Octa­rubidium di-μ-sulfato-κ4O:O′-bis­[cis-dioxido-cis-disulfatotungstate(VI)]

Ståhl, K.; Berg, R.W.

doi:10.1107/S1600536809046431

inorganic compounds

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Volume 65| Part 12| December 2009| Page i88

doi:10.1107/S1600536809046431

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Octarubidium di-μ-sulfato-κ⁴O:O′-bis[cis-dioxido-cis-disulfatotungstate(VI)]

Kenny Ståhl ^a ^* and Rolf W. Berg ^a

^aTechnical University of Denmark, Department of Chemistry, Building 207, DK-2800 Lyngby, Denmark
^*Correspondence e-mail: kenny@kemi.dtu.dk

(Received 14 September 2009; accepted 4 November 2009; online 11 November 2009)

The title compound, Rb₈[W₂O₄(SO₄)₆], was precipitated from a melt of tungsten(VI) oxide and rubidium sulfate in rubidium disulfate. The unit cell contains two discrete [{W^VIO₂(SO₄)₂}₂(μ-SO₄)₂]⁸⁻ units connected by Rb–O coordination. The W atom is octahedrally surrounded by two oxide ligands, two terminal sulfate ligands and two bridging sulfate groups. One Rb atom is coordinated by eight O atoms, whereas the three other Rb atoms are coordinated by nine O atoms from sulfate and oxide groups, leading to distorted [RbO_x] polyhedra.

Related literature

For methods used in the synthesis, see: Berg et al. (2006 ); Borup et al. (1990 ); Nørbygaard et al. (1998 ). For the crystal structure of the potassium analog, see: Schäffer & Berg (2005 ).

Experimental

Crystal data

Rb₈[W₂O₄(SO₄)₆]
M_r = 1691.86
Monoclinic, P 2₁ /n
a = 9.6405 (5) Å
b = 13.9890 (7) Å
c = 10.7692 (5) Å
β = 90.472 (1)°
V = 1452.30 (12) Å³
Z = 2
Mo Kα radiation
μ = 21.77 mm⁻¹
T = 120 K
0.45 × 0.20 × 0.05 mm

Data collection

Bruker SMART APEX diffractometer
Absorption correction: multi-scan (SADABS; Sheldrick, 2002 ) T_min = 0.077, T_max = 0.59
18895 measured reflections
3496 independent reflections
3360 reflections with I > 2σ(I)
R_int = 0.036

Refinement

R[F² > 2σ(F²)] = 0.020
wR(F²) = 0.052
S = 1.11
3496 reflections
200 parameters
Δρ_max = 1.35 e Å⁻³
Δρ_min = −1.51 e Å⁻³

Table 1
Selected bond lengths (Å)

W1—O1	1.716 (2)
W1—O2	1.721 (2)
W1—O3	1.960 (2)
W1—O4	2.009 (2)
W1—O5	2.097 (2)
W1—O6	2.254 (2)
Rb1—O1	2.877 (2)
Rb1—O8	2.931 (2)
Rb1—O7	2.939 (3)
Rb1—O9ⁱ	2.955 (3)
Rb1—O6ⁱⁱ	3.009 (2)
Rb1—O11ⁱⁱⁱ	3.010 (2)
Rb1—O2ⁱⁱⁱ	3.084 (2)
Rb1—O5ⁱⁱ	3.185 (2)
Rb2—O14^iv	2.761 (3)
Rb2—O7^v	2.893 (2)
Rb2—O9^vi	2.903 (3)
Rb2—O2	2.939 (3)
Rb2—O13ⁱⁱ	2.986 (2)
Rb2—O8	3.082 (3)
Rb2—O10^v	3.106 (3)
Rb2—O9	3.337 (3)
Rb2—O1	3.374 (3)
Rb3—O11	2.776 (2)
Rb3—O10ⁱⁱ	2.788 (3)
Rb3—O7^v	2.874 (2)
Rb3—O14^vii	2.935 (2)
Rb3—O12ⁱ	3.101 (2)
Rb3—O11^vii	3.170 (2)
Rb3—O12^v	3.173 (3)
Rb3—O1	3.220 (2)
Rb3—O13^v	3.225 (3)
Rb4—O8^viii	2.910 (3)
Rb4—O3ⁱ	2.914 (2)
Rb4—O10	2.941 (3)
Rb4—O14	2.964 (2)
Rb4—O13ⁱ	2.981 (3)
Rb4—O12ⁱ	3.103 (3)
Rb4—O6ⁱ	3.221 (2)
Rb4—O5	3.253 (2)
Rb4—O4	3.423 (2)
S1—O11	1.445 (2)
S1—O14	1.449 (2)
S1—O6^ix	1.490 (2)
S1—O4	1.531 (2)
S2—O12	1.451 (3)
S2—O9	1.452 (3)
S2—O8	1.454 (3)
S2—O3	1.575 (2)
S3—O13	1.461 (2)
S3—O7	1.464 (3)
S3—O10	1.464 (3)
S3—O5	1.528 (2)
Symmetry codes: (i) $[x-{\script{1\over 2}}, -y+{\script{1\over 2}}, z-{\script{1\over 2}}]$ ; (ii) $[x+{\script{1\over 2}}, -y+{\script{1\over 2}}, z-{\script{1\over 2}}]$ ; (iii) $[-x+{\script{1\over 2}}, y+{\script{1\over 2}}, -z+{\script{3\over 2}}]$ ; (iv) x+1, y, z; (v) $[-x+{\script{1\over 2}}, y-{\script{1\over 2}}, -z+{\script{3\over 2}}]$ ; (vi) -x+1, -y, -z+2; (vii) -x, -y, -z+1; (viii) x-1, y, z; (ix) -x, -y, -z+2.

Data collection: SMART (Bruker, 2002 ); cell refinement: SAINT-Plus (Bruker, 2002); data reduction: SAINT-Plus; program(s) used to solve structure: SHELXTL (Sheldrick, 2008 ); program(s) used to refine structure: SHELXTL; molecular graphics: ORTEP-3 (Farrugia, 1997 ) and ATOMS (Dowty, 2000 ); software used to prepare material for publication: SHELXTL.

Supporting information

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536809046431/fi2090sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536809046431/fi2090Isup2.hkl

checkCIF report

Comment top

Tungsten trioxide is known as a highly inert solid, practically insoluble in acids. It was discovered that WO₃ can be dissolved in considerable amounts in acidic sulfate melts at high temperatures (Schäffer and Berg, 2005 and Berg et al., 2006). When therefore WO₃, Rb₂SO₄ and Rb₂S₂O₇ are mixed in varying molar amounts in sealed ampoules and heated for equilibration in a rocking furnace at appr. 600 °C for appr. 1 hr, clear melts are formed (Rb₂S₂O₇ is hygroscopic and needs to be handled in a dry box). It has been shown that [WO₂]²⁺ ions formed are solvated by SO₄^2- ions. The stoichiometry of the reaction have been determined fairly accurately as 1:1:1, or 2WO₃ + 2M₂SO₄ + 2M₂S₂O₇ → M₈[(WO₂)₂(µ-SO₄)₂(SO₄)₄] for the case of M = K, Schäffer and Berg, 2005. Here we have studied the case of M = Rb and have found closely analogous results for single crystals of the compound, 1WO₃:1Rb₂S₂O₇:1Rb₂SO₄. The main difference for M = Rb as compared to M = K is as expected in the M - O coordination: Rb1/K1, CN = 8/8, <M - O> = 2.999 (1)/2.822 (1); Rb2/K2, CN = 9/7, <M - O> = 3.042 (1)/2.825 (1); Rb3/K3, CN = 9/8, <M - O> = 3.029 (1)/2.909 (1); Rb4/K4, CN = 9/9, <M - O> = 3.079 (1)/2.945 (1). As the oxo-sulfatotungstate groups are extended in the b-direction, the major changes in the unit cell axes are observered in the a- and c- directions.

Related literature top

For methods used in the synthesis, see: Berg et al. (2006); Borup et al. (1990); Nørbygaard et al. (1998). For the crystal structure of the potassium analog, see: Schäffer & Berg (2005).

Experimental top

The crystals were grown from a melt of 20.6 mol % tungsten trioxide and 19.9 mol % rubidium sulfate in rubidium disulfate, using the methods described by Borup et al. (1990), Nørbygaard et al. (1998) and Berg et al. (2006).

Computing details top

Data collection: SMART (Bruker, 2002); cell refinement: SAINT-Plus (Bruker, 2002); data reduction: SAINT-Plus (Bruker, 2002) and SADABS (Sheldrick, 2002); program(s) used to solve structure: SHELXTL (Sheldrick, 2008); program(s) used to refine structure: SHELXTL (Sheldrick, 2008); molecular graphics: ORTEP-3 (Farrugia, 1997) and ATOMS (Dowty, 2000); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).

Figures top

	Fig. 1. The asymmetric unit of (I) showing 50% probability displacement ellipsoids and the atomic numbering. O6^iv was added to complete the S1 coordination.
	Fig. 2. The crystal packing of (I) viewed down the a axis. W atoms are in the centers of the octahedra and S atoms are in the centers of the tetrahedra. Rb are shown as large and O as small spheres.

Octarubidium di-µ-sulfato-κ⁴O:O'-bis[cis-dioxido-cis- disulfatotungstate(VI)] top

Crystal data top

Rb₈[W₂O₄(SO₄)₆]	F(000) = 1528
M_r = 1691.86	D_x = 3.869 Mg m⁻³
Monoclinic, P2₁/n	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2yn	Cell parameters from 6979 reflections
a = 9.6405 (5) Å	θ = 2.4–28.0°
b = 13.9890 (7) Å	µ = 21.77 mm⁻¹
c = 10.7692 (5) Å	T = 120 K
β = 90.472 (1)°	Irregular, colourless
V = 1452.30 (12) Å³	0.45 × 0.20 × 0.05 mm
Z = 2

Data collection top

Bruker SMART APEX diffractometer	3496 independent reflections
Radiation source: fine-focus sealed tube	3360 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.036
ω scan, frame data integration	θ_max = 28.0°, θ_min = 2.4°
Absorption correction: multi-scan (SADABS; Sheldrick, 2002)	h = −12→12
T_min = 0.077, T_max = 0.59	k = −18→18
18895 measured reflections	l = −14→14

Refinement top

Refinement on F²	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F² > 2σ(F²)] = 0.020	w = 1/[σ²(F_o²) + (0.0287P)² + 1.1918P] where P = (F_o² + 2F_c²)/3
wR(F²) = 0.052	(Δ/σ)_max = 0.001
S = 1.11	Δρ_max = 1.35 e Å⁻³
3496 reflections	Δρ_min = −1.51 e Å⁻³
200 parameters	Extinction correction: SHELXTL (Sheldrick, 2008), Fc^*=kFc[1+0.001xFc²λ³/sin(2θ)]^-1/4
0 restraints	Extinction coefficient: 0.00175 (10)

Crystal data top

Rb₈[W₂O₄(SO₄)₆]	V = 1452.30 (12) Å³
M_r = 1691.86	Z = 2
Monoclinic, P2₁/n	Mo Kα radiation
a = 9.6405 (5) Å	µ = 21.77 mm⁻¹
b = 13.9890 (7) Å	T = 120 K
c = 10.7692 (5) Å	0.45 × 0.20 × 0.05 mm
β = 90.472 (1)°

Data collection top

Bruker SMART APEX diffractometer	3496 independent reflections
Absorption correction: multi-scan (SADABS; Sheldrick, 2002)	3360 reflections with I > 2σ(I)
T_min = 0.077, T_max = 0.59	R_int = 0.036
18895 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.020	200 parameters
wR(F²) = 0.052	0 restraints
S = 1.11	Δρ_max = 1.35 e Å⁻³
3496 reflections	Δρ_min = −1.51 e Å⁻³

Special details top

Experimental. Oxford Cryosystem liquid nitrogen cryostream cooler

Geometry. All e.s.d.'s 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.

Refinement. A series of identical frames was collected twice during the experiment to monitor decay. No decay was detected and decay correction was not applied. Systematic conditions suggested the unambiguous space group. The structure was solved by direct methods (Sheldrick, 2008). The space group choice was confirmed by successful convergence of the full-matrix least-squares refinement on F² (Sheldrick, 2008). 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 > 2σ(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. The highest peak in the final difference Fourier map was 0.85Å and the deepest hole was 0.78Å from W1. The final map had no other significant features. A final analysis of variance between observed and calculated structure factors showed no dependence on amplitude or resolution.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å²) top

	x	y	z	U_iso*/U_eq
W1	0.168190 (12)	0.117132 (8)	0.917586 (11)	0.00604 (6)
Rb1	0.31202 (3)	0.30953 (2)	0.65221 (3)	0.01095 (8)
Rb2	0.50882 (3)	0.01145 (2)	0.79641 (3)	0.01149 (8)
Rb3	0.19055 (3)	0.01388 (2)	0.51347 (3)	0.01057 (8)
Rb4	−0.23085 (3)	0.22589 (2)	0.74755 (3)	0.01173 (8)
S1	−0.07712 (8)	−0.01972 (5)	0.80402 (7)	0.00671 (15)
S2	0.46037 (8)	0.22894 (6)	0.97953 (7)	0.00823 (15)
S3	0.03580 (8)	0.34141 (5)	0.94629 (7)	0.00726 (15)
O1	0.2116 (3)	0.13695 (17)	0.7656 (2)	0.0126 (5)
O2	0.2550 (3)	0.01169 (17)	0.9456 (2)	0.0134 (5)
O3	0.3015 (2)	0.20560 (17)	0.9939 (2)	0.0105 (5)
O4	−0.0203 (2)	0.06004 (16)	0.8874 (2)	0.0095 (4)
O5	0.0314 (2)	0.23235 (16)	0.9395 (2)	0.0113 (5)
O6	0.0953 (2)	0.10525 (15)	1.1153 (2)	0.0086 (4)
O7	0.1394 (3)	0.37617 (16)	0.8585 (2)	0.0123 (5)
O8	0.4896 (3)	0.22782 (18)	0.8473 (2)	0.0146 (5)
O9	0.5342 (3)	0.1533 (2)	1.0446 (3)	0.0221 (6)
O10	−0.1042 (3)	0.37142 (17)	0.9097 (2)	0.0143 (5)
O11	0.0230 (3)	−0.04158 (17)	0.7090 (2)	0.0118 (5)
O12	0.4761 (3)	0.32204 (18)	1.0374 (2)	0.0160 (5)
O13	0.0695 (3)	0.36869 (18)	1.0740 (2)	0.0168 (5)
O14	−0.2088 (3)	0.01462 (17)	0.7559 (2)	0.0121 (5)

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
W1	0.00608 (8)	0.00633 (8)	0.00575 (8)	−0.00051 (4)	0.00225 (5)	−0.00028 (4)
Rb1	0.01021 (15)	0.01196 (15)	0.01072 (15)	−0.00113 (11)	0.00177 (11)	0.00109 (11)
Rb2	0.01089 (16)	0.01125 (15)	0.01242 (16)	−0.00146 (11)	0.00470 (11)	−0.00220 (11)
Rb3	0.01010 (15)	0.01395 (15)	0.00769 (15)	−0.00045 (11)	0.00251 (11)	0.00227 (10)
Rb4	0.01259 (16)	0.01381 (15)	0.00883 (15)	−0.00152 (12)	0.00221 (11)	−0.00042 (11)
S1	0.0069 (3)	0.0080 (3)	0.0052 (3)	−0.0015 (3)	0.0008 (3)	0.0002 (3)
S2	0.0065 (3)	0.0102 (4)	0.0080 (4)	−0.0011 (3)	0.0004 (3)	0.0005 (3)
S3	0.0086 (4)	0.0070 (3)	0.0062 (3)	0.0008 (3)	0.0016 (3)	−0.0007 (3)
O1	0.0157 (12)	0.0143 (11)	0.0077 (11)	−0.0046 (10)	0.0025 (9)	−0.0001 (9)
O2	0.0144 (12)	0.0098 (11)	0.0161 (12)	0.0047 (9)	0.0057 (9)	0.0011 (9)
O3	0.0071 (11)	0.0141 (11)	0.0104 (11)	−0.0017 (9)	0.0015 (8)	−0.0033 (9)
O4	0.0099 (11)	0.0093 (10)	0.0094 (11)	−0.0024 (9)	0.0007 (8)	−0.0019 (8)
O5	0.0088 (11)	0.0081 (10)	0.0170 (12)	0.0002 (9)	0.0006 (9)	0.0009 (9)
O6	0.0110 (11)	0.0068 (10)	0.0080 (11)	−0.0025 (8)	0.0025 (9)	0.0006 (8)
O7	0.0123 (12)	0.0127 (12)	0.0120 (12)	−0.0024 (9)	0.0043 (9)	0.0030 (8)
O8	0.0156 (12)	0.0178 (12)	0.0105 (12)	−0.0028 (10)	0.0057 (9)	−0.0012 (9)
O9	0.0171 (13)	0.0202 (14)	0.0288 (15)	0.0015 (11)	−0.0074 (11)	0.0102 (11)
O10	0.0099 (12)	0.0123 (11)	0.0207 (14)	0.0039 (9)	0.0018 (10)	−0.0009 (9)
O11	0.0142 (12)	0.0130 (11)	0.0084 (11)	−0.0017 (9)	0.0049 (8)	−0.0008 (9)
O12	0.0153 (12)	0.0157 (12)	0.0170 (13)	−0.0054 (10)	0.0020 (10)	−0.0047 (10)
O13	0.0250 (15)	0.0173 (12)	0.0079 (12)	0.0004 (11)	−0.0014 (10)	−0.0039 (9)
O14	0.0110 (12)	0.0151 (12)	0.0102 (11)	0.0011 (9)	−0.0017 (9)	0.0014 (9)

Geometric parameters (Å, º) top

W1—O1	1.716 (2)	Rb3—O12ⁱ	3.101 (2)
W1—O2	1.721 (2)	Rb3—O11^vii	3.170 (2)
W1—O3	1.960 (2)	Rb3—O12^v	3.173 (3)
W1—O4	2.009 (2)	Rb3—O1	3.220 (2)
W1—O5	2.097 (2)	Rb3—O13^v	3.225 (3)
W1—O6	2.254 (2)	Rb4—O8^viii	2.910 (3)
Rb1—O1	2.877 (2)	Rb4—O3ⁱ	2.914 (2)
Rb1—O8	2.931 (2)	Rb4—O10	2.941 (3)
Rb1—O7	2.939 (3)	Rb4—O14	2.964 (2)
Rb1—O9ⁱ	2.955 (3)	Rb4—O13ⁱ	2.981 (3)
Rb1—O6ⁱⁱ	3.009 (2)	Rb4—O12ⁱ	3.103 (3)
Rb1—O11ⁱⁱⁱ	3.010 (2)	Rb4—O6ⁱ	3.221 (2)
Rb1—O2ⁱⁱⁱ	3.084 (2)	Rb4—O5	3.253 (2)
Rb1—O5ⁱⁱ	3.185 (2)	Rb4—O4	3.423 (2)
Rb2—O14^iv	2.761 (3)	S1—O11	1.445 (2)
Rb2—O7^v	2.893 (2)	S1—O14	1.449 (2)
Rb2—O9^vi	2.903 (3)	S1—O6^ix	1.490 (2)
Rb2—O2	2.939 (3)	S1—O4	1.531 (2)
Rb2—O13ⁱⁱ	2.986 (2)	S2—O12	1.451 (3)
Rb2—O8	3.082 (3)	S2—O9	1.452 (3)
Rb2—O10^v	3.106 (3)	S2—O8	1.454 (3)
Rb2—O9	3.337 (3)	S2—O3	1.575 (2)
Rb2—O1	3.374 (3)	S3—O13	1.461 (2)
Rb3—O11	2.776 (2)	S3—O7	1.464 (3)
Rb3—O10ⁱⁱ	2.788 (3)	S3—O10	1.464 (3)
Rb3—O7^v	2.874 (2)	S3—O5	1.528 (2)
Rb3—O14^vii	2.935 (2)

O1—W1—O2	100.59 (12)	O7^v—Rb3—O12ⁱ	146.54 (7)
O1—W1—O3	97.67 (11)	O14^vii—Rb3—O12ⁱ	103.19 (7)
O2—W1—O3	98.71 (11)	O11—Rb3—O11^vii	103.26 (6)
O1—W1—O4	97.90 (10)	O10ⁱⁱ—Rb3—O11^vii	94.90 (7)
O2—W1—O4	97.20 (11)	O7^v—Rb3—O11^vii	143.97 (6)
O3—W1—O4	155.24 (9)	O14^vii—Rb3—O11^vii	46.63 (6)
O1—W1—O5	98.15 (11)	O12ⁱ—Rb3—O11^vii	62.82 (6)
O2—W1—O5	160.75 (11)	O11—Rb3—O12^v	66.26 (7)
O3—W1—O5	83.02 (9)	O10ⁱⁱ—Rb3—O12^v	141.04 (7)
O4—W1—O5	75.81 (9)	O7^v—Rb3—O12^v	78.58 (6)
O1—W1—O6	173.62 (10)	O14^vii—Rb3—O12^v	75.47 (7)
O2—W1—O6	85.75 (10)	O12ⁱ—Rb3—O12^v	107.66 (6)
O3—W1—O6	81.90 (9)	O11^vii—Rb3—O12^v	69.40 (6)
O4—W1—O6	80.50 (9)	O11—Rb3—O1	62.79 (7)
O5—W1—O6	75.48 (9)	O10ⁱⁱ—Rb3—O1	89.42 (7)
O1—Rb1—O8	64.22 (7)	O7^v—Rb3—O1	85.54 (6)
O1—Rb1—O7	75.57 (7)	O14^vii—Rb3—O1	154.44 (7)
O8—Rb1—O7	84.99 (7)	O12ⁱ—Rb3—O1	64.64 (6)
O1—Rb1—O9ⁱ	90.40 (8)	O11^vii—Rb3—O1	127.46 (6)
O8—Rb1—O9ⁱ	150.64 (8)	O12^v—Rb3—O1	128.76 (6)
O7—Rb1—O9ⁱ	73.96 (7)	O11—Rb3—O13^v	117.97 (7)
O1—Rb1—O6ⁱⁱ	134.22 (7)	O10ⁱⁱ—Rb3—O13^v	74.48 (7)
O8—Rb1—O6ⁱⁱ	73.97 (7)	O7^v—Rb3—O13^v	46.39 (7)
O7—Rb1—O6ⁱⁱ	119.62 (6)	O14^vii—Rb3—O13^v	64.96 (6)
O9ⁱ—Rb1—O6ⁱⁱ	134.35 (7)	O12ⁱ—Rb3—O13^v	166.10 (7)
O1—Rb1—O11ⁱⁱⁱ	123.25 (6)	O11^vii—Rb3—O13^v	108.61 (6)
O8—Rb1—O11ⁱⁱⁱ	67.10 (7)	O12^v—Rb3—O13^v	77.31 (7)
O7—Rb1—O11ⁱⁱⁱ	72.87 (7)	O1—Rb3—O13^v	122.86 (6)
O9ⁱ—Rb1—O11ⁱⁱⁱ	123.13 (7)	O8^viii—Rb4—O3ⁱ	116.73 (7)
O6ⁱⁱ—Rb1—O11ⁱⁱⁱ	46.76 (6)	O8^viii—Rb4—O10	98.95 (7)
O1—Rb1—O2ⁱⁱⁱ	147.59 (7)	O3ⁱ—Rb4—O10	106.38 (7)
O8—Rb1—O2ⁱⁱⁱ	136.20 (7)	O8^viii—Rb4—O14	93.69 (7)
O7—Rb1—O2ⁱⁱⁱ	81.33 (6)	O3ⁱ—Rb4—O14	110.37 (7)
O9ⁱ—Rb1—O2ⁱⁱⁱ	61.21 (7)	O10—Rb4—O14	130.00 (7)
O6ⁱⁱ—Rb1—O2ⁱⁱⁱ	77.25 (6)	O8^viii—Rb4—O13ⁱ	68.94 (7)
O11ⁱⁱⁱ—Rb1—O2ⁱⁱⁱ	69.12 (6)	O3ⁱ—Rb4—O13ⁱ	68.39 (7)
O1—Rb1—O5ⁱⁱ	112.24 (7)	O10—Rb4—O13ⁱ	160.41 (7)
O8—Rb1—O5ⁱⁱ	93.25 (6)	O14—Rb4—O13ⁱ	67.81 (7)
O7—Rb1—O5ⁱⁱ	170.30 (6)	O8^viii—Rb4—O12ⁱ	150.99 (7)
O9ⁱ—Rb1—O5ⁱⁱ	110.80 (7)	O3ⁱ—Rb4—O12ⁱ	46.59 (6)
O6ⁱⁱ—Rb1—O5ⁱⁱ	50.90 (6)	O10—Rb4—O12ⁱ	108.45 (7)
O11ⁱⁱⁱ—Rb1—O5ⁱⁱ	97.65 (6)	O14—Rb4—O12ⁱ	76.14 (7)
O2ⁱⁱⁱ—Rb1—O5ⁱⁱ	93.51 (6)	O13ⁱ—Rb4—O12ⁱ	82.09 (7)
