inorganic compounds\(\def\hfill{\hskip 5em}\def\hfil{\hskip 3em}\def\eqno#1{\hfil {#1}}\)

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Ti insertion in the MTe5 (M = Zr, Hf) structure type: Hf0.78Ti0.22Te5

aDivision of Energy Systems Research and Department of Chemistry, Ajou University, Suwon 443-749, Republic of Korea
*Correspondence e-mail: hsyun@ajou.ac.kr

(Received 23 January 2012; accepted 14 February 2012; online 17 February 2012)

The group 5 mixed-metal telluride, Hf0.78Ti0.22Te5 (hafnium titanium penta­telluride), is isostructural with the binary phases HfTe5 and ZrTe5 and forms a layered structure extending parallel to (010). The layers are made up from chains of bicapped metal-centered trigonal prisms and zigzag Te chains. The metal site (site symmetry m2m) is occupied by statistically disordered Hf [78.1 (5)%] and Ti [21.9 (5)%]. In addition to the regular Te—Te pair [2.7448 (13) Å] forming the short base of the equilateral triangle of the trigonal prism, an inter­mediate Te⋯Te separation [2.9129 (9) Å] is also found. The classical charge balance of the compound can be described as [M4+][Te2−][Te22−][Te20] (M = Hf, Ti). The individual metal content can vary in different crystals, apparently forming a random substitutional solid solution (Hf1-xTix)Te5, with 0.15 ≤ x ≤ 0.22.

Related literature

For the synthesis and structure of HfTe5 and ZrTe5, see: Brattås & Kjekshus (1971[Brattås, L. & Kjekshus, A. (1971). Acta Chem. Scand. 25, 2783-2785.]); Furuseth et al. (1973[Furuseth, S., Brattås, L. & Kjekshus, A. (1973). Acta Chem. Scand. 27, 2367-2374.], 1975[Furuseth, S., Brattås, L. & Kjekshus, A. (1975). Acta Chem. Scand. A29, 623-631.]). For properties of HfTe5 and ZrTe5, see: DiSalvo et al. (1981[DiSalvo, F. J., Fleming, R. M. & Waszczak, J. V. (1981). Phys. Rev. B14, 2935-2939.]). For extensive Te⋯Te inter­actions in metal tellurides, see: Pell & Ibers (1996[Pell, M. A. & Ibers, J. A. (1996). Chem. Mater. 8, 1386-1390.]); Mar & Ibers (1993[Mar, A. & Ibers, J. A. (1993). J. Am. Chem. Soc. 115, 3227-3238.]).

Experimental

Crystal data
  • Hf0.78Ti0.22Te5

  • Mr = 787.76

  • Orthorhombic, C m c m

  • a = 3.9595 (3) Å

  • b = 14.4350 (13) Å

  • c = 13.7062 (9) Å

  • V = 783.39 (10) Å3

  • Z = 4

  • Mo Kα radiation

  • μ = 28.76 mm−1

  • T = 290 K

  • 0.30 × 0.04 × 0.02 mm

Data collection
  • Rigaku R-AXIS RAPID diffractometer

  • Absorption correction: multi-scan (NUMABS; Higashi, 2000[Higashi, T. (2000). NUMABS. Rigaku Corporation, Tokyo, Japan.]) Tmin = 0.263, Tmax = 1.000

  • 3405 measured reflections

  • 533 independent reflections

  • 516 reflections with I > 2σ(I)

  • Rint = 0.059

Refinement
  • R[F2 > 2σ(F2)] = 0.029

  • wR(F2) = 0.068

  • S = 1.16

  • 533 reflections

  • 23 parameters

  • Δρmax = 2.38 e Å−3

  • Δρmin = −2.07 e Å−3

Table 1
Selected geometric parameters (Å, °)

M = Hf or Ti

M—Te2i 2.9251 (6)
M—Te1ii 2.9446 (8)
M—Te3 2.9498 (7)
Te3ii—Te3—Te3iii 85.63 (3)
Symmetry codes: (i) [x+{\script{1\over 2}}, y+{\script{1\over 2}}, z]; (ii) [-x+{\script{3\over 2}}, -y+{\script{1\over 2}}, -z]; (iii) [-x+{\script{5\over 2}}, -y+{\script{1\over 2}}, -z].

Data collection: RAPID-AUTO (Rigaku, 2006[Rigaku (2006). RAPID-AUTO. Rigaku Corporation, Tokyo, Japan.]); cell refinement: RAPID-AUTO; data reduction: RAPID-AUTO; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]); molecular graphics: DIAMOND3 (Brandenburg, 1999[Brandenburg, K. (1999). DIAMOND. Crystal Impact GbR, Bonn, Germany.]); software used to prepare material for publication: WinGX (Farrugia, 1999[Farrugia, L. J. (1999). J. Appl. Cryst. 32, 837-838.]).

