supplementary materials


Acta Cryst. (2012). E68, i2    [ doi:10.1107/S1600536811051919 ]

Cs3Sm7Se12

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

Abstract top

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 [dØ(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.

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+–Se2-) = 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+–Se2-) = 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+–Se2-) = 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.

Refinement top

In the final difference Fourier map the highest peak is 1.24 Å away from Se2 and the deepest hole is located 0.83 Å away from Sm2.

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
[Figure 1] Fig. 1. Channel-structure representation of Cs3Sm7Se12 as octahedral framework with indicated unit cell.
[Figure 2] 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.
[Figure 3] 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
Cs3Sm7Se12F(000) = 2014
Mr = 2398.70Dx = 5.408 Mg m3
Orthorhombic, PnnmMo Kα radiation, λ = 0.71069 Å
Hall symbol: -P 2 2nCell parameters from 5000 reflections
a = 13.0387 (9) Åθ = 2.1–29.3°
b = 26.6742 (19) ŵ = 32.19 mm1
c = 4.2351 (3) ÅT = 293 K
V = 1472.95 (18) Å3Needle, yellow
Z = 20.10 × 0.07 × 0.05 mm
Data collection top
Stoe IPDS-I
diffractometer
2135 independent reflections
Radiation source: fine-focus sealed tube1587 reflections with I > 2σ(I)
graphiteRint = 0.065
imaging plate detector system scansθmax = 29.0°, θmin = 2.8°
Absorption correction: numerical
(X-SHAPE; Stoe & Cie, 1999)
h = 1717
Tmin = 0.115, Tmax = 0.216k = 3636
15080 measured reflectionsl = 55
Refinement top
Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.035 w = 1/[σ2(Fo2) + (0.0371P)2]
where P = (Fo2 + 2Fc2)/3
wR(F2) = 0.072(Δ/σ)max = 0.014
S = 0.97Δρmax = 2.09 e Å3
2135 reflectionsΔρmin = 1.78 e Å3
72 parametersExtinction correction: SHELXL97 (Sheldrick, 2008), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
0 restraintsExtinction coefficient: 0.00017 (4)
Crystal data top
Cs3Sm7Se12V = 1472.95 (18) Å3
Mr = 2398.70Z = 2
Orthorhombic, PnnmMo Kα radiation
a = 13.0387 (9) ŵ = 32.19 mm1
b = 26.6742 (19) ÅT = 293 K
c = 4.2351 (3) Å0.10 × 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)
Tmin = 0.115, Tmax = 0.216Rint = 0.065
15080 measured reflectionsθmax = 29.0°
Refinement top
R[F2 > 2σ(F2)] = 0.035Δρmax = 2.09 e Å3
wR(F2) = 0.072Δρmin = 1.78 e Å3
S = 0.97Absolute structure: ?
2135 reflectionsFlack parameter: ?
72 parametersRogers parameter: ?
0 restraints
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
xyzUiso*/UeqOcc. (<1)
Cs10.28796 (6)0.36600 (3)0.00000.0252 (2)
Cs20.56532 (14)0.03154 (7)0.00000.0311 (5)0.50
Sm10.00000.00000.50000.0124 (2)
Sm20.21848 (5)0.08314 (2)0.00000.01316 (15)