O14^iv—Rb2—O7^v	113.73 (7)	O8^viii—Rb4—O6ⁱ	71.11 (7)
O14^iv—Rb2—O9^vi	104.59 (7)	O3ⁱ—Rb4—O6ⁱ	53.40 (6)
O7^v—Rb2—O9^vi	75.43 (7)	O10—Rb4—O6ⁱ	88.10 (6)
O14^iv—Rb2—O2	155.92 (7)	O14—Rb4—O6ⁱ	141.38 (6)
O7^v—Rb2—O2	84.64 (7)	O13ⁱ—Rb4—O6ⁱ	73.59 (6)
O9^vi—Rb2—O2	63.56 (7)	O12ⁱ—Rb4—O6ⁱ	99.87 (6)
O14^iv—Rb2—O13ⁱⁱ	70.38 (7)	O8^viii—Rb4—O5	118.84 (7)
O7^v—Rb2—O13ⁱⁱ	90.22 (7)	O3ⁱ—Rb4—O5	119.85 (6)
O9^vi—Rb2—O13ⁱⁱ	161.61 (8)	O10—Rb4—O5	44.51 (6)
O2—Rb2—O13ⁱⁱ	127.42 (7)	O14—Rb4—O5	87.33 (6)
O14^iv—Rb2—O8	94.19 (7)	O13ⁱ—Rb4—O5	154.80 (6)
O7^v—Rb2—O8	135.64 (7)	O12ⁱ—Rb4—O5	88.19 (6)
O9^vi—Rb2—O8	131.74 (8)	O6ⁱ—Rb4—O5	131.24 (6)
O2—Rb2—O8	81.38 (7)	O8^viii—Rb4—O4	113.04 (6)
O13ⁱⁱ—Rb2—O8	66.65 (7)	O3ⁱ—Rb4—O4	124.58 (6)
O14^iv—Rb2—O10^v	66.37 (7)	O10—Rb4—O4	88.06 (6)
O7^v—Rb2—O10^v	47.37 (7)	O14—Rb4—O4	43.02 (6)
O9^vi—Rb2—O10^v	88.01 (8)	O13ⁱ—Rb4—O4	110.63 (6)
O2—Rb2—O10^v	130.12 (7)	O12ⁱ—Rb4—O4	77.99 (6)
O13ⁱⁱ—Rb2—O10^v	73.72 (7)	O6ⁱ—Rb4—O4	174.76 (6)
O8—Rb2—O10^v	139.93 (7)	O5—Rb4—O4	44.32 (5)
O14^iv—Rb2—O9	92.92 (7)	O11—S1—O14	113.92 (14)
O7^v—Rb2—O9	152.12 (7)	O11—S1—O6^ix	108.97 (14)
O9^vi—Rb2—O9	90.56 (7)	O14—S1—O6^ix	111.57 (14)
O2—Rb2—O9	67.50 (7)	O11—S1—O4	109.38 (14)
O13ⁱⁱ—Rb2—O9	107.16 (7)	O14—S1—O4	106.03 (14)
O8—Rb2—O9	43.73 (6)	O6^ix—S1—O4	106.66 (13)
O10^v—Rb2—O9	158.07 (7)	O12—S2—O9	113.40 (16)
O14^iv—Rb2—O1	144.45 (6)	O12—S2—O8	114.19 (15)
O7^v—Rb2—O1	82.45 (6)	O9—S2—O8	111.50 (16)
O9^vi—Rb2—O1	110.23 (7)	O12—S2—O3	104.03 (14)
O2—Rb2—O1	48.93 (6)	O9—S2—O3	105.97 (15)
O13ⁱⁱ—Rb2—O1	78.50 (7)	O8—S2—O3	106.88 (13)
O8—Rb2—O1	56.93 (6)	O13—S3—O7	111.90 (16)
O10^v—Rb2—O1	120.93 (6)	O13—S3—O10	112.06 (16)
O9—Rb2—O1	79.98 (6)	O7—S3—O10	111.32 (15)
O11—Rb3—O10ⁱⁱ	152.16 (7)	O13—S3—O5	108.18 (14)
O11—Rb3—O7^v	77.41 (7)	O7—S3—O5	108.64 (14)
O10ⁱⁱ—Rb3—O7^v	100.02 (7)	O10—S3—O5	104.36 (14)
O11—Rb3—O14^vii	138.78 (7)	S2—O3—W1	136.45 (14)
O10ⁱⁱ—Rb3—O14^vii	68.51 (7)	S1—O4—W1	134.71 (14)
O7^v—Rb3—O14^vii	110.14 (7)	S3—O5—W1	139.07 (14)
O11—Rb3—O12ⁱ	75.60 (7)	S1^ix—O6—W1	130.47 (13)
O10ⁱⁱ—Rb3—O12ⁱ	94.76 (7)

