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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

2

Te

3

Abdeljalil 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

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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

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supporting information

sup-1

Acta Cryst. (2006). E62, i17–i18

supporting information

Acta Cryst. (2006). E62, i17–i18 [doi:10.1107/S1600536805041747]

The sesquitelluride Sc

2

Te

3

Abdeljalil 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

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[image:4.610.130.486.72.259.2]

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 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

(5)

supporting information

sup-3

Acta Cryst. (2006). E62, i17–i18

Special 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)

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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)

Figure

Figure 1
Figure 1

References

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