Low-temperature modification of Ba(BF4)2(H2O)3

Goreshnik, E.; Vakulka, A.; Tavčar, G.

doi:10.1107/S2414314623004881

inorganic compounds

IUCrDATA

ISSN: 2414-3146

Volume 8| Part 6| June 2023| x230488

https://doi.org/10.1107/S2414314623004881

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Low-temperature modification of Ba(BF₄)₂(H₂O)₃

Evgeny Goreshnik,^a ^* Andrii Vakulka ^b and Gašper Tavčar ^a

^aDepartment of Inorganic Chemistry and Technology, Jožef Stefan Institute, Jamova 39 1000 Ljubljana, Slovenia, and ^bFaculty of Mechanical Engineering, University of Ljubljana, Aškerčeva cesta 6, 1000 Ljubljana, Slovenia
^*Correspondence e-mail: evgeny.goreshnik@ijs.si

Edited by M. Weil, Vienna University of Technology, Austria (Received 19 May 2023; accepted 5 June 2023; online 9 June 2023)

The crystal structure of the low-temperature modification of Ba(BF₄)₂(H₂O)₃, barium bis(tetrafluoridoborate) trihydrate, was determined at 150 K. In contrast to the room-temperature modification, which crystallizes in the space group C222₁ [a = 7.1763 (6), b = 18.052 (2), c = 7.1631 (6) Å, V = 927.93 (15) Å³ at 300 K, Z = 4; Charkin et al. (2023 ). J. Struct. Chem. 64, 253–261], the low-temperature phase is monoclinic, space group P2₁ [a = 7.0550 (4), b = 7.1706 (3), c = 9.4182 (6) Å, β = 109.295 (7)^o, V = 449.68 (5) Å³, Z = 2]. The structure of the low-temperature modification of Ba(BF₄)₂(H₂O)₃ features O—H⋯F and O—H⋯O hydrogen bonding between water molecules and BF₄⁻ anions. One of the coordinating water molecules in the low-temperature modification is disordered over two sets of sites.

Keywords: low-temperature modification; phase transition; barium tetrafluoridoborate; crystal structure.

CCDC reference: 2267617

Structure description

Recently, the orthorhombic crystal structure of the compound Ba(BF₄)₂(H₂O)₃ was reported on the basis of room-temperature (RT) single-crystal data in space group C222₁ (Charkin et al., 2023). The authors observed a phase transition at decreasing temperature but were unable to solve the crystal structure of the low-temperature (LT) modification. We have now succeeded in solving the crystal structure of LT-Ba(BF₄)₂(H₂O)₃.

The asymmetric unit of LT-Ba(BF₄)₂(H₂O)₃ contains one Ba²⁺ cation, two tetrahedral BF₄⁻ anions and three water molecules, one of which (O3) is disordered over two sets of sites with approximately equal occupancy [ratio 0.56 (2):0.44 (2)]. The Ba²⁺ cation has a coordination number of 10 and is coordinated by seven F ligands from six BF₄⁻ anions and by three water ligands (Fig. 1). In anhydrous Ba(BF₄)₂ (Bunič et al., 2007 ), the Ba²⁺ cation is surrounded by ten BF₄⁻ anions. The B(1)F₄ unit in LT-Ba(BF₄)₂(H₂O)₃ is bound to four Ba²⁺ cations, while the B(2)F₄ unit is connected in a chelate mode to one Ba²⁺ cation and to another via a μ₂-bridging F ligand. Each [BaF₇O₃] coordination polyhedron shares two vertices with two other [BaF₇O₃] polyhedra. The shortest Ba⋯Ba distances amounts to 5.9210 (2) Å. Ba—F bond lengths range from 2.698 (7) to 3.035 (8) Å, and Ba—O bond lengths from 2.777 (9) to 2.821 (8) Å (for ordered water molecules). The spread of Ba—F distances in LT-Ba(BF₄)₂(H₂O)₃ is greater than for the RT-modification [2.729 (4) to 2.843 (17) Å; Charkin et al., 2023]. The B—F distances in LT-Ba(BF₄)₂(H₂O)₃ are in normal ranges, 1.352 (12)–1.406 (16) Å.

