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Ytterbium selenide, Yb2Se3, was prepared by reacting the elements at 1173 K in an evacuated silica tube in an Sn flux. The ytterbium sesquiselenide crystallizes in the orthorhombic space group Fddd, adopting the Sc2S3 structure type. Its structure consists of edge-sharing (slightly distorted) YbSe6 octahedra, and may be regarded as a defect NaCl structure.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S1600536803013242/br6104sup1.cif
Contains datablocks I, global

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S1600536803013242/br6104Isup2.hkl
Contains datablock I

Key indicators

  • Single-crystal X-ray study
  • T = 298 K
  • Mean [sigma](Yb-Se) = 0.001 Å
  • R factor = 0.033
  • wR factor = 0.074
  • Data-to-parameter ratio = 45.3

checkCIF results

No syntax errors found

ADDSYM reports no extra symmetry








Comment top

The sesquichalcogenides of the rare earth elements adopt different structure types. While the La–Gd chalcogenides crystallize in defect variants of the Th3P4 type (Mauricot et al., 1995), Yb2S3 adopts the α-Al2O3 structure (El Fadli et al., 1994). Based on powder diffractograms, the Sc, Y and Dy–Yb selenides (Dismukes & White, 1965; Flahaut et al., 1965) were reported to form the Sc2S3 structure (Tremblet et al., 1963). The cell dimensions for Yb2Se3 (orthorhombic system) were determined by Dismukes & White (1965) to be a = 11.274 Å, b = 8.021 Å, c = 23.98 Å and V = 2168.5 Å, and by Flahaut et al. (1965) to be a = 11.27 Å, b = 8.02 Å, c = 23.96 Å and V = 2165.6 Å. The atomic positions of Yb2Se3 were not refined in either case; Flahaut et al. (1965) merely extrapolated them from the ideal NaCl structure type. Our single-crystal structure study on Yb2Se3 confirms the suggested Sc2S3 type, and delivers crystallographic details with high accuracy. It is evident that the shifts from the NaCl structure are significant; e.g. the x parameters of Se1 and Se2 are not 3/8 = 0.375, but 0.37062 (10) for Se1 and 0.38115 (7) for Se2. This is reflected in deviations from the ideal Se—Yb—Se bond angles of up to 4.5° and Yb—Se bond lengths varying from 2.7943 (6) to 2.8184 (6) Å (Yb1) and from 2.7967 (6) to 2.8188 (3) Å (Yb2).

Experimental top

Yb2Se3 was obtained from a reaction of elemental ytterbium and selenium in a tin flux. The mixture was annealed at 1173 K over a period of 4 d, and then slowly cooled (3 K h−1) to room temperature. Yb2Se3 crystallized in the form of black block-shaped crystals.

Computing details top

Data collection: SMART (Bruker, 2000); cell refinement: SAINT (Bruker, 1999); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997).

Figures top
[Figure 1] Fig. 1. A projection of Yb2Se3 along the a axis. Displacement ellipsoids are drawn at the 99.9% probability level. Colour code: blue Yb and yellow Se.
Ytterbium selenide top
Crystal data top
Yb2Se3F(000) = 3872
Mr = 582.96Dx = 7.152 Mg m3
Orthorhombic, FdddMo Kα radiation, λ = 0.71073 Å
Hall symbol: -F 2uv 2vwCell parameters from 5337 reflections
a = 8.0183 (7) Åθ = 3.2–35.0°
b = 11.272 (1) ŵ = 54.32 mm1
c = 23.961 (2) ÅT = 298 K
V = 2165.7 (3) Å3Block, black
Z = 160.01 × 0.01 × 0.01 mm
Data collection top
Bruker SMART APEX CCD
diffractometer
1179 independent reflections
Radiation source: fine-focus sealed tube937 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.049
ϕ and ω scansθmax = 35.0°, θmin = 3.2°
Absorption correction: ψ scan
(SAINT; Bruker, 1999)
h = 1212
Tmin = 0.487, Tmax = 0.581k = 1717
5337 measured reflectionsl = 3238
Refinement top
Refinement on F2Primary atom site location: isomorphous structure methods
Least-squares matrix: full w = 1/[σ2(Fo2) + (0.0244P)2]
where P = (Fo2 + 2Fc2)/3
R[F2 > 2σ(F2)] = 0.033(Δ/σ)max = 0.001
wR(F2) = 0.074Δρmax = 1.70 e Å3
S = 1.12Δρmin = 3.52 e Å3
1179 reflectionsExtinction correction: SHELXL97, Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
26 parametersExtinction coefficient: 0.000397 (11)
0 restraints
Crystal data top
Yb2Se3V = 2165.7 (3) Å3
Mr = 582.96Z = 16
Orthorhombic, FdddMo Kα radiation
a = 8.0183 (7) ŵ = 54.32 mm1
b = 11.272 (1) ÅT = 298 K
c = 23.961 (2) Å0.01 × 0.01 × 0.01 mm
Data collection top
Bruker SMART APEX CCD
diffractometer
1179 independent reflections
Absorption correction: ψ scan
(SAINT; Bruker, 1999)
937 reflections with I > 2σ(I)
Tmin = 0.487, Tmax = 0.581Rint = 0.049
5337 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.03326 parameters
wR(F2) = 0.0740 restraints
S = 1.12Δρmax = 1.70 e Å3
1179 reflectionsΔρmin = 3.52 e Å3
Special details top

Experimental. The absorption correction was performed using the SAINT package (Bruker, 1999b); the routine is called SADABS.

