An ortho­rhom­bic polymorph of cerium(III) ultraphosphate, CeP₅O₁₄

Cerium(III) ultraphosphate, CeP₅O₁₄, was synthesized by a high-temperature solution reaction between CeO₂ and NH₄H₂PO₄ in a Ce-P molar ratio of 1:12. Colourless crystals of the ortho­rhom­bic polymorph were obtained by cooling the melt of the mixture. The structure contains (P₅O₁₄)^3- anionic ribbons linked by distorted CeO₈ polyhedra.

Key indicators

• Single-crystal X-ray study
• T = 293 K
• Mean [sigma](P-O) = 0.007 Å
• R factor = 0.048
• wR factor = 0.094
• Data-to-parameter ratio = 12.7

checkCIF/PLATON results

No syntax errors found



Alert level B
CHEMS01_ALERT_1_B  The sum formula contains elements in the wrong order.
            P  precedes O
            Sequence must be C, H, then alphabetical.

Alert level C
            Value of measurement temperature given =   293.000
            Value of melting point given =     0.000
PLAT213_ALERT_2_C Atom O3      has ADP max/min Ratio .............       3.20 prola
PLAT213_ALERT_2_C Atom O5      has ADP max/min Ratio .............       3.80 prola
PLAT241_ALERT_2_C Check High      Ueq as Compared to Neighbors for         O3
PLAT241_ALERT_2_C Check High      Ueq as Compared to Neighbors for         O5
PLAT395_ALERT_2_C Deviating  X-O-Y  Angle from 120 Deg for      O3     141.90 Deg.
PLAT041_ALERT_1_C Calc. and Rep. SumFormula Strings    Differ ....          ?
PLAT042_ALERT_1_C Calc. and Rep. MoietyFormula Strings Differ ....          ?

Alert level G
PLAT199_ALERT_1_G Check the Reported _cell_measurement_temperature        293 K
PLAT200_ALERT_1_G Check the Reported _diffrn_ambient_temperature .        293 K

   0 ALERT level A = In general: serious problem
   1 ALERT level B = Potentially serious problem
   7 ALERT level C = Check and explain
   2 ALERT level G = General alerts; check

   5 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   5 ALERT type 2 Indicator that the structure model may be wrong or deficient
   0 ALERT type 3 Indicator that the structure quality may be low
   0 ALERT type 4 Improvement, methodology, query or suggestion
   0 ALERT type 5 Informative message, check

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S1. Comment

Rare-earth ultraphosphates, LnP₅O₁₄ (Ln = rare-earth element), have attracted wide interest because of their potential applications in the laser domain (Schulz et al., 1974; Kobayashi et al., 1976; Katrusiak & Kaczmarek, 1995; Cole et al., 2000). These compounds can be generally classified into four structure types: monoclinic (P2₁/a), monoclinic (C2/c), orthorhombic (Pnma), and triclinic (P1) (Averbuch-Pouchot & Durif, 1992). In this chemical system, many of the compounds are isotypic, and some are polymorphic. However, many polymorphs of ultraphosphates LnP₅O₁₄ have not been realised to date. Herein, we present the synthesis and crystal structure of an orthorhombic polymorph of CeP₅O₁₄.

In the structure (Figs. 1 and 2), the Ce³⁺ cation plays an important bridging role, connecting neighbouring (P₅O₁₄)^3- anionic ribbons. The CeO₈ polyhedron is corner-sharing with eight PO₄ tetrahedra, with the Ce—O bond distances ranging from 2.436 (5) to 2.534 (8) Å. The shortest Ce—Ce distance is 5.2271 (9) Å. The (P₅O₁₄)^3- anionic ribbon may be described as two PO₄ infinite chains linked by P(2)O₄ tetrahedra, as shown in Fig. 3. P(1)O₄, P(3)O₄, and P(4)O₄ tetrahedra are corner-shared to form screwed infinite chains along the b axis. P(2)O₄ tetrahedra are corner-shared with two surrounding PO₄ infinite chains along the a axis. Thus, a (P₅O₁₄)^3- anionic ribbon is observed parallel to b.

Related literature

For applications of rare-earth ultraphosphates, see: Cole et al. (2000); Katrusiak & Kaczmarek (1995); Kobayashi et al. (1976); Schulz et al. (1974). For a discussion of structure types in this chemical system, see: Averbuch-Pouchot & Durif (1992). For the triclinic polymorph of CeP₅O₁₄, see: Rzaigui et al. (1984).

S2. Experimental

The title compound was prepared by a high-temperature solution reaction, using analytical reagent CeO₂ and NH₄H₂PO₄ in a molar ratio corresponding to Ce/P = 1:12. Starting mixtures were finely ground in an agate mortar to ensure optimal homogeneity and reactivity, then placed in a platinum crucible and heated at 373 K for 4 h. Afterwards, the mixtures were reground and heated to 973 K for 24 h. Finally, the temperature was cooled to 773 K at a rate of 2 K/h and air-quenched to room temperature. A few colourless, block-shaped crystals were obtained from the melt of the mixture.