Figure 1
The environment of the Ba²⁺ cation in the crystal structure of LT-Ba(BF₄)₂(H₂O)₃. Displacement ellipsoids are drawn at the 50% probability level. Hydrogen bonds are shown as dashed lines. [Symmetry codes: (i) −x + 1, y − $[{1\over 2}]$ , −z; (ii) x + 1, y, z; (iii) −x + 1, y + $[{1\over 2}]$ , −z; (iv) −x + 2, y + $[{1\over 2}]$ , −z + 1; (v) x − 1, y, z; (vi) −x + 2, y − $[{1\over 2}]$ , −z + 1.]

The packing of LT-Ba(BF₄)₂(H₂O)₃ is shown in Fig. 2. The two ordered water molecules form O—H⋯F hydrogen bonds, and the disordered water molecule forms both O—H⋯F and O—H⋯O hydrogen bonds (Fig. 1, Table 1).

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O1—H1A⋯F5ⁱ	0.829 (10)	2.075 (8)	2.892 (12)	168.8 (7)
O1—H1B⋯F7ⁱⁱ	0.842 (10)	2.016 (7)	2.849 (13)	170.5 (7)
O2—H2A⋯F4	0.974 (9)	2.331 (9)	3.119 (13)	137.4 (5)
O2—H2B⋯F8ⁱⁱⁱ	0.977 (9)	2.053 (11)	3.002 (15)	163.5 (7)
O3A—H3AA⋯O2ⁱⁱⁱ	0.88 (2)	2.191 (11)	2.96 (3)	146.5 (18)
O3A—H3AB⋯F7^iv	0.84 (2)	2.386 (8)	3.13 (2)	147.7 (17)
O3B—H3BA⋯F5	0.86 (3)	2.355 (9)	3.15 (3)	153.0 (16)
Symmetry codes: (i) ; (ii) $[-x+2, y-{\script{1\over 2}}, -z+1]$ ; (iii) $[-x+2, y+{\script{1\over 2}}, -z]$ ; (iv) $[-x+2, y+{\script{1\over 2}}, -z+1]$ .

Figure 2
Crystal structure of LT-Ba(BF₄)₂(H₂O)₃ in a view approximately along [100]. Displacement ellipsoids are the same as in Fig. 1

. Display of hydrogen-bonding interactions was omitted for clarity.

The RT unit cell in space group C222₁ with a = 7.1763 (6) Å, b = 18.052 (2) Å, c = 7.1631 (6) Å (Charkin et al., 2023) is related to the LT mP unit cell in P2₁ by the transformation –a, –c, 1/2a + 1/2b, suggesting a translationengleiche symmetry relationship of index 2 (Müller, 2013 ). Considering the significant difference in crystal density for both modifications (2.59 g cm-³ for the RT modification at 300 K, 2.63 g cm⁻³ for the LT modification at 280 K, and 2.59 g cm⁻³ at 150 K), it can be assumed that the formation of a structure with more effective packing is the driving force of the observed phase transition.

We also tried to determine the temperature of the phase transition. It is noteworthy that at 280 K the LT modification remains unchanged, with significantly enlarged unit-cell parameters (Table 2). At 300 K, an orthorhombic cell was indexed with 100% of all observed reflections and with similar lattice parameters as given by Charkin et al. (2023). Thus, we can conclude that the ordered oC ⇌ mP phase transition of Ba(BF₄)₂(H₂O)₃ (accompanied by twinning of the monoclinic LT phase) occurs between 280 and 300 K.

