å⁻³

Crystal data top

NaSm(PO₃)₄	V = 927.2 (3) Å³
M_r = 489.22	Z = 4
Monoclinic, P2₁/n	Mo Kα radiation
a = 7.1924 (13) Å	µ = 7.14 mm⁻¹
b = 13.091 (2) Å	T = 293 K
c = 9.8480 (17) Å	0.20 × 0.02 × 0.02 mm
β = 90.396 (10)°

Data collection top

Rigaku Mercury70 CCD diffractometer	2111 independent reflections
Absorption correction: multi-scan (ABSCOR; Higashi, 1995)	1868 reflections with I > 2σ(I)
T_min = 0.329, T_max = 0.870	R_int = 0.041
7036 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.037	163 parameters
wR(F²) = 0.068	0 restraints
S = 1.15	Δρ_max = 2.38 e Å⁻³
2111 reflections	Δρ_min = −0.80 e Å⁻³

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 F^2^ against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F^2^, conventional R-factors R are based on F, with F set to zero for negative F^2^. The threshold expression of F^2^ > σ(F^2^) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F^2^ 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

	x	y	z	U_iso*/U_eq
Na1	−0.0002 (4)	0.7220 (2)	0.5648 (3)	0.0210 (6)
Sm1	0.51300 (4)	0.71807 (2)	0.47634 (3)	0.00716 (10)
P1	0.2493 (2)	0.60065 (11)	0.74392 (15)	0.0064 (3)
P2	0.8781 (2)	0.61480 (12)	0.26404 (15)	0.0063 (3)
P3	0.2690 (2)	0.59026 (12)	0.19783 (15)	0.0065 (3)
P4	0.6463 (2)	0.62775 (12)	0.80511 (15)	0.0065 (3)
O1	0.2374 (6)	0.6610 (3)	0.0824 (4)	0.0117 (9)
O2	0.7180 (5)	0.7105 (3)	0.8947 (4)	0.0099 (9)
O3	0.2829 (6)	0.4784 (3)	0.1343 (4)	0.0091 (9)
O4	0.8029 (6)	0.6454 (3)	0.3976 (4)	0.0095 (9)
O5	0.0936 (6)	0.6652 (3)	0.7951 (4)	0.0103 (9)
O6	0.0886 (6)	0.5804 (3)	0.2895 (4)	0.0105 (9)
O7	0.2159 (6)	0.4860 (3)	0.7898 (4)	0.0098 (9)
O8	0.6799 (6)	0.6328 (3)	0.6572 (4)	0.0100 (9)
O9	0.8672 (6)	0.6896 (3)	0.1519 (4)	0.0105 (9)
O10	0.2860 (6)	0.6073 (3)	0.5963 (4)	0.0102 (9)
O11	0.4284 (6)	0.6243 (3)	0.8331 (4)	0.0082 (9)
O12	0.4293 (6)	0.6102 (3)	0.2901 (4)	0.0135 (9)

