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ISSN: 2414-3146

Rubidium tetra­fluorido­bromate(III): redetermination of the crystal structure from single-crystal X-ray diffraction data

aNational Research Tomsk Polytechnic University, 30 Lenina Avenue, 634050 Tomsk, Russian Federation, and bFachbereich Chemie, Philipps-Universität Marburg, Hans-Meerwein-Str. 4, 35032 Marburg, Germany
*Correspondence e-mail: f.kraus@uni-marburg.de

Edited by M. Weil, Vienna University of Technology, Austria (Received 14 November 2019; accepted 26 November 2019; online 29 November 2019)

Single crystals of rubidium tetra­fluorido­bromate(III), RbBrF4, were grown by melting and recrystallizing RbBrF4 from its melt. This is the first determination of the crystal structure of RbBrF4 using single-crystal X-ray diffraction data. We confirmed that the structure contains square-planar [BrF4] anions and rubidium cations that are coordinated by F atoms in a square-anti­prismatic manner. The compound crystallizes in the KBrF4 structure type. Atomic coordinates and bond lengths and angles were determined with higher precision than in a previous report based on powder X-ray diffraction data [Ivlev et al. (2015[Ivlev, S., Karttunen, A. J., Ostvald, R. & Kraus, F. (2015). Z. Anorg. Allg. Chem. 641, 2593-2598.]). Z. Anorg. Allg. Chem. 641, 2593–2598].

3D view (loading...)
[Scheme 3D1]

Structure description

The first attempt to determine the lattice parameters of rubidium tetra­fluorido­bromate(III) from powder X-ray diffraction data was undertaken by Popov et al. (1987[Popov, A. I., Kiselev, Y. M., Sukhoverkhov, V. F., Chumaevskii, N. A., Krasnyanskaya, O. A. & Sadikova, A. T. (1987). Russ. J. Inorg. Chem. 32, 619-622.]). They reported the following tetra­gonal I-centered unit cell: a = 6.401 (3), c = 11.1538 (7) Å, V = 472.7 (6) Å3 at room temperature. The authors stated that the structure of RbBrF4 is isotypic to that of KBrF4 but did not provide further crystallographic details. The next report on the crystal structure of RbBrF4 was published by Seppelt and coworkers, stating that the crystal structure is not isotypic to KBrF4 (Mahjoub et al., 1989[Mahjoub, A. R., Hoser, A., Fuchs, J. & Seppelt, K. (1989). Angew. Chem. 101, 1528-1529.]). In a later study we showed that the structure model by Mahjoub et al. (1989[Mahjoub, A. R., Hoser, A., Fuchs, J. & Seppelt, K. (1989). Angew. Chem. 101, 1528-1529.]) was not correct. Indeed, the crystal-structure model obtained from powder X-ray diffraction data [I4/mcm, a = 6.37181 (15), c = 11.4934 (3) Å, V = 466.63 (2) Å3 at 293 K; Ivlev et al., 2015[Ivlev, S., Karttunen, A. J., Ostvald, R. & Kraus, F. (2015). Z. Anorg. Allg. Chem. 641, 2593-2598.]] revealed isotypism to KBrF4. On basis of the obtained powder X-ray diffraction data, only the Rb and Br atoms could be refined with anisotropic displacement parameters. We were now able to grow single crystals of RbBrF4 and present our results on the basis of single-crystal X-ray diffraction data at 100 K, which allowed for anisotropic refinement of all atoms and confirmed our previous model with higher precision.

The lattice parameters of RbBrF4 obtained from the current single-crystal X-ray diffraction data (Table 1[link]) are, as expected, slightly smaller than those of the room temperature powder X-ray data given above. In the structure, all atoms are located on special positions: Rb1 occupies Wyckoff position 4a (site symmetry 422), Br1 4d (m.mm), and F1 16l (..m). The rubidium cation is coordinated in a square-anti­prismatic manner by fluorine atoms (Fig. 1[link]), whereas the bromine(III) atom shows a square-planar coordination by fluorine atoms.