Table 2
Unit-cell parameters (Å, °, Å³) of Ba(BF₄)₂(H₂O)₃ at different temperatures (K)

T	a	b	c	β	V
100	7.0406 (5)	7.1567 (3)	9.3926 (9)	109.292 (7)	446.69 (5)
150	7.0550 (4)	7.1706 (3)	9.4182 (6)	109.295 (7)	449.68 (5)
280	7.1469 (5)	7.1775 (4)	9.5820 (7)	110.254 (6)	461.13 (5)
300	7.1763 (6)	18.052 (2)	7.1631 (6)		927.93 (15)

Synthesis and crystallization

Single crystals of Ba(BF₄)₂(H₂O)₃ were grown from an aqueous solution of Ba(BF₄)₂. Barium carbonate was added in small portions to 40%_wt HBF₄. After completion of the gaseous CO₂ release, the solution was decanted from residual BaCO₃. Evaporation of water at room temperature yielded small crystals of Ba(BF₄)₂(H₂O)₃. Note that an excess of HBF₄ led to the formation of crystals of anhydrous Ba(BF₄)₂ in our experiments.

Refinement

Crystal data, data collection and structure refinement details are summarized in Table 3. The obtained crystals suffer from racemic twinning and additionally show twinning by pseudo-merohedry at decreasing temperature. To avoid complicated refinement, many crystals were tested until a crystal with a Flack parameter (Flack, 1983 ) close to zero was found. The twin law corresponding to a 180° rotation around the [100] direction was determined, and the reflection array was indexed as a two-component twin with a negligible amount of non-indexed reflections. Because of the relatively small amount (BASF = 0.26) of the second domain, the final refinement was performed with a HKLF5-type file containing reflections from the first domain and overlapping reflections. Because of unstable refinement, EADP commands in SHELXL (Sheldrick, 2015 ) were applied to the pair of disordered O3 atoms and also to the pair of B atoms. Hydrogen atoms were placed on calculated positions and refined with AFIX 7 restrictions. One reflection with an error/e.s.d. ratio of 5.5 was omitted.

Table 3
Experimental details

Crystal data
Chemical formula	Ba(BF₄)₂(H₂O)₃
M_r	365.01
Crystal system, space group	Monoclinic, P2₁
Temperature (K)	150
a, b, c (Å)	7.0550 (4), 7.1706 (3), 9.4182 (6)
β (°)	109.295 (7)
V (Å³)	449.68 (5)
Z	2
Radiation type	Mo Kα
μ (mm⁻¹)	4.53
Crystal size (mm)	0.36 × 0.27 × 0.07

Data collection
Diffractometer	New Gemini, Dual, Cu at home/near, Atlas
Absorption correction	Analytical (CrysAlis PRO; Rigaku OD, 2023)
T_min, T_max	0.075, 0.472
No. of measured, independent and observed [I > 2σ(I)] reflections	2386, 2386, 2212
(sin θ/λ)_max (Å⁻¹)	0.674

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.036, 0.089, 1.07
No. of reflections	2386
No. of parameters	120
No. of restraints	1
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.93, −1.05
Absolute structure	Classical Flack method preferred over Parsons because s.u. lower
Absolute structure parameter	−0.03 (4)
Computer programs: CrysAlis PRO (Rigaku OD, 2023 $[Rigaku OD (2023). CrysAlis Pro. Rigaku Oxford Diffraction, Yarnton, England.]$ ), SHELXS (Sheldrick, 2008 ), SHELXL (Sheldrick, 2015), DIAMOND (Putz et al., 2023 ) and OLEX2 (Dolomanov et al., 2009 ).

Structural data

CCDC reference: 2267617

Crystal structure: contains datablock I. DOI: https://doi.org/10.1107/S2414314623004881/wm4190sup1.cif

Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S2414314623004881/wm4190Isup3.hkl

checkCIF report

Computing details top

Data collection: CrysAlis PRO (Rigaku OD, 2023); cell refinement: CrysAlis PRO (Rigaku OD, 2023); data reduction: CrysAlis PRO (Rigaku OD, 2023); program(s) used to solve structure: SHELXS (Sheldrick, 2008); program(s) used to refine structure: SHELXL (Sheldrick, 2015); molecular graphics: DIAMOND (Putz et al., 2023); software used to prepare material for publication: Olex2 (Dolomanov et al., 2009).

