inorganic papers
Acta Cryst.(2006). E62, i17–i18 doi:10.1107/S1600536805041747 Assoud and Kleinke Sc
2Te3
i17
Acta Crystallographica Section E Structure Reports Online
ISSN 1600-5368
The sesquitelluride Sc
2Te
3Abdeljalil Assoud and Holger Kleinke*
Department of Chemistry, University of Waterloo, Waterloo, Ontario, Canada N2L 3G1
Correspondence e-mail: kleinke@uwaterloo.ca
Key indicators
Single-crystal X-ray study T= 298 K
Mean(Te–Sc) = 0.000 A˚ Rfactor = 0.031 wRfactor = 0.089
Data-to-parameter ratio = 33.0
For details of how these key indicators were automatically derived from the article, see http://journals.iucr.org/e.
#2006 International Union of Crystallography Printed in Great Britain – all rights reserved
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 groupFdddand 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.
Comment
Recently, we reported the crystal structure of Yb2Se3, which crystallizes in the Sc2S3 structure type (Assoud & Kleinke, 2003). The chalcogenides Ln2Q3(Ln = lanthanide,Q= chal-cogen) adopt different structure types depending on the radius of the lanthanide. The large lanthanide chalcogenides prefer the defect variant of the Th3P4type (Mauricot et al., 1995), whereas the smaller ones crystallize in the-Al2O3(El Fadliet
al., 1994) and Sc2S3types (Dismukes & White, 1965; Flahautet
al., 1965).
In the system Sc–Te, several binaries have 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 Sc2Te3was reported, on the basis of X-ray powder diffraction data (Men’kov et al., 1959), to exhibit the -Al2O3structure type. The second, rhombohedral modifica-tion 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 Sc2Te3shows a third modification, which adopts the Sc2S3type (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 withx= 0.375 tox= 0.37907 (2) (Te1) and x= 0.375092 (12) (Te2). The Sc—Te bond lengths vary slightly around 2.91 A˚ (Table 1), and the Te—Sc—Te angles deviate up to 2from the ideal octahedral angles.
Experimental
Sc2Te3was 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 h1) to room temperature. The X-ray powder diagram obtained from the ground sample (utilizing the INEL powder diffractometer with position-sensitive detector) revealed the presence of Sc2Te3, NiTe and NiTe2. Sc2Te3crystallized in the form of black block-shaped crystals.
Crystal data
Sc2Te3 Mr= 472.72
Orthorhombic,Fddd a= 8.2223 (6) A˚
b= 11.6292 (9) A˚
c= 24.6085 (18) A˚
V= 2353.0 (3) A˚3
Z= 16
Dx= 5.338 Mg m 3
MoKradiation Cell parameters from 4570
reflections = 3.2–30.0
= 16.73 mm1 T= 298 (2) K Block, black
0.020.020.01 mm
Data collection
Bruker SMART APEX CCD diffractometer
’and!scans
Absorption correction: multi-scan (SADABS; Sheldrick, 1996)
Tmin= 0.70,Tmax= 0.90 4570 measured reflections
858 independent reflections 672 reflections withI> 2(I)
Rint= 0.030
max= 30.0 h=11!11
k=16!16
l=34!33
Refinement
Refinement onF2 R[F2> 2(F2)] = 0.031 wR(F2) = 0.089
S= 1.41 858 reflections 26 parameters
w= 1/[2
(Fo 2
) + (0.0244P)2] whereP= (Fo2+ 2Fc2)/3
(/)max= 0.001
max= 1.27 e A˚ 3
min=2.84 e A˚ 3
Extinction correction:SHELXL97
Extinction coefficient: 0.00165 (5)
Table 1
Selected bond distances (A˚ ).
Sc1—Te1 2.9047 (4)
Sc1—Te2i
2.9091 (2) Sc1—Te2ii
2.9275 (4)
Sc2—Te2iii 2.8960 (4)
Sc2—Te1i
2.9075 (2)
Sc2—Te2 2.9084 (4)
Symmetry codes: (i) xþ1 2;y;zþ
1
2; (ii) xþ 3 4;yþ
1 4;z
1 2; (iii)
xþ3 4;y;zþ
3 4.
The highest peak is located 0.06 A˚ from Sc1 and the deepest hole 0.66 A˚ from Te1.
Data collection:SMART(Bruker, 2000); cell refinement:SAINT
(Bruker, 1999); data reduction:SAINT; method used to solve struc-ture: coordinates taken from the isotypic Sc2S3compound (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.
