The type IV polymorph of KEu(PO3)4

Oudahmane, A.; Daoud, M.; Tanouti, B.; Avignant, D.; Zambon, D.

doi:10.1107/S1600536809048788

inorganic compounds

CRYSTALLOGRAPHIC
COMMUNICATIONS

ISSN: 2056-9890

Volume 65| Part 12| December 2009| Pages i91-i92

doi:10.1107/S1600536809048788

Open

access

The type IV polymorph of KEu(PO₃)₄

Abdelghani Oudahmane,^a Mohamed Daoud,^a Boumediene Tanouti,^a Daniel Avignant ^b and Daniel Zambon ^b ^*

^aUniversité Cadi Ayyad, Laboratoire de Physico-Chimie des Matériaux et Environnement, Faculté des Sciences Semlalia, Département de Chimie, BP 2390, 40000, Marrakech, Morocco, and ^bUniversité Blaise Pascal, Laboratoire des Matériaux Inorganiques, UMR CNRS 6002, 24 Avenue des Landais, 63177 Aubière, France
^*Correspondence e-mail: daniel.zambon@univ-bpclermont.fr

(Received 10 November 2009; accepted 16 November 2009; online 21 November 2009)

Single crystals of KEu(PO₃)₄, potassium europium(III) polyphosphate, were obtained by solid-state reactions. This monoclinic form is the second polymorph described for this composition and belongs to type IV of long-chain polyphosphates with general formula A^IB^III(PO₃)₄. It is isotypic with its KEr(PO₃)₄ and KDy(PO₃)₄ homologues. The crystal structure is built of infinite helical chains of corner-sharing PO₄ tetrahedra with a repeating unit of eight tetrahedra. These chains are further linked by isolated EuO₈ square antiprisms, forming a three-dimensional framework. The K⁺ ions are located in pseudo-hexagonal channels running along [ $[\overline{2}]$ 01] and are surrounded by nine O atoms in a distorted environment.

Related literature

Besides crystals of the title compound, crystals of the type III polymorph (Hu et al., 1984 )) have also been obtained. For isotypic AB(PO₃)₄ structures, where A is an alkali metal, Tl or NH₄⁺, and B is a rare earth element, see: Palkina et al. (1977 ) for TlNd; Maksimova et al. (1978 ) for RbNd; Dago et al. (1980 ) for KEr; Maksimova et al. (1981 ) for CsNd; Maksimova et al. (1982 ) for RbHo; Horchani et al. (2004 ) for RbEr; Rekik et al. (2004 ) for KGd; Naïli & Mhiri (2005 ) for CsGd; Ben Zarkouna et al. (2006 ) for (NH₄)Gd; Khlissa & Férid (2006 ) for RbTb; Ettis et al. (2006 ) for RbGd; Chehimi-Moumen & Férid (2007 ) for KDy; Horchani-Naifer & Férid (2007 ) for CsPr; Zhu et al. (2009 ) for CsEu. For a review on the crystal chemisty of polyphosphates, see: Durif (1995 ). Jaouadi et al. (2003 ) have discussed the main crystal chemical characteristics of the seven AB(PO₃)₄ structure types. For applications of rare earth polyphosphates, see: Rashchi & Finch (2000 ); Barsukov et al. (2004 ). For general background, see: Porai-Koshits & Aslanov (1972 ). For ionic radii, see: Shannon (1976 ).

Experimental

Crystal data

KEu(PO₃)₄
M_r = 506.94
Monoclinic, P 2₁ /n
a = 10.3723 (1) Å
b = 8.9721 (1) Å
c = 10.8320 (1) Å
β = 106.053 (1)°
V = 968.73 (2) Å³
Z = 4
Mo Kα radiation
μ = 7.63 mm⁻¹
T = 296 K
0.12 × 0.11 × 0.10 mm

Data collection

Bruker APEXII CCD diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2008 ) T_min = 0.466, T_max = 0.513
24299 measured reflections
6201 independent reflections
5023 reflections with I > 2σ(I)
R_int = 0.045

Refinement

R[F² > 2σ(F²)] = 0.030
wR(F²) = 0.072
S = 1.04
6201 reflections
163 parameters
Δρ_max = 1.72 e Å⁻³
Δρ_min = −2.04 e Å⁻³