Barium bis(tetrafluoridoborate) trihydrate top

Crystal data top

Ba(BF₄)₂(H₂O)₃₂(BF₄)·3(H₂O)·Ba	F(000) = 336
M_r = 365.01	D_x = 2.696 Mg m⁻³
Monoclinic, P2₁	Mo Kα radiation, λ = 0.71073 Å
a = 7.0550 (4) Å	Cell parameters from 5692 reflections
b = 7.1706 (3) Å	θ = 3.0–28.2°
c = 9.4182 (6) Å	µ = 4.53 mm⁻¹
β = 109.295 (7)°	T = 150 K
V = 449.68 (5) Å³	Plate, colourless
Z = 2	0.36 × 0.27 × 0.07 mm

Data collection top

New Gemini, Dual, Cu at home/near, Atlas diffractometer	2386 measured reflections
Radiation source: fine-focus sealed X-ray tube, Enhance (Mo) X-ray Source	2386 independent reflections
Graphite monochromator	2212 reflections with I > 2σ(I)
Detector resolution: 10.6426 pixels mm^-1	θ_max = 28.6°, θ_min = 2.3°
ω scans	h = −9→9
Absorption correction: analytical (CrysAlisPro; Rigaku OD, 2023)	k = −9→9
T_min = 0.075, T_max = 0.472	l = −12→12

Refinement top

Refinement on F²	Hydrogen site location: difference Fourier map
Least-squares matrix: full	H-atom parameters constrained
R[F² > 2σ(F²)] = 0.036	w = 1/[σ²(F_o²) + (0.0656P)²] where P = (F_o² + 2F_c²)/3
wR(F²) = 0.089	(Δ/σ)_max = 0.009
S = 1.07	Δρ_max = 0.93 e Å⁻³
2386 reflections	Δρ_min = −1.05 e Å⁻³
120 parameters	Absolute structure: Classical Flack method preferred over Parsons because s.u. lower
1 restraint	Absolute structure parameter: −0.03 (4)

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.

Refinement. Refined as a 2-component twin.

1. Twinned data refinement Scales: 0.738 (3) 0.262 (3) 2. Fixed Uiso At 1.5 times of: All O(H,H,H,H,H,H,H,H) groups 3. Uiso/Uaniso restraints and constraints Uanis(O3B) = Uanis(O3A) Uanis(B2) = Uanis(B1) Uanis(F4) = Uanis(F2) 4. Others Sof(O3B)=Sof(H3BA)=Sof(H3BB)=1-FVAR(1) Sof(O3A)=Sof(H3AA)=Sof(H3AB)=FVAR(1) Fixed X: H1A(1.393391) H1B(1.25841) H3AA(0.82474) H3AB(0.919749) H3BA(0.70805) H3BB(0.82046) H2A(1.436299) H2B(1.27384) Fixed Y: H1A(0.843861) H1B(0.70964) H3AA(1.34448) H3AB(1.39917) H3BA(1.19412) H3BB(1.354321) H2A(0.999499) H2B(1.11445) Fixed Z: H1A(0.62203) H1B(0.62415) H3AA(0.77378) H3AB(0.663441) H3BA(0.651361) H3BB(0.66705) H2A(1.1758) H2B(1.21389)

