Cs3Sm7Se12

Schneck, C.; Elbe, A.; Schurz, C.M.; Schleid, T.

doi:10.1107/S1600536811051919

inorganic compounds

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ISSN: 2056-9890

Volume 68| Part 1| January 2012| Page i2

doi:10.1107/S1600536811051919

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Cs₃Sm₇Se₁₂

Christof Schneck,^a Andreas Elbe,^a Christian M. Schurz ^a and Thomas Schleid ^a ^*

^aInstitut für Anorganische Chemie, Universität Stuttgart, Pfaffenwaldring 55, 70569 Stuttgart, Germany
^*Correspondence e-mail: schleid@iac.uni-stuttgart.de

(Received 14 November 2011; accepted 1 December 2011; online 7 December 2011)

The title compound, tricaesium heptasamarium(III) dodecaselenide, is setting a new starting point for realization of the channel structure of the Cs₃M₇Se₁₂ series, now with M = Sm, Gd–Er. This Cs₃Y₇Se₁₂-type arrangement is structurally based on the Z-type sesquiselenides M₂Se₃ adopting the Sc₂S₃ structure. Thus, the structural set-up of Cs₃Sm₇Se₁₂ consists of edge- and vertex-connected [SmSe₆]⁹⁻ octahedra [d_Ø(Sm³⁺ – Se²⁻) = 2.931 Å], forming a rock-salt-related network [Sm₇Se₁₂]³⁻ with channels along [001] that are apt to take up monovalent cations (here Cs⁺) with coordination numbers of 7 + 1 for one and of 6 for the second cation. The latter cation has a trigonal–prismatic coordination and shows half-occupancy, resulting in an impossible short distance [2.394 (4) Å] between symmetrically coupled Cs⁺ cations of the same kind. While one Sm atom occupies Wyckoff position 2b with site symmetry ..2/m, all other 11 crystallographically different atoms (namely 2 × Cs, 3 × Sm and 6 × Se) are located at Wyckoff positions 4g with site symmetry ..m.

Related literature

For prototypic Cs₃Y₇Se₁₂ or Rb₃Yb₇Se₁₂, see: Folchnandt & Schleid (1996 ); Kim et al. (1996 ). For other representatives of the A₃M₇Ch₁₂ series, see: Folchnandt & Schleid (1997 , 1998 , 2000 ); Tougaît et al. (2001 ); Lissner et al. (2002 ). A detailed description of the relation between the crystal structures of the Cs₃M₇Se₁₂ series and Z-type Sc₂Ch₃ (Dismukes & White, 1964 ) is provided by Folchnandt & Schleid (1998).

Experimental

Crystal data

Cs₃Sm₇Se₁₂
M_r = 2398.70
Orthorhombic,
a = 13.0387 (9) Å
b = 26.6742 (19) Å
c = 4.2351 (3) Å
V = 1472.95 (18) Å³
Z = 2
Mo Kα radiation
μ = 32.19 mm⁻¹
T = 293 K
0.10 × 0.07 × 0.05 mm

Data collection

Stoe IPDS-I diffractometer
Absorption correction: numerical (X-SHAPE; Stoe & Cie, 1999 ) T_min = 0.115, T_max = 0.216
15080 measured reflections
2135 independent reflections
1587 reflections with I > 2σ(I)
R_int = 0.065

Refinement

R[F² > 2σ(F²)] = 0.035
wR(F²) = 0.072
S = 0.97
2135 reflections
72 parameters
Δρ_max = 2.09 e Å⁻³
Δρ_min = −1.78 e Å⁻³

Table 1
Selected bond lengths (Å)

Cs1—Se4ⁱ	3.6071 (12)
Cs1—Se4ⁱⁱ	3.6071 (12)
Cs1—Se6ⁱⁱ	3.7129 (12)
Cs1—Se6ⁱ	3.7129 (12)
Cs1—Se3ⁱⁱⁱ	3.7639 (14)
Cs1—Se5ⁱ	3.8053 (12)
Cs1—Se5ⁱⁱ	3.8053 (12)
Cs1—Se1	4.5421 (14)
Cs2—Se2ⁱⁱ	3.5286 (16)
Cs2—Se2ⁱ	3.5286 (16)
Cs2—Se2^v	3.6917 (17)
Cs2—Se2^vi	3.6917 (17)
Cs2—Se5ⁱⁱⁱ	3.719 (2)
Cs2—Se6ⁱⁱⁱ	3.924 (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) ; (iv) ; (v) $[x+{\script{1\over 2}}, -y+{\script{1\over 2}}, -z-{\script{1\over 2}}]$ ; (vi) $[x+{\script{1\over 2}}, -y+{\script{1\over 2}}, -z+{\script{1\over 2}}]$ .

