Supporting information
Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270107036864/fa3102sup1.cif | |
Structure factor file (CIF format) https://doi.org/10.1107/S0108270107036864/fa3102Isup2.hkl | |
Structure factor file (CIF format) https://doi.org/10.1107/S0108270107036864/fa3102IIsup3.hkl |
Sr(BF_{4})_{2} was prepared by the reaction between SrF_{2} (Alfa Aesar, 99.99%) and excess BF_{3} (Union Carbide, 99.5%) in anhydrous HF (Fluka, purum) as solvent. When the reaction was complete, the solvent and excess BF_{3} were removed on a vacuum line. Ba(BF_{4})_{2} was prepared in a similar way starting from BaF_{2} (Alfa Aesar, 99.99%). The bulk samples were characterized by Raman spectroscopy [793, 533, 353 cm^{-1} for Sr(BF_{4})_{2}; 783, 536, 355 cm^{-1} for Ba(BF_{4})_{2}] and X-ray powder diffraction. Samples for diffraction analysis were grown by crystallization of an M(BF_{4})_{2} (M = Sr and Ba) solution in anhydrous HF with a temperature gradient of 10 ° in an FEP crystallization vessel. Crystals were immersed in perfluoronated oil (ABCR, FO5960) in a dry box, selected under the microscope and transferred into the cold nitrogen stream of the diffractometer.
For both compounds, data collection: CrystalClear (Rigaku Corporation, 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, 1997); molecular graphics: Diamond (Pennington, 1999); software used to prepare material for publication: WinGX (Version 1.70; Farrugia, 1999) and enCIFer (Version 1.2; Allen et al., 2004).
Ba(BF_{4})_{2} | F(000) = 276 |
M_{r} = 310.96 | D_{x} = 3.724 Mg m^{−}^{3} |
Monoclinic, C2/m | Mo Kα radiation, λ = 0.71069 Å |
Hall symbol: -C 2y | Cell parameters from 51 reflections |
a = 12.513 (9) Å | θ = 3.5–28.7° |
b = 5.0135 (13) Å | µ = 7.27 mm^{−}^{1} |
c = 4.7628 (15) Å | T = 200 K |
β = 111.854 (4)° | Chunk, colourless |
V = 277.3 (2) Å^{3} | 0.1 × 0.08 × 0.06 mm |
Z = 2 |
Rigaku Mercury CCD diffractometer | 342 reflections with I > 2σ(I) |
ω scans | R_{int} = 0.049 |
Absorption correction: multi-scan (Blessing, 1995) | θ_{max} = 28.6°, θ_{min} = 3.5° |
T_{min} = 0.471, T_{max} = 0.650 | h = −15→6 |
596 measured reflections | k = −6→6 |
342 independent reflections | l = −6→6 |
Refinement on F^{2} | 0 restraints |
Least-squares matrix: full | Primary atom site location: structure-invariant direct methods |
R[F^{2} > 2σ(F^{2})] = 0.029 | Secondary atom site location: difference Fourier map |
wR(F^{2}) = 0.070 | w = 1/[σ^{2}(F_{o}^{2}) + (0.0297P)^{2} + 0.5815P] where P = (F_{o}^{2} + 2F_{c}^{2})/3 |
S = 1.19 | (Δ/σ)_{max} < 0.001 |