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 (Å2) top
xyzUiso*/Ueq
Yb10.12500.12500.041383 (14)0.00754 (10)
Yb20.12500.12500.377464 (14)0.00745 (10)
Se10.37062 (10)0.12500.12500.00751 (16)
Se20.38115 (7)0.12282 (5)0.45668 (2)0.00758 (13)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Yb10.00865 (17)0.00734 (17)0.00664 (17)0.00092 (14)0.0000.000
Yb20.00657 (16)0.00766 (17)0.00813 (17)0.00168 (11)0.0000.000
Se10.0078 (4)0.0058 (3)0.0090 (4)0.0000.0000.0001 (3)
Se20.0068 (3)0.0085 (3)0.0074 (3)0.0029 (3)0.00142 (17)0.00012 (19)
Geometric parameters (Å, º) top
Yb1—Se2i2.7943 (6)Yb2—Se2vii2.8086 (7)
Yb1—Se2ii2.7943 (6)Yb2—Se1i2.8188 (3)
Yb1—Se12.8095 (6)Yb2—Se1ii2.8188 (2)
Yb1—Se1iii2.8095 (6)Se1—Yb1viii2.8095 (6)
Yb1—Se2iv2.8184 (6)Se1—Yb2i2.8188 (3)
Yb1—Se2v2.8184 (6)Se1—Yb2ix2.8188 (2)
Yb2—Se22.7967 (6)Se2—Yb1i2.7943 (6)
Yb2—Se2iii2.7967 (6)Se2—Yb2vii2.8086 (6)
Yb2—Se2vi2.8086 (7)Se2—Yb1x2.8184 (6)
Se2i—Yb1—Se2ii178.09 (3)Se2—Yb2—Se2iii94.52 (3)
Se2i—Yb1—Se190.028 (12)Se2—Yb2—Se2vi176.864 (19)
Se2ii—Yb1—Se188.610 (13)Se2iii—Yb2—Se2vi88.614 (17)
Se2i—Yb1—Se1iii88.610 (13)Se2—Yb2—Se2vii88.614 (17)
Se2ii—Yb1—Se1iii90.028 (12)Se2iii—Yb2—Se2vii176.864 (19)
Se1—Yb1—Se1iii89.02 (3)Se2vi—Yb2—Se2vii88.25 (2)
Se2i—Yb1—Se2iv89.486 (17)Se2—Yb2—Se1i89.788 (17)
Se2ii—Yb1—Se2iv91.888 (18)Se2iii—Yb2—Se1i91.841 (17)
Se1—Yb1—Se2iv179.236 (16)Se2vi—Yb2—Se1i90.136 (17)
Se1iii—Yb1—Se2iv91.562 (18)Se2vii—Yb2—Se1i88.141 (17)
Se2i—Yb1—Se2v91.888 (18)Se2—Yb2—Se1ii91.841 (17)
Se2ii—Yb1—Se2v89.486 (17)Se2iii—Yb2—Se1ii89.788 (17)
Se1—Yb1—Se2v91.562 (18)Se2vi—Yb2—Se1ii88.141 (17)
Se1iii—Yb1—Se2v179.236 (16)Se2vii—Yb2—Se1ii90.136 (17)
Se2iv—Yb1—Se2v87.86 (3)Se1i—Yb2—Se1ii177.600 (14)
Symmetry codes: (i) x+1/2, y, z+1/2; (ii) x1/4, y+1/4, z+1/2; (iii) x+1/4, y+1/4, z; (iv) x1/2, y, z1/2; (v) x+3/4, y+1/4, z1/2; (vi) x1/2, y+1/4, z+3/4; (vii) x+3/4, y, z+3/4; (viii) x+1/4, y, z+1/4; (ix) x+1/4, y+1/2, z1/4; (x) x+1/2, y, z+1/2.

Experimental details

Crystal data
Chemical formulaYb2Se3
Mr582.96
Crystal system, space groupOrthorhombic, Fddd
Temperature (K)298
a, b, c (Å)8.0183 (7), 11.272 (1), 23.961 (2)
V3)2165.7 (3)
Z16
Radiation typeMo Kα
µ (mm1)54.32
Crystal size (mm)0.01 × 0.01 × 0.01
Data collection
DiffractometerBruker SMART APEX CCD
diffractometer
Absorption correctionψ scan
(SAINT; Bruker, 1999)
Tmin, Tmax0.487, 0.581
No. of measured, independent and
observed [I > 2σ(I)] reflections
5337, 1179, 937
Rint0.049
(sin θ/λ)max1)0.807
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.033, 0.074, 1.12
No. of reflections1179
No. of parameters26
Δρmax, Δρmin (e Å3)1.70, 3.52

Computer programs: SMART (Bruker, 2000), SAINT (Bruker, 1999), SAINT, SHELXS97 (Sheldrick, 1997), SHELXL97 (Sheldrick, 1997).

Selected bond lengths (Å) top
Yb1—Se2i2.7943 (6)Yb2—Se22.7967 (6)
Yb1—Se2ii2.7943 (6)Yb2—Se2iii2.7967 (6)
Yb1—Se12.8095 (6)Yb2—Se2vi2.8086 (7)
Yb1—Se1iii2.8095 (6)Yb2—Se2vii2.8086 (7)
Yb1—Se2iv2.8184 (6)Yb2—Se1i2.8188 (3)
Yb1—Se2v2.8184 (6)Yb2—Se1ii2.8188 (2)
Symmetry codes: (i) x+1/2, y, z+1/2; (ii) x1/4, y+1/4, z+1/2; (iii) x+1/4, y+1/4, z; (iv) x1/2, y, z1/2; (v) x+3/4, y+1/4, z1/2; (vi) x1/2, y+1/4, z+3/4; (vii) x+3/4, y, z+3/4.
 

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