Supporting information


Comment top

The existence of the binary pentatellurides, MTe5 (M = Zr, Hf) was established in 1971 by Brattås & Kjekshus. These compounds have been the most chalcogen-rich stoichiometric transition metal binary chalcogenides since then. These phases are important not only because of their unusually high chalcogen contents but because of the anomalies in their transport properties (DiSalvo et al., 1981). The Ti analogue of this phase is desired to study the relationship between structure and properties. However, efforts to find TiTe5 have not been successful despite numerous attempts (Furuseth et al., 1973). Indeed, no Ti analogue of the MTe8 polyhedra found in MTe5 (Furuseth et al., 1975) has been observed up to now. During attempts to synthesize new metal tellurides, we found the new Ti-containing mixed-metallic phase Hf0.78Ti0.22Te5.

The title compound is isostructural with HfTe5 and ZrTe5. Detailed descriptions of this structural type have been reported previously (Furuseth et al., 1973). A view of the structure down the a axis is given in Fig. 1, which shows the layered nature parallel to (010). The structure is composed of chains made up from bicapped trigonal prismatic MTe8 units. The metal (M) site occupied by statistically disordered Hf (78.1 (5) %) and Ti (21.9 (5) %) is surrounded by eight Te atoms. Three crystallographically independent Te sites are found in the title compound. Both Te1 (site symmetry m2m) and Te2 (site symmetry m..) are at the corners of a triangular prism and they are bridging the M atoms to form a chain. Two Te3 (site symmetry m..) atoms outside the rectangular faces of the prism are connected to the neighboring Te3 to form the infinite zigzag Te chain. Finally, the MTe5 layer is formed by the alternate linking of these chains (Fig. 2).

The structure shows a wide range of Te···Te interactions. In the prism, the Te2—Te2 pair (2.7448 (13) Å) forming the short base of the equilateral triangle exhibits a regular Te—Te bond, Te22- (e.g. discussed by Pell & Ibers, 1996). In addition, an intermediate Te3···Te3 separation (2.9129 (9) Å) is indicative of a weak single bond (Mar & Ibers, 1993) but we assign an oxidation state of 0 for Te3 (1[Te0]). The classical charge balance of the compound can be described as [M4+][Te2-][Te22-][Te20] (M=Hf, Ti).

Structury analysis of three different crystals from the same reaction tube showed that the metal content can vary, apparently forming a random substitutional solid solution (Hf1-xTix)Te5, 0.15 x 0.22.

Related literature top

For the synthesis and structure of HfTe5 and ZrTe5, see: Brattås & Kjekshus (1971); Furuseth et al. (1973, 1975). For properties of HfTe5 and ZrTe5, see: DiSalvo et al. (1981). For extensive Te···Te interactions in metal tellurides, see: Pell & Ibers (1996); Mar & Ibers (1993).

Experimental top

The title compound, Hf0.78Ti0.22Te5, was prepared by the reaction of the elements with the use of the reactive halide-flux technique. Hf powder (CERAC 99.8%), Ti powder (CERAC 99.5%), and Te powder (CERAC 99.95%) were mixed in a fused silica tube in a molar ratio of Hf: Ti: Te = 1: 1: 10 and then CsCl (CERAC 99.9%) was added in a weight ratio of HfTiTe10: CsCl = 1: 2. The tube was evacuated to 0.133 Pa, sealed and heated gradually (50 K/h) to 650 K, where it was kept for 72 h. The tube was then cooled to room temperature at the rate of 3 K/h. The excess halide was removed with distilled water and dark block-shaped crystals were obtained. The crystals are stable in air and water. A qualitative X-ray fluorescence analysis of the crystals indicated the presence of Hf, Ti, and Te. A quantitative XRF analysis indicated that the Hf: Ti ratio is 80: 20. The composition of the compound was determined by single-crystal X-ray diffraction.

Refinement top

The statistically disordered nature of the M site in the title compound was checked by refining the anisotropic displacement parameters (ADPs). When the model was refined assuming HfTe5 or TiTe5, the displacement parameters of the metal site were very large and small, respectively. In both cases the reliability indices were rather high (wR2 > 0.127). In the refined mixed-metal model, the ADPs of the metal atoms are comparable with those of the other atoms and the residuals were reduced significantly (wR2 = 0.068). The remaining highest and lowest electron densities are found 0.81 and 0.77 Å from atom Te1.

Computing details top

Data collection: RAPID-AUTO (Rigaku, 2006); cell refinement: RAPID-AUTO (Rigaku, 2006); data reduction: RAPID-AUTO (Rigaku, 2006); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: DIAMOND3 (Brandenburg, 1999); software used to prepare material for publication: WinGX (Farrugia, 1999).