Table 1
Selected bond lengths (Å)

P1—O7	1.480 (2)
P1—O4ⁱ	1.483 (2)
P1—O12	1.588 (2)
P1—O3ⁱⁱ	1.5968 (19)
P2—O10ⁱⁱⁱ	1.4795 (19)
P2—O5	1.483 (2)
P2—O11ⁱⁱⁱ	1.6015 (18)
P2—O3^iv	1.602 (2)
P3—O6	1.482 (2)
P3—O2	1.4873 (19)
P3—O11	1.6005 (19)
P3—O1	1.6033 (19)
P4—O9	1.4784 (19)
P4—O8^v	1.484 (2)
P4—O1	1.601 (2)
P4—O12ⁱⁱⁱ	1.601 (2)
Symmetry codes: (i) $[-x+{\script{3\over 2}}, y+{\script{1\over 2}}, -z+{\script{1\over 2}}]$ ; (ii) x+1, y, z; (iii) -x+1, -y+2, -z; (iv) $[x+{\script{1\over 2}}, -y+{\script{3\over 2}}, z-{\script{1\over 2}}]$ ; (v) $[x-{\script{1\over 2}}, -y+{\script{3\over 2}}, z-{\script{1\over 2}}]$ .

Data collection: APEX2 (Bruker, 2008); cell refinement: SAINT (Bruker, 2008); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: DIAMOND (Brandenburg, 1999 ); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).

Supporting information

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536809048788/wm2282sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536809048788/wm2282Isup2.hkl

checkCIF report

Comment top

Rare earth polyphosphates are interesting materials and bear potential applications (Rashchi & Finch, 2000; Barsukov et al., 2004). The title compound is a member of a large family of polyphosphates with general formula A^IB^III(PO₃)₄ (where A^I is a monovalent cation: Li, Na, K, Rb, Cs, Tl, NH₄, Ag and B^III is a trivalent cation: Ln,Y, Bi). It is now well known that these compounds are classified into seven structural types usually labelled by roman numerals from I to VII. A short recapitulation of the main crystal chemical characteristics of these seven structural types has recently been given by Jaouadi et al. (2003). The KEu(PO₃)₄ polymorph described in this article belongs to the IV structural type.

In the crystal structure the Eu³⁺ ion is eight-coordinated by the oxygen atoms and its 8-coordination polyhedron is better described as a square antiprism than a dodecahedron according to the criteria of Porai-Koshits & Aslanov (1972) (δ₁ = 10.37°, δ₂ = 10.85°, δ₃ = 47.97°, δ₄ = 53.54°). The Eu—O distances range from 2.3199 (19) Å to 2.4827 (19) Å with an average <Eu—O> distance of 2.399 Å that is slightly shorter than the sum of the ionic radii i.e. 2.466 Å (Shannon, 1976). The structure of this type IV polymorph is built of infinite helical chains of corner-sharing PO₄ tetrahedra further linked by isolated EuO₈ square antiprisms. The (PO₃)_∞ chains exhibit a repeating unit of eight PO₄ tetrahedra (Fig. 1) and are running along the [101] direction. The three-dimensional framework resulting from the edge-sharing between the PO₄ tetrahedra and the EuO₈ square antiprisms exhibits pseudo hexagonal channels where the K⁺ ions reside. The K⁺ ion is 9-coordinated by oxygen atoms with distances ranging from 2.789 (2) Å to 3.370 (3) Å. By sharing corners, the KO₉ coordination polyhedra form corrugated chains running along the [010] direction (Fig. 2). Whereas the K atoms are separated by 6.599 (2) Å within the chain, the shortest K—K distance in the structure, 4.770 (2) Å, occurs between two adjacent (KO₉)_∞ chains. This shortest distance corresponds to the separation between two K⁺ ions within the channels of the structure running along the [201] direction. This separation distance A^I—A^I is strongly dependent on the nature of the A^I element and decreases as the size of the A^I element increases. For instance, in the A^IGd(PO₃)₄ homologue series, where A^I = K, Rb, Cs, this A^I—A^I shortest distance varies from 4.801 Å for K to 4.211 Å for Cs (4.524 Å for Rb). For CsEu(PO₃)₄ the shortest Cs—Cs distance is equal to 4.237Å (Zhu et al. 2009).