342 reflections | Δρ_{max} = 1.14 e Å^{−}^{3} |
32 parameters | Δρ_{min} = −1.11 e Å^{−}^{3} |
Ba(BF_{4})_{2} | V = 277.3 (2) Å^{3} |
M_{r} = 310.96 | Z = 2 |
Monoclinic, C2/m | Mo Kα radiation |
a = 12.513 (9) Å | µ = 7.27 mm^{−}^{1} |
b = 5.0135 (13) Å | T = 200 K |
c = 4.7628 (15) Å | 0.1 × 0.08 × 0.06 mm |
β = 111.854 (4)° |
Rigaku Mercury CCD diffractometer | 342 independent reflections |
Absorption correction: multi-scan (Blessing, 1995) | 342 reflections with I > 2σ(I) |
T_{min} = 0.471, T_{max} = 0.650 | R_{int} = 0.049 |
596 measured reflections |
R[F^{2} > 2σ(F^{2})] = 0.029 | 32 parameters |
wR(F^{2}) = 0.070 | 0 restraints |
S = 1.19 | Δρ_{max} = 1.14 e Å^{−}^{3} |
342 reflections | Δρ_{min} = −1.11 e Å^{−}^{3} |
x | y | z | U_{iso}*/U_{eq} | ||
Ba1 | 0.0000 | 0.0000 | 1.0000 | 0.0151 (2) | |
F1 | 0.1010 (4) | 0.5000 | 0.9273 (9) | 0.0152 (9) | |
F2 | 0.2704 (3) | 0.5000 | 0.8507 (10) | 0.0156 (9) | |
F3 | 0.1154 (3) | 0.2718 (7) | 0.5323 (7) | 0.0206 (7) | |
B1 | 0.1531 (7) | 0.5000 | 0.7084 (17) | 0.0118 (15) |
U^{11} | U^{22} | U^{33} | U^{12} | U^{13} | U^{23} | |
Ba1 | 0.0149 (3) | 0.0145 (4) | 0.0135 (3) | 0.000 | 0.0026 (2) | 0.000 |
F1 | 0.0160 (19) | 0.017 (2) | 0.014 (2) | 0.000 | 0.0076 (16) | 0.000 |
F2 | 0.0106 (19) | 0.017 (2) | 0.018 (2) | 0.000 | 0.0038 (16) | 0.000 |
F3 | 0.0223 (15) | 0.0168 (16) | 0.0189 (15) | 0.0011 (13) | 0.0034 (12) | −0.0093 (13) |
B1 | 0.016 (4) | 0.009 (4) | 0.008 (3) | 0.000 | 0.003 (3) | 0.000 |
Ba1—F2^{i} | 2.690 (5) | F1—B1 | 1.420 (9) |
Ba1—F3^{ii} | 2.765 (3) | F2—B1 | 1.369 (9) |
Ba1—F1 | 2.886 (2) | F3—B1 | 1.393 (5) |
Ba1—Ba1^{iii} | 4.7628 (15) | ||
F2^{i}—Ba1—F3^{ii} | 112.60 (10) | F3^{vii}—Ba1—F1 | 115.82 (11) |
F2^{iv}—Ba1—F3^{ii} | 67.40 (10) | F1—Ba1—F1^{viii} | 120.60 (15) |
F3^{ii}—Ba1—F3^{v} | 59.07 (15) | F1^{ix}—Ba1—F1^{viii} | 59.40 (15) |
F3^{vi}—Ba1—F3^{v} | 120.93 (15) | Ba1—F1—Ba1^{x} | 120.60 (15) |
F2^{i}—Ba1—F1 | 63.85 (8) | F2—B1—F3 | 111.0 (4) |
F2^{iv}—Ba1—F1 | 116.15 (8) | F3—B1—F3^{xi} | 110.4 (6) |
F3^{ii}—Ba1—F1 | 114.89 (11) | F2—B1—F1 | 109.7 (6) |
F3^{vi}—Ba1—F1 | 65.11 (11) | F3—B1—F1 | 107.3 (4) |
F3^{v}—Ba1—F1 | 64.18 (11) |
Symmetry codes: (i) −x+1/2, −y+1/2, −z+2; (ii) −x, −y, −z+1; (iii) x, y, z−1; (iv) x−1/2, y−1/2, z; (v) −x, y, −z+1; (vi) x, y, z+1; (vii) x, −y, z+1; (viii) x, y−1, z; (ix) −x, −y, −z+2; (x) x, y+1, z; (xi) x, −y+1, z. |
Sr(BF_{4})_{2} | F(000) = 960 |
M_{r} = 261.24 | D_{x} = 3.313 Mg m^{−}^{3} |
Orthorhombic, Pbca | Mo Kα radiation, λ = 0.71069 Å |
Hall symbol: -P 2ac 2ab | Cell parameters from 77 reflections |