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Na1	0.0172 (14)	0.0309 (16)	0.0149 (12)	0.0063 (13)	−0.0028 (11)	0.0029 (12)
Sm1	0.00640 (16)	0.00857 (15)	0.00651 (15)	−0.00002 (13)	0.00033 (11)	−0.00033 (13)
P1	0.0049 (7)	0.0065 (7)	0.0078 (7)	−0.0001 (6)	−0.0001 (6)	−0.0006 (6)
P2	0.0055 (7)	0.0053 (7)	0.0082 (7)	0.0002 (6)	0.0012 (6)	0.0002 (6)
P3	0.0046 (7)	0.0064 (7)	0.0084 (7)	0.0013 (6)	0.0000 (6)	−0.0001 (6)
P4	0.0053 (7)	0.0059 (7)	0.0084 (7)	−0.0007 (6)	0.0001 (6)	−0.0007 (6)
O1	0.010 (2)	0.013 (2)	0.012 (2)	0.0027 (18)	0.0012 (18)	0.0029 (18)
O2	0.005 (2)	0.009 (2)	0.016 (2)	−0.0013 (17)	−0.0032 (17)	−0.0044 (18)
O3	0.014 (2)	0.005 (2)	0.009 (2)	0.0016 (17)	−0.0019 (17)	−0.0014 (17)
O4	0.007 (2)	0.012 (2)	0.009 (2)	0.0009 (17)	0.0012 (17)	−0.0007 (17)
O5	0.005 (2)	0.013 (2)	0.013 (2)	0.0014 (17)	0.0020 (17)	−0.0007 (18)
O6	0.008 (2)	0.015 (2)	0.008 (2)	−0.0019 (18)	0.0034 (17)	0.0022 (18)
O7	0.014 (2)	0.005 (2)	0.011 (2)	−0.0042 (17)	−0.0001 (18)	−0.0013 (16)
O8	0.010 (2)	0.013 (2)	0.0064 (19)	0.0015 (18)	0.0028 (17)	0.0026 (17)
O9	0.011 (2)	0.008 (2)	0.012 (2)	0.0023 (17)	0.0018 (18)	0.0028 (17)
O10	0.012 (2)	0.010 (2)	0.009 (2)	−0.0015 (18)	0.0019 (18)	−0.0004 (17)
O11	0.007 (2)	0.010 (2)	0.0076 (19)	−0.0012 (17)	−0.0028 (17)	−0.0021 (16)
O12	0.008 (2)	0.015 (2)	0.017 (2)	−0.0020 (18)	−0.0044 (18)	−0.0047 (18)

Geometric parameters (Å, º) top

Na1—O4ⁱ	2.386 (5)	P2—O6^vii	1.598 (4)
Na1—O1ⁱⁱ	2.438 (5)	P3—O1	1.482 (4)
Na1—O2ⁱⁱⁱ	2.468 (5)	P3—O12	1.486 (4)
Na1—O5	2.475 (5)	P3—O6	1.591 (4)
Na1—O10	2.565 (5)	P3—O3	1.596 (4)
Na1—O8ⁱ	2.741 (5)	P4—O8	1.479 (4)
Na1—O9ⁱⁱ	3.005 (5)	P4—O2	1.487 (4)
Sm1—O9ⁱⁱ	2.362 (4)	P4—O11	1.594 (4)
Sm1—O12	2.389 (4)	P4—O3^vi	1.595 (4)
Sm1—O8	2.415 (4)	O1—Na1^iv	2.438 (5)
Sm1—O5^iv	2.423 (4)	O1—Sm1ⁱⁱⁱ	2.486 (4)
Sm1—O4	2.424 (4)	O2—Sm1^v	2.449 (4)
Sm1—O2ⁱⁱⁱ	2.449 (4)	O2—Na1^v	2.468 (5)
Sm1—O1^v	2.486 (4)	O3—P4^vi	1.595 (4)
Sm1—O10	2.488 (4)	O4—Na1^vii	2.386 (5)
P1—O10	1.482 (4)	O5—Sm1ⁱⁱ	2.423 (4)
P1—O5	1.494 (4)	O6—P2ⁱ	1.598 (4)
P1—O11	1.584 (4)	O7—P2^vi	1.574 (4)
P1—O7	1.586 (4)	O8—Na1^vii	2.741 (5)
P2—O9	1.477 (4)	O9—Sm1^iv	2.362 (4)
P2—O4	1.481 (4)	O9—Na1^iv	3.005 (5)
P2—O7^vi	1.574 (4)