S3. Refinement

The position of the Ce atom was obtained using direct methods, and the remaining atoms were located in succesive difference Fourier syntheses. The chemical composition of the single crystal was confirmed by energy-dispersive X-ray (EDX) analysis, and no impurity elements were detected.

Computing details

Data collection: CrystalClear (Molecular Structure Corporation & Rigaku, 2001); cell refinement: CrystalClear (Molecular Structure Corporation & Rigaku, 2001); data reduction: CrystalClear (Molecular Structure Corporation & Rigaku, 2001); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008) and DIAMOND (Brandenburg, 2005); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008).

Figures

	Fig. 1. Asymmetric unit with displacement ellipsoids shown at 50% probability.
	Fig. 2. Projection of the structure along the b axis. The tetrahedra represent PO4 groups and the gray circles represent Ce^3+ cations.
	Fig. 3. (P5O14)^3- anionic ribbon running parallel to the b axis.

Cerium(III) ultraphosphate

Crystal data

CeP5O14	F(000) = 980
Mr = 518.97	Dx = 3.289 Mg m^−3
Orthorhombic, Pmna	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ac 2	Cell parameters from 2047 reflections
a = 13.1252 (12) Å	θ = 2.3–27.5°
b = 8.7991 (9) Å	µ = 5.19 mm^−1
c = 9.0741 (9) Å	T = 293 K
V = 1047.97 (18) Å^3	Block, colourless
Z = 4	0.08 × 0.08 × 0.05 mm

Data collection

Rigaku Mercury CCD diffractometer	1262 independent reflections
Radiation source: fine-focus sealed tube	1212 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.072
ω scans	θmax = 27.5°, θmin = 2.3°
Absorption correction: multi-scan (CrystalClear; Molecular Structure Corporation & Rigaku, 2001)	h = −17→16
Tmin = 0.663, Tmax = 0.771	k = −11→11
7608 measured reflections	l = −11→11

Refinement

Refinement on F^2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.048	w = 1/[σ^2(Fo^2) + 37.6801P] where P = (Fo^2 + 2Fc^2)/3
wR(F^2) = 0.094	(Δ/σ)max = 0.001
S = 1.00	Δρmax = 1.70 e Å^−3
1262 reflections	Δρmin = −1.08 e Å^−3
99 parameters	Extinction correction: SHELXL97 (Sheldrick, 2008), Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
0 restraints	Extinction coefficient: 0.0114 (15)

Special details

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 (Ų)

	x	y	z	Uiso*/Ueq
Ce	0.5000	0.72337 (7)	0.68985 (6)	0.00797 (19)
P1	0.2936 (2)	0.5000	0.5000	0.0113 (6)
P2	0.0000	0.3121 (3)	0.7524 (3)	0.0091 (5)
P3	0.3233 (2)	0.0000	0.5000	0.0102 (5)
P4	0.16332 (14)	0.2351 (2)	0.54996 (19)	0.0098 (4)
O1	0.1129 (4)	0.2256 (7)	0.4081 (6)	0.0189 (12)
O2	0.3474 (4)	0.5859 (7)	0.6151 (6)	0.0182 (12)
O3	0.2451 (5)	0.1123 (8)	0.5815 (6)	0.0295 (16)
O4	0.0000	0.4655 (9)	0.6859 (9)	0.0155 (16)
O5	0.2151 (5)	0.3901 (7)	0.5849 (7)	0.0307 (17)
O6	0.3778 (4)	−0.0799 (6)	0.6175 (6)	0.0165 (12)
O7	0.0000	0.2893 (10)	0.9131 (8)	0.0176 (17)
O8	0.0934 (4)	0.2133 (6)	0.6876 (6)	0.0161 (11)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Ce	0.0074 (3)	0.0090 (3)	0.0075 (3)	0.000	0.000	0.0003 (2)
P1	0.0062 (11)	0.0135 (13)	0.0143 (13)	0.000	0.000	−0.0033 (11)
P2	0.0089 (12)	0.0120 (13)	0.0063 (11)	0.000	0.000	−0.0008 (10)
P3	0.0080 (11)	0.0124 (13)	0.0102 (12)	0.000	0.000	−0.0013 (10)
P4	0.0059 (8)	0.0152 (10)	0.0083 (8)	0.0002 (7)	0.0001 (6)	−0.0019 (7)
O1	0.021 (3)	0.023 (3)	0.013 (2)	0.006 (3)	−0.008 (2)	−0.001 (2)
O2	0.014 (3)	0.023 (3)	0.018 (3)	−0.006 (2)	−0.003 (2)	0.000 (2)
O3	0.029 (3)	0.050 (4)	0.010 (3)	0.028 (3)	0.001 (2)	−0.004 (3)
O4	0.019 (4)	0.012 (4)	0.016 (4)	0.000	0.000	−0.005 (3)
O5	0.034 (4)	0.031 (4)	0.027 (3)	−0.027 (3)	0.019 (3)	−0.015 (3)
O6	0.016 (3)	0.017 (3)	0.016 (3)	0.006 (2)	−0.002 (2)	0.001 (2)
O7	0.021 (4)	0.024 (4)	0.008 (3)	0.000	0.000	−0.002 (3)
O8	0.017 (3)	0.017 (3)	0.014 (2)	0.007 (2)	0.005 (2)	0.004 (2)