Sm30.40590 (4)0.71214 (2)0.00000.01224 (15)
Sm40.07792 (5)0.68240 (2)0.00000.01271 (15)
Se10.25592 (8)0.19644 (4)0.00000.0125 (3)
Se20.12980 (9)0.57736 (4)0.00000.0142 (3)
Se30.43019 (9)0.60350 (4)0.00000.0129 (3)
Se40.05307 (8)0.78890 (4)0.00000.0133 (3)
Se50.15051 (9)0.98065 (4)0.00000.0142 (3)
Se60.42742 (9)0.82140 (4)0.00000.0133 (3)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Cs10.0214 (4)0.0295 (4)0.0247 (6)0.0002 (3)0.0000.000
Cs20.0266 (9)0.0273 (9)0.0393 (14)0.0114 (7)0.0000.000
Sm10.0147 (4)0.0109 (4)0.0116 (6)0.0030 (3)0.0000.000
Sm20.0153 (3)0.0135 (3)0.0107 (4)0.0027 (2)0.0000.000
Sm30.0137 (3)0.0117 (3)0.0113 (4)0.0018 (2)0.0000.000
Sm40.0131 (3)0.0130 (3)0.0121 (4)0.0034 (2)0.0000.000
Se10.0123 (5)0.0153 (5)0.0101 (7)0.0004 (4)0.0000.000
Se20.0147 (6)0.0142 (5)0.0137 (8)0.0007 (4)0.0000.000
Se30.0154 (5)0.0096 (5)0.0138 (7)0.0007 (4)0.0000.000
Se40.0144 (5)0.0128 (5)0.0126 (8)0.0000 (4)0.0000.000
Se50.0155 (5)0.0129 (5)0.0141 (8)0.0004 (4)0.0000.000
Se60.0140 (5)0.0134 (5)0.0124 (8)0.0008 (4)0.0000.000
Geometric parameters (Å, °) top
Cs1—Se4i3.6071 (12)Sm1—Se5xi2.9328 (8)
Cs1—Se4ii3.6071 (12)Sm1—Se5xii2.9328 (8)
Cs1—Se6ii3.7129 (12)Sm1—Se5xiii2.9328 (8)
Cs1—Se6i3.7129 (12)Sm2—Se5xiii2.8738 (13)
Cs1—Se3iii3.7639 (14)Sm2—Se2i2.9020 (10)
Cs1—Se5i3.8053 (12)Sm2—Se2ii2.9020 (10)
Cs1—Se5ii3.8053 (12)Sm2—Se3ii2.9217 (9)
Cs1—Se14.5421 (14)Sm2—Se3i2.9217 (9)
Cs1—Cs1iv4.2351 (3)Sm2—Se13.0614 (13)
Cs1—Cs1v4.2351 (3)Sm3—Se4xiv2.8578 (9)
Cs2—Cs2vi2.394 (4)Sm3—Se4xv2.8578 (9)
Cs2—Se2ii3.5286 (16)Sm3—Se32.9152 (13)
Cs2—Se2i3.5286 (16)Sm3—Se62.9279 (13)
Cs2—Se2vii3.6917 (17)Sm3—Se1xvi3.0185 (9)
Cs2—Se2viii3.6917 (17)Sm3—Se1xvii3.0185 (9)
Cs2—Se5iii3.719 (2)Sm4—Se42.8591 (13)
Cs2—Se6iii3.924 (2)Sm4—Se22.8823 (13)
Cs2—Sm2vi4.1597 (18)Sm4—Se6xviii2.8888 (9)
Sm1—Se3i2.9070 (11)Sm4—Se6xix2.8888 (9)
Sm1—Se3ix2.9070 (11)Sm4—Se1xvii3.0526 (9)
Sm1—Se5x2.9328 (8)Sm4—Se1xvi3.0526 (9)
Se4i—Cs1—Se4ii71.90 (3)Se2ii—Sm2—Se186.77 (3)
Se4i—Cs1—Se6ii125.93 (3)Se3ii—Sm2—Se185.54 (3)
Se4ii—Cs1—Se6ii85.24 (2)Se3i—Sm2—Se185.54 (3)
Se4i—Cs1—Se6i85.24 (2)Se4xiv—Sm3—Se4xv95.63 (4)
Se4ii—Cs1—Se6i125.93 (3)Se4xiv—Sm3—Se385.26 (3)
Se6ii—Cs1—Se6i69.55 (3)Se4xv—Sm3—Se385.26 (3)
Se4i—Cs1—Se3iii64.04 (3)Se4xiv—Sm3—Se686.87 (3)
Se4ii—Cs1—Se3iii64.04 (3)Se4xv—Sm3—Se686.87 (3)
Se6ii—Cs1—Se3iii143.874 (16)Se3—Sm3—Se6168.27 (4)
Se6i—Cs1—Se3iii143.874 (16)Se4xiv—Sm3—Se1xvi171.05 (4)
Se4i—Cs1—Se5i90.60 (2)Se4xv—Sm3—Se1xvi87.03 (2)
Se4ii—Cs1—Se5i131.59 (3)Se3—Sm3—Se1xvi86.44 (3)
Se6ii—Cs1—Se5i137.25 (3)Se6—Sm3—Se1xvi101.84 (3)
Se6i—Cs1—Se5i95.72 (2)Se4xiv—Sm3—Se1xvii87.03 (2)
Se3iii—Cs1—Se5i67.69 (3)Se4xv—Sm3—Se1xvii171.05 (4)
Se4i—Cs1—Se5ii131.59 (3)Se3—Sm3—Se1xvii86.44 (3)
Se4ii—Cs1—Se5ii90.60 (2)Se6—Sm3—Se1xvii101.84 (3)
Se6ii—Cs1—Se5ii95.72 (2)Se1xvi—Sm3—Se1xvii89.10 (3)