For isotypic AB(PO₃)₄ structures, where A is an alkali metal, Tl or NH₄⁺, and B is a rare earth element, see: Palkina et al. (1977) for TlNd, Maksimova et al. (1978) for RbNd, Dago et al. (1980) for KEr, Maksimova et al. (1981) for CsNd, Maksimova et al. (1982) for RbHo, Horchani et al. (2004) for RbEr, Rekik et al. (2004) for KGd, Naïli & Mhiri (2005) for CsGd, Ben Zarkouna et al. (2006) for (NH₄)Gd, Khlissa & Férid (2006) for RbTb, Ettis et al. (2006) for RbGd, Chehimi-Moumen & Férid (2007) for KDy, Horchani-Naifer & Férid (2007) for CsPr, and Zhu et al. (2009) for CsEu. For a review on the crystal chemisty of polyphosphates, see: Durif (1995).

Related literature top

Besides crystals of the title compound, crystals of the type III polymorph (Hu et al., 1984)) have also been obtained. For isotypic AB(PO₃)₄ structures, where A is an alkali metal, Tl or NH₄⁺, and B is a rare earth element, see: Palkina et al. (1977) for TlNd; Maksimova et al. (1978) for RbNd; Dago et al. (1980) for KEr; Maksimova et al. (1981) for CsNd; Maksimova et al. (1982) for RbHo; Horchani et al. (2004) for RbEr; Rekik et al. (2004) for KGd; Naïli & Mhiri (2005) for CsGd; Ben Zarkouna et al. (2006) for (NH₄)Gd; Khlissa & Férid (2006) for RbTb; Ettis et al. (2006) for RbGd; Chehimi-Moumen & Férid (2007) for KDy; Horchani-Naifer & Férid (2007) for CsPr; Zhu et al. (2009) for CsEu. For a review on the crystal chemisty of polyphosphates, see: Durif (1995). Jaouadi et al. (2003) have discussed the main crystal chemical characteristics of the seven AB(PO₃)₄ structure types. For applications of rare earth polyphosphates, see: Rashchi & Finch (2000); Barsukov et al. (2004). For general background, see: Porai-Koshits & Aslanov (1972). For ionic radii, see: Shannon (1976).

Experimental top

Crystals of the title compound were synthesized by reacting Eu₂O₃ with (NH₄)H₂PO₄ and K₂CO₃ in a platinum crucible. A mixture of these reagents in the molar ratio 34:57:9 was used for the synthesis. The mixture was heated at 473 K for 6 h, then at 573 K for 6 h and finally at 873 K for 24 h. The furnace was then cooled down first to 773 K at the rate of 2 K^.h^-1 and then to room temperature at the rate of K^.h^-1. Single crystals were extracted from the batch by washing with hot water. Besides crystals of the title compound, crystals of the type III polymorph (Hu et al., 1984)) have also been obtained.

Computing details top

Data collection: APEX2 (Bruker, 2008); cell refinement: SAINT (Bruker, 2008); data reduction: SAINT (Bruker, 2008); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: DIAMOND (Brandenburg, 1999); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).

Figures top

Fig. 1. ORTEP-3 view of the repeating unit with eight PO₄ tetrahedra, leading to helical (PO₃)_∞ chains. Displacement ellipsoids are drawn at the 50 % probability level. Symmetry codes: (a) -1/2+x, 3/2-y, 1/2+z; (b) -1+x, -1+y, z; (c) x, -1+y, 1+z; (d) -1+x, y, z; (e) -1/2+x, 1/2-y, 1/2+z; (f) 3-x, 1-y, 1-z; (g) 2-x, 1-y, 1-z; (h) 5/2-x, -1/2+y, 1/2-z; (i) -3/2+x, 1/2-y, -1/2+z; (j) 3/2-x, -1/2+y, 1/2-z; (k) 2-x, 1-y, -z.