a = 9.121 (7) Å | θ = 1.6–28.7° |
b = 8.714 (6) Å | µ = 10.41 mm^{−}^{1} |
c = 13.180 (9) Å | T = 200 K |
V = 1047.6 (13) Å^{3} | Chunk, colourless |
Z = 8 | 0.07 × 0.07 × 0.05 mm |
Rigaku Mercury CCD (2 × 2 bin mode) diffractometer | 1253 independent reflections |
Radiation source: fine-focus sealed tube | 1132 reflections with I > 2σ(I) |
Graphite monochromator | R_{int} = 0.016 |
Detector resolution: 14.7059 pixels mm^{-1} | θ_{max} = 28.7°, θ_{min} = 3.1° |
dtprofit.ref scans | h = −10→12 |
Absorption correction: multi-scan (Blessing; 1995) | k = −11→10 |
T_{min} = 0.486, T_{max} = 0.595 | l = −17→14 |
4207 measured reflections |
Refinement on F^{2} | 0 restraints |
Least-squares matrix: full | Primary atom site location: structure-invariant direct methods |
R[F^{2} > 2σ(F^{2})] = 0.046 | Secondary atom site location: difference Fourier map |
wR(F^{2}) = 0.153 | w = 1/[σ^{2}(F_{o}^{2}) + (0.0951P)^{2} + 10.4343P] where P = (F_{o}^{2} + 2F_{c}^{2})/3 |
S = 1.09 | (Δ/σ)_{max} = 0.001 |
1253 reflections | Δρ_{max} = 2.11 e Å^{−}^{3} |
100 parameters | Δρ_{min} = −1.48 e Å^{−}^{3} |
Sr(BF_{4})_{2} | V = 1047.6 (13) Å^{3} |
M_{r} = 261.24 | Z = 8 |
Orthorhombic, Pbca | Mo Kα radiation |
a = 9.121 (7) Å | µ = 10.41 mm^{−}^{1} |
b = 8.714 (6) Å | T = 200 K |
c = 13.180 (9) Å | 0.07 × 0.07 × 0.05 mm |
Rigaku Mercury CCD (2 × 2 bin mode) diffractometer | 1253 independent reflections |
Absorption correction: multi-scan (Blessing; 1995) | 1132 reflections with I > 2σ(I) |
T_{min} = 0.486, T_{max} = 0.595 | R_{int} = 0.016 |
4207 measured reflections |
R[F^{2} > 2σ(F^{2})] = 0.046 | 0 restraints |
wR(F^{2}) = 0.153 | w = 1/[σ^{2}(F_{o}^{2}) + (0.0951P)^{2} + 10.4343P] where P = (F_{o}^{2} + 2F_{c}^{2})/3 |
S = 1.09 | Δρ_{max} = 2.11 e Å^{−}^{3} |
1253 reflections | Δρ_{min} = −1.48 e Å^{−}^{3} |
100 parameters |
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 F^{2} against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F^{2}, conventional R-factors R are based on F, with F set to zero for negative F^{2}. The threshold expression of F^{2} > σ(F^{2}) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F^{2} are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger. |
x | y | z | U_{iso}*/U_{eq} | ||
Sr1 | 1.03288 (5) | 0.78148 (6) | 0.60416 (3) | 0.0087 (2) | |
F11 | 0.8753 (5) | 0.5772 (5) | 0.6205 (3) | 0.0288 (9) | |
F12 | 0.6983 (5) | 0.3937 (5) | 0.6186 (3) | 0.0319 (10) | |
F13 | 0.6772 (5) | 0.5992 (5) | 0.5156 (3) | 0.0345 (10) | |
F14 | 0.8550 (5) | 0.4215 (5) | 0.4832 (3) | 0.0322 (10) | |
