Lutetium(III) cyclo­tetra­phosphate

Single crystals of the title compound, tetra­lutetium(III) tris­(cyclo­tetra­phosphate), Lu₄(P₄O₁₂)₃, were obtained by solid-state reaction. The cubic structure is isotypic with its Al^III and Sc^III analogues and is built up from four-membered (P₄O₁₂)^4- phosphate ring anions ( symmetry), isolated from each other and further linked through isolated LuO₆ octa­hedra (.3. symmetry) via corner sharing. Each LuO₆ octa­hedron is linked to six (P₄O₁₂)^4- rings, while each (P₄O₁₂)^4- ring is linked to eight LuO₆ octa­hedra.

Key indicators

• Single-crystal X-ray study
• T = 296 K
• Mean [sigma](Lu-O) = 0.003 Å
• R factor = 0.020
• wR factor = 0.038
• Data-to-parameter ratio = 17.5

checkCIF/PLATON results

No syntax errors found



Alert level C
PLAT910_ALERT_3_C Missing # of FCF Reflections Below Th(Min) .....          1
PLAT915_ALERT_3_C Low Friedel Pair Coverage ......................      75.77 Perc.
PLAT041_ALERT_1_C Calc. and Reported SumFormula    Strings  Differ          ?
PLAT042_ALERT_1_C Calc. and Reported MoietyFormula Strings  Differ          ?
PLAT045_ALERT_1_C Calculated and Reported Z Differ by ............       0.50 Ratio
PLAT950_ALERT_1_C Reported and Calculated Hmax Values Differ by ..          4

Alert level G
REFLT03_ALERT_1_G ALERT: Expected hkl max differ from CIF values
           From the CIF: _diffrn_reflns_theta_max           30.41
           From the CIF: _reflns_number_total                717
           From the CIF: _diffrn_reflns_limit_ max hkl   11.   20.    9.
           From the CIF: _diffrn_reflns_limit_ min hkl  -16.   -6.  -19.
           TEST1: Expected hkl limits for theta max
           Calculated maximum hkl   20.   20.   20.
           Calculated minimum hkl  -20.  -20.  -20.
REFLT03_ALERT_4_G Please check that the estimate of the number of Friedel pairs is
            correct. If it is not, please give the correct count in the
            _publ_section_exptl_refinement section of the submitted CIF.
           From the CIF: _diffrn_reflns_theta_max           30.41
           From the CIF: _reflns_number_total                717
           Count of symmetry unique reflns          444
           Completeness (_total/calc)            161.49%
           TEST3: Check Friedels for noncentro structure
           Estimate of Friedel pairs measured       273
           Fraction of Friedel pairs measured     0.615
           Are heavy atom types Z>Si present        yes
PLAT180_ALERT_4_G Check Cell Rounding: # of Values Ending with 0 =          3
PLAT792_ALERT_1_G The Model has Chirality at P       (Verify) ....          S
PLAT850_ALERT_4_G Check Flack Parameter Exact Value 0.00 and su ..       0.01

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

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

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S1. Comment

The title compound is the third polymorph of composition Lu(PO₃)₃ besides the monoclinic form described by Höppe & Sedlmaier (2007) and Yuan et al. (2008) and the trigonal form more recently reported by Bejaoui et al. (2008). The title compound is also the less dense polymorph with a calculated density of 3.451 Mg^.m³ versus 3.587 Mg^.m³ for the trigonal and 3.708 Mg^.m³ for the monoclinic form and is probably the highest temperature form. This cyclotetraphosphate belongs to a structural type (cubic, with space group I43d) known since 1927 through the archetype Al₄(P₄O₁₂)₃ determined by Hendricks & Wyckoff (1927). Then Pauling & Sherman (1937) gave the first description of the structure and reported roughly estimated atomic coordinates deduced from geometrical considerations. Since this time only five members of this family, viz. Cr₄^III(P₄O₁₂)₃ (Rémy & Boullé, 1964), Ti₄^III(P₄O₁₂)₃ (Liebau & Williams, 1964), Fe₄^III(P₄O₁₂)₃ (d'Yvoire et al., 1962), Sc₄^III(P₄O₁₂)₃ (Bagieu-Beucher, 1976; Mezentseva et al.,1977 and Smolin et al., 1978) and Yb₄^III(P₄O₁₂)₃ (Chudinova, 1979), have been identified. Corresponding unit cell parameters are listed in Durif (1995). Among these isotypic compounds only the structure of the Sc₄(P₄O₁₂)₃ cyclotetraphosphate has almost simultaneously been refined from single-crystal data by Bagieu-Beucher & Guittel (1978) and Smolin et al. (1978). Their refinements confirmed the description of Pauling & Sherman (1937) according to which all the crystallographically independent atoms except the A^III element (.3. symmetry) are in general positions. The structure is built of four-membered phosphate ring anions (P₄O₁₂)^4- (Fig. 1), isolated from each other and further linked by LuO₆ octahedra by sharing corners. Each LuO₆ octahedron is linked to six (P₄O₁₂)^4- rings (Fig. 2a) while each (P₄O₁₂)^4- ring is linked to eight LuO₆ octahedra (Fig. 2b) through oxygen atoms with shorter P—O distances (1.464 (4) and 1.481 (4) Å). The (P₄O₁₂)^4- ring anions are located around the 12a Wyckoff positions of space group I43d and exhibit 4 symmetry. Comparison of the (P₄O₁₂)^4- ring anions in both Sc₄(P₄O₁₂)₃ and Lu₄(P₄O₁₂)₃ structures shows these two ring anions being geometrically quite identical with alternating upward- and downward-pointing tetrahedra and P—O—P angles of 137.1° and 136.9 (2)°, respectively. The P—O distances in the PO₄ groups are identical within their e.s.d.. The four bridging oxygen atoms of these ring anions are located at the apices of a flattened tetrahedron with characteristic angles of 148.22° and 94.30° for Sc and 147.95° and 94.37° for the Lu cyclotetraphosphate. The LuO₆ octahedron is very slightly distorted along a threefold axis, resulting in two sets of Lu—O distances equal to 2.182 (3) and 2.185 (4) Å, respectively.