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

	x	y	z	U_iso*/U_eq	Occ. (<1)
Ba1	0.84596 (6)	0.54566 (15)	0.18707 (5)	0.01069 (17)
F1	0.1744 (12)	0.6957 (9)	−0.0772 (9)	0.0392 (19)
F2	0.4423 (11)	0.5754 (14)	0.0977 (9)	0.0449 (16)
F3	0.1320 (13)	0.4559 (13)	0.0610 (12)	0.050 (3)
F4	0.2873 (13)	0.4098 (13)	−0.1086 (11)	0.0449 (16)
F5	1.4219 (11)	0.4296 (12)	0.4972 (9)	0.0361 (18)
F6	1.2726 (11)	0.2125 (11)	0.5958 (8)	0.0299 (16)
F7	1.1150 (11)	0.4849 (9)	0.5097 (9)	0.0311 (18)
F8	1.1510 (13)	0.2707 (18)	0.3442 (11)	0.035 (3)
O1	0.6644 (13)	0.2926 (16)	0.3248 (12)	0.031 (2)
O2	0.6901 (12)	0.565 (2)	−0.1296 (9)	0.033 (2)
B1	0.2610 (14)	0.537 (4)	−0.0048 (10)	0.0136 (15)
B2	1.2421 (17)	0.3491 (17)	0.4874 (13)	0.0136 (15)
O3A	1.128 (3)	0.813 (4)	0.298 (2)	0.025 (4)	0.56 (2)
O3B	1.197 (4)	0.756 (4)	0.284 (3)	0.025 (4)	0.44 (2)
H1A	0.606609	0.343861	0.377970	0.038*
H1B	0.741590	0.209640	0.375850	0.038*
H3AA	1.175261	0.844480	0.226220	0.038*	0.56 (2)
H3AB	1.080250	0.899170	0.336559	0.038*	0.56 (2)
H3BA	1.291950	0.694120	0.348640	0.038*	0.44 (2)
H3BB	1.179539	0.854321	0.332950	0.038*	0.44 (2)
H2A	0.563701	0.499499	−0.175799	0.038*
H2B	0.726160	0.614450	−0.213891	0.038*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Ba1	0.0098 (2)	0.0107 (2)	0.0114 (3)	−0.0003 (4)	0.00317 (18)	−0.0011 (4)
F1	0.044 (5)	0.021 (3)	0.049 (5)	0.011 (3)	0.010 (4)	0.022 (3)
F2	0.029 (3)	0.052 (4)	0.052 (4)	0.000 (3)	0.011 (3)	−0.013 (3)
F3	0.043 (5)	0.048 (5)	0.082 (7)	0.010 (4)	0.051 (5)	0.030 (5)
F4	0.029 (3)	0.052 (4)	0.052 (4)	0.000 (3)	0.011 (3)	−0.013 (3)
F5	0.014 (4)	0.056 (5)	0.038 (5)	−0.005 (3)	0.008 (3)	0.003 (4)
F6	0.037 (4)	0.031 (4)	0.022 (4)	0.005 (3)	0.010 (3)	0.016 (3)
F7	0.028 (4)	0.024 (4)	0.040 (5)	0.008 (3)	0.009 (3)	0.001 (3)
F8	0.040 (6)	0.048 (6)	0.011 (4)	0.006 (4)	0.000 (3)	−0.002 (5)
O1	0.029 (5)	0.022 (5)	0.045 (7)	0.002 (3)	0.017 (5)	0.008 (4)
O2	0.026 (4)	0.055 (7)	0.013 (3)	0.006 (6)	0.000 (3)	−0.001 (6)
B1	0.010 (3)	0.021 (4)	0.010 (3)	−0.003 (4)	0.003 (3)	0.002 (4)
B2	0.010 (3)	0.021 (4)	0.010 (3)	−0.003 (4)	0.003 (3)	0.002 (4)
O3A	0.020 (10)	0.028 (11)	0.034 (8)	−0.007 (6)	0.017 (7)	−0.017 (7)
O3B	0.020 (10)	0.028 (11)	0.034 (8)	−0.007 (6)	0.017 (7)	−0.017 (7)

Geometric parameters (Å, º) top

Ba1—F1ⁱ	2.700 (6)	F4—B1	1.39 (2)
Ba1—F2	2.698 (7)	F5—B2	1.369 (13)
Ba1—F3ⁱⁱ	2.735 (7)	F6—B2	1.379 (14)
Ba1—F4ⁱⁱⁱ	2.791 (9)	F7—B2	1.385 (14)
Ba1—F6^iv	2.728 (7)	F8—B2	1.406 (16)
Ba1—F7	3.035 (8)	O1—H1A	0.83
Ba1—F8	2.933 (10)	O1—H1B	0.84
Ba1—O1	2.777 (9)	O2—H2A	0.97
Ba1—O2	2.821 (8)	O2—H2B	0.98
Ba1—O3A	2.71 (2)	O3A—H3AA	0.88
Ba1—O3B	2.78 (2)	O3A—H3AB	0.84
F1—B1	1.36 (2)	O3B—H3BA	0.86
F2—B1	1.352 (12)	O3B—H3BB	0.88
F3—B1	1.387 (15)