Financial support from the Natural Sciences and Engi-neering Research Council of Canada is gratefully acknowl-edged.
References
Assoud, A. & Kleinke, H. (2003).Acta Cryst.E59, i103–i104. Bergerhoff, G. (1999).DIAMOND. Version 2.1a. Bonn, Germany.
Bruker (1999).SAINT. Version 7.02. Bruker AXS, Madison, Wisconsin, USA. Bruker (2000).SMART. Version 5. Bruker AXS, Madison, Wisconsin, USA. Dismukes, J. P. & White, J. G. (1964).Inorg. Chem.3, 1220–1228.
Dismukes, J. P. & White, J. G. (1965).Inorg. Chem.4, 970–973.
El Fadli, Z., Lemoine, P., Guittard, M. & Tomas, A. (1994).Acta Cryst.C50, 166–168.
Flahaut, J., Laruelle, P., Pardo, M. P. & Guittard, M. (1965).Bull. Soc. Chim. Fr.
pp. 1399–1404.
Maggard, P. A. & Corbett, J. D. (1997).Angew. Chem. Int. Ed. Engl.36, 1974– 1976.
Maggard, P. A. & Corbett, J. D. (1998).Inorg. Chem.37, 814–820. Maggard, P. A. & Corbett, J. D. (2000).J. Am. Chem. Soc.122, 838–843. Mauricot, R., Gressier, P., Evain, M. & Brec, R. (1995).J. Alloys Compd,223,
130–138.
Men’kov, A. A., Komissarova, L. N., Simanov, Yu. P. & Spicyn, V. I. (1959).
Dokl. Akad. Nauk SSSR,128, 92–94. (In Russian.)
Men’kov, A. A., Komissarova, L. N., Simanov, Yu. P. & Spicyn, V. I. (1961).
Dokl. Akad. Nauk SSSR,141, 364–367. (In Russian.)
[image:2.610.314.569.69.206.2]Sheldrick, G. M. (1996).SADABS. University of Go¨ttingen, Germany. Sheldrick, G. M. (1997).SHELXL97. University of Go¨ttingen, Germany. White, J. G. & Dismukes, J. P. (1965).Inorg. Chem.4, 1760–1763.
Figure 1
The crystal structure of Sc2Te3, with anisotropic displacement ellipsoids
supporting information
sup-1
Acta Cryst. (2006). E62, i17–i18supporting information
Acta Cryst. (2006). E62, i17–i18 [doi:10.1107/S1600536805041747]
The sesquitelluride Sc
2Te
3Abdeljalil Assoud and Holger Kleinke
S1. Comment
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.
S2. Experimental
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.
S3. Refinement
Figure 1
The crystal structure of Sc2Te3, with anisotropic displacement ellipsoids drawn at the 90% probability level.
Discandium tritelluride
Crystal data
Sc2Te3
Mr = 472.72
Orthorhombic, Fddd
Hall symbol: -F 2uv 2vw
a = 8.2223 (6) Å
b = 11.6292 (9) Å
c = 24.6085 (18) Å
V = 2353.0 (3) Å3
Z = 16
F(000) = 3168
Dx = 5.338 Mg m−3
Mo Kα radiation, λ = 0.71073 Å Cell parameters from 4570 reflections
θ = 3.2–30.0°
µ = 16.73 mm−1
T = 298 K Block, black
0.02 × 0.02 × 0.01 mm
Data collection
Bruker SMART APEX CCD diffractometer
Radiation source: fine-focus sealed tube Graphite monochromator
φ and ω scans
Absorption correction: multi-scan (SADABS; Sheldrick, 1996)
Tmin = 0.70, Tmax = 0.90