Figures top
[Figure 1] Fig. 1. A perspective view of Hf0.78Ti0.22Te5 down the a axis showing the stacking of the layers. Filled and open circles represent metals and S atoms, respectively. The displacement ellipsoids are drawn at the 90% probability level.
[Figure 2] Fig. 2. A view of the layer of Hf0.78Ti0.22Te5. Anisotropic displacement ellipsoids are drawn at the 90% probability level. Atoms are as marked as in Fig. 1. [Symmetry code: (i) 1/2 + x, 1/2 - y, 1 - z].
Hafnium titanium pentatelluride top
Crystal data top
Hf0.78Ti0.22Te5F(000) = 1284
Mr = 787.76Dx = 6.679 Mg m3
Orthorhombic, CmcmMo Kα radiation, λ = 0.71073 Å
Hall symbol: -C 2c 2Cell parameters from 3264 reflections
a = 3.9595 (3) Åθ = 3.2–27.5°
b = 14.4350 (13) ŵ = 28.76 mm1
c = 13.7062 (9) ÅT = 290 K
V = 783.39 (10) Å3Needle, black
Z = 40.30 × 0.04 × 0.02 mm
Data collection top
Rigaku R-AXIS RAPID
diffractometer
533 independent reflections
Radiation source: fine-focus sealed tube516 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.059
ω scansθmax = 27.5°, θmin = 2.8°
Absorption correction: multi-scan
(NUMABS; Higashi, 2000)
h = 45
Tmin = 0.263, Tmax = 1.000k = 1818
3405 measured reflectionsl = 1717
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)] = 0.029 w = 1/[σ2(Fo2) + (0.0304P)2 + 7.5394P]
where P = (Fo2 + 2Fc2)/3
wR(F2) = 0.068(Δ/σ)max < 0.001
S = 1.16Δρmax = 2.38 e Å3
533 reflectionsΔρmin = 2.07 e Å3
23 parametersExtinction correction: SHELXL97 (Sheldrick, 2008)
0 restraintsExtinction coefficient: 0.00109 (14)
Crystal data top
Hf0.78Ti0.22Te5V = 783.39 (10) Å3
Mr = 787.76Z = 4
Orthorhombic, CmcmMo Kα radiation
a = 3.9595 (3) ŵ = 28.76 mm1
b = 14.4350 (13) ÅT = 290 K
c = 13.7062 (9) Å0.30 × 0.04 × 0.02 mm
Data collection top
Rigaku R-AXIS RAPID
diffractometer
533 independent reflections
Absorption correction: multi-scan
(NUMABS; Higashi, 2000)
516 reflections with I > 2σ(I)
Tmin = 0.263, Tmax = 1.000Rint = 0.059
3405 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.02923 parameters
wR(F2) = 0.0680 restraints
S = 1.16Δρmax = 2.38 e Å3
533 reflectionsΔρmin = 2.07 e Å3
Special details top

Geometry. All s.u.'s (except the s.u. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell s.u.'s are taken into account individually in the estimation of s.u.'s in distances, angles and torsion angles; correlations between s.u.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell s.u.'s is used for estimating s.u.'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 > 2σ(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)
Hf10.31435 (5)0.250.0109 (3)0.781 (5)
Ti10.31435 (5)0.250.0109 (3)0.219 (5)
Te110.33665 (6)0.250.0128 (3)
Te210.07070 (5)0.14987 (5)0.0169 (3)
Te310.20952 (5)0.06526 (4)0.0154 (2)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Hf0.0103 (4)0.0122 (4)0.0102 (4)000
Ti0.0103 (4)0.0122 (4)0.0102 (4)000
Te10.0129 (4)0.0121 (5)0.0134 (4)000
Te20.0164 (4)0.0164 (4)0.0178 (4)000.0051 (2)
Te30.0155 (4)0.0190 (4)0.0116 (3)000.0010 (2)
Geometric parameters (Å, º) top
M—Te2i2.9251 (6)Te1—Mv2.9446 (8)
M—Te2ii2.9251 (6)Te1—Mvi2.9446 (8)
M—Te2iii2.9251 (6)Te1—Mvi2.9446 (8)
M—Te2iv2.9251 (6)Te2—Te2vii2.7448 (13)
M—Te1v2.9446 (8)Te2—Mviii2.9251 (6)
M—Te1vi2.9446 (8)Te2—Mviii2.9251 (6)
M—Te32.9498 (7)Te2—Mix2.9251 (6)
M—Te3vii2.9498 (7)Te2—Mix2.9251 (6)
Te1—Mv2.9446 (8)Te3—Te3v2.9129 (9)
Te2i—M—Te2ii55.96 (3)Te2iv—M—Te3vii83.583 (16)
Te2i—M—Te2iii110.88 (3)Te1v—M—Te3vii67.683 (15)
Te2ii—M—Te2iii85.19 (2)Te1vi—M—Te3vii67.683 (15)
Te2i—M—Te2iv85.19 (2)Te3—M—Te3vii118.27 (3)
Te2ii—M—Te2iv110.88 (3)Mv—Te1—Mv0.000 (18)
Te2iii—M—Te2iv55.96 (3)Mv—Te1—Mvi84.50 (3)
Te2i—M—Te1v151.040 (16)Mv—Te1—Mvi84.50 (3)
Te2ii—M—Te1v151.040 (16)Mv—Te1—Mvi84.50 (3)
Te2iii—M—Te1v87.986 (16)Mv—Te1—Mvi84.50 (3)
Te2iv—M—Te1v87.986 (16)Mvi—Te1—Mvi0
Te2i—M—Te1vi87.986 (16)Te2vii—Te2—Mviii62.019 (13)
Te2ii—M—Te1vi87.986 (16)Te2vii—Te2—Mviii62.019 (13)
Te2iii—M—Te1vi151.040 (16)Mviii—Te2—Mviii0.00 (2)
Te2iv—M—Te1vi151.040 (16)Te2vii—Te2—Mix62.019 (13)
Te1v—M—Te1vi84.49 (3)Mviii—Te2—Mix85.19 (2)
Te2i—M—Te3133.927 (10)Mviii—Te2—Mix85.19 (2)
Te2ii—M—Te383.584 (16)Te2vii—Te2—Mix62.019 (13)
Te2iii—M—Te383.583 (16)Mviii—Te2—Mix85.19 (2)
Te2iv—M—Te3133.927 (10)Mviii—Te2—Mix85.19 (2)
Te1v—M—Te367.683 (15)Mix—Te2—Mix0.00 (2)
Te1vi—M—Te367.683 (15)Te3v—Te3—Te3vi85.63 (3)
Te2i—M—Te3vii83.583 (16)Te3v—Te3—M108.74 (3)
Te2ii—M—Te3vii133.927 (10)Te3vi—Te3—M108.74 (3)
Te2iii—M—Te3vii133.927 (10)
Symmetry codes: (i) x+1/2, y+1/2, z+1/2; (ii) x+1/2, y+1/2, z; (iii) x1/2, y+1/2, z; (iv) x1/2, y+1/2, z+1/2; (v) x+3/2, y+1/2, z; (vi) x+5/2, y+1/2, z; (vii) x, y, z+1/2; (viii) x1/2, y1/2, z; (ix) x+1/2, y1/2, z.

Experimental details

Crystal data
Chemical formulaHf0.78Ti0.22Te5
Mr787.76
Crystal system, space groupOrthorhombic, Cmcm
Temperature (K)290
a, b, c (Å)3.9595 (3), 14.4350 (13), 13.7062 (9)
V3)783.39 (10)
Z4
Radiation typeMo Kα
µ (mm1)28.76
Crystal size (mm)0.30 × 0.04 × 0.02
Data collection
DiffractometerRigaku R-AXIS RAPID
diffractometer
Absorption correctionMulti-scan
(NUMABS; Higashi, 2000)
Tmin, Tmax0.263, 1.000
No. of measured, independent and
observed [I > 2σ(I)] reflections
3405, 533, 516
Rint0.059
(sin θ/λ)max1)0.649
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.029, 0.068, 1.16
No. of reflections533
No. of parameters23
Δρmax, Δρmin (e Å3)2.38, 2.07

Computer programs: RAPID-AUTO (Rigaku, 2006), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), DIAMOND3 (Brandenburg, 1999), WinGX (Farrugia, 1999).

Selected geometric parameters (Å, º) top
M—Te2i2.9251 (6)M—Te1iii2.9446 (8)
M—Te2ii2.9251 (6)M—Te32.9498 (7)
Te3iii—Te3—Te3iv85.63 (3)
Symmetry codes: (i) x+1/2, y+1/2, z; (ii) x1/2, y+1/2, z+1/2; (iii) x+3/2, y+1/2, z; (iv) x+5/2, y+1/2, z.
 

Acknowledgements

This research was supported by the Basic Science Research Program through the National Research Foundation of Korea funded by the Ministry of Education, Science and Technology (grant No. 2011–0011309)

References

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First citationBrattås, L. & Kjekshus, A. (1971). Acta Chem. Scand. 25, 2783–2785.  Google Scholar
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First citationRigaku (2006). RAPID-AUTO. Rigaku Corporation, Tokyo, Japan.  Google Scholar
First citationSheldrick, G. M. (2008). Acta Cryst. A64, 112–122.  Web of Science CrossRef CAS IUCr Journals Google Scholar

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