Data collection: DIF4 (Stoe & Cie, 1992 ); cell refinement: DIF4; data reduction: REDU4 (Stoe & Cie, 1992); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: DIAMOND (Brandenburg, 2006 ); software used to prepare material for publication: SHELXL97.

Supporting information

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536811051919/wm2561sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536811051919/wm2561Isup2.hkl

checkCIF report

Comment top

Cs₃Sm₇Se₁₂ crystallizes isotypically to the large family of ternary A₃M₇Ch₁₂ representatives with a channel-like structure. For Ch = S, A = K, Rb, M = Er, see: Lissner et al. (2002); for Ch = Se, A = Rb, M = Dy, Yb, see: Folchnandt & Schleid (2000), Kim et al. (1996); for Ch = Se, A = Cs, M = Y, Gd – Er, see: Folchnandt & Schleid (1996, 1997, 1998); for Ch = Te, A = Cs, M = Sm, Gd, Tb, see: Tougaît et al. (2001).

In the title compound, [SmSe₆]^9- octahedra (d(Sm³⁺–Se^2-) = 2.8578 (9)–3.0614 (13) Å) are connected via edges and corners to form a [Sm₇Se₁₂]^3- network with triple-channels occupied by Cs⁺ cations (Fig. 1). This network represents a defect rock-salt-type structure strongly related to that of the Z-type sesquiselenides M₂Se₃ (Dismukes & White, 1964) according to the formula [□]₄[M]₈[Se]₁₂. In tricaesium heptasamarium(III) dodecaselenide three Cs⁺ cations replace one Sm³⁺ for charge balance. The triple-channels are arranged in a herringbone pattern and run through the structure parallel to [001]. They are filled with two crystallographically different Cs⁺ cations (Fig. 2). While Cs1⁺ exhibits a coordination number of 7+1 with an extra secondary contact (d(Cs1⁺–Se^2-) = 3.6071 (12)–3.8053 (12) Å and 4.5421 (14) Å; Fig. 2, left), the Cs2⁺ cations have only six selenide anions as nearest neighbours in the shape of a trigonal prism (d(Cs2⁺–Se^2-) = 3.5286 (16) – 3.924 (2) Å; Fig. 2, right). Owing to the very close distances between these Cs2⁺ cations (d(Cs2⁺···Cs2⁺) = 2.394 (4) Å) only a half-occupation of this position is possible (Fig. 2, right and Fig. 3) and stoichiometrically meaningful.

Related literature top

For prototypic Cs₃Y₇Se₁₂ or Rb₃Yb₇Se₁₂, see: Folchnandt & Schleid (1996); Kim et al. (1996). For other representatives of the A₃M₇Ch₁₂ series, see: Folchnandt & Schleid (1997, 1998, 2000); Tougaît et al. (2001); Lissner et al. (2002). A detailed description of the relation between the crystal structures of the Cs₃M₇Se₁₂ series and Z-type Sc₂Ch₃ (Dismukes & White, 1964) is provided by Folchnandt & Schleid (1998).

Experimental top

Yellow, transparent, needle-shaped single crystals of Cs₃Sm₇Se₁₂ were obtained as the main product of a reaction between 0.10 g Sm, 0.08 g Se and 0.50 g CsCl added as flux and caesium source upon heating at 1073 K for 10 days in a sealed, evacuated fused-silica vessel.

Computing details top

Data collection: DIF4 (Stoe & Cie, 1992); cell refinement: DIF4 (Stoe & Cie, 1992); data reduction: REDU4 (Stoe & Cie, 1992); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: DIAMOND (Brandenburg, 2006); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008).

