Cs₂Bi(PO₄)(WO₄)

Dicaesium bis­muth(III) phosphate(V) tungstate(VI), Cs₂Bi(PO₄)(WO₄), has been synthesized during complex investigation in a molten pseudo-quaternary Cs₂O–Bi₂O₃–P₂O₅–WO₃ system. It is isotypic with K₂Bi(PO₄)(WO₄). The three-dimensional framework is built up from [Bi(PO₄)(WO₄)] nets, which are organized by adhesion of [BiPO₄] layers and [WO₄] tetra­hedra above and below of those layers. The inter­stitial space is occupied by Cs atoms. Bi, W and P atoms lie on crystallographic twofold axes.

Related literature

For the isotypic potassium analogue, see: Zatovsky et al. (2006). For a related structure, see: Terebilenko et al. (2008). For caesium coordination, see Borel et al. (2000); Yakubovich et al. (2006)

Experimental

Crystal data

• Cs₂Bi(PO₄)(WO₄)

• M_r = 817.61

• Orthorhombic, I b c a

• a = 21.3144 (10) Å

• b = 12.6352 (5) Å

• c = 7.1412 (3) Å

• V = 1923.21 (14) ų

• Z = 8

• Mo Kα radiation

• μ = 37.87 mm⁻¹

• T = 293 K

• 0.08 × 0.07 × 0.05 mm

Data collection

• Oxford Diffraction XCalibur-3 diffractometer

• Absorption correction: multi-scan (Blessing, 1995) T_min = 0.061, T_max = 0.174 (expected range = 0.053–0.151)

• 10697 measured reflections

• 1396 independent reflections

• 1227 reflections with I > 2σ(I)

• R_int = 0.156

Refinement

• R[F² > 2σ(F²)] = 0.052

• wR(F²) = 0.115

• S = 1.21

• 1396 reflections

• 61 parameters

• Δρ_max = 2.17 e Å⁻³

• Δρ_min = −2.63 e Å⁻³

Table 1
Selected bond lengths (Å)

Bi1—O2	2.388 (8)
Bi1—O1^i	2.389 (8)
Bi1—O3^ii	2.463 (8)
Bi1—O1^iii	2.669 (8)
Cs1—O2^ii	2.990 (8)
Cs1—O4^iv	3.031 (9)
Cs1—O2^i	3.046 (8)
Cs1—O3^v	3.088 (9)
Cs1—O4^vi	3.111 (10)
Cs1—O4^vii	3.140 (9)
Cs1—O1	3.338 (9)
Cs1—O3^vii	3.339 (9)
W1—O4	1.774 (9)
W1—O3^vi	1.792 (9)
P1—O1	1.539 (8)
P1—O1^ii	1.539 (8)
P1—O2^ii	1.549 (8)
Symmetry codes: (i) ; (ii) ; (iii) ; (iv) ; (v) ; (vi) ; (vii) .

Data collection: CrysAlis CCD (Oxford Diffraction, 2006); cell refinement: CrysAlis CCD; data reduction: CrysAlis RED (Oxford Diffraction, 2006); 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: WinGX (Farrugia, 1999) and enCIFer (Allen et al., 2004).

Supporting information

S1. Comment

Chemistry of caesium phosphates shows a great diversity due to its structural flexibility in adopting different coordination environment. In metal phosphates caesium resides generally in complex polyhedron with up to fourteen vertices providing formation of two- and three-dimensional frameworks. Depending on crystal structure caesium is believed to occupy big cavities and tunnels adapting their geometry. For instance, the structure of Cs₃Mo₈O₁₁(PO₄)₈ (Borel et al., 2000) represents two types of irregular surrounding with nine and ten oxygen coordination, Cs₂Ti(VO₂)₃(PO₄)₃ (Yakubovich et al.,2006) - twelve and fourteen. Herein, the structure of K₂Bi(PO₄)(WO₄) (Zatovsky et al., 2006) represents an interesting host for substitution of potassium atoms by caesium ones, that leads to formation of the first example of caesium-containing phosphate-tungstate Cs₂Bi(PO₄)(WO₄) (Fig 1). Three-dimensional framework of the title compound is organized by linking together [Bi(PO₄)(WO₄)] nets which are formed by adhesion [BiPO₄] layers and WO₄ tetrahedra above and below of those layers (Fig. 2). Both phosphate and tungstate tetrahedra have almost regular geometry with typical bond lengths. Caesium atom resides in interlayer space having eightfold coordination duplicating potassium ones' environment in the structure of K₂Bi(PO₄)(WO₄) (Zatovsky et al., 2006). Due to bigger ionic radius of Cs, the distance between two successive nets (a half of a cell dimension a) is 10.657 Å, while for K-analogue is 9.862 Å.

Related literature

For related structures, see: Zatovsky et al. (2006); Terebilenko et al. (2008). For a description of caesium coordination, see Borel et al. (2000); Yakubovich et al. (2006)

S2. Experimental

Single crystals of the title compound were obtained during investigation in the pseudo-quaternary molten system Cs₂O—Bi₂O₃—P₂O₅—WO₃. A mixture of CsPO₃ (1.060 g), Cs₂W₂O₇ (3.725 g) and Bi₂O₃ (0.840 g) were mixed in an agate mortar, and heated in a platinum crucible up to 1223 K to obtain a homogeneous melt. It was held at this temperature for an hour and cooled down with a rate of 40 K h^-1 to 833 K. Crystalline product was leached out from the solidified melt with hot water.