Related literature

The title compound belongs to a structural type discovered a long time ago through the Al₄(P₄O₁₂)₃ member, the structure of which was first investigated by Hendricks & Wyckoff (1927) and then described by Pauling & Sherman (1937). Since then, five isotypic compounds have been characterized: Cr₄(P₄O₁₂)₃ (Rémy & Boullé, 1964); Ti₄(P₄O₁₂)₃ (Liebau & Williams, 1964); Fe₄(P₄O₁₂)₃ (d'Yvoire et al., 1962); Sc₄(P₄O₁₂)₃ (Bagieu-Beucher, 1976; Mezentseva et al., 1977; Bagieu-Beucher & Guitel, 1978; Smolin et al. 1978) and Yb₄(P₄O₁₂)₃ (Chudinova, 1979). For a review of the crystal chemistry of cyclotetraphosphates, see: Durif (1995). For other polymorphs of composition Lu(PO₃)₃, see: Höppe & Sedlmaier (2007); Yuan et al. (2008); Bejaoui et al. (2008).

S2. Experimental

Single crystals of the title compound were obtained by solid state reaction while attempting to synthesized a long chain polyphosphate by reacting Lu₂O₃ with (NH₄)H₂PO₄ and Rb₂CO₃ in an alumina boat. A mixture of these reagents in the molar ratio 27 : 85.5 : 8.7 was used for the synthesis. The mixture was successively heated at 473 K for 24 hours, then at 573 K for 24 additional hours and finally at 813 K for 24 hours. Then the sample was cooled down to 683 K at the rate of 3 K h^-1 and maintained at this temperature for 36 hours. Finally, the sample was cooled down to room temperature by shutting the muffle furnace off. Single crystals were extracted from the batch by washing with hot water and filtering. The crystals were dried at 353 K in an oven. A translucent octahedral crystal of the title compound was selected for the structure refinement.

S3. Refinement

The highest residual peak in the final difference Fourier map was located 0.87 Å from atom Lu and the deepest hole was located 0.99 Å from atom Lu.

Computing details

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: CaRine (Boudias & Monceau, 1998) and ORTEP-3 (Farrugia, 1997); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).

Figures

	Fig. 1. ORTEP-3 view of the four-membered phosphate (P4O12)^4- ring anion. Displacement ellipsoids are drawn at the 50% probability level. Symmetry codes: (i) 1-z, 3/2-x, y ; (ii) 3/4+y, 5/4-x, 3/4-z ; (iii) 5/4-y, -3/4+x,3/4-z ; (iv) -1/4+x, 1/4-z, 3/4-y ; (v) 9/4-x, 1/4+z, 3/4-y ;(vi) 2-x, 1/2-y, z ; (vii) 1+z, -1+x, y.
	Fig. 2. Partial view of the Lu4(P4O12)3 structure showing: (a) the connections between the LuO6 octahedron and the (P4O12)^4- ring anions, (b) the connections between the (P4O12)^4- ring anion and the LuO6 octahedra.