Table 1
Experimental details

Crystal data
Chemical formula RbBrF4
Mr 241.38
Crystal system, space group Tetragonal, I4/mcm
Temperature (K) 100
a, c (Å) 6.2991 (5), 11.4659 (10)
V3) 454.95 (8)
Z 4
Radiation type Mo Kα
μ (mm−1) 19.61
Crystal size (mm) 0.19 × 0.15 × 0.03
 
Data collection
Diffractometer Bruker D8 QUEST area detector
Absorption correction Multi-scan (SADABS; Krause et al., 2015[Krause, L., Herbst-Irmer, R., Sheldrick, G. M. & Stalke, D. (2015). J. Appl. Cryst. 48, 3-10.])
Tmin, Tmax 0.151, 0.480
No. of measured, independent and observed [I > 2σ(I)] reflections 5872, 322, 189
Rint 0.070
(sin θ/λ)max−1) 0.833
 
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.020, 0.038, 1.06
No. of reflections 322
No. of parameters 13
Δρmax, Δρmin (e Å−3) 0.66, −0.73
Computer programs: APEX3 (Bruker, 2018[Bruker (2018). APEX3. Bruker AXS Inc., Madison, Wisconsin, USA.]), SHELXT (Sheldrick, 2015a[Sheldrick, G. M. (2015a). Acta Cryst. A71, 3-8.]), SHELXL (Sheldrick, 2015b[Sheldrick, G. M. (2015b). Acta Cryst. C71, 3-8.]), DIAMOND (Brandenburg, 2018[Brandenburg, K. (2018). DIAMOND. Crystal Impact GbR, Bonn, Germany.]) and publCIF (Westrip, 2010[Westrip, S. P. (2010). J. Appl. Cryst. 43, 920-925.]).
[Figure 1]
Figure 1
The square-anti­prismatic coordination sphere of the Rb+ cation by F anions. Atoms are shown with arbitrary radii.

The resulting Br—F bond length of 1.8905 (16) Å is comparable with the value of 1.932 (8) Å obtained from powder X-ray diffraction data at 293 K, as well as with the Br—F bond lengths reported for other tetra­fluorido­bromates(III) (Ivlev et al., 2015[Ivlev, S., Karttunen, A. J., Ostvald, R. & Kraus, F. (2015). Z. Anorg. Allg. Chem. 641, 2593-2598.]). The Rb—F distance amounts to 2.8447 (10) Å, likewise in good agreement with powder X-ray data (2.851 (7) Å).

A section of the crystal structure of RbBrF4 is shown in Fig. 2[link].

[Figure 2]
Figure 2
The crystal structure of the title compound in a projection along the a axis. Displacement ellipsoids are shown at the 70% probability level.

Synthesis and crystallization

Rubidium tetra­fluorido­bromate(III) was synthesized by direct reaction of bromine trifluoride with rubidium chloride. The reaction was carried out under Freon-113, which acted as a protective layer against hydrolysis and as a heat absorber. The mixture of RbCl and BrF3 was kept in a closed Teflon vessel. After three days, the Freon was removed by vacuum distillation and RbBrF4 was obtained as a solid white residue. The powder was melted at 523 K and subsequently cooled down to room temperature. Single crystals of RbBrF4 were obtained as small plates after crushing the solid lumps.

Refinement

Crystal data, data collection and structure refinement details are given in Table 1[link].

Structural data


Computing details top

Data collection: APEX3 (Bruker, 2018); cell refinement: APEX3 (Bruker, 2018); data reduction: APEX3 (Bruker, 2018); program(s) used to solve structure: SHELXT (Sheldrick, 2015a); program(s) used to refine structure: SHELXL (Sheldrick, 2015b); molecular graphics: DIAMOND (Brandenburg, 2018); software used to prepare material for publication: publCIF (Westrip, 2010).

Rubidium tetrafluoridobromate(III) top
Crystal data top
RbBrF4Dx = 3.524 Mg m3
Dm = 3.33 Mg m3
Dm measured by helium pycnometry
Mr = 241.38Mo Kα radiation, λ = 0.71073 Å
Tetragonal, I4/mcmCell parameters from 285 reflections
a = 6.2991 (5) Åθ = 4.5–31.3°
c = 11.4659 (10) ŵ = 19.61 mm1
V = 454.95 (8) Å3T = 100 K
Z = 4Plate, colorless
F(000) = 4320.19 × 0.14 × 0.03 mm
Data collection top
Bruker D8 QUEST area detector
diffractometer
322 independent reflections
Radiation source: microfocus sealed X-ray tube, Incoatec Iµs189 reflections with I > 2σ(I)
Detector resolution: 7.9 pixels mm-1Rint = 0.070
ω and φ scansθmax = 36.3°, θmin = 3.6°
Absorption correction: multi-scan
(SADABS; Krause et al., 2015)
h = 910
Tmin = 0.151, Tmax = 0.480k = 910
5872 measured reflectionsl = 1919
Refinement top
Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: full w = 1/[σ2(Fo2) + (0.004P)2 + 1.2951P]
where P = (Fo2 + 2Fc2)/3
R[F2 > 2σ(F2)] = 0.020(Δ/σ)max < 0.001
wR(F2) = 0.038Δρmax = 0.66 e Å3
S = 1.06Δρmin = 0.73 e Å3
322 reflectionsExtinction correction: SHELXL (Sheldrick, 2015b), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
13 parametersExtinction coefficient: 0.0016 (3)
0 restraints
Special details top

Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
Br10.5000000.0000000.5000000.00663 (14)
Rb10.5000000.5000000.7500000.00956 (15)
F10.6501 (2)0.1501 (2)0.61660 (13)0.0138 (3)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Br10.00693 (19)0.00693 (19)0.0060 (2)0.0008 (2)0.0000.000
Rb10.0099 (2)0.0099 (2)0.0088 (2)0.0000.0000.000
F10.0147 (5)0.0147 (5)0.0120 (7)0.0003 (8)0.0047 (5)0.0047 (5)
Geometric parameters (Å, º) top
Br1—F11.8905 (16)Rb1—F1viii2.8447 (10)
Br1—F1i1.8906 (16)Rb1—F1ix2.8447 (9)
Br1—F1ii1.8906 (16)Rb1—F1x2.8447 (9)
Br1—F1iii1.8906 (16)Rb1—F12.8447 (9)
Rb1—F1iv2.8447 (10)Rb1—Rb1xi4.4541 (4)
Rb1—F1v2.8447 (10)Rb1—Rb1xii4.4541 (4)
Rb1—F1vi2.8447 (10)Rb1—Rb1xiii4.4541 (4)
Rb1—F1vii2.8447 (10)Rb1—Rb1vi4.4541 (4)
F1—Br1—F1i180.0F1viii—Rb1—Rb1xi141.53 (2)
F1—Br1—F1ii90.01 (10)F1ix—Rb1—Rb1xi71.76 (3)
F1i—Br1—F1ii89.99 (10)F1x—Rb1—Rb1xi108.24 (3)
F1—Br1—F1iii89.99 (10)F1—Rb1—Rb1xi71.76 (3)
F1i—Br1—F1iii90.01 (10)F1iv—Rb1—Rb1xii38.47 (2)
F1ii—Br1—F1iii180.0F1v—Rb1—Rb1xii141.53 (2)
F1iv—Rb1—F1v143.52 (7)F1vi—Rb1—Rb1xii71.76 (3)
F1iv—Rb1—F1vi73.20 (3)F1vii—Rb1—Rb1xii141.53 (2)
F1v—Rb1—F1vi141.19 (6)F1viii—Rb1—Rb1xii38.47 (2)
F1iv—Rb1—F1vii114.95 (5)F1ix—Rb1—Rb1xii108.24 (3)
F1v—Rb1—F1vii76.95 (5)F1x—Rb1—Rb1xii71.76 (3)
F1vi—Rb1—F1vii73.20 (3)F1—Rb1—Rb1xii108.24 (3)
F1iv—Rb1—F1viii76.95 (5)Rb1xi—Rb1—Rb1xii180.0
F1v—Rb1—F1viii114.95 (5)F1iv—Rb1—Rb1xiii71.76 (3)
F1vi—Rb1—F1viii78.41 (7)F1v—Rb1—Rb1xiii71.76 (3)
F1vii—Rb1—F1viii143.52 (7)F1vi—Rb1—Rb1xiii141.53 (2)
F1iv—Rb1—F1ix73.20 (3)F1vii—Rb1—Rb1xiii108.24 (3)
F1v—Rb1—F1ix78.41 (7)F1viii—Rb1—Rb1xiii108.24 (3)
F1vi—Rb1—F1ix114.95 (5)F1ix—Rb1—Rb1xiii38.47 (2)
F1vii—Rb1—F1ix73.20 (3)F1x—Rb1—Rb1xiii38.47 (2)
F1viii—Rb1—F1ix141.19 (6)F1—Rb1—Rb1xiii141.53 (2)
F1iv—Rb1—F1x78.41 (7)Rb1xi—Rb1—Rb1xiii90.0
F1v—Rb1—F1x73.20 (3)Rb1xii—Rb1—Rb1xiii90.0
F1vi—Rb1—F1x143.52 (7)F1iv—Rb1—Rb1vi108.24 (3)
F1vii—Rb1—F1x141.19 (6)F1v—Rb1—Rb1vi108.24 (3)
F1viii—Rb1—F1x73.20 (3)F1vi—Rb1—Rb1vi38.47 (2)
F1ix—Rb1—F1x76.95 (5)F1vii—Rb1—Rb1vi71.76 (3)
F1iv—Rb1—F1141.19 (6)F1viii—Rb1—Rb1vi71.76 (3)
F1v—Rb1—F173.19 (3)F1ix—Rb1—Rb1vi141.53 (2)
F1vi—Rb1—F176.95 (5)F1x—Rb1—Rb1vi141.53 (2)
F1vii—Rb1—F178.41 (7)F1—Rb1—Rb1vi38.47 (2)
F1viii—Rb1—F173.20 (3)Rb1xi—Rb1—Rb1vi90.0
F1ix—Rb1—F1143.52 (7)Rb1xii—Rb1—Rb1vi90.0
F1x—Rb1—F1114.95 (5)Rb1xiii—Rb1—Rb1vi180.0
F1iv—Rb1—Rb1xi141.53 (2)Br1—F1—Rb1vi126.98 (3)
F1v—Rb1—Rb1xi38.47 (2)Br1—F1—Rb1126.98 (3)
F1vi—Rb1—Rb1xi108.24 (3)Rb1vi—F1—Rb1103.05 (5)
F1vii—Rb1—Rb1xi38.47 (2)
Symmetry codes: (i) x+1, y, z+1; (ii) x, y, z+1; (iii) x+1, y, z; (iv) y+1/2, x+3/2, z+3/2; (v) y, x+1, z; (vi) x+3/2, y+1/2, z+3/2; (vii) y+1/2, x1/2, z+3/2; (viii) y+1, x, z; (ix) x1/2, y+1/2, z+3/2; (x) x+1, y+1, z; (xi) x+1/2, y+1/2, z+3/2; (xii) x+3/2, y+3/2, z+3/2; (xiii) x+1/2, y+3/2, z+3/2.
 

Acknowledgements

We thank the Russian Governmental Program 'Nauka' N 4.3967.2017/PCh for support. We thank the Deutsche Forschungsgemeinschaft for generous funding.

References

First citationBrandenburg, K. (2018). DIAMOND. Crystal Impact GbR, Bonn, Germany.  Google Scholar
First citationBruker (2018). APEX3. Bruker AXS Inc., Madison, Wisconsin, USA.  Google Scholar
First citationIvlev, S., Karttunen, A. J., Ostvald, R. & Kraus, F. (2015). Z. Anorg. Allg. Chem. 641, 2593–2598.  Web of Science CrossRef ICSD CAS Google Scholar
First citationKrause, L., Herbst-Irmer, R., Sheldrick, G. M. & Stalke, D. (2015). J. Appl. Cryst. 48, 3–10.  Web of Science CSD CrossRef ICSD CAS IUCr Journals Google Scholar
First citationMahjoub, A. R., Hoser, A., Fuchs, J. & Seppelt, K. (1989). Angew. Chem. 101, 1528–1529.  CrossRef CAS Google Scholar
First citationPopov, A. I., Kiselev, Y. M., Sukhoverkhov, V. F., Chumaevskii, N. A., Krasnyanskaya, O. A. & Sadikova, A. T. (1987). Russ. J. Inorg. Chem. 32, 619–622.  Google Scholar
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First citationSheldrick, G. M. (2015b). Acta Cryst. C71, 3–8.  Web of Science CrossRef IUCr Journals Google Scholar
First citationWestrip, S. P. (2010). J. Appl. Cryst. 43, 920–925.  Web of Science CrossRef CAS IUCr Journals Google Scholar

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