Aqua­tri­fluorido­boron–1,3-dioxolan-2-one (1/2)

Radan, K.; Forero-Saboya, J.; Ponrouch, A.; Lozinšek, M.

doi:10.1107/S2414314623000627

organic compounds

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ISSN: 2414-3146

Volume 8| Part 1| January 2023| x230062

https://doi.org/10.1107/S2414314623000627

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Aquatrifluoridoboron–1,3-dioxolan-2-one (1/2)

Kristian Radan,^a Juan Forero-Saboya,^b Alexandre Ponrouch ^b and Matic Lozinšek ^a ^*

^aJožef Stefan Institute, Jamova cesta 39, 1000 Ljubljana, Slovenia, and ^bInstitut de Ciència de Materials de Barcelona, ICMAB-CSIC, Campus UAB 08193, Bellaterra, Spain
^*Correspondence e-mail: matic.lozinsek@ijs.si

Edited by M. Weil, Vienna University of Technology, Austria (Received 13 January 2023; accepted 24 January 2023; online 26 January 2023)

The crystal structure of the co-crystal of aquatrifluoridoboron with two ethylene carbonate (systematