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Acta Crystallogr Sect E Struct Rep Online. 2010 September 1; 66(Pt 9): i67.
Published online 2010 August 21. doi:  10.1107/S1600536810032538
PMCID: PMC3007875

Redetermination of tantalum penta­bromide, (TaBr5)2

Abstract

Crystals of di-μ-bromido-bis­[tetra­bromidotantalum(V)], (TaBr5)2, were obtained by recrystallization at 773 K. A first crystal structure study of (TaBr5)2 was reported by Rolsten [J. Am. Chem. Soc. (1958) [triangle], 80, 2952–2953], who analysed the powder diffraction pattern and came to the conclusion that it crystallizes isotypically with (NbBr5)2 in a primitive ortho­rhom­bic cell. These findings are not in agreement with our current results of a monoclinic C-centred structure. (TaBr5)2 is isotypic with α-(NbCl5)2. The crystal structure contains [TaBr6] octa­hedra sharing common edges forming [TaBr5]2 dimers. Two crystallographically independent dimers with symmetries m and 2/m and Ta(...)Ta distances of 4.1574 (11) and 4.1551 (15) Å, respectively, are present in the structure.

Related literature

For a previous study of (TaBr5)2, see: Rolsten (1958a [triangle]), who also reported the crystal structure of (NbBr5)2 (Rolsten, 1958b [triangle]). (TaBr5)2 is isotypic with α-(NbCl5)2, the structure of which was first described by Zalkin & Sands (1958 [triangle]) and was redetermined by Hoenle & von Schnering (1990 [triangle]). For a summary of all possible stackings of double octa­hedral mol­ecules in penta­halides of Nb and Ta, see: Müller (1978 [triangle]). Experimental details can be found in Brauer’s handbook (Brauer, 1962 [triangle]). For data analysis, see: Spek (2009 [triangle]).

Experimental

Crystal data

  • Ta2Br10
  • M r = 1161.00
  • Monoclinic, An external file that holds a picture, illustration, etc.
Object name is e-66-00i67-efi1.jpg
  • a = 19.433 (3) Å
  • b = 18.775 (2) Å
  • c = 6.2034 (10) Å
  • β = 90.716 (13)°
  • V = 2263.2 (6) Å3
  • Z = 6
  • Mo Kα radiation
  • μ = 40.93 mm−1
  • T = 293 K
  • 0.14 × 0.09 × 0.04 mm

Data collection

  • Stoe IPDS 2 diffractometer
  • Absorption correction: numerical (X-SHAPE; Stoe & Cie, 1999 [triangle]) T min = 0.014, T max = 0.089
  • 17962 measured reflections
  • 2605 independent reflections
  • 1678 reflections with I > 2σ(I)
  • R int = 0.125

Refinement

  • R[F 2 > 2σ(F 2)] = 0.042
  • wR(F 2) = 0.109
  • S = 0.95
  • 2605 reflections
  • 88 parameters
  • Δρmax = 1.71 e Å−3
  • Δρmin = −1.53 e Å−3

Data collection: X-AREA (Stoe & Cie, 2002 [triangle]); cell refinement: X-RED (Stoe & Cie, 2002 [triangle]); data reduction: X-RED; program(s) used to solve structure: SIR92 (Altomare et al., 1994 [triangle]); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 [triangle]); molecular graphics: DIAMOND (Brandenburg, 2005 [triangle]); software used to prepare material for publication: SHELXL97.

Supplementary Material

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536810032538/wm2384sup1.cif

Structure factors: contains datablocks I. DOI: 10.1107/S1600536810032538/wm2384Isup2.hkl

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

Acknowledgments

Financial support from the State of Nordrhein-Westfalen and Universität zu Köln is greatly appreciated.

supplementary crystallographic information

Comment

(TaBr5)2 was first described by Rolsten (Rolsten, 1958a). He compared the powder diffraction pattern of (TaBr5)2 with orthorhombic NbBr5 (space group Pbam) and came to the conclusion that the structures are alike. The structure of (NbBr5)2 was already known from single-crystal structure analysis (Rolsten, 1958b). However, the apparent isotypism between (TaBr5)2 and (NbBr5)2 is not in agreement with our result that shows (TaBr5)2 to crystallize in the monoclinic space goup C2/m.

The crystal structures of all pentahalides besides the fluorides contain [MX6] octahedra (M = Nb, Ta; X = Cl, B, I) sharing common edges forming [MX5]2 dimers. These double octahedra can be stacked in different ways, resulting in different structure types. In the title compound, the stacking of the (TaBr5)2 layers along b can be described as A1B1A1B1··· . Within one layer the molecules are stacked in a "2 1" stacking scheme (Fig. 1). A summary of all possible stacking possibilities has been given by Müller (1978). The [TaBr6] octahedra are distorted due to the repulsive forces of the highly charged metal atoms centering the octahedra with d(Ta—Ta) = 4.1574 (11) Å for the (Ta1Br5)2 dimer (m symmetry) and 4.1551 (15) Å for the (Ta2Br5)2 dimer (2/m symmetry).

(TaBr5)2 is isotypic with α-(NbCl5)2 (Zalkin & Sands, 1958; Hoenle & von Schnering, 1990).

Experimental

TaBr5 was synthesized according to an experimental procedure reported in Brauer's handbook (Brauer, 1962). Orange polyhedric crystals were obtained by recrystallization of TaBr5 in a silica ampoule. The ampoule was heated with 50 K per hour to 773 K and annealed for 12 h, after which it was slowly cooled to room temperature with 2 K per hour. Single crystals of TaBr5 were selected under a microscope in an argon-filled glove box.

Refinement

PLATON (Spek, 2009) indicates higher (pseudo)-symmetry and suggests a change of the crystal system from monoclinic C to orthorhombic C, but the experimentally determined unit cell angles differ with 0.72° considerably from orthogonality. The maximum residual density lies 1.29Å from Ta1 and the density minimum lies at the Br4 atom.

Figures

Fig. 1.
Unit cell of TaBr5 in a view along [001]. Double octahedral molecules are coloured in orange or blue for depth perception. Thermal ellipsoids are given on the 99% probability level.

Crystal data

Ta2Br10F(000) = 2976
Mr = 1161.00none
Monoclinic, C2/mDx = 5.111 Mg m3
Hall symbol: -C 2yMo Kα radiation, λ = 0.71073 Å
a = 19.433 (3) ÅCell parameters from 7929 reflections
b = 18.775 (2) Åθ = 2.1–27.1°
c = 6.2034 (10) ŵ = 40.93 mm1
β = 90.716 (13)°T = 293 K
V = 2263.2 (6) Å3Polyhedron, orange
Z = 60.14 × 0.09 × 0.04 mm

Data collection

Stoe IPDS 2 diffractometer2605 independent reflections
Radiation source: fine-focus sealed tube1678 reflections with I > 2σ(I)
graphiteRint = 0.125
Detector resolution: 0 pixels mm-1θmax = 27.3°, θmin = 1.5°
oscillation scansh = −24→24
Absorption correction: numerical (X-SHAPE; Stoe & Cie, 1999)k = −24→24
Tmin = 0.014, Tmax = 0.089l = −7→7
17962 measured reflections

Refinement

Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.042 w = 1/[σ2(Fo2) + (0.0563P)2] where P = (Fo2 + 2Fc2)/3
wR(F2) = 0.109(Δ/σ)max = 0.001
S = 0.95Δρmax = 1.71 e Å3
2605 reflectionsΔρmin = −1.53 e Å3
88 parametersExtinction correction: SHELXL97 (Sheldrick, 2008), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
0 restraintsExtinction coefficient: 0.00064 (4)
0 constraints

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)

xyzUiso*/Ueq
Ta11.00000.38934 (4)0.50000.0296 (2)
Ta20.66677 (3)0.38928 (3)0.97909 (7)0.02938 (18)
Br10.61422 (10)0.50001.2034 (3)0.0326 (4)
Br20.61078 (9)0.30802 (8)1.2210 (2)0.0430 (4)
Br30.56469 (8)0.40167 (8)0.7436 (2)0.0406 (3)
Br40.72279 (9)0.30797 (8)0.7378 (2)0.0430 (4)
Br50.71903 (11)0.50000.7544 (3)0.0321 (4)
Br60.89789 (8)0.40192 (8)0.7271 (2)0.0421 (3)
Br70.76900 (8)0.40188 (8)1.2143 (2)0.0415 (3)
Br81.05614 (9)0.30768 (8)0.7446 (2)0.0451 (4)
Br91.05245 (11)0.50000.7294 (3)0.0323 (4)

Atomic displacement parameters (Å2)