Fig. 2. Partial view of infinite chains of corner-sharing KO₉ polyhedra.

potassium europium(III) polyphosphate top

Crystal data top

KEu(PO₃)₄	F(000) = 952
M_r = 506.94	D_x = 3.476 Mg m⁻³
Monoclinic, P2₁/n	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2yn	Cell parameters from 6203 reflections
a = 10.3723 (1) Å	θ = 2.6–40.6°
b = 8.9721 (1) Å	µ = 7.63 mm⁻¹
c = 10.8320 (1) Å	T = 296 K
β = 106.053 (1)°	Hexagonal prism, colourless
V = 968.73 (2) Å³	0.12 × 0.11 × 0.10 mm
Z = 4

Data collection top

Bruker APEXII CCD diffractometer	6201 independent reflections
Radiation source: fine-focus sealed tube	5023 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.045
Detector resolution: 8.3333 pixels mm^-1	θ_max = 40.6°, θ_min = 3.1°
ω and ϕ scans	h = −18→18
Absorption correction: multi-scan (SADABS; Bruker, 2008)	k = −16→16
T_min = 0.466, T_max = 0.513	l = −19→5
24299 measured reflections

Refinement top

Refinement on F²	0 constraints
Least-squares matrix: full	Primary atom site location: structure-invariant direct methods
R[F² > 2σ(F²)] = 0.030	Secondary atom site location: difference Fourier map
wR(F²) = 0.072	w = 1/[σ²(F_o²) + (0.0311P)² + 1.1689P] where P = (F_o² + 2F_c²)/3
S = 1.04	(Δ/σ)_max = 0.002
6201 reflections	Δρ_max = 1.72 e Å⁻³
163 parameters	Δρ_min = −2.04 e Å⁻³
0 restraints

Crystal data top

KEu(PO₃)₄	V = 968.73 (2) Å³
M_r = 506.94	Z = 4
Monoclinic, P2₁/n	Mo Kα radiation
a = 10.3723 (1) Å	µ = 7.63 mm⁻¹
b = 8.9721 (1) Å	T = 296 K
c = 10.8320 (1) Å	0.12 × 0.11 × 0.10 mm
β = 106.053 (1)°

Data collection top

Bruker APEXII CCD diffractometer	6201 independent reflections
Absorption correction: multi-scan (SADABS; Bruker, 2008)	5023 reflections with I > 2σ(I)
T_min = 0.466, T_max = 0.513	R_int = 0.045
24299 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.030	163 parameters
wR(F²) = 0.072	0 restraints
S = 1.04	Δρ_max = 1.72 e Å⁻³
6201 reflections	Δρ_min = −2.04 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 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

	x	y	z	U_iso*/U_eq
K	0.79467 (11)	0.57090 (14)	0.04227 (10)	0.0395 (2)
Eu	0.500385 (11)	0.772652 (13)	0.184899 (12)	0.00645 (3)
P1	0.85428 (6)	0.90558 (7)	0.24010 (7)	0.00615 (10)
P2	0.54001 (6)	0.82848 (7)	−0.14102 (7)	0.00607 (10)
P3	0.24938 (6)	1.02436 (7)	0.22927 (6)	0.00609 (10)
P4	0.17657 (6)	0.89469 (7)	−0.01962 (6)	0.00626 (10)
O1	0.14215 (17)	0.9549 (2)	0.10673 (19)	0.0085 (3)
O2	0.35389 (19)	0.9131 (2)	0.29039 (19)	0.0093 (3)
O3	−0.02278 (19)	0.7943 (2)	0.2518 (2)	0.0103 (3)
O4	0.6017 (2)	0.5368 (2)	0.1754 (2)	0.0117 (3)
O5	0.5648 (2)	0.7615 (2)	−0.0114 (2)	0.0117 (3)
O6	0.17180 (19)	1.0919 (2)	0.3112 (2)	0.0106 (3)
O7	0.73783 (19)	0.8192 (2)	0.2547 (2)	0.0134 (4)
O8	0.5691 (2)	0.7074 (2)	0.4090 (2)	0.0114 (3)
O9	0.31707 (19)	0.8419 (2)	0.0175 (2)	0.0121 (3)
O10	0.53947 (19)	1.0334 (2)	0.1765 (2)	0.0121 (3)
O11	0.31589 (17)	1.1548 (2)	0.1668 (2)	0.0092 (3)
O12	0.8309 (2)	0.9497 (2)	0.0936 (2)	0.0125 (3)