F1ⁱ—Ba1—F3ⁱⁱ	64.4 (3)	O2—Ba1—F7	164.1 (2)
F1ⁱ—Ba1—F4ⁱⁱⁱ	142.9 (3)	O2—Ba1—F8	122.1 (3)
F1ⁱ—Ba1—F6^iv	134.8 (2)	O3A—Ba1—F3ⁱⁱ	77.3 (5)
F1ⁱ—Ba1—F7	100.8 (2)	O3A—Ba1—F4ⁱⁱⁱ	65.1 (6)
F1ⁱ—Ba1—F8	60.4 (3)	O3A—Ba1—F6^iv	76.6 (4)
F1ⁱ—Ba1—O1	66.3 (3)	O3A—Ba1—F7	65.2 (6)
F1ⁱ—Ba1—O2	71.8 (3)	O3A—Ba1—F8	87.7 (5)
F1ⁱ—Ba1—O3A	138.1 (5)	O3A—Ba1—O1	132.5 (5)
F1ⁱ—Ba1—O3B	123.8 (6)	O3A—Ba1—O2	110.6 (6)
F2—Ba1—F1ⁱ	92.1 (3)	O3B—Ba1—F7	63.6 (6)
F2—Ba1—F3ⁱⁱ	137.5 (3)	O3B—Ba1—F8	76.9 (6)
F2—Ba1—F4ⁱⁱⁱ	67.4 (3)	O3B—Ba1—O2	108.2 (6)
F2—Ba1—F6^iv	69.2 (2)	B1—F1—Ba1ⁱⁱⁱ	157.8 (7)
F2—Ba1—F7	124.8 (2)	B1—F2—Ba1	149.2 (8)
F2—Ba1—F8	137.2 (3)	B1—F3—Ba1^v	141.5 (12)
F2—Ba1—O1	66.1 (3)	B1—F4—Ba1ⁱ	133.4 (10)
F2—Ba1—O2	70.4 (2)	B2—F6—Ba1^vi	148.7 (7)
F2—Ba1—O3A	128.9 (6)	B2—F7—Ba1	99.9 (6)
F2—Ba1—O3B	142.5 (6)	B2—F8—Ba1	104.0 (8)
F3ⁱⁱ—Ba1—F4ⁱⁱⁱ	109.7 (3)	Ba1—O1—H1A	113.0
F3ⁱⁱ—Ba1—F7	95.4 (3)	Ba1—O1—H1B	115.0
F3ⁱⁱ—Ba1—F8	62.4 (3)	H1A—O1—H1B	109.0
F3ⁱⁱ—Ba1—O1	124.7 (3)	Ba1—O2—H2A	115.0
F3ⁱⁱ—Ba1—O2	68.8 (3)	F1—B1—F3	108.8 (10)
F3ⁱⁱ—Ba1—O3B	64.1 (6)	F1—B1—F4	109.7 (8)
F4ⁱⁱⁱ—Ba1—F7	116.4 (2)	F2—B1—F1	110.5 (17)
F4ⁱⁱⁱ—Ba1—F8	152.8 (3)	F2—B1—F3	111.8 (9)
F4ⁱⁱⁱ—Ba1—O2	72.2 (4)	F2—B1—F4	108.7 (10)
F6^iv—Ba1—F3ⁱⁱ	151.8 (3)	F3—B1—F4	107.3 (17)
F6^iv—Ba1—F4ⁱⁱⁱ	68.2 (3)	F5—B2—F6	109.6 (9)
F6^iv—Ba1—F7	63.8 (2)	F5—B2—F7	109.0 (10)
F6^iv—Ba1—F8	105.8 (3)	F5—B2—F8	110.6 (10)
F6^iv—Ba1—O1	68.5 (3)	F6—B2—F7	109.8 (9)
F6^iv—Ba1—O2	131.5 (3)	F6—B2—F8	109.7 (10)
F6^iv—Ba1—O3B	88.8 (5)	F7—B2—F8	108.2 (10)
F8—Ba1—F7	44.5 (2)	Ba1—O3A—H3AA	108.0
O1—Ba1—F4ⁱⁱⁱ	124.6 (3)	Ba1—O3A—H3AB	110.0
O1—Ba1—F7	70.8 (3)	H3AA—O3A—H3AB	117.0
O1—Ba1—F8	72.5 (3)	Ba1—O3B—H3BA	111.0
O1—Ba1—O2	116.6 (3)	Ba1—O3B—H3BB	110.0
O1—Ba1—O3B	134.4 (6)	H3BA—O3B—H3BB	104.0

