Strontium tetra­fluoro­borate. Erratum

Goreshnik, E.; Vakulka, A.; Žemva, B.

doi:10.1107/S0108270109054286

addenda and errata

STRUCTURAL
CHEMISTRY

ISSN: 2053-2296

Volume 66| Part 3| March 2010| Page e9

doi:10.1107/S0108270109054286

Strontium tetrafluoroborate. Erratum

Evgeny Goreshnik,^a ^* Andrii Vakulka ^a and Boris Žemva ^a

^aDepartment of Inorganic Chemistry and Technology, Jožef Stefan Institute, Jamova 39 1000 Ljubljana, Slovenia
^*Correspondence e-mail: evgeny.goreshnik@ijs.si

(Received 14 December 2009; accepted 16 December 2009; online 27 February 2010)

In the paper by Bunič, Tavčar, Goreshnik & Žemva [Acta Cryst. (2007 ), C63, i75–i76], the structure reported as Sr(BF₄)₂ is actually that of Cd(BF₄)₂. The correct structure of Sr(BF₄)₂ is now reported.

1. Comment

This erratum is to correct the report of the crystal structure of strontium tetrafluoroborate (Bunič et al., 2007). The investigated compound was Cd(BF₄)₂ and not the reported Sr(BF₄)₂ because of experimental error. We report here the correct structure of strontium tetrafluoroborate, which appears to be isomorphous with the previously published structures of Ca(BF₄)₂ (Jordan et al., 1975 ) and Cd(BF₄)₂ (Tavčar & Žemva, 2005 ). In the Sr(BF₄)₂ structure, the metal atom possesses a coordination number of eight with a square-antiprismatic coordination polyhedron. The Sr—F distances lie in the narrow range 2.490 (4)–2.538 (4) Å, compared with Ca—F distances in the range 2.330 (2)–2.401 (2) Å in Ca(BF₄)₂ and Cd—F distances in the range 2.296 (2)–2.381 (3) Å in Cd(BF₄)₂. The Sr metal center is bonded to eight BF₄⁻ units. In turn, each anion is connected to four Sr atoms. All four F atoms in each anion act as μ₂-bridges between B and Sr atoms, resulting in similar B—F bond lengths of 1.376 (7)–1.402 (7) Å.

2. Experimental

Routine crystallization of strontium tetrafluoroborate from different solvents usually gives crystals of various solvates. However, crystals of the anhydrous salt were grown by dissolving Sr(BF₄)₂·2H₂O, prepared by the reaction between SrCO₃ (Aldrich, 99.99%) and excess aqueous HF (Aldrich, 40%), in acetone and further very slow crystallization.

2.1.1. Crystal data

Sr(BF₄)₂
M_r = 261.24
Orthorhombic, P b c a
a = 9.602 (5) Å
b = 9.259 (5) Å
c = 13.890 (6) Å
V = 1235.0 (10) Å³
Z = 8
Mo Kα radiation
μ = 8.83 mm⁻¹
T = 296 K
0.1 × 0.1 × 0.08 mm

2.1.2. Data collection

Rigaku Mercury CCD (2×2 bin mode) diffractometer
Absorption correction: multi-scan (Blessing, 1995 ) T_min = 0.427, T_max = 0.504
9319 measured reflections
1534 independent reflections
1348 reflections with I > 2σ(I)
R_int = 0.055

2.1.3. Refinement

R[F² > 2σ(F²)] = 0.059
wR(F²) = 0.111
S = 1.34
1534 reflections
101 parameters
Δρ_max = 1.49 e Å⁻³
Δρ_min = −0.76 e Å⁻³

Data collection: CrystalClear (Rigaku, 1999 ); cell refinement: CrystalClear; data reduction: CrystalClear; program(s) used to solve structure: SIR92 (Altomare et al., 1993 ) and TEXSAN (Molecular Structure Corporation, 1999 ); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ); software used to prepare material for publication: WinGX (Version 1.70; Farrugia, 1999 ) and enCIFer (Version 1.2; Allen et al., 2004 ).

Supporting information

Crystal structure: contains datablocks global, I. DOI: 10.1107/S0108270109054286/ln3136sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S0108270109054286/ln3136Isup2.hkl

Comment top

This erratum is to correct the report of the crystal structure of strontium tetrafluoroborate (Bunič et al.., 2007). The investigated compound was Cd(BF₄)₂ and not the reported Sr(BF₄)₂ because of experimental error. We report here the correct structure of strontium tetrafluoroborate, which appears to be isomorphous with the previously published structures of Ca(BF₄)₂ (Jordan et al., 1975) and Cd(BF₄)₂) (Tavčar & Žemva, 2005). In the Sr(BF₄)₂ structure, the metal atom possesses a coordination number of eight with a square-antiprismatic coordination polyhedron. The Sr—F distances lie in the narrow range 2.490 (4)–2.538 (4)Å, compared with Ca—F distances in the range 2.330 (2)–2.401 (2)Å in Ca(BF₄)₂ and Cd—F distances in the range 2.296 (2)–2.381 (3)Å in Cd(BF₄)₂. The Sr metal center is bonded to eight BF₄^- units. In turn, each anion is connected to four Sr atoms. All four F atoms in each anion act as µ₂-bridges between B and Sr atoms, resulting in similar B—F bond lengths of 1.376 (7)–1.402 (7)Å.