U11U22U33U12U13U23
Ta10.0289 (4)0.0278 (4)0.0320 (4)0.0000.0032 (3)0.000
Ta20.0292 (3)0.0280 (3)0.0310 (3)0.0002 (2)0.00055 (19)−0.00014 (18)
Br10.0353 (11)0.0314 (9)0.0312 (8)0.0000.0070 (7)0.000
Br20.0464 (10)0.0408 (8)0.0419 (7)−0.0076 (6)0.0083 (6)0.0062 (5)
Br30.0338 (8)0.0460 (8)0.0419 (7)−0.0012 (6)−0.0074 (5)−0.0021 (5)
Br40.0465 (10)0.0396 (7)0.0431 (7)0.0060 (7)0.0079 (6)−0.0087 (6)
Br50.0343 (11)0.0316 (9)0.0305 (8)0.0000.0067 (7)0.000
Br60.0353 (8)0.0457 (8)0.0455 (7)−0.0017 (6)0.0125 (6)0.0023 (6)
Br70.0349 (8)0.0453 (8)0.0440 (7)0.0008 (6)−0.0079 (5)0.0031 (6)
Br80.0464 (10)0.0400 (7)0.0487 (8)0.0075 (7)−0.0038 (6)0.0096 (6)
Br90.0360 (11)0.0305 (8)0.0303 (8)0.000−0.0039 (7)0.000

Geometric parameters (Å, °)

Ta1—Br8i2.4087 (15)Ta2—Br32.4598 (16)
Ta1—Br82.4087 (15)Ta2—Br72.4613 (17)
Ta1—Br62.4591 (14)Ta2—Br52.7075 (12)
Ta1—Br6i2.4591 (14)Ta2—Br12.7084 (12)
Ta1—Br92.7100 (13)Br1—Ta2iii2.7084 (12)
Ta1—Br9ii2.7100 (13)Br5—Ta2iii2.7075 (12)
Ta2—Br42.4075 (14)Br9—Ta1ii2.7100 (13)
Ta2—Br22.4092 (15)
Br8i—Ta1—Br8100.93 (9)Br2—Ta2—Br393.59 (6)
Br8i—Ta1—Br693.41 (6)Br4—Ta2—Br793.53 (6)
Br8—Ta1—Br693.60 (6)Br2—Ta2—Br793.39 (6)
Br8i—Ta1—Br6i93.60 (6)Br3—Ta2—Br7169.06 (5)
Br8—Ta1—Br6i93.41 (6)Br4—Ta2—Br589.51 (5)
Br6—Ta1—Br6i168.98 (8)Br2—Ta2—Br5169.14 (5)
Br8i—Ta1—Br9169.48 (6)Br3—Ta2—Br585.79 (6)
Br8—Ta1—Br989.59 (5)Br7—Ta2—Br585.77 (6)
Br6—Ta1—Br985.78 (6)Br4—Ta2—Br1169.22 (5)
Br6i—Ta1—Br985.77 (6)Br2—Ta2—Br189.43 (5)
Br8i—Ta1—Br9ii89.59 (5)Br3—Ta2—Br185.76 (6)
Br8—Ta1—Br9ii169.48 (6)Br7—Ta2—Br185.90 (6)
Br6—Ta1—Br9ii85.77 (6)Br5—Ta2—Br179.71 (4)
Br6i—Ta1—Br9ii85.78 (6)Ta2—Br1—Ta2iii100.26 (6)
Br9—Ta1—Br9ii79.90 (6)Ta2—Br5—Ta2iii100.31 (6)
Br4—Ta2—Br2101.35 (6)Ta1—Br9—Ta1ii100.10 (6)
Br4—Ta2—Br393.34 (6)

Symmetry codes: (i) −x+2, y, −z+1; (ii) −x+2, −y+1, −z+1; (iii) x, −y+1, z.

Footnotes

Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: WM2384).

References

  • Altomare, A., Cascarano, G., Giacovazzo, C., Guagliardi, A., Burla, M. C., Polidori, G. & Camalli, M. (1994). J. Appl. Cryst.27, 435.
  • Brandenburg, K. (2005). DIAMOND Crystal Impact GbR, Bonn, Germany.
  • Brauer, G. (1962). Handbuch der präparativen Anorganischen Chemie, Band II, p. 1152. Stuttgart: F. Enke-Verlag.
  • Hoenle, W. & von Schnering, H. G. (1990). Z. Kristallogr.191, 139–140.
  • Müller, U. (1978). Acta Cryst. A34, 256–267.
  • Rolsten, R. F. (1958a). J. Am. Chem. Soc.80, 2952–2953.
  • Rolsten, R. F. (1958b). J. Phys. Chem.62, 126–127.
  • Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. [PubMed]
  • Spek, A. L. (2009). Acta Cryst. D65, 148–155. [PMC free article] [PubMed]
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