F21 | 0.9248 (6) | 0.7683 (5) | 0.4418 (3) | 0.0303 (9) | |
F22 | 0.7504 (5) | 0.7765 (5) | 0.3172 (3) | 0.0324 (10) | |
F23 | 0.9134 (6) | 0.9745 (5) | 0.3345 (3) | 0.0364 (10) | |
F24 | 0.9899 (5) | 0.7414 (6) | 0.2754 (4) | 0.0303 (10) | |
B1 | 0.7770 (8) | 0.4970 (9) | 0.5596 (6) | 0.0241 (14) | |
B2 | 0.8943 (9) | 0.8161 (10) | 0.3424 (6) | 0.0241 (14) |
U^{11} | U^{22} | U^{33} | U^{12} | U^{13} | U^{23} | |
Sr1 | 0.0082 (3) | 0.0086 (4) | 0.0092 (3) | −0.00038 (15) | 0.00023 (14) | 0.00025 (15) |
F11 | 0.029 (2) | 0.029 (2) | 0.0282 (19) | −0.0052 (18) | −0.0043 (17) | 0.0008 (16) |
F12 | 0.029 (2) | 0.034 (2) | 0.033 (2) | −0.0095 (19) | −0.0014 (17) | 0.0058 (18) |
F13 | 0.035 (2) | 0.035 (2) | 0.034 (2) | 0.0085 (19) | −0.0038 (18) | 0.0020 (18) |
F14 | 0.029 (2) | 0.031 (2) | 0.037 (2) | 0.0013 (18) | 0.0027 (18) | −0.0075 (18) |
F21 | 0.032 (2) | 0.039 (3) | 0.021 (2) | −0.0011 (19) | 0.0001 (19) | 0.0017 (17) |
F22 | 0.0226 (19) | 0.047 (3) | 0.027 (2) | −0.0050 (18) | 0.0010 (18) | −0.0036 (18) |
F23 | 0.047 (3) | 0.029 (2) | 0.033 (2) | −0.004 (2) | −0.001 (2) | −0.0035 (18) |
F24 | 0.029 (2) | 0.037 (2) | 0.025 (2) | 0.004 (2) | 0.0037 (19) | −0.0014 (19) |
B1 | 0.021 (3) | 0.026 (3) | 0.025 (4) | −0.001 (3) | −0.004 (3) | 0.002 (3) |
B2 | 0.024 (3) | 0.028 (4) | 0.020 (3) | 0.001 (3) | −0.003 (3) | −0.006 (3) |
Sr1—F22^{i} | 2.294 (5) | F11—B1 | 1.392 (9) |
Sr1—F11 | 2.298 (5) | F12—B1 | 1.389 (9) |
Sr1—F24^{ii} | 2.299 (5) | F13—B1 | 1.399 (8) |
Sr1—F13^{i} | 2.303 (4) | F14—B1 | 1.397 (9) |
Sr1—F23^{iii} | 2.327 (5) | F21—B2 | 1.402 (9) |
Sr1—F12^{iv} | 2.333 (5) | F22—B2 | 1.398 (9) |
Sr1—F14^{v} | 2.345 (4) | F23—B2 | 1.395 (10) |
Sr1—F21 | 2.359 (5) | F24—B2 | 1.401 (9) |
Sr1—Sr1^{iii} | 4.733 (2) | ||
F22^{i}—Sr1—F11 | 109.12 (17) | F13^{i}—Sr1—F21 | 68.86 (17) |
F22^{i}—Sr1—F24^{ii} | 71.64 (17) | F23^{iii}—Sr1—F21 | 116.60 (16) |
F11—Sr1—F24^{ii} | 74.58 (16) | F12^{iv}—Sr1—F21 | 73.53 (16) |
F22^{i}—Sr1—F13^{i} | 85.11 (17) | F14^{v}—Sr1—F21 | 72.55 (16) |
F11—Sr1—F13^{i} | 140.48 (16) | B1—F11—Sr1 | 137.5 (4) |
F24^{ii}—Sr1—F13^{i} | 144.01 (17) | B1—F12—Sr1^{vi} | 133.8 (4) |
F22^{i}—Sr1—F23^{iii} | 82.09 (17) | B1—F13—Sr1^{vii} | 160.6 (4) |
F11—Sr1—F23^{iii} | 143.80 (17) | B1—F14—Sr1^{v} | 158.6 (4) |
F24^{ii}—Sr1—F23^{iii} | 76.93 (17) | B2—F21—Sr1 | 156.3 (5) |
F13^{i}—Sr1—F23^{iii} | 72.86 (17) | B2—F22—Sr1^{vii} | 139.4 (4) |
F22^{i}—Sr1—F12^{iv} | 146.84 (15) | B2—F23—Sr1^{iii} | 154.7 (4) |
F11—Sr1—F12^{iv} | 75.63 (18) | B2—F24—Sr1^{viii} | 139.9 (4) |