O4ⁱ—Na1—O1ⁱⁱ	81.77 (16)	O10—P1—O5	115.9 (2)
O4ⁱ—Na1—O2ⁱⁱⁱ	93.40 (16)	O10—P1—O11	112.5 (2)
O1ⁱⁱ—Na1—O2ⁱⁱⁱ	108.62 (17)	O5—P1—O11	108.1 (2)
O4ⁱ—Na1—O5	131.55 (19)	O10—P1—O7	111.3 (2)
O1ⁱⁱ—Na1—O5	109.24 (16)	O5—P1—O7	108.9 (2)
O2ⁱⁱⁱ—Na1—O5	123.97 (17)	O11—P1—O7	98.7 (2)
O4ⁱ—Na1—O10	108.05 (17)	O9—P2—O4	117.8 (2)
O1ⁱⁱ—Na1—O10	168.60 (18)	O9—P2—O7^vi	106.5 (2)
O2ⁱⁱⁱ—Na1—O10	77.17 (15)	O4—P2—O7^vi	111.6 (2)
O5—Na1—O10	60.02 (14)	O9—P2—O6^vii	110.5 (2)
O4ⁱ—Na1—O8ⁱ	63.56 (14)	O4—P2—O6^vii	106.8 (2)
O1ⁱⁱ—Na1—O8ⁱ	65.92 (15)	O7^vi—P2—O6^vii	102.8 (2)
O2ⁱⁱⁱ—Na1—O8ⁱ	156.55 (17)	O1—P3—O12	118.2 (3)
O5—Na1—O8ⁱ	78.01 (15)	O1—P3—O6	111.4 (2)
O10—Na1—O8ⁱ	112.69 (17)	O12—P3—O6	107.4 (2)
O4ⁱ—Na1—O9ⁱⁱ	151.14 (16)	O1—P3—O3	106.4 (2)
O1ⁱⁱ—Na1—O9ⁱⁱ	114.66 (17)	O12—P3—O3	110.5 (2)
O2ⁱⁱⁱ—Na1—O9ⁱⁱ	59.56 (14)	O6—P3—O3	101.6 (2)
O5—Na1—O9ⁱⁱ	67.70 (14)	O8—P4—O2	119.5 (3)
O10—Na1—O9ⁱⁱ	59.17 (13)	O8—P4—O11	109.8 (2)
O8ⁱ—Na1—O9ⁱⁱ	143.89 (15)	O2—P4—O11	104.8 (2)
P1—Na1—O9ⁱⁱ	60.64 (10)	O8—P4—O3^vi	110.7 (2)
O9ⁱⁱ—Sm1—O12	138.95 (15)	O2—P4—O3^vi	107.7 (2)
O9ⁱⁱ—Sm1—O8	85.27 (14)	O11—P4—O3^vi	102.9 (2)
O12—Sm1—O8	114.50 (15)	P3—O1—Sm1ⁱⁱⁱ	144.7 (2)
O9ⁱⁱ—Sm1—O5^iv	109.05 (14)	Na1^iv—O1—Sm1ⁱⁱⁱ	94.05 (16)
O12—Sm1—O5^iv	82.37 (15)	P4—O2—Sm1^v	140.3 (2)
O8—Sm1—O5^iv	135.61 (14)	P4—O2—Na1^v	116.4 (2)
O9ⁱⁱ—Sm1—O4	145.34 (14)	Sm1^v—O2—Na1^v	101.18 (16)
O12—Sm1—O4	74.63 (14)	P4^vi—O3—P3	132.3 (3)
O8—Sm1—O4	68.31 (13)	P2—O4—Na1^vii	120.5 (2)
O5^iv—Sm1—O4	78.51 (14)	P2—O4—Sm1	135.3 (2)
O9ⁱⁱ—Sm1—O2ⁱⁱⁱ	69.92 (14)	Na1^vii—O4—Sm1	97.01 (16)
O12—Sm1—O2ⁱⁱⁱ	76.16 (14)	P1—O5—Sm1ⁱⁱ	142.1 (2)
O8—Sm1—O2ⁱⁱⁱ	147.54 (13)	P1—O5—Na1	93.5 (2)
O5^iv—Sm1—O2ⁱⁱⁱ	74.25 (14)	Sm1ⁱⁱ—O5—Na1	114.88 (18)
O4—Sm1—O2ⁱⁱⁱ	142.17 (13)	P3—O6—P2ⁱ	131.6 (3)
O9ⁱⁱ—Sm1—O1^v	69.91 (14)	P2^vi—O7—P1	139.8 (3)
O12—Sm1—O1^v	149.17 (14)	P4—O8—Sm1	131.5 (2)
O8—Sm1—O1^v	70.50 (14)	P4—O8—Na1^vii	119.3 (2)
O5^iv—Sm1—O1^v	75.54 (14)	Sm1—O8—Na1^vii	88.43 (14)
O4—Sm1—O1^v	80.05 (14)	P2—O9—Sm1^iv	149.9 (3)
O2ⁱⁱⁱ—Sm1—O1^v	116.94 (14)	P2—O9—Na1^iv	120.7 (2)
O9ⁱⁱ—Sm1—O10	69.79 (14)	Sm1^iv—O9—Na1^iv	89.30 (14)
O12—Sm1—O10	81.81 (14)	P1—O10—Sm1	128.5 (2)
O8—Sm1—O10	72.84 (14)	P1—O10—Na1	90.3 (2)
O5^iv—Sm1—O10	151.45 (14)	Sm1—O10—Na1	97.49 (15)
O4—Sm1—O10	119.46 (14)	P1—O11—P4	135.0 (3)
O2ⁱⁱⁱ—Sm1—O10	78.97 (14)	P3—O12—Sm1	139.8 (3)
O1^v—Sm1—O10	126.71 (13)