4570 measured reflections 858 independent reflections 672 reflections with I > 2σ(I)
Rint = 0.030
θmax = 30.0°, θmin = 3.2°
h = −11→11
k = −16→16
l = −34→33
Refinement
Refinement on F2
Least-squares matrix: full
R[F2 > 2σ(F2)] = 0.031
wR(F2) = 0.089
S = 1.41 858 reflections 26 parameters 0 restraints
Primary atom site location: isomorphous structure methods
w = 1/[σ2(F
o2) + (0.0244P)2]
where P = (Fo2 + 2Fc2)/3
(Δ/σ)max = 0.001
Δρmax = 1.27 e Å−3
Δρmin = −2.84 e Å−3
Extinction correction: SHELXL97, Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
supporting information
sup-3
Acta Cryst. (2006). E62, i17–i18Special details
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)
x y z Uiso*/Ueq
Sc1 0.1250 0.1250 0.042989 (19) 0.0096 (2) Sc2 0.1250 0.1250 0.37467 (2) 0.0094 (2) Te1 0.37907 (2) 0.1250 0.1250 0.00811 (19) Te2 0.375092 (12) 0.125142 (10) 0.458253 (4) 0.00822 (19)
Atomic displacement parameters (Å2)
U11 U22 U33 U12 U13 U23
Sc1 0.0099 (4) 0.0095 (3) 0.0095 (3) −0.0004 (2) 0.000 0.000 Sc2 0.0093 (3) 0.0085 (3) 0.0103 (3) 0.00058 (16) 0.000 0.000 Te1 0.0087 (3) 0.0062 (3) 0.0094 (3) 0.000 0.000 0.00004 (5) Te2 0.0077 (3) 0.0096 (3) 0.0073 (3) −0.00037 (11) −0.00146 (4) −0.00027 (4)
Geometric parameters (Å, º)
Sc1—Te1 2.9047 (4) Sc2—Te1ii 2.9075 (2)
Sc1—Te1i 2.9047 (4) Sc2—Te2 2.9084 (4)
Sc1—Te2ii 2.9091 (3) Sc2—Te2i 2.9084 (4)
Sc1—Te2iii 2.9091 (2) Te1—Sc1viii 2.9047 (4)
Sc1—Te2iv 2.9275 (4) Te1—Sc2ix 2.9075 (2)
Sc1—Te2v 2.9275 (4) Te1—Sc2iii 2.9075 (2)
Sc2—Te2vi 2.8960 (4) Te2—Sc2vii 2.8960 (4)
Sc2—Te2vii 2.8960 (4) Te2—Sc1iii 2.9091 (2)
Sc2—Te1iii 2.9075 (2) Te2—Sc1x 2.9275 (4)
Te1—Sc1—Te1i 91.978 (15) Te2vi—Sc2—Te2 179.797 (14)
Te1—Sc1—Te2ii 90.408 (7) Te2vii—Sc2—Te2 89.808 (6)
Te1i—Sc1—Te2ii 90.429 (7) Te1iii—Sc2—Te2 90.388 (8)
Te1—Sc1—Te2iii 90.429 (7) Te1ii—Sc2—Te2 89.389 (8)
Te1i—Sc1—Te2iii 90.408 (7) Te2vi—Sc2—Te2i 89.809 (7)
Te2ii—Sc1—Te2iii 178.796 (19) Te2vii—Sc2—Te2i 179.797 (14)
Te1—Sc1—Te2iv 178.590 (13) Te1iii—Sc2—Te2i 89.389 (8)
Te1i—Sc1—Te2iv 89.432 (7) Te1ii—Sc2—Te2i 90.387 (8)
Te2ii—Sc1—Te2iv 89.549 (7) Te2—Sc2—Te2i 89.988 (15)
Te2iii—Sc1—Te2iv 89.593 (7) Sc1—Te1—Sc1viii 88.022 (15)
Te1i—Sc1—Te2v 178.590 (13) Sc1viii—Te1—Sc2ix 89.635 (7)
Te2ii—Sc1—Te2v 89.593 (7) Sc1—Te1—Sc2iii 89.635 (7)
Te2iii—Sc1—Te2v 89.549 (7) Sc1viii—Te1—Sc2iii 89.415 (7)
Te2iv—Sc1—Te2v 89.158 (14) Sc2ix—Te1—Sc2iii 178.680 (8)
Te2vi—Sc2—Te2vii 90.395 (15) Sc2vii—Te2—Sc2 90.191 (6)
Te2vi—Sc2—Te1iii 89.610 (7) Sc2vii—Te2—Sc1iii 89.554 (7)
Te2vii—Sc2—Te1iii 90.612 (8) Sc2—Te2—Sc1iii 89.531 (7)
Te2vi—Sc2—Te1ii 90.612 (8) Sc2vii—Te2—Sc1x 90.224 (11)
Te2vii—Sc2—Te1ii 89.610 (7) Sc2—Te2—Sc1x 179.580 (10)
Te1iii—Sc2—Te1ii 179.684 (19) Sc1iii—Te2—Sc1x 90.407 (7)