Related literature top

For related literature, see: Bunič et al. (2007); Jordan et al. (1975); Tavčar & Žemva (2005).

Experimental top

Routine crystallization of strontium tetrafluoroborate from different solvents usually gives crystals of various solvates. However, crystals of the anhydrous salt were grown by dissolving Sr(BF₄)₂.2H₂O, prepared by the reaction between SrCO₃ (Aldrich, 99.99%) and excess aqueous HF (Aldrich, 40%), in acetone and further very slow crystallization.

Computing details top

Data collection: CrystalClear (Rigaku, 1999); cell refinement: CrystalClear (Rigaku, 1999); data reduction: CrystalClear (Rigaku, 1999); program(s) used to solve structure: SIR92 (Altomare et al., 1993) and TEXSAN (Molecular Structure Corporation, 1999); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); software used to prepare material for publication: WinGX (Version 1.70; Farrugia, 1999) and enCIFer (Version 1.2; Allen et al., 2004).

Strontium bis(tetrafluoroborate) top

Crystal data top

Sr(BF₄)₂	F(000) = 960
M_r = 261.24	D_x = 2.81 Mg m⁻³
Orthorhombic, Pbca	Mo Kα radiation, λ = 0.71069 Å
Hall symbol: -P 2ac 2ab	Cell parameters from 3850 reflections
a = 9.602 (5) Å	θ = 2.1–28.8°
b = 9.259 (5) Å	µ = 8.83 mm⁻¹
c = 13.890 (6) Å	T = 296 K
V = 1235.0 (10) Å³	Chunk, colourless
Z = 8	0.1 × 0.1 × 0.08 mm

Data collection top

Rigaku Mercury CCD (2×2 bin mode) diffractometer	1348 reflections with I > 2σ(I)
dtprofit.ref scans	R_int = 0.055
Absorption correction: multi-scan (Blessing, 1995)	θ_max = 29.1°, θ_min = 2.9°
T_min = 0.427, T_max = 0.504	h = −12→12
9319 measured reflections	k = −12→12
1534 independent reflections	l = −13→18

Refinement top

Refinement on F²	0 restraints
Least-squares matrix: full	w = 1/[σ²(F_o²) + (0.0304P)² + 3.9371P] where P = (F_o² + 2F_c²)/3
R[F² > 2σ(F²)] = 0.059	(Δ/σ)_max < 0.001
wR(F²) = 0.111	Δρ_max = 1.49 e Å⁻³
S = 1.34	Δρ_min = −0.76 e Å⁻³
1534 reflections	Extinction correction: SHELXL97 (Sheldrick, 2008), Fc^*=kFc[1+0.001xFc²λ³/sin(2θ)]^-1/4
101 parameters	Extinction coefficient: 0.0060 (6)

Crystal data top

Sr(BF₄)₂	V = 1235.0 (10) Å³
M_r = 261.24	Z = 8
Orthorhombic, Pbca	Mo Kα radiation
a = 9.602 (5) Å	µ = 8.83 mm⁻¹
b = 9.259 (5) Å	T = 296 K
c = 13.890 (6) Å	0.1 × 0.1 × 0.08 mm

Data collection top

Rigaku Mercury CCD (2×2 bin mode) diffractometer	1534 independent reflections
Absorption correction: multi-scan (Blessing, 1995)	1348 reflections with I > 2σ(I)
T_min = 0.427, T_max = 0.504	R_int = 0.055
9319 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.059	101 parameters
wR(F²) = 0.111	0 restraints
S = 1.34	Δρ_max = 1.49 e Å⁻³
1534 reflections	Δρ_min = −0.76 e Å⁻³