Figures top

	Fig. 1. Channel-structure representation of Cs₃Sm₇Se₁₂ as octahedral framework with indicated unit cell.
	Fig. 2. Coordination spheres of the Cs1⁺ (left) and Cs2⁺ (right) cations in Cs₃Sm₇Se₁₂. Displacement ellipsoids are drawn at the 90% probability level. 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, -y+1, -z; (viii) -x+1, -y, -z; (ix) x+1/2, -y+1/2, -z-1/2; (x) x+1/2, -y+1/2, -z+1/2.
	Fig. 3. Interplay of the Cs⁺ cations situated in the triple-channels of the crystal structure of Cs₃Sm₇Se₁₂. Displacement ellipsoids are drawn at the 90% probability level.

tricaesium heptasamarium(III) dodecaselenide top

Crystal data top

Cs₃Sm₇Se₁₂	F(000) = 2014
M_r = 2398.70	D_x = 5.408 Mg m⁻³
Orthorhombic, Pnnm	Mo Kα radiation, λ = 0.71069 Å
Hall symbol: -P 2 2n	Cell parameters from 5000 reflections
a = 13.0387 (9) Å	θ = 2.1–29.3°
b = 26.6742 (19) Å	µ = 32.19 mm⁻¹
c = 4.2351 (3) Å	T = 293 K
V = 1472.95 (18) Å³	Needle, yellow
Z = 2	0.10 × 0.07 × 0.05 mm

Data collection top

Stoe IPDS-I diffractometer	2135 independent reflections
Radiation source: fine-focus sealed tube	1587 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.065
imaging plate detector system scans	θ_max = 29.0°, θ_min = 2.8°
Absorption correction: numerical (X-SHAPE; Stoe & Cie, 1999)	h = −17→17
T_min = 0.115, T_max = 0.216	k = −36→36
15080 measured reflections	l = −5→5

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)] = 0.035	w = 1/[σ²(F_o²) + (0.0371P)²] where P = (F_o² + 2F_c²)/3
wR(F²) = 0.072	(Δ/σ)_max = 0.014
S = 0.97	Δρ_max = 2.09 e Å⁻³
2135 reflections	Δρ_min = −1.78 e Å⁻³
72 parameters	Extinction correction: SHELXL97 (Sheldrick, 2008), Fc^*=kFc[1+0.001xFc²λ³/sin(2θ)]^-1/4
0 restraints	Extinction coefficient: 0.00017 (4)

Crystal data top

Cs₃Sm₇Se₁₂	V = 1472.95 (18) Å³
M_r = 2398.70	Z = 2
Orthorhombic, Pnnm	Mo Kα radiation
a = 13.0387 (9) Å	µ = 32.19 mm⁻¹
b = 26.6742 (19) Å	T = 293 K
c = 4.2351 (3) Å	0.10 × 0.07 × 0.05 mm

Data collection top

Stoe IPDS-I diffractometer	2135 independent reflections
Absorption correction: numerical (X-SHAPE; Stoe & Cie, 1999)	1587 reflections with I > 2σ(I)
T_min = 0.115, T_max = 0.216	R_int = 0.065
15080 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.035	72 parameters
wR(F²) = 0.072	0 restraints
S = 0.97	Δρ_max = 2.09 e Å⁻³
2135 reflections	Δρ_min = −1.78 e Å⁻³

Special details top

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 > 2sigma(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	Occ. (<1)
Cs1	0.28796 (6)	0.36600 (3)	0.0000	0.0252 (2)
Cs2	0.56532 (14)	0.03154 (7)	0.0000	0.0311 (5)	0.50
Sm1	0.0000	0.0000	0.5000	0.0124 (2)
Sm2	0.21848 (5)	0.08314 (2)	0.0000	0.01316 (15)
Sm3	0.40590 (4)	0.71214 (2)	0.0000	0.01224 (15)
Sm4	0.07792 (5)	0.68240 (2)	0.0000	0.01271 (15)
Se1	0.25592 (8)	0.19644 (4)	0.0000	0.0125 (3)
Se2	0.12980 (9)	0.57736 (4)	0.0000	0.0142 (3)
Se3	0.43019 (9)	0.60350 (4)	0.0000	0.0129 (3)
Se4	0.05307 (8)	0.78890 (4)	0.0000	0.0133 (3)
Se5	0.15051 (9)	0.98065 (4)	0.0000	0.0142 (3)
Se6	0.42742 (9)	0.82140 (4)	0.0000	0.0133 (3)

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Cs1	0.0214 (4)	0.0295 (4)	0.0247 (6)	−0.0002 (3)	0.000	0.000
Cs2	0.0266 (9)	0.0273 (9)	0.0393 (14)	0.0114 (7)	0.000	0.000
Sm1	0.0147 (4)	0.0109 (4)	0.0116 (6)	−0.0030 (3)	0.000	0.000
Sm2	0.0153 (3)	0.0135 (3)	0.0107 (4)	−0.0027 (2)	0.000	0.000
Sm3	0.0137 (3)	0.0117 (3)	0.0113 (4)	−0.0018 (2)	0.000	0.000
Sm4	0.0131 (3)	0.0130 (3)	0.0121 (4)	0.0034 (2)	0.000	0.000
Se1	0.0123 (5)	0.0153 (5)	0.0101 (7)	−0.0004 (4)	0.000	0.000
Se2	0.0147 (6)	0.0142 (5)	0.0137 (8)	0.0007 (4)	0.000	0.000
Se3	0.0154 (5)	0.0096 (5)	0.0138 (7)	0.0007 (4)	0.000	0.000
Se4	0.0144 (5)	0.0128 (5)	0.0126 (8)	0.0000 (4)	0.000	0.000
Se5	0.0155 (5)	0.0129 (5)	0.0141 (8)	−0.0004 (4)	0.000	0.000
Se6	0.0140 (5)	0.0134 (5)	0.0124 (8)	0.0008 (4)	0.000	0.000

Geometric parameters (Å, º) top

Cs1—Se4ⁱ	3.6071 (12)	Sm1—Se5^xi	2.9328 (8)
Cs1—Se4ⁱⁱ	3.6071 (12)	Sm1—Se5^xii	2.9328 (8)
Cs1—Se6ⁱⁱ	3.7129 (12)	Sm1—Se5^xiii	2.9328 (8)
Cs1—Se6ⁱ	3.7129 (12)	Sm2—Se5^xiii	2.8738 (13)
Cs1—Se3ⁱⁱⁱ	3.7639 (14)	Sm2—Se2ⁱ	2.9020 (10)
Cs1—Se5ⁱ	3.8053 (12)	Sm2—Se2ⁱⁱ	2.9020 (10)
Cs1—Se5ⁱⁱ	3.8053 (12)	Sm2—Se3ⁱⁱ	2.9217 (9)
Cs1—Se1	4.5421 (14)	Sm2—Se3ⁱ	2.9217 (9)
Cs1—Cs1^iv	4.2351 (3)	Sm2—Se1	3.0614 (13)
Cs1—Cs1^v	4.2351 (3)	Sm3—Se4^xiv	2.8578 (9)
Cs2—Cs2^vi	2.394 (4)	Sm3—Se4^xv	2.8578 (9)
Cs2—Se2ⁱⁱ	3.5286 (16)	Sm3—Se3	2.9152 (13)
Cs2—Se2ⁱ	3.5286 (16)	Sm3—Se6	2.9279 (13)
Cs2—Se2^vii	3.6917 (17)	Sm3—Se1^xvi	3.0185 (9)
Cs2—Se2^viii	3.6917 (17)	Sm3—Se1^xvii	3.0185 (9)
Cs2—Se5ⁱⁱⁱ	3.719 (2)	Sm4—Se4	2.8591 (13)
Cs2—Se6ⁱⁱⁱ	3.924 (2)	Sm4—Se2	2.8823 (13)
Cs2—Sm2^vi	4.1597 (18)	Sm4—Se6^xviii	2.8888 (9)
Sm1—Se3ⁱ	2.9070 (11)	Sm4—Se6^xix	2.8888 (9)
Sm1—Se3^ix	2.9070 (11)	Sm4—Se1^xvii	3.0526 (9)
Sm1—Se5^x	2.9328 (8)	Sm4—Se1^xvi	3.0526 (9)

Se4ⁱ—Cs1—Se4ⁱⁱ	71.90 (3)	Se2ⁱⁱ—Sm2—Se1	86.77 (3)
Se4ⁱ—Cs1—Se6ⁱⁱ	125.93 (3)	Se3ⁱⁱ—Sm2—Se1	85.54 (3)
Se4ⁱⁱ—Cs1—Se6ⁱⁱ	85.24 (2)	Se3ⁱ—Sm2—Se1	85.54 (3)
Se4ⁱ—Cs1—Se6ⁱ	85.24 (2)	Se4^xiv—Sm3—Se4^xv	95.63 (4)
Se4ⁱⁱ—Cs1—Se6ⁱ	125.93 (3)	Se4^xiv—Sm3—Se3	85.26 (3)
Se6ⁱⁱ—Cs1—Se6ⁱ	69.55 (3)	Se4^xv—Sm3—Se3	85.26 (3)
Se4ⁱ—Cs1—Se3ⁱⁱⁱ	64.04 (3)	Se4^xiv—Sm3—Se6	86.87 (3)
Se4ⁱⁱ—Cs1—Se3ⁱⁱⁱ	64.04 (3)	Se4^xv—Sm3—Se6	86.87 (3)
Se6ⁱⁱ—Cs1—Se3ⁱⁱⁱ	143.874 (16)	Se3—Sm3—Se6	168.27 (4)
Se6ⁱ—Cs1—Se3ⁱⁱⁱ	143.874 (16)	Se4^xiv—Sm3—Se1^xvi	171.05 (4)
Se4ⁱ—Cs1—Se5ⁱ	90.60 (2)	Se4^xv—Sm3—Se1^xvi	87.03 (2)
Se4ⁱⁱ—Cs1—Se5ⁱ	131.59 (3)	Se3—Sm3—Se1^xvi	86.44 (3)
Se6ⁱⁱ—Cs1—Se5ⁱ	137.25 (3)	Se6—Sm3—Se1^xvi	101.84 (3)
Se6ⁱ—Cs1—Se5ⁱ	95.72 (2)	Se4^xiv—Sm3—Se1^xvii	87.03 (2)
Se3ⁱⁱⁱ—Cs1—Se5ⁱ	67.69 (3)	Se4^xv—Sm3—Se1^xvii	171.05 (4)
Se4ⁱ—Cs1—Se5ⁱⁱ	131.59 (3)	Se3—Sm3—Se1^xvii	86.44 (3)
Se4ⁱⁱ—Cs1—Se5ⁱⁱ	90.60 (2)	Se6—Sm3—Se1^xvii	101.84 (3)
Se6ⁱⁱ—Cs1—Se5ⁱⁱ	95.72 (2)	Se1^xvi—Sm3—Se1^xvii	89.10 (3)
Se6ⁱ—Cs1—Se5ⁱⁱ	137.25 (3)	Se4—Sm4—Se2	172.93 (4)
Se3ⁱⁱⁱ—Cs1—Se5ⁱⁱ	67.69 (3)	Se4—Sm4—Se6^xviii	87.59 (3)
Se5ⁱ—Cs1—Se5ⁱⁱ	67.63 (2)	Se2—Sm4—Se6^xviii	97.20 (3)
Se2ⁱⁱ—Cs2—Se2^vii	95.31 (3)	Se4—Sm4—Se6^xix	87.59 (3)
Se2ⁱ—Cs2—Se2^vii	141.35 (6)	Se2—Sm4—Se6^xix	97.20 (3)
Se2ⁱⁱ—Cs2—Se2^viii	141.35 (6)	Se6^xviii—Sm4—Se6^xix	94.28 (4)
Se2ⁱ—Cs2—Se2^viii	95.31 (3)	Se4—Sm4—Se1^xvii	87.63 (3)
Se2^vii—Cs2—Se2^viii	70.00 (4)	Se2—Sm4—Se1^xvii	87.29 (3)
Se2ⁱⁱ—Cs2—Se5ⁱⁱⁱ	138.46 (3)	Se6^xviii—Sm4—Se1^xvii	174.23 (4)
Se2ⁱ—Cs2—Se5ⁱⁱⁱ	138.46 (3)	Se6^xix—Sm4—Se1^xvii	88.74 (2)
Se2^vii—Cs2—Se5ⁱⁱⁱ	72.81 (4)	Se4—Sm4—Se1^xvi	87.63 (3)
Se2^viii—Cs2—Se5ⁱⁱⁱ	72.81 (4)	Se2—Sm4—Se1^xvi	87.29 (3)
Se2ⁱⁱ—Cs2—Se6ⁱⁱⁱ	70.80 (4)	Se6^xviii—Sm4—Se1^xvi	88.74 (2)
Se2ⁱ—Cs2—Se6ⁱⁱⁱ	70.80 (4)	Se6^xix—Sm4—Se1^xvi	174.23 (4)
Se2^vii—Cs2—Se6ⁱⁱⁱ	141.36 (3)	Se1^xvii—Sm4—Se1^xvi	87.85 (3)
Se2^viii—Cs2—Se6ⁱⁱⁱ	141.36 (3)	Sm3ⁱⁱ—Se1—Sm3ⁱ	89.10 (3)
Se5ⁱⁱⁱ—Cs2—Se6ⁱⁱⁱ	93.63 (5)	Sm3ⁱⁱ—Se1—Sm4ⁱ	178.80 (4)
Se3ⁱ—Sm1—Se3^ix	180.000 (14)	Sm3ⁱ—Se1—Sm4ⁱ	91.519 (12)
Se3ⁱ—Sm1—Se5^x	92.43 (3)	Sm3ⁱⁱ—Se1—Sm4ⁱⁱ	91.519 (12)
Se3^ix—Sm1—Se5^x	87.57 (3)	Sm3ⁱ—Se1—Sm4ⁱⁱ	178.80 (4)
Se3ⁱ—Sm1—Se5^xi	87.57 (3)	Sm4ⁱ—Se1—Sm4ⁱⁱ	87.85 (3)
Se3^ix—Sm1—Se5^xi	92.43 (3)	Sm3ⁱⁱ—Se1—Sm2	91.46 (3)
Se5^x—Sm1—Se5^xi	180.00 (4)	Sm3ⁱ—Se1—Sm2	91.46 (3)
Se3ⁱ—Sm1—Se5^xii	92.43 (3)	Sm4ⁱ—Se1—Sm2	89.55 (3)
Se3^ix—Sm1—Se5^xii	87.57 (3)	Sm4ⁱⁱ—Se1—Sm2	89.55 (3)
Se5^x—Sm1—Se5^xii	92.44 (3)	Sm4—Se2—Sm2^xvii	96.22 (3)
Se5^xi—Sm1—Se5^xii	87.56 (3)	Sm4—Se2—Sm2^xvi	96.22 (3)
Se3ⁱ—Sm1—Se5^xiii	87.57 (3)	Sm2^xvii—Se2—Sm2^xvi	93.72 (4)
Se3^ix—Sm1—Se5^xiii	92.43 (3)	Sm1^viii—Se3—Sm3	167.99 (5)
Se5^x—Sm1—Se5^xiii	87.56 (3)	Sm1^viii—Se3—Sm2^xvi	91.79 (3)
Se5^xi—Sm1—Se5^xiii	92.44 (3)	Sm3—Se3—Sm2^xvi	96.47 (3)
Se5^xii—Sm1—Se5^xiii	180.0	Sm1^viii—Se3—Sm2^xvii	91.79 (3)
Se5^xiii—Sm2—Se2ⁱ	99.19 (3)	Sm3—Se3—Sm2^xvii	96.47 (3)
Se5^xiii—Sm2—Se2ⁱⁱ	99.19 (3)	Sm2^xvi—Se3—Sm2^xvii	92.90 (4)
Se2ⁱ—Sm2—Se2ⁱⁱ	93.72 (4)	Sm3^xviii—Se4—Sm3^xix	95.63 (4)
Se5^xiii—Sm2—Se3ⁱⁱ	88.41 (3)	Sm3^xviii—Se4—Sm4	93.81 (3)
Se2ⁱ—Sm2—Se3ⁱⁱ	172.31 (4)	Sm3^xix—Se4—Sm4	93.81 (3)
Se2ⁱⁱ—Sm2—Se3ⁱⁱ	86.18 (2)	Sm2^xx—Se5—Sm1^xxi	92.23 (3)
Se5^xiii—Sm2—Se3ⁱ	88.41 (3)	Sm2^xx—Se5—Sm1^xx	92.23 (3)
Se2ⁱ—Sm2—Se3ⁱ	86.18 (2)	Sm1^xxi—Se5—Sm1^xx	92.44 (3)
Se2ⁱⁱ—Sm2—Se3ⁱ	172.31 (4)	Sm4^xiv—Se6—Sm4^xv	94.28 (4)
Se3ⁱⁱ—Sm2—Se3ⁱ	92.90 (4)	Sm4^xiv—Se6—Sm3	91.72 (3)
Se5^xiii—Sm2—Se1	171.21 (4)	Sm4^xv—Se6—Sm3	91.72 (3)
Se2ⁱ—Sm2—Se1	86.77 (3)