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
K	0.0363 (5)	0.0581 (6)	0.0243 (4)	0.0047 (4)	0.0085 (4)	−0.0045 (4)
Eu	0.00596 (4)	0.00617 (4)	0.00701 (5)	0.00051 (3)	0.00144 (3)	0.00084 (4)
P1	0.0054 (2)	0.0053 (2)	0.0068 (2)	−0.00011 (17)	0.0002 (2)	0.00105 (19)
P2	0.0060 (2)	0.0053 (2)	0.0071 (2)	−0.00059 (17)	0.0021 (2)	−0.00025 (19)
P3	0.0057 (2)	0.0065 (2)	0.0062 (3)	0.00066 (17)	0.0020 (2)	−0.00024 (19)
P4	0.0052 (2)	0.0077 (2)	0.0050 (2)	−0.00047 (17)	0.00004 (19)	0.00081 (19)
O1	0.0071 (6)	0.0106 (7)	0.0078 (7)	−0.0029 (5)	0.0023 (6)	−0.0027 (6)
O2	0.0094 (7)	0.0093 (7)	0.0087 (8)	0.0032 (5)	0.0015 (6)	0.0013 (6)
O3	0.0108 (7)	0.0104 (7)	0.0101 (8)	0.0053 (6)	0.0036 (6)	0.0047 (6)
O4	0.0163 (8)	0.0086 (7)	0.0117 (8)	0.0013 (6)	0.0063 (7)	0.0015 (6)
O5	0.0135 (8)	0.0155 (8)	0.0074 (8)	0.0021 (6)	0.0048 (7)	0.0014 (6)
O6	0.0114 (7)	0.0126 (7)	0.0095 (8)	0.0022 (6)	0.0059 (7)	−0.0018 (6)
O7	0.0073 (7)	0.0148 (8)	0.0173 (10)	−0.0029 (6)	0.0019 (7)	0.0051 (7)
O8	0.0114 (7)	0.0125 (8)	0.0093 (8)	0.0046 (6)	0.0011 (6)	0.0038 (6)
O9	0.0083 (7)	0.0193 (9)	0.0080 (8)	0.0053 (6)	0.0011 (6)	0.0024 (7)
O10	0.0099 (7)	0.0060 (6)	0.0212 (10)	0.0017 (5)	0.0059 (7)	0.0020 (7)
O11	0.0060 (6)	0.0077 (6)	0.0146 (9)	−0.0005 (5)	0.0040 (6)	0.0009 (6)
O12	0.0191 (9)	0.0087 (7)	0.0069 (8)	−0.0009 (6)	−0.0009 (7)	0.0026 (6)

Geometric parameters (Å, º) top

K—O4	2.789 (2)	P1—O7	1.480 (2)
K—O5	2.860 (2)	P1—O4^vi	1.483 (2)
K—O6ⁱ	2.874 (2)	P1—O12	1.588 (2)
K—O2ⁱ	2.961 (2)	P1—O3ⁱⁱⁱ	1.5968 (19)
K—O10ⁱⁱ	3.075 (3)	P1—K^vi	3.4868 (13)
K—O3ⁱⁱⁱ	3.221 (2)	P2—O10^iv	1.4795 (19)
K—O7ⁱⁱ	3.234 (3)	P2—O5	1.483 (2)
K—O11^iv	3.326 (2)	P2—O11^iv	1.6015 (18)
K—O7	3.370 (3)	P2—O3ⁱ	1.602 (2)
K—P3ⁱ	3.4008 (12)	P3—O6	1.482 (2)
K—P1ⁱⁱ	3.4868 (13)	P3—O2	1.4873 (19)
Eu—O9	2.3199 (19)	P3—O11	1.6005 (19)
Eu—O4	2.3775 (19)	P3—O1	1.6033 (19)
Eu—O10	2.3799 (18)	P3—K^vii	3.4008 (12)
Eu—O5	2.401 (2)	P4—O9	1.4784 (19)
Eu—O7	2.4045 (19)	P4—O8^viii	1.484 (2)
Eu—O8	2.406 (2)	P4—O1	1.601 (2)
Eu—O6^v	2.4214 (18)	P4—O12^iv	1.601 (2)
Eu—O2	2.4827 (19)