F24^{ii}—Sr1—F12^{iv} | 78.57 (16) | F12—B1—F11 | 109.5 (6) |
F13^{i}—Sr1—F12^{iv} | 112.55 (17) | F12—B1—F14 | 111.2 (6) |
F23^{iii}—Sr1—F12^{iv} | 77.22 (18) | F11—B1—F14 | 108.9 (6) |
F22^{i}—Sr1—F14^{v} | 71.26 (16) | F12—B1—F13 | 108.0 (6) |
F11—Sr1—F14^{v} | 74.61 (16) | F11—B1—F13 | 109.8 (6) |
F24^{ii}—Sr1—F14^{v} | 119.42 (18) | F14—B1—F13 | 109.4 (6) |
F13^{i}—Sr1—F14^{v} | 75.79 (16) | F23—B2—F22 | 110.1 (6) |
F23^{iii}—Sr1—F14^{v} | 140.16 (17) | F23—B2—F24 | 109.6 (7) |
F12^{iv}—Sr1—F14^{v} | 138.64 (16) | F22—B2—F24 | 108.7 (6) |
F22^{i}—Sr1—F21 | 139.50 (17) | F23—B2—F21 | 109.8 (6) |
F11—Sr1—F21 | 77.64 (16) | F22—B2—F21 | 109.6 (6) |
F24^{ii}—Sr1—F21 | 144.57 (17) | F24—B2—F21 | 109.1 (6) |
Symmetry codes: (i) x+1/2, −y+3/2, −z+1; (ii) x, −y+3/2, z+1/2; (iii) −x+2, −y+2, −z+1; (iv) −x+3/2, y+1/2, z; (v) −x+2, −y+1, −z+1; (vi) −x+3/2, y−1/2, z; (vii) x−1/2, −y+3/2, −z+1; (viii) x, −y+3/2, z−1/2. |
Experimental details
(I) | (II) | |
Crystal data | ||
Chemical formula | Ba(BF_{4})_{2} | Sr(BF_{4})_{2} |
M_{r} | 310.96 | 261.24 |
Crystal system, space group | Monoclinic, C2/m | Orthorhombic, Pbca |
Temperature (K) | 200 | 200 |
a, b, c (Å) | 12.513 (9), 5.0135 (13), 4.7628 (15) | 9.121 (7), 8.714 (6), 13.180 (9) |
α, β, γ (°) | 90, 111.854 (4), 90 | 90, 90, 90 |
V (Å^{3}) | 277.3 (2) | 1047.6 (13) |
Z | 2 | 8 |
Radiation type | Mo Kα | Mo Kα |
µ (mm^{−}^{1}) | 7.27 | 10.41 |
Crystal size (mm) | 0.1 × 0.08 × 0.06 | 0.07 × 0.07 × 0.05 |
Data collection | ||
Diffractometer | Rigaku Mercury CCD diffractometer | Rigaku Mercury CCD (2 × 2 bin mode) diffractometer |
Absorption correction | Multi-scan (Blessing, 1995) | Multi-scan (Blessing; 1995) |
T_{min}, T_{max} | 0.471, 0.650 | 0.486, 0.595 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 596, 342, 342 | 4207, 1253, 1132 |
R_{int} | 0.049 | 0.016 |
(sin θ/λ)_{max} (Å^{−}^{1}) | 0.673 | 0.676 |
Refinement | ||
R[F^{2} > 2σ(F^{2})], wR(F^{2}), S | 0.029, 0.070, 1.19 | 0.046, 0.153, 1.09 |
No. of reflections | 342 | 1253 |
No. of parameters | 32 | 100 |
w = 1/[σ^{2}(F_{o}^{2}) + (0.0297P)^{2} + 0.5815P] where P = (F_{o}^{2} + 2F_{c}^{2})/3 | w = 1/[σ^{2}(F_{o}^{2}) + (0.0951P)^{2} + 10.4343P] where P = (F_{o}^{2} + 2F_{c}^{2})/3 | |
Δρ_{max}, Δρ_{min} (e Å^{−}^{3}) | 1.14, −1.11 | 2.11, −1.48 |
Computer programs: CrystalClear (Rigaku Corporation, 1999), CrystalClear, SIR92 (Altomare et al., 1993) and TEXSAN (Molecular Structure Corporation, 1999), SHELXL97 (Sheldrick, 1997), Diamond (Pennington, 1999), WinGX (Version 1.70; Farrugia, 1999) and enCIFer (Version 1.2; Allen et al., 2004).