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, −y+1, −z; (iv) x, y, z−1; (v) x, y, z+1; (vi) −x+1, −y, −z; (vii) x+1/2, −y+1/2, −z−1/2; (viii) x+1/2, −y+1/2, −z+1/2; (ix) x−1/2, −y+1/2, −z+1/2; (x) −x, −y+1, −z; (xi) x, y−1, z+1; (xii) −x, −y+1, −z+1; (xiii) x, y−1, z; (xiv) x+1/2, −y+3/2, −z+1/2; (xv) x+1/2, −y+3/2, −z−1/2; (xvi) −x+1/2, y+1/2, z−1/2; (xvii) −x+1/2, y+1/2, z+1/2; (xviii) x−1/2, −y+3/2, −z−1/2; (xix) x−1/2, −y+3/2, −z+1/2; (xx) x, y+1, z; (xxi) x, y+1, z−1.

Experimental details

Crystal data
Chemical formula	Cs₃Sm₇Se₁₂
M_r	2398.70
Crystal system, space group	Orthorhombic, Pnnm
Temperature (K)	293
a, b, c (Å)	13.0387 (9), 26.6742 (19), 4.2351 (3)
V (Å³)	1472.95 (18)
Z	2
Radiation type	Mo Kα
µ (mm⁻¹)	32.19
Crystal size (mm)	0.10 × 0.07 × 0.05

Data collection
Diffractometer	Stoe IPDS-I diffractometer
Absorption correction	Numerical (X-SHAPE; Stoe & Cie, 1999)
T_min, T_max	0.115, 0.216
No. of measured, independent and observed [I > 2σ(I)] reflections	15080, 2135, 1587
R_int	0.065
(sin θ/λ)_max (Å⁻¹)	0.681

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.035, 0.072, 0.97
No. of reflections	2135
No. of parameters	72
Δρ_max, Δρ_min (e Å⁻³)	2.09, −1.78

Computer programs: DIF4 (Stoe & Cie, 1992), REDU4 (Stoe & Cie, 1992), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), DIAMOND (Brandenburg, 2006).

Selected bond lengths (Å) top

Cs1—Se4ⁱ	3.6071 (12)	Cs2—Cs2^iv	2.394 (4)
Cs1—Se4ⁱⁱ	3.6071 (12)	Cs2—Se2ⁱⁱ	3.5286 (16)
Cs1—Se6ⁱⁱ	3.7129 (12)	Cs2—Se2ⁱ	3.5286 (16)
Cs1—Se6ⁱ	3.7129 (12)	Cs2—Se2^v	3.6917 (17)
Cs1—Se3ⁱⁱⁱ	3.7639 (14)	Cs2—Se2^vi	3.6917 (17)
Cs1—Se5ⁱ	3.8053 (12)	Cs2—Se5ⁱⁱⁱ	3.719 (2)
Cs1—Se5ⁱⁱ	3.8053 (12)	Cs2—Se6ⁱⁱⁱ	3.924 (2)
Cs1—Se1	4.5421 (14)

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, −y+1, −z; (iv) −x+1, −y, −z; (v) x+1/2, −y+1/2, −z−1/2; (vi) x+1/2, −y+1/2, −z+1/2.

Acknowledgements

This work was supported by the State of Baden-Württemberg (Stuttgart) and the German Research Foundation (DFG; Bonn) within the funding programme Open Access Publishing. We thank Dr Falk Lissner for the data collection.

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