Ba1ⁱⁱⁱ—F1—B1—F2	25 (2)	Ba1ⁱ—F4—B1—F3	−3.8 (15)
Ba1ⁱⁱⁱ—F1—B1—F3	148.0 (14)	Ba1^vi—F6—B2—F5	136.5 (11)
Ba1ⁱⁱⁱ—F1—B1—F4	−95 (2)	Ba1^vi—F6—B2—F7	16.9 (19)
Ba1—F2—B1—F1	−111 (2)	Ba1^vi—F6—B2—F8	−101.9 (14)
Ba1—F2—B1—F3	127.5 (12)	Ba1—F7—B2—F5	103.0 (8)
Ba1—F2—B1—F4	9 (3)	Ba1—F7—B2—F6	−137.0 (8)
Ba1^v—F3—B1—F1	−31.2 (17)	Ba1—F7—B2—F8	−17.3 (9)
Ba1^v—F3—B1—F2	91.1 (18)	Ba1—F8—B2—F5	−101.1 (9)
Ba1^v—F3—B1—F4	−149.9 (11)	Ba1—F8—B2—F6	138.0 (7)
Ba1ⁱ—F4—B1—F1	−121.8 (12)	Ba1—F8—B2—F7	18.2 (10)
Ba1ⁱ—F4—B1—F2	117.3 (11)

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

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
O1—H1A···F5^v	0.829 (10)	2.075 (8)	2.892 (12)	168.8 (7)
O1—H1B···F7^vi	0.842 (10)	2.016 (7)	2.849 (13)	170.5 (7)
O2—H2A···F4	0.974 (9)	2.331 (9)	3.119 (13)	137.4 (5)
O2—H2B···F8^vii	0.977 (9)	2.053 (11)	3.002 (15)	163.5 (7)
O3A—H3AA···O2^vii	0.88 (2)	2.191 (11)	2.96 (3)	146.5 (18)
O3A—H3AB···F7^iv	0.84 (2)	2.386 (8)	3.13 (2)	147.7 (17)
O3B—H3BA···F5	0.86 (3)	2.355 (9)	3.15 (3)	153.0 (16)

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

Unit-cell parameters (Å, °, Å³) of Ba(BF₄)₂(H₂O)₃ at different temperatures (K) top

T	a	b	c	β	V
100	7.0406 (5)	7.1567 (3)	9.3926 (9)	109.292 (7)	446.69 (5)
150	7.0550 (4)	7.1706 (3)	9.4182 (6)	109.295 (7)	449.68 (5)
280	7.1469 (5)	7.1775 (4)	9.5820 (7)	110.254 (6)	461.13 (5)
300	7.1763 (6)	18.052 (2)	7.1631 (6)		927.93 (15)

Transformation matrix oC–mP (HT–LT phase transition of Ba(BF₄)₂(H₃O)₃ top

-1	0	0
0	0	-1
1/2	-1/2	0

Acknowledgements

The authors acknowledge financial support from the Slovenian Research Agency (research core funding No. P1–0045; Inorganic Chemistry and Technology).

Funding information

Funding for this research was provided by: Javna Agencija za Raziskovalno Dejavnost RS (grant No. P1-0045).

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