Special details top

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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å²) top

	x	y	z	U_iso*/U_eq
Sr1	0.53509 (5)	0.78270 (6)	0.39754 (4)	0.0214 (2)
F2	0.2628 (4)	0.7814 (5)	0.6796 (3)	0.0431 (10)
F3	0.6301 (4)	0.4245 (4)	0.6141 (2)	0.0374 (9)
F4	0.4129 (5)	0.9714 (4)	0.6689 (3)	0.0486 (11)
F5	0.4293 (4)	0.7833 (5)	0.5643 (3)	0.0434 (10)
F6	0.7968 (4)	0.6007 (5)	0.6175 (3)	0.0496 (11)
F7	0.8134 (4)	0.4170 (5)	0.5121 (3)	0.0519 (11)
F8	0.6463 (4)	0.5843 (4)	0.4918 (3)	0.0445 (10)
F9	0.4886 (4)	0.7529 (4)	0.7219 (3)	0.0399 (9)
B10	0.3972 (7)	0.8234 (8)	0.6588 (5)	0.0272 (15)
B11	0.7214 (7)	0.5074 (7)	0.5589 (5)	0.0256 (14)

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Sr1	0.0213 (3)	0.0216 (3)	0.0214 (4)	−0.0015 (2)	−0.0008 (2)	−0.0003 (2)
F2	0.0295 (19)	0.060 (3)	0.040 (2)	−0.0102 (18)	−0.0007 (17)	0.0045 (19)
F3	0.043 (2)	0.034 (2)	0.035 (2)	−0.0143 (17)	0.0036 (16)	0.0031 (16)
F4	0.069 (3)	0.031 (2)	0.046 (2)	−0.010 (2)	−0.002 (2)	0.0059 (18)
F5	0.043 (2)	0.065 (3)	0.022 (2)	0.004 (2)	0.0027 (16)	−0.0021 (18)
F6	0.045 (2)	0.056 (3)	0.047 (2)	−0.025 (2)	−0.0024 (19)	−0.008 (2)
F7	0.056 (2)	0.051 (3)	0.049 (2)	0.022 (2)	0.018 (2)	−0.001 (2)
F8	0.038 (2)	0.042 (2)	0.054 (2)	0.0036 (18)	−0.0078 (18)	0.0224 (19)
F9	0.043 (2)	0.052 (2)	0.025 (2)	0.0079 (18)	−0.0078 (16)	0.0040 (17)
B10	0.024 (3)	0.037 (4)	0.022 (4)	−0.002 (3)	−0.002 (3)	0.009 (3)
B11	0.025 (3)	0.027 (3)	0.025 (4)	0.002 (3)	0.001 (3)	0.001 (3)

Geometric parameters (Å, º) top

Sr1—F7ⁱ	2.490 (4)	F2—B10	1.378 (7)
Sr1—F3ⁱⁱ	2.495 (4)	F3—B11	1.395 (7)
Sr1—F8	2.496 (4)	F4—B10	1.386 (8)
Sr1—F9ⁱⁱⁱ	2.502 (4)	F5—B10	1.398 (8)
Sr1—F2^iv	2.506 (4)	F6—B11	1.390 (8)
Sr1—F4^v	2.507 (4)	F7—B11	1.379 (7)
Sr1—F5	2.529 (4)	F8—B11	1.376 (7)
Sr1—F6^vi	2.538 (4)	F9—B10	1.402 (7)

F7ⁱ—Sr1—F3ⁱⁱ	142.89 (13)	F9ⁱⁱⁱ—Sr1—F6^vi	79.36 (13)
F7ⁱ—Sr1—F8	77.41 (14)	F2^iv—Sr1—F6^vi	148.44 (13)
F3ⁱⁱ—Sr1—F8	74.94 (13)	F4^v—Sr1—F6^vi	76.29 (16)
F7ⁱ—Sr1—F9ⁱⁱⁱ	142.51 (13)	F5—Sr1—F6^vi	73.28 (13)
F3ⁱⁱ—Sr1—F9ⁱⁱⁱ	73.85 (12)	B10—F2—Sr1^vi	142.6 (4)
F8—Sr1—F9ⁱⁱⁱ	119.39 (14)	B11—F3—Sr1ⁱⁱ	141.9 (4)
F7ⁱ—Sr1—F2^iv	83.19 (14)	B10—F4—Sr1^v	151.9 (4)
F3ⁱⁱ—Sr1—F2^iv	110.18 (14)	B10—F5—Sr1	161.5 (4)
F8—Sr1—F2^iv	71.13 (13)	B11—F6—Sr1^iv	133.3 (4)
F9ⁱⁱⁱ—Sr1—F2^iv	73.00 (13)	B11—F7—Sr1^vii	168.1 (4)
F7ⁱ—Sr1—F4^v	70.44 (14)	B11—F8—Sr1	163.7 (4)
F3ⁱⁱ—Sr1—F4^v	143.24 (14)	B10—F9—Sr1^viii	141.6 (4)
F8—Sr1—F4^v	140.92 (14)	F2—B10—F4	111.1 (6)
F9ⁱⁱⁱ—Sr1—F4^v	78.25 (13)	F2—B10—F5	109.2 (5)
F2^iv—Sr1—F4^v	83.34 (14)	F4—B10—F5	109.5 (5)
F7ⁱ—Sr1—F5	69.41 (14)	F2—B10—F9	108.9 (5)
F3ⁱⁱ—Sr1—F5	78.79 (13)	F4—B10—F9	109.2 (5)
F8—Sr1—F5	72.12 (13)	F5—B10—F9	109.0 (5)
F9ⁱⁱⁱ—Sr1—F5	145.25 (13)	F8—B11—F7	109.3 (5)
F2^iv—Sr1—F5	137.93 (13)	F8—B11—F6	110.3 (5)
F4^v—Sr1—F5	114.53 (14)	F7—B11—F6	108.6 (5)
F7ⁱ—Sr1—F6^vi	111.52 (15)	F8—B11—F3	109.2 (5)
F3ⁱⁱ—Sr1—F6^vi	75.44 (15)	F7—B11—F3	109.1 (5)
F8—Sr1—F6^vi	137.88 (14)	F6—B11—F3	110.3 (5)

