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Scandium sesquitelluride, Sc2Te3, was obtained as a side product by reacting the elements Sc, Ni and Te at 1073 K in an evacuated silica tube. This is the third modification of Sc2Te3, which crystallizes in the ortho­rhom­bic space group Fddd and adopts the Sc2S3 structure type [Dismukes & White (1964). Inorg. Chem. 3, 1220-1228]. The structure consists of edge-sharing (slightly distorted) ScTe6 octa­hedra and may be regarded as a defect variant of the NaCl type.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S1600536805041747/wm6121sup1.cif
Contains datablocks I, global

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S1600536805041747/wm6121Isup2.hkl
Contains datablock I

Key indicators

  • Single-crystal X-ray study
  • T = 298 K
  • Mean [sigma](e-Sc) = 0.000 Å
  • R factor = 0.031
  • wR factor = 0.089
  • Data-to-parameter ratio = 33.0

checkCIF/PLATON results

No syntax errors found



Alert level C PLAT062_ALERT_4_C Rescale T(min) & T(max) by ..................... 0.97
0 ALERT level A = In general: serious problem 0 ALERT level B = Potentially serious problem 1 ALERT level C = Check and explain 0 ALERT level G = General alerts; check 0 ALERT type 1 CIF construction/syntax error, inconsistent or missing data 0 ALERT type 2 Indicator that the structure model may be wrong or deficient 0 ALERT type 3 Indicator that the structure quality may be low 1 ALERT type 4 Improvement, methodology, query or suggestion

Comment top

Recently, we reported the crystal structure of Yb2Se3, which crystallizes in the Sc2S3 structure type (Assoud & Kleinke, 2003). The chalcogenides Ln2Q3 (Ln = lanthanide, Q = chalcogen) adopt different structure types depending on the radius of the lanthanide. The large lanthanide chalcogenides prefer the defect variant of the Th3P4 type (Mauricot et al., 1995), whereas the smaller ones crystallize in the α-Al2O3 (El Fadli et al., 1994) and Sc2S3 types (Dismukes & White, 1965; Flahaut et al., 1965).

In the system Sc–Te, several binaries ave been synthesized and their crystal structures characterized, viz. ScTe, Sc2/3Te (Men'kov et al., 1961), Sc2Te3, Sc2.3Te3 (White & Dismukes, 1965), Sc2Te (Maggard & Corbett, 1997), Sc9Te2 (Maggard & Corbett, 2000) and Sc8Te3 (Maggard & Corbett, 1998). The first modification of Sc2Te3 was reported, on the basis of X-ray powder diffraction data (Men'kov et al., 1959), to exhibit the γ-Al2O3 structure type. The second, rhombohedral modification was found by reacting the mixture of elements at the same reaction temperature (1325 K) but using chemical transport reactions. This modification was described as comprising alternating regions of NaCl and NiAs structure types (White & Dismukes, 1965).

Our single-crystal structure study on Sc2Te3 shows a third modification, which adopts the Sc2S3 type (Dismukes & White, 1964). This seems to be the low-temperature form, as we have routinely observed it at reaction temperatures below 1100 K, regardless of whether nickel was present in the reaction mixture or not. This structure is a distorted deficient variant of the NaCl type, forming a 12-fold supercell (a = 21/2a, b = 2b, c = 3 × 21/2c). A detailed description of the Sc2S3 type and its relation to NaCl was given by Dismukes & White (1964). The distortion can be seen in, for example, the shifts of the Te atoms from the ideal position with x = 0.375 to x = 0.37907 (2) (Te1) and x = 0.375092 (12) (Te2). The Sc—Te bond lengths scatter slightly around 2.91 Å (Table 1), and the Te—Sc—Te angles deviate up to 2° from the ideal octahedral angles.

Experimental top

Sc2Te3 was obtained from a reaction of elemental scandium, nickel and tellurium in the ratio 1:4:7. The mixture was heated at 1073 K over a period of 3 d, annealed at 923 K for 5 d, and then cooled slowly (5 K h−1) to room temperature. The X-ray diagram obtained from the ground sample (utilizing the INEL powder diffractometer with position-sensitive detector) revealed the presence of Sc2Te3, NiTe and NiTe2. Sc2Te3 crystallized in the form of black block-shaped crystals.