O4—K—O5	59.57 (6)	O5—Eu—O2	141.68 (7)
O4—K—O6ⁱ	100.70 (7)	O7—Eu—O2	118.10 (7)
O5—K—O6ⁱ	89.02 (7)	O8—Eu—O2	72.99 (6)
O4—K—O2ⁱ	147.48 (7)	O6^v—Eu—O2	77.51 (6)
O5—K—O2ⁱ	99.06 (6)	O7—P1—O4^vi	118.08 (13)
O6ⁱ—K—O2ⁱ	51.47 (5)	O7—P1—O12	109.51 (12)
O4—K—O10ⁱⁱ	76.15 (6)	O4^vi—P1—O12	110.78 (11)
O5—K—O10ⁱⁱ	118.26 (7)	O7—P1—O3ⁱⁱⁱ	108.73 (11)
O6ⁱ—K—O10ⁱⁱ	143.04 (7)	O4^vi—P1—O3ⁱⁱⁱ	110.13 (12)
O2ⁱ—K—O10ⁱⁱ	135.75 (6)	O12—P1—O3ⁱⁱⁱ	97.66 (11)
O4—K—O3ⁱⁱⁱ	94.01 (6)	O10^iv—P2—O5	121.60 (13)
O5—K—O3ⁱⁱⁱ	93.77 (6)	O10^iv—P2—O11^iv	110.86 (11)
O6ⁱ—K—O3ⁱⁱⁱ	164.29 (7)	O5—P2—O11^iv	106.08 (11)
O2ⁱ—K—O3ⁱⁱⁱ	112.83 (6)	O10^iv—P2—O3ⁱ	107.58 (12)
O10ⁱⁱ—K—O3ⁱⁱⁱ	46.46 (5)	O5—P2—O3ⁱ	109.67 (12)
O4—K—O7ⁱⁱ	49.24 (5)	O11^iv—P2—O3ⁱ	98.65 (10)
O5—K—O7ⁱⁱ	108.54 (6)	O6—P3—O2	117.21 (12)
O6ⁱ—K—O7ⁱⁱ	97.63 (6)	O6—P3—O11	108.85 (11)
O2ⁱ—K—O7ⁱⁱ	138.36 (6)	O2—P3—O11	109.42 (10)
O10ⁱⁱ—K—O7ⁱⁱ	52.04 (5)	O6—P3—O1	106.70 (11)
O3ⁱⁱⁱ—K—O7ⁱⁱ	96.13 (6)	O2—P3—O1	111.17 (11)
O4—K—O11^iv	105.76 (6)	O11—P3—O1	102.44 (11)
O5—K—O11^iv	46.23 (5)	O9—P4—O8^viii	119.05 (12)
O6ⁱ—K—O11^iv	78.27 (6)	O9—P4—O1	108.15 (11)
O2ⁱ—K—O11^iv	57.13 (5)	O8^viii—P4—O1	109.93 (11)
O10ⁱⁱ—K—O11^iv	138.47 (6)	O9—P4—O12^iv	108.86 (12)
O3ⁱⁱⁱ—K—O11^iv	92.53 (6)	O8^viii—P4—O12^iv	110.62 (12)
O7ⁱⁱ—K—O11^iv	153.96 (6)	O1—P4—O12^iv	98.17 (11)
O4—K—O7	55.48 (6)	P4—O1—P3	124.84 (11)