Symmetry codes: (i) x−1, y, z; (ii) x−1/2, −y+3/2, z+1/2; (iii) x−1/2, −y+3/2, z−1/2; (iv) x+1/2, −y+3/2, z−1/2; (v) x+1/2, −y+3/2, z+1/2; (vi) −x+1, −y+1, −z+1; (vii) x+1, y, z.

Experimental details

Crystal data
Chemical formula	NaSm(PO₃)₄
M_r	489.22
Crystal system, space group	Monoclinic, P2₁/n
Temperature (K)	293
a, b, c (Å)	7.1924 (13), 13.091 (2), 9.8480 (17)
β (°)	90.396 (10)
V (Å³)	927.2 (3)
Z	4
Radiation type	Mo Kα
µ (mm⁻¹)	7.14
Crystal size (mm)	0.20 × 0.02 × 0.02

Data collection
Diffractometer	Rigaku Mercury70 CCD diffractometer
Absorption correction	Multi-scan (ABSCOR; Higashi, 1995)
T_min, T_max	0.329, 0.870
No. of measured, independent and observed [I > 2σ(I)] reflections	7036, 2111, 1868
R_int	0.041
(sin θ/λ)_max (Å⁻¹)	0.649

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.037, 0.068, 1.15
No. of reflections	2111
No. of parameters	163
Δρ_max, Δρ_min (e Å⁻³)	2.38, −0.80

Computer programs: CrystalClear (Rigaku, 2004), SHELXS97 (Sheldrick, 2008) and PLATON (Spek, 2009), SHELXL97 (Sheldrick, 2008), DIAMOND (Brandenburg, 2004), SHELXTL (Sheldrick, 2008).

Selected bond lengths (Å) top

P1—O10	1.482 (4)	P3—O1	1.482 (4)
P1—O5	1.494 (4)	P3—O12	1.486 (4)
P1—O11	1.584 (4)	P3—O6	1.591 (4)
P1—O7	1.586 (4)	P3—O3	1.596 (4)
P2—O9	1.477 (4)	P4—O8	1.479 (4)
P2—O4	1.481 (4)	P4—O2	1.487 (4)
P2—O7ⁱ	1.574 (4)	P4—O11	1.594 (4)
P2—O6ⁱⁱ	1.598 (4)	P4—O3ⁱ	1.595 (4)

Symmetry codes: (i) −x+1, −y+1, −z+1; (ii) x+1, y, z.

Acknowledgements

The authors acknowledge the Doctoral Foundation of Henan Polytechnic University (B2010–92, 648483).

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