Se6i—Cs1—Se5ii137.25 (3)Se4—Sm4—Se2172.93 (4)
Se3iii—Cs1—Se5ii67.69 (3)Se4—Sm4—Se6xviii87.59 (3)
Se5i—Cs1—Se5ii67.63 (2)Se2—Sm4—Se6xviii97.20 (3)
Se2ii—Cs2—Se2vii95.31 (3)Se4—Sm4—Se6xix87.59 (3)
Se2i—Cs2—Se2vii141.35 (6)Se2—Sm4—Se6xix97.20 (3)
Se2ii—Cs2—Se2viii141.35 (6)Se6xviii—Sm4—Se6xix94.28 (4)
Se2i—Cs2—Se2viii95.31 (3)Se4—Sm4—Se1xvii87.63 (3)
Se2vii—Cs2—Se2viii70.00 (4)Se2—Sm4—Se1xvii87.29 (3)
Se2ii—Cs2—Se5iii138.46 (3)Se6xviii—Sm4—Se1xvii174.23 (4)
Se2i—Cs2—Se5iii138.46 (3)Se6xix—Sm4—Se1xvii88.74 (2)
Se2vii—Cs2—Se5iii72.81 (4)Se4—Sm4—Se1xvi87.63 (3)
Se2viii—Cs2—Se5iii72.81 (4)Se2—Sm4—Se1xvi87.29 (3)
Se2ii—Cs2—Se6iii70.80 (4)Se6xviii—Sm4—Se1xvi88.74 (2)
Se2i—Cs2—Se6iii70.80 (4)Se6xix—Sm4—Se1xvi174.23 (4)
Se2vii—Cs2—Se6iii141.36 (3)Se1xvii—Sm4—Se1xvi87.85 (3)
Se2viii—Cs2—Se6iii141.36 (3)Sm3ii—Se1—Sm3i89.10 (3)
Se5iii—Cs2—Se6iii93.63 (5)Sm3ii—Se1—Sm4i178.80 (4)
Se3i—Sm1—Se3ix180.000 (14)Sm3i—Se1—Sm4i91.519 (12)
Se3i—Sm1—Se5x92.43 (3)Sm3ii—Se1—Sm4ii91.519 (12)
Se3ix—Sm1—Se5x87.57 (3)Sm3i—Se1—Sm4ii178.80 (4)
Se3i—Sm1—Se5xi87.57 (3)Sm4i—Se1—Sm4ii87.85 (3)
Se3ix—Sm1—Se5xi92.43 (3)Sm3ii—Se1—Sm291.46 (3)
Se5x—Sm1—Se5xi180.00 (4)Sm3i—Se1—Sm291.46 (3)
Se3i—Sm1—Se5xii92.43 (3)Sm4i—Se1—Sm289.55 (3)
Se3ix—Sm1—Se5xii87.57 (3)Sm4ii—Se1—Sm289.55 (3)
Se5x—Sm1—Se5xii92.44 (3)Sm4—Se2—Sm2xvii96.22 (3)
Se5xi—Sm1—Se5xii87.56 (3)Sm4—Se2—Sm2xvi96.22 (3)
Se3i—Sm1—Se5xiii87.57 (3)Sm2xvii—Se2—Sm2xvi93.72 (4)
Se3ix—Sm1—Se5xiii92.43 (3)Sm1viii—Se3—Sm3167.99 (5)
Se5x—Sm1—Se5xiii87.56 (3)Sm1viii—Se3—Sm2xvi91.79 (3)
Se5xi—Sm1—Se5xiii92.44 (3)Sm3—Se3—Sm2xvi96.47 (3)
Se5xii—Sm1—Se5xiii180.0Sm1viii—Se3—Sm2xvii91.79 (3)
Se5xiii—Sm2—Se2i99.19 (3)Sm3—Se3—Sm2xvii96.47 (3)
Se5xiii—Sm2—Se2ii99.19 (3)Sm2xvi—Se3—Sm2xvii92.90 (4)
Se2i—Sm2—Se2ii93.72 (4)Sm3xviii—Se4—Sm3xix95.63 (4)
Se5xiii—Sm2—Se3ii88.41 (3)Sm3xviii—Se4—Sm493.81 (3)
Se2i—Sm2—Se3ii172.31 (4)Sm3xix—Se4—Sm493.81 (3)
Se2ii—Sm2—Se3ii86.18 (2)Sm2xx—Se5—Sm1xxi92.23 (3)
Se5xiii—Sm2—Se3i88.41 (3)Sm2xx—Se5—Sm1xx92.23 (3)
Se2i—Sm2—Se3i86.18 (2)Sm1xxi—Se5—Sm1xx92.44 (3)
Se2ii—Sm2—Se3i172.31 (4)Sm4xiv—Se6—Sm4xv94.28 (4)
Se3ii—Sm2—Se3i92.90 (4)Sm4xiv—Se6—Sm391.72 (3)
Se5xiii—Sm2—Se1171.21 (4)Sm4xv—Se6—Sm391.72 (3)
Se2i—Sm2—Se186.77 (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.
Table 1
Selected geometric parameters (Å)
top
Cs1—Se4i3.6071 (12)Cs2—Cs2iv2.394 (4)
Cs1—Se4ii3.6071 (12)Cs2—Se2ii3.5286 (16)
Cs1—Se6ii3.7129 (12)Cs2—Se2i3.5286 (16)
Cs1—Se6i3.7129 (12)Cs2—Se2v3.6917 (17)
Cs1—Se3iii3.7639 (14)Cs2—Se2vi3.6917 (17)
Cs1—Se5i3.8053 (12)Cs2—Se5iii3.719 (2)
Cs1—Se5ii3.8053 (12)Cs2—Se6iii3.924 (2)
Cs1—Se14.5421 (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 top

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.

references
References top

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