Ba1—F2^{i} | 2.690 (5) | F1—B1 | 1.420 (9) |
Ba1—F3^{ii} | 2.765 (3) | F2—B1 | 1.369 (9) |
Ba1—F1 | 2.886 (2) | F3—B1 | 1.393 (5) |
Ba1—Ba1^{iii} | 4.7628 (15) | ||
F2—B1—F3 | 111.0 (4) | F2—B1—F1 | 109.7 (6) |
F3—B1—F3^{iv} | 110.4 (6) | F3—B1—F1 | 107.3 (4) |
Symmetry codes: (i) −x+1/2, −y+1/2, −z+2; (ii) −x, −y, −z+1; (iii) x, y, z−1; (iv) x, −y+1, z. |
Sr(BF_{4})_{2} appears to be isomorphous with the previously reported compound Ca(BF_{4})_{2} (Jordan et al., 1975). In this structure, the metal atom possesses coordination number 8 with a square-antiprismatic coordination polyhedron. The Sr—F distances lie in the narrow range of 2.294 (5)–2.359 (4) Å compared with 2.33–2.401 Å in Ca(BF_{4})_{2}. The metal center is bonded to eight BF_{4}^{-} units. In turn, each anion is connected to four Sr atoms. All four F atoms in each anion act as µ_{2} bridges between B and Sr atoms, resulting in very similar B—F bond lengths of 1.389 (9)–1.399 (9) Å [please check range of values].
Because of the much greater coordination ability of barium compared with strontium, the structure of Ba(BF_{4})_{2} appears to be more complicated. The Ba atom, located on special position 2a (2/m), possesses coordination number 14 (or 10 + 4). Ten Ba—F bond lengths lie in the range 2.690 (5)–2.886 (2) Å, and there are four longer Ba—F distances of 3.361 (5) Å. Each Ba atom is surrounded by ten BF_{4}^{-} anions. The coordination polyhedron of barium shares two edges and two rectangular planes with four other metal centers. The shortest Ba···Ba distances are 4.763 (2) Å for two Ba atoms with a shared plane and 5.014 (1) Å for a pair of metal atoms connected by a shared edge (Fig. 1).
The B atom and two of the three crystallographically independent F atoms of each BF_{4}^{-} unit lie on mirror planes (4i Wyckoff positions). Each tetrafluoridoborate anion is bonded to five Ba atoms. The B—F distances clearly correlate with the bridging function of each F atom. The shortest B—F distance [B1—F2 = 1.369 (9) Å] is associated with the µ_{2} bridging function of atom F2. Two B1—F3 bond lengths of 1.393 (5) Å correspond to the µ_{3} bridging function of atom F3, which forms a shared corner between two Ba atoms. The longest B—F distance [B1—F1 = 1.420 (9) Å] corresponds to the location of atom F1 on an edge shared by two barium polyhedra. The bridging functions of both cations and anions result in the formation of a three-dimensional network (Fig. 2).
The results obtained for Ba(BF_{4})_{2} differ strongly from those from a previously published structure of Ba(BF_{4})_{2} [published as Ba_{2}(BF_{4})_{4} (Lin et al., 1998); space group P2_{1}/n, a = 8.339 (3) Å, b = 16.530 (7) Å, c = 10.212 (4) Å, β = 106.64 (3)°, V = 1349 (2) Å^{3}], in which the Ba atom possesses the unusually low coordination number 9 and the Ba—F distances are in the range 2.69 (2)–2.91 (3) Å. The radial distribution functions for the Ba(BF_{4})_{2} and Ba_{2}(BF_{4})_{4} structures are noticeably different.