O5—K—O7	56.64 (6)	P3—O2—Eu	126.82 (12)
O6ⁱ—K—O7	144.25 (6)	P3—O2—K^vii	93.80 (9)
O2ⁱ—K—O7	135.83 (6)	Eu—O2—K^vii	139.28 (8)
O10ⁱⁱ—K—O7	63.35 (5)	P1^ix—O3—P2^vii	130.06 (14)
O3ⁱⁱⁱ—K—O7	44.54 (5)	P1^ix—O3—K^ix	91.84 (9)
O7ⁱⁱ—K—O7	85.78 (3)	P2^vii—O3—K^ix	97.17 (9)
O11^iv—K—O7	83.30 (6)	P1ⁱⁱ—O4—Eu	138.08 (12)
O9—Eu—O4	118.75 (7)	P1ⁱⁱ—O4—K	105.27 (10)
O9—Eu—O10	79.54 (7)	Eu—O4—K	108.28 (7)
O4—Eu—O10	142.30 (6)	P2—O5—Eu	143.49 (12)
O9—Eu—O5	71.81 (7)	P2—O5—K	110.57 (10)
O4—Eu—O5	71.94 (7)	Eu—O5—K	105.40 (8)
O10—Eu—O5	85.13 (7)	P3—O6—Eu^x	144.03 (13)
O9—Eu—O7	138.27 (7)	P3—O6—K^vii	97.49 (9)
O4—Eu—O7	75.03 (7)	Eu^x—O6—K^vii	118.48 (8)
O10—Eu—O7	70.79 (7)	P1—O7—Eu	148.46 (13)
O5—Eu—O7	76.95 (8)	P1—O7—K^vi	87.05 (10)
O9—Eu—O8	143.51 (7)	Eu—O7—K^vi	92.57 (7)
O4—Eu—O8	79.39 (7)	P1—O7—K	88.34 (10)
O10—Eu—O8	105.75 (7)	Eu—O7—K	91.59 (7)
O5—Eu—O8	143.72 (7)	K^vi—O7—K	175.37 (7)
O7—Eu—O8	74.50 (7)	P4^xi—O8—Eu	130.26 (12)
O9—Eu—O6^v	75.16 (7)	P4—O9—Eu	146.27 (13)
O4—Eu—O6^v	75.02 (7)	P2^iv—O10—Eu	138.15 (12)
O10—Eu—O6^v	142.48 (6)	P2^iv—O10—K^vi	106.53 (11)
O5—Eu—O6^v	112.01 (7)	Eu—O10—K^vi	97.15 (7)
O7—Eu—O6^v	143.80 (7)	P3—O11—P2^iv	132.40 (12)
O8—Eu—O6^v	80.43 (7)	P3—O11—K^iv	136.15 (9)
O9—Eu—O2	75.52 (7)	P2^iv—O11—K^iv	88.55 (8)
O4—Eu—O2	143.69 (7)	P1—O12—P4^iv	133.66 (14)
O10—Eu—O2	69.57 (7)