Refinement top

The highest peak is located 0.06 Å from Sc1 and the deepest hole 0.66 Å from Te1.

Computing details top

Data collection: SMART (Bruker, 2000); cell refinement: SAINT (Bruker, 1999); data reduction: SAINT; program(s) used to solve structure: coordinates taken from the isotypic Sc2S3 compound (Dismukes & White, 1964); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: DIAMOND (Bergerhoff, 1999); software used to prepare material for publication: SHELXL97.

Figures top
[Figure 1] Fig. 1. The crystal structure of Sc2Te3, with anisotropic displacement ellipsoids drawn at the 90% probability level.
Discandium tritelluride top
Crystal data top
Sc2Te3F(000) = 3168
Mr = 472.72Dx = 5.338 Mg m3
Orthorhombic, FdddMo Kα radiation, λ = 0.71073 Å
Hall symbol: -F 2uv 2vwCell parameters from 4570 reflections
a = 8.2223 (6) Åθ = 3.2–30.0°
b = 11.6292 (9) ŵ = 16.73 mm1
c = 24.6085 (18) ÅT = 298 K
V = 2353.0 (3) Å3Block, black
Z = 160.02 × 0.02 × 0.01 mm
Data collection top
Bruker SMART APEX CCD
diffractometer
858 independent reflections
Radiation source: fine-focus sealed tube672 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.030
ϕ and ω scansθmax = 30.0°, θmin = 3.2°
Absorption correction: multi-scan
(SADABS; Sheldrick, 1996)
h = 1111
Tmin = 0.70, Tmax = 0.90k = 1616
4570 measured reflectionsl = 3433
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)] = 0.031(Δ/σ)max = 0.001
wR(F2) = 0.089Δρmax = 1.27 e Å3
S = 1.41Δρmin = 2.84 e Å3
858 reflectionsExtinction correction: SHELXL97, Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
26 parametersExtinction coefficient: 0.00165 (5)
0 restraints
Crystal data top
Sc2Te3V = 2353.0 (3) Å3
Mr = 472.72Z = 16
Orthorhombic, FdddMo Kα radiation
a = 8.2223 (6) ŵ = 16.73 mm1
b = 11.6292 (9) ÅT = 298 K
c = 24.6085 (18) Å0.02 × 0.02 × 0.01 mm
Data collection top
Bruker SMART APEX CCD
diffractometer
858 independent reflections
Absorption correction: multi-scan
(SADABS; Sheldrick, 1996)
672 reflections with I > 2σ(I)
Tmin = 0.70, Tmax = 0.90Rint = 0.030
4570 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.03126 parameters
wR(F2) = 0.0890 restraints
S = 1.41Δρmax = 1.27 e Å3
858 reflectionsΔρmin = 2.84 e Å3
Special details top