Geometric parameters (Å, º)

Ce—O2	2.436 (5)	P2—O8^ix	1.614 (5)
Ce—O2^i	2.436 (5)	P2—O8	1.614 (5)
Ce—O6^ii	2.449 (5)	P3—O6^x	1.464 (5)
Ce—O6^iii	2.449 (5)	P3—O6	1.464 (5)
Ce—O7^iv	2.513 (7)	P3—O3^x	1.606 (6)
Ce—O1^v	2.514 (5)	P3—O3	1.606 (6)
Ce—O1^vi	2.514 (5)	P4—O1	1.450 (5)
Ce—O4^vii	2.534 (8)	P4—O3	1.549 (6)
P1—O2	1.470 (6)	P4—O5	1.557 (6)
P1—O2^viii	1.470 (6)	P4—O8	1.562 (5)
P1—O5^viii	1.609 (6)	O1—Ce^iv	2.514 (5)
P1—O5	1.609 (6)	O4—Ce^xi	2.534 (7)
P2—O7	1.472 (8)	O6—Ce^xii	2.449 (5)
P2—O4	1.479 (8)	O7—Ce^vi	2.513 (7)
O2—Ce—O2^i	110.6 (3)	O2^viii—P1—O5^viii	106.0 (3)
O2—Ce—O6^ii	144.55 (18)	O2—P1—O5	106.0 (3)
O2^i—Ce—O6^ii	74.82 (19)	O2^viii—P1—O5	109.8 (3)
O2—Ce—O6^iii	74.82 (19)	O5^viii—P1—O5	100.4 (6)
O2^i—Ce—O6^iii	144.55 (18)	O7—P2—O4	121.9 (5)
O6^ii—Ce—O6^iii	81.8 (3)	O7—P2—O8^ix	106.7 (3)
O2—Ce—O7^iv	72.54 (17)	O4—P2—O8^ix	110.1 (3)
O2^i—Ce—O7^iv	72.54 (17)	O7—P2—O8	106.7 (3)
O6^ii—Ce—O7^iv	76.3 (2)	O4—P2—O8	110.1 (3)
O6^iii—Ce—O7^iv	76.3 (2)	O8^ix—P2—O8	98.9 (4)
O2—Ce—O1^v	142.43 (19)	O6^x—P3—O6	121.5 (5)
O2^i—Ce—O1^v	79.83 (19)	O6^x—P3—O3^x	105.8 (3)
O6^ii—Ce—O1^v	72.48 (18)	O6—P3—O3^x	110.6 (3)
O6^iii—Ce—O1^v	118.08 (19)	O6^x—P3—O3	110.6 (3)
O7^iv—Ce—O1^v	142.65 (14)	O6—P3—O3	105.8 (3)
O2—Ce—O1^vi	79.83 (19)	O3^x—P3—O3	100.5 (5)
O2^i—Ce—O1^vi	142.43 (19)	O1—P4—O3	116.1 (3)
O6^ii—Ce—O1^vi	118.08 (19)	O1—P4—O5	115.5 (4)
O6^iii—Ce—O1^vi	72.48 (18)	O3—P4—O5	105.7 (4)
O7^iv—Ce—O1^vi	142.65 (14)	O1—P4—O8	115.8 (3)
O1^v—Ce—O1^vi	72.2 (3)	O3—P4—O8	100.0 (3)
O2—Ce—O4^vii	71.29 (16)	O5—P4—O8	101.6 (3)
O2^i—Ce—O4^vii	71.29 (16)	P4—O1—Ce^iv	163.4 (4)
O6^ii—Ce—O4^vii	138.78 (13)	P1—O2—Ce	148.0 (4)
O6^iii—Ce—O4^vii	138.78 (14)	P4—O3—P3	141.9 (4)
O7^iv—Ce—O4^vii	113.9 (3)	P2—O4—Ce^xi	129.5 (5)
O1^v—Ce—O4^vii	79.0 (2)	P4—O5—P1	135.1 (4)
O1^vi—Ce—O4^vii	79.0 (2)	P3—O6—Ce^xii	148.7 (3)
O2—P1—O2^viii	122.6 (5)	P2—O7—Ce^vi	174.7 (6)
O2—P1—O5^viii	109.8 (3)	P4—O8—P2	132.2 (4)

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