Tetralutetium(III) tris(cyclotetraphosphate)

Crystal data

Lu4(P4O12)3	Dx = 3.451 Mg m^−3
Mr = 1647.52	Mo Kα radiation, λ = 0.71073 Å
Cubic, I43d	Cell parameters from 1548 reflections
Hall symbol: I -4bd 2c 3	θ = 3.4–30.3°
a = 14.6920 (6) Å	µ = 13.08 mm^−1
V = 3171.3 (2) Å^3	T = 296 K
Z = 4	Truncated octahedron, colourless
F(000) = 3008	0.18 × 0.10 × 0.08 mm

Data collection

Bruker APEXII CCD diffractometer	717 independent reflections
Radiation source: fine-focus sealed tube	659 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.034
Detector resolution: 8.3333 pixels mm^-1	θmax = 30.4°, θmin = 3.9°
φ and ω scans	h = −16→11
Absorption correction: multi-scan (SADABS; Bruker, 2008)	k = −6→20
Tmin = 0.534, Tmax = 0.746	l = −19→9
3088 measured reflections

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)] = 0.020	w = 1/[σ^2(Fo^2) + (0.0088P)^2] where P = (Fo^2 + 2Fc^2)/3
wR(F^2) = 0.038	(Δ/σ)max < 0.001
S = 1.03	Δρmax = 0.90 e Å^−3
717 reflections	Δρmin = −0.67 e Å^−3
41 parameters	Absolute structure: Flack (1983), 272 Friedel pairs
0 restraints	Absolute structure parameter: 0.000 (15)
0 constraints

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 (Ų)

	x	y	z	Uiso*/Ueq
Lu	0.896610 (13)	0.396610 (13)	0.103390 (13)	0.00602 (8)
P	0.95737 (9)	0.37294 (9)	0.33447 (9)	0.0077 (2)
O1	1.0613 (2)	0.3432 (2)	0.3430 (2)	0.0128 (7)
O2	1.0325 (2)	0.3642 (3)	0.0522 (2)	0.0188 (8)
O3	0.9295 (2)	0.3498 (3)	0.2404 (2)	0.0142 (7)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Lu	0.00602 (8)	0.00602 (8)	0.00602 (8)	0.00039 (8)	−0.00039 (8)	−0.00039 (8)
P	0.0097 (5)	0.0051 (6)	0.0082 (6)	0.0017 (5)	−0.0008 (5)	0.0015 (4)
O1	0.0113 (15)	0.0146 (18)	0.0123 (17)	0.0007 (15)	−0.0025 (14)	0.0054 (17)
O2	0.0103 (17)	0.024 (2)	0.022 (2)	0.0016 (18)	0.0015 (16)	−0.0014 (18)
O3	0.0202 (19)	0.0141 (19)	0.0084 (16)	0.0012 (16)	−0.0050 (15)	0.0023 (16)

Geometric parameters (Å, º)

Lu—O3^i	2.182 (3)	P—O2^iii	1.464 (4)
Lu—O3^ii	2.182 (3)	P—O3	1.481 (4)
Lu—O3	2.182 (3)	P—O1^iv	1.583 (3)
Lu—O2^i	2.185 (4)	P—O1	1.594 (3)
Lu—O2^ii	2.185 (4)	O1—P^v	1.583 (3)
Lu—O2	2.185 (4)	O2—P^vi	1.464 (4)
O3^i—Lu—O3^ii	89.06 (14)	O3—Lu—O2	92.64 (13)
O3^i—Lu—O3	89.06 (14)	O2^i—Lu—O2	87.72 (15)
O3^ii—Lu—O3	89.06 (14)	O2^ii—Lu—O2	87.72 (15)
O3^i—Lu—O2^i	92.64 (13)	O2^iii—P—O3	118.0 (2)
O3^ii—Lu—O2^i	178.26 (14)	O2^iii—P—O1^iv	107.3 (2)
O3—Lu—O2^i	90.59 (14)	O3—P—O1^iv	111.5 (2)
O3^i—Lu—O2^ii	90.59 (14)	O2^iii—P—O1	109.2 (2)
O3^ii—Lu—O2^ii	92.64 (13)	O3—P—O1	106.0 (2)
O3—Lu—O2^ii	178.26 (14)	O1^iv—P—O1	103.9 (2)
O2^i—Lu—O2^ii	87.72 (15)	P^v—O1—P	136.9 (2)
O3^i—Lu—O2	178.26 (14)	P^vi—O2—Lu	164.9 (2)
O3^ii—Lu—O2	90.59 (14)	P—O3—Lu	148.2 (2)

Symmetry codes: (i) −z+1, x−1/2, −y+1/2; (ii) y+1/2, −z+1/2, −x+1; (iii) −z+1, −x+3/2, y; (iv) −y+5/4, x−3/4, −z+3/4; (v) y+3/4, −x+5/4, −z+3/4; (vi) −y+3/2, z, −x+1.