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
Sc10.12500.12500.042989 (19)0.0096 (2)
Sc20.12500.12500.37467 (2)0.0094 (2)
Te10.37907 (2)0.12500.12500.00811 (19)
Te20.375092 (12)0.125142 (10)0.458253 (4)0.00822 (19)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Sc10.0099 (4)0.0095 (3)0.0095 (3)0.0004 (2)0.0000.000
Sc20.0093 (3)0.0085 (3)0.0103 (3)0.00058 (16)0.0000.000
Te10.0087 (3)0.0062 (3)0.0094 (3)0.0000.0000.00004 (5)
Te20.0077 (3)0.0096 (3)0.0073 (3)0.00037 (11)0.00146 (4)0.00027 (4)
Geometric parameters (Å, º) top
Sc1—Te12.9047 (4)Sc2—Te1ii2.9075 (2)
Sc1—Te1i2.9047 (4)Sc2—Te22.9084 (4)
Sc1—Te2ii2.9091 (3)Sc2—Te2i2.9084 (4)
Sc1—Te2iii2.9091 (2)Te1—Sc1viii2.9047 (4)
Sc1—Te2iv2.9275 (4)Te1—Sc2ix2.9075 (2)
Sc1—Te2v2.9275 (4)Te1—Sc2iii2.9075 (2)
Sc2—Te2vi2.8960 (4)Te2—Sc2vii2.8960 (4)
Sc2—Te2vii2.8960 (4)Te2—Sc1iii2.9091 (2)
Sc2—Te1iii2.9075 (2)Te2—Sc1x2.9275 (4)
Te1—Sc1—Te1i91.978 (15)Te2vi—Sc2—Te2179.797 (14)
Te1—Sc1—Te2ii90.408 (7)Te2vii—Sc2—Te289.808 (6)
Te1i—Sc1—Te2ii90.429 (7)Te1iii—Sc2—Te290.388 (8)
Te1—Sc1—Te2iii90.429 (7)Te1ii—Sc2—Te289.389 (8)
Te1i—Sc1—Te2iii90.408 (7)Te2vi—Sc2—Te2i89.809 (7)
Te2ii—Sc1—Te2iii178.796 (19)Te2vii—Sc2—Te2i179.797 (14)
Te1—Sc1—Te2iv178.590 (13)Te1iii—Sc2—Te2i89.389 (8)
Te1i—Sc1—Te2iv89.432 (7)Te1ii—Sc2—Te2i90.387 (8)
Te2ii—Sc1—Te2iv89.549 (7)Te2—Sc2—Te2i89.988 (15)
Te2iii—Sc1—Te2iv89.593 (7)Sc1—Te1—Sc1viii88.022 (15)
Te1—Sc1—Te2v89.432 (7)Sc1—Te1—Sc2ix89.415 (7)
Te1i—Sc1—Te2v178.590 (13)Sc1viii—Te1—Sc2ix89.635 (7)
Te2ii—Sc1—Te2v89.593 (7)Sc1—Te1—Sc2iii89.635 (7)
Te2iii—Sc1—Te2v89.549 (7)Sc1viii—Te1—Sc2iii89.415 (7)
Te2iv—Sc1—Te2v89.158 (14)Sc2ix—Te1—Sc2iii178.680 (8)
Te2vi—Sc2—Te2vii90.395 (15)Sc2vii—Te2—Sc290.191 (6)
Te2vi—Sc2—Te1iii89.610 (7)Sc2vii—Te2—Sc1iii89.554 (7)
Te2vii—Sc2—Te1iii90.612 (8)Sc2—Te2—Sc1iii89.531 (7)
Te2vi—Sc2—Te1ii90.612 (8)Sc2vii—Te2—Sc1x90.224 (11)
Te2vii—Sc2—Te1ii89.610 (7)Sc2—Te2—Sc1x179.580 (10)
Te1iii—Sc2—Te1ii179.684 (19)Sc1iii—Te2—Sc1x90.407 (7)
Symmetry codes: (i) x+1/4, y+1/4, z; (ii) x1/4, y+1/4, z+1/2; (iii) x+1/2, y, z+1/2; (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 formulaSc2Te3
Mr472.72
Crystal system, space groupOrthorhombic, Fddd
Temperature (K)298
a, b, c (Å)8.2223 (6), 11.6292 (9), 24.6085 (18)
V3)2353.0 (3)
Z16
Radiation typeMo Kα
µ (mm1)16.73
Crystal size (mm)0.02 × 0.02 × 0.01
Data collection
DiffractometerBruker SMART APEX CCD
diffractometer
Absorption correctionMulti-scan
(SADABS; Sheldrick, 1996)
Tmin, Tmax0.70, 0.90
No. of measured, independent and
observed [I > 2σ(I)] reflections
4570, 858, 672
Rint0.030
(sin θ/λ)max1)0.703
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.031, 0.089, 1.41
No. of reflections858
No. of parameters26
Δρmax, Δρmin (e Å3)1.27, 2.84

Computer programs: SMART (Bruker, 2000), SAINT (Bruker, 1999), SAINT, coordinates taken from the isotypic Sc2S3 compound (Dismukes & White, 1964), SHELXL97 (Sheldrick, 1997), DIAMOND (Bergerhoff, 1999), SHELXL97.

Selected bond lengths (Å) top
Sc1—Te12.9047 (4)Sc2—Te2iii2.8960 (4)
Sc1—Te2i2.9091 (2)Sc2—Te1i2.9075 (2)
Sc1—Te2ii2.9275 (4)Sc2—Te22.9084 (4)
Symmetry codes: (i) x+1/2, y, z+1/2; (ii) x+3/4, y+1/4, z1/2; (iii) x+3/4, y, z+3/4.
 

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