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

Experimental details

Crystal data
Chemical formula	Rb₈[W₂O₄(SO₄)₆]
M_r	1691.86
Crystal system, space group	Monoclinic, P2₁/n
Temperature (K)	120
a, b, c (Å)	9.6405 (5), 13.9890 (7), 10.7692 (5)
β (°)	90.472 (1)
V (Å³)	1452.30 (12)
Z	2
Radiation type	Mo Kα
µ (mm⁻¹)	21.77
Crystal size (mm)	0.45 × 0.20 × 0.05

Data collection
Diffractometer	Bruker SMART APEX diffractometer
Absorption correction	Multi-scan (SADABS; Sheldrick, 2002)
T_min, T_max	0.077, 0.59
No. of measured, independent and observed [I > 2σ(I)] reflections	18895, 3496, 3360
R_int	0.036
(sin θ/λ)_max (Å⁻¹)	0.661

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.020, 0.052, 1.11
No. of reflections	3496
No. of parameters	200
Δρ_max, Δρ_min (e Å⁻³)	1.35, −1.51

Computer programs: SMART (Bruker, 2002), SAINT-Plus (Bruker, 2002) and SADABS (Sheldrick, 2002), SHELXTL (Sheldrick, 2008), ORTEP-3 (Farrugia, 1997) and ATOMS (Dowty, 2000).

Selected bond lengths (Å) top

W1—O1	1.716 (2)	Rb3—O12ⁱ	3.101 (2)
W1—O2	1.721 (2)	Rb3—O11^vii	3.170 (2)
W1—O3	1.960 (2)	Rb3—O12^v	3.173 (3)
W1—O4	2.009 (2)	Rb3—O1	3.220 (2)
W1—O5	2.097 (2)	Rb3—O13^v	3.225 (3)
W1—O6	2.254 (2)	Rb4—O8^viii	2.910 (3)
Rb1—O1	2.877 (2)	Rb4—O3ⁱ	2.914 (2)
Rb1—O8	2.931 (2)	Rb4—O10	2.941 (3)
Rb1—O7	2.939 (3)	Rb4—O14	2.964 (2)
Rb1—O9ⁱ	2.955 (3)	Rb4—O13ⁱ	2.981 (3)
Rb1—O6ⁱⁱ	3.009 (2)	Rb4—O12ⁱ	3.103 (3)
Rb1—O11ⁱⁱⁱ	3.010 (2)	Rb4—O6ⁱ	3.221 (2)
Rb1—O2ⁱⁱⁱ	3.084 (2)	Rb4—O5	3.253 (2)
Rb1—O5ⁱⁱ	3.185 (2)	Rb4—O4	3.423 (2)
Rb2—O14^iv	2.761 (3)	S1—O11	1.445 (2)
Rb2—O7^v	2.893 (2)	S1—O14	1.449 (2)
Rb2—O9^vi	2.903 (3)	S1—O6^ix	1.490 (2)
Rb2—O2	2.939 (3)	S1—O4	1.531 (2)
Rb2—O13ⁱⁱ	2.986 (2)	S2—O12	1.451 (3)
Rb2—O8	3.082 (3)	S2—O9	1.452 (3)
Rb2—O10^v	3.106 (3)	S2—O8	1.454 (3)
Rb2—O9	3.337 (3)	S2—O3	1.575 (2)
Rb2—O1	3.374 (3)	S3—O13	1.461 (2)
Rb3—O11	2.776 (2)	S3—O7	1.464 (3)
Rb3—O10ⁱⁱ	2.788 (3)	S3—O10	1.464 (3)
Rb3—O7^v	2.874 (2)	S3—O5	1.528 (2)
Rb3—O14^vii	2.935 (2)

Acknowledgements

The authors thank Astrid Schöneberg and Bodil Holten for technical assistance.

References

Berg, R. W., Ferre, I. M. & Schäffer, S. J. C. (2006). Vib. Spectrosc. 42, 346–352. Web of Science CrossRef CAS Google Scholar
Borup, F., Berg, R. W. & Nielsen, K. (1990). Acta Chem. Scand. 44, 328–331. CrossRef CAS Web of Science Google Scholar
Bruker (2002). SMART and SAINT-Plus. Bruker AXS Inc., Madison, Wisconsin, USA. Google Scholar
Dowty, E. (2000). ATOMS. Shape Software, Kingsport, Tennessee 37663, USA. Google Scholar
Farrugia, L. J. (1997). J. Appl. Cryst. 30, 565. CrossRef IUCr Journals Google Scholar
Nørbygaard, T., Berg, R. W. & Nielsen, K. (1998). Molten Salts XI Electrochem. Soc. Proc. 98–11, 553–565. Google Scholar
Schäffer, S. J. C. & Berg, R. W. (2005). Acta Cryst. E61, i49–i51. Web of Science CrossRef IUCr Journals Google Scholar
Sheldrick, G. M. (2002). SADABS. University of Göttingen, Germany. Google Scholar
Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. Web of Science CrossRef CAS IUCr Journals Google Scholar

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