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

Experimental details

Crystal data
Chemical formula	KEu(PO₃)₄
M_r	506.94
Crystal system, space group	Monoclinic, P2₁/n
Temperature (K)	296
a, b, c (Å)	10.3723 (1), 8.9721 (1), 10.8320 (1)
β (°)	106.053 (1)
V (Å³)	968.73 (2)
Z	4
Radiation type	Mo Kα
µ (mm⁻¹)	7.63
Crystal size (mm)	0.12 × 0.11 × 0.10

Data collection
Diffractometer	Bruker APEXII CCD diffractometer
Absorption correction	Multi-scan (SADABS; Bruker, 2008)
T_min, T_max	0.466, 0.513
No. of measured, independent and observed [I > 2σ(I)] reflections	24299, 6201, 5023
R_int	0.045
(sin θ/λ)_max (Å⁻¹)	0.915

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.030, 0.072, 1.04
No. of reflections	6201
No. of parameters	163
Δρ_max, Δρ_min (e Å⁻³)	1.72, −2.04

Computer programs: APEX2 (Bruker, 2008), SAINT (Bruker, 2008), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), DIAMOND (Brandenburg, 1999), SHELXTL (Sheldrick, 2008).

Selected bond lengths (Å) top

P1—O7	1.480 (2)	P3—O6	1.482 (2)
P1—O4ⁱ	1.483 (2)	P3—O2	1.4873 (19)
P1—O12	1.588 (2)	P3—O11	1.6005 (19)
P1—O3ⁱⁱ	1.5968 (19)	P3—O1	1.6033 (19)
P2—O10ⁱⁱⁱ	1.4795 (19)	P4—O9	1.4784 (19)
P2—O5	1.483 (2)	P4—O8^v	1.484 (2)
P2—O11ⁱⁱⁱ	1.6015 (18)	P4—O1	1.601 (2)
P2—O3^iv	1.602 (2)	P4—O12ⁱⁱⁱ	1.601 (2)

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

References

Barsukov, I. V., Syťko, V. V. & Umreiko, D. S. (2004). J. Appl. Spectrosc. 71, 676–680. CrossRef CAS Google Scholar
Ben Zarkouna, E., Driss, A. & Férid, M. (2006). Acta Cryst. C62, i64–i66. Web of Science CrossRef CAS IUCr Journals Google Scholar
Brandenburg, K. (1999). DIAMOND. Crystal Impact GbR, Bonn, Germany. Google Scholar
Bruker (2008). SADABS, APEX2 and SAINT. Bruker AXS Inc., Madison,Wisconsin, USA. Google Scholar
Chehimi-Moumen, F. & Férid, M. (2007). Acta Cryst. E63, i129–i130. Web of Science CrossRef IUCr Journals Google Scholar
Dago, A. M., Pushcharovskii, D. Yu., Pobedimskaya, E. A. & Belov, N. V. (1980). Sov. Phys. Dolk. 25, 231–233. Google Scholar
Durif, A. (1995). Crystal Chemistry of Condensed Phosphates. New York and London: Plenum Press. Google Scholar
Ettis, H., Naïli, H. & Mhiri, T. (2006). Acta Cryst. E62, i166–i168. Web of Science CrossRef IUCr Journals Google Scholar
Horchani, K., Amami, J., Merle, D. & Férid, M. (2004). J. Phys. IV, 122, 123–128. CAS Google Scholar
Horchani-Naifer, K. & Férid, M. (2007). Acta Cryst. E63, i131–i132. Web of Science CrossRef IUCr Journals Google Scholar
Hu, N., Lin, Y., Zhou, Q.-L. & Liu, S.-Z. (1984). Yingyong Huaxue, 1, 47–50. CAS Google Scholar
Jaouadi, K., Naïli, H., Zouari, N., Mhiri, T. & Daoud, A. (2003). J. Alloys Compd, 354, 104–114. Web of Science CrossRef CAS Google Scholar
Khlissa, F. & Férid, M. (2006). Acta Cryst. E62, i272–i273. Web of Science CrossRef IUCr Journals Google Scholar
Maksimova, S. I., Palkina, K. K. & Chibiskova, N. T. (1982). Izv. Akad. Nauk SSSR Neorg. Mater. 18, 653–700. CAS Google Scholar
Maksimova, S. I., Palkina, K. K. & Loshchenov, V. V. (1981). Izv. Akad. Nauk SSSR Neorg. Mater. 17, 116–120. CAS Google Scholar
Maksimova, S. I., Palkina, K. K., Loshchenov, V. B. & Kuznetsov, V. G. (1978). Zh. Neorg. Khim. 23, 2959–2965. CAS Google Scholar
Naïli, H. & Mhiri, T. (2005). Acta Cryst. E61, i204–i207. Web of Science CrossRef IUCr Journals Google Scholar
Palkina, K. K., Saifuddinov, V. Z., Kuznetsov, V. G. & Chudinova, N. N. (1977). Sov. Phys. Dolk. 237, 837–839. CAS Google Scholar
Porai-Koshits, M. A. & Aslanov, L. A. (1972). J. Struct. Chem. 13, 244–253. CrossRef Google Scholar
Rashchi, F. & Finch, J. A. (2000). Miner. Eng. 13, 1019–1035. Web of Science CrossRef CAS Google Scholar
Rekik, W., Naïli, H. & Mhiri, T. (2004). Acta Cryst. C60, i50–i52. Web of Science CrossRef CAS IUCr Journals Google Scholar
Shannon, R. D. (1976). Acta Cryst. A32, 751–767. CrossRef CAS IUCr Journals Web of Science Google Scholar
Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. Web of Science CrossRef CAS IUCr Journals Google Scholar
Zhu, J., Cheng, W.-D. & Zhang, H. (2009). Acta Cryst. E65, i70. Web of Science CrossRef IUCr Journals Google Scholar