S3. Refinement

Convergence factors (R, wR) and R_int are high due to low intensity of the reflections which is connected with poor quality of crystals. Experiments were carried out for several crystals from different synthetic points, unfortunately, better results than is presented were not found. Taking into account the previous structures isotypic to titled compound there is no doubts in structure determination.

The highest peak and the deepest hole in the final difference map are located at 0.77Šfrom P1 (2.173 e/ų) and 0.70Šfrom P2 (-2.633 e/ų) respectively.

Computing details

Data collection: CrysAlis CCD (Oxford Diffraction, 2006); cell refinement: CrysAlis CCD (Oxford Diffraction, 2006); data reduction: CrysAlis RED (Oxford Diffraction, 2006); 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: WinGX (Farrugia, 1999) and enCIFer (Allen et al., 2004).

Figures

	Fig. 1. View of the title compound with displacement ellipsoids at the 50% probability level.
	Fig. 2. View of Cs2Bi(PO4)(WO4).

Dicaesium bismuth(III) phosphate(V) tungstate(VI)

Crystal data

Cs2Bi(PO4)(WO4)	F(000) = 2768
Mr = 817.61	Dx = 5.648 Mg m^−3
Orthorhombic, Ibca	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -I 2b 2c	Cell parameters from 10697 reflections
a = 21.3144 (10) Å	θ = 3.2–30.0°
b = 12.6352 (5) Å	µ = 37.87 mm^−1
c = 7.1412 (3) Å	T = 293 K
V = 1923.21 (14) Å^3	Prism, colourless
Z = 8	0.08 × 0.07 × 0.05 mm

Data collection

Oxford Diffraction XCalibur-3 diffractometer	1396 independent reflections
Radiation source: fine-focus sealed tube	1227 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.156
ϕ and ω scans	θmax = 30.0°, θmin = 3.2°
Absorption correction: multi-scan (Blessing, 1995)	h = −27→29
Tmin = 0.061, Tmax = 0.174	k = −17→17
10697 measured reflections	l = −10→10

Refinement

Refinement on F^2	0 restraints
Least-squares matrix: full	Primary atom site location: structure-invariant direct methods
R[F^2 > 2σ(F^2)] = 0.052	Secondary atom site location: difference Fourier map
wR(F^2) = 0.115	w = 1/[σ^2(Fo^2) + (0.0396P)^2 + 22.3992P] where P = (Fo^2 + 2Fc^2)/3
S = 1.21	(Δ/σ)max < 0.001
1396 reflections	Δρmax = 2.17 e Å^−3
61 parameters	Δρmin = −2.63 e Å^−3

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
Bi1	0.25	0.58662 (4)	0	0.01381 (17)
Cs1	0.09029 (3)	0.83471 (6)	0.21999 (11)	0.0233 (2)
W1	0.09279 (3)	0.5	0.25	0.01566 (18)
P1	0.25	0.8232 (3)	0	0.0081 (6)
O1	0.2413 (4)	0.8984 (6)	0.1675 (11)	0.0204 (17)
O2	0.3072 (4)	0.7487 (6)	0.0220 (11)	0.0173 (15)
O3	0.1403 (4)	0.5328 (8)	0.0513 (13)	0.0258 (18)
O4	0.0440 (4)	0.3925 (8)	0.1847 (13)	0.031 (2)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Bi1	0.0116 (3)	0.0135 (3)	0.0162 (3)	0	−0.00033 (18)	0
Cs1	0.0166 (4)	0.0290 (4)	0.0243 (4)	0.0014 (3)	−0.0003 (2)	0.0005 (3)
W1	0.0107 (3)	0.0162 (3)	0.0201 (3)	0	0	0.0007 (2)
P1	0.0077 (15)	0.0086 (13)	0.0080 (15)	0	−0.0014 (10)	0
O1	0.034 (5)	0.015 (3)	0.012 (4)	−0.004 (3)	0.002 (3)	−0.003 (3)
O2	0.013 (4)	0.017 (3)	0.021 (4)	−0.001 (3)	0.000 (3)	0.003 (3)
O3	0.013 (4)	0.036 (5)	0.028 (4)	−0.007 (4)	−0.004 (3)	0.006 (4)
O4	0.020 (5)	0.032 (5)	0.040 (5)	−0.013 (4)	0.007 (4)	−0.013 (4)

Bond lengths (Å)

Bi1—O2	2.388 (8)	Cs1—O4^viii	3.111 (10)
Bi1—O2^i	2.388 (8)	Cs1—O4^ix	3.140 (9)
Bi1—O1^ii	2.389 (8)	Cs1—O1	3.338 (9)
Bi1—O1^iii	2.389 (8)	Cs1—O3^ix	3.339 (9)
Bi1—O3^i	2.463 (8)	W1—O4	1.774 (9)
Bi1—O3	2.463 (8)	W1—O4^viii	1.774 (9)
Bi1—O1^iv	2.669 (8)	W1—O3^viii	1.792 (9)
Bi1—O1^v	2.669 (8)	W1—O3	1.792 (9)
Cs1—O2^i	2.990 (8)	P1—O1	1.539 (8)
Cs1—O4^vi	3.031 (9)	P1—O1^i	1.539 (8)
Cs1—O2^ii	3.046 (8)	P1—O2^i	1.549 (8)
Cs1—O3^vii	3.088 (9)	P1—O2	1.549 (8)

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