Symmetry codes: (i) −x+3/2, y+1/2, z; (ii) −x+1, −y+1, −z+1; (iii) x, −y+3/2, z−1/2; (iv) x+1/2, −y+3/2, −z+1; (v) −x+1, −y+2, −z+1; (vi) x−1/2, −y+3/2, −z+1; (vii) −x+3/2, y−1/2, z; (viii) x, −y+3/2, z+1/2.

Experimental details

Crystal data
Chemical formula	Sr(BF₄)₂
M_r	261.24
Crystal system, space group	Orthorhombic, Pbca
Temperature (K)	296
a, b, c (Å)	9.602 (5), 9.259 (5), 13.890 (6)
V (Å³)	1235.0 (10)
Z	8
Radiation type	Mo Kα
µ (mm⁻¹)	8.83
Crystal size (mm)	0.1 × 0.1 × 0.08

Data collection
Diffractometer	Rigaku Mercury CCD (2×2 bin mode) diffractometer
Absorption correction	Multi-scan (Blessing, 1995)
T_min, T_max	0.427, 0.504
No. of measured, independent and observed [I > 2σ(I)] reflections	9319, 1534, 1348
R_int	0.055
(sin θ/λ)_max (Å⁻¹)	0.685

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.059, 0.111, 1.34
No. of reflections	1534
No. of parameters	101
Δρ_max, Δρ_min (e Å⁻³)	1.49, −0.76

Computer programs: CrystalClear (Rigaku, 1999), SIR92 (Altomare et al., 1993) and TEXSAN (Molecular Structure Corporation, 1999), SHELXL97 (Sheldrick, 2008), WinGX (Version 1.70; Farrugia, 1999) and enCIFer (Version 1.2; Allen et al., 2004).

Acknowledgements

The authors gratefully acknowledge Dr Stefan Adams (Department of Materials Science and Engineering, National University of Singapore), who first noted some discrepancies in the structure, erroneously entitled as strontium tetrafluoroborate, and to the Slovenian Research Agency (ARRS) for the financial support of the Research Program P1-0045 (Inorganic Chemistry and Technology).

References

Allen, F. H., Johnson, O., Shields, G. P., Smith, B. R. & Towler, M. (2004). J. Appl. Cryst. 37, 335–338. Web of Science CrossRef CAS IUCr Journals Google Scholar
Altomare, A., Cascarano, G., Giacovazzo, C. & Guagliardi, A. (1993). J. Appl. Cryst. 26, 343–350. CrossRef Web of Science IUCr Journals Google Scholar
Blessing, R. H. (1995). Acta Cryst. A51, 33–38. CrossRef CAS Web of Science IUCr Journals Google Scholar
Bunič, T., Tavčar, G., Goreshnik, E. & Žemva, B. (2007). Acta Cryst. C63, i75–i76. Web of Science CrossRef IUCr Journals Google Scholar
Farrugia, L. J. (1999). J. Appl. Cryst. 32, 837–838. CrossRef CAS IUCr Journals Google Scholar
Jordan, T. H., Dickens, B., Schroeder, L. W. & Brown, W. E. (1975). Acta Cryst. B31, 669–672. CrossRef CAS IUCr Journals Web of Science Google Scholar
Molecular Structure Corporation (1999). TEXSAN for Windows. Version 1.06. MSC, The Woodlands, Texas, USA. Google Scholar
Rigaku (1999). CrystalClear. Rigaku Corporation, Tokyo, Japan. Google Scholar
Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. Web of Science CrossRef CAS IUCr Journals Google Scholar
Tavčar, G. & Žemva, B. (2005). Inorg. Chem. 44, 1525–1529. Web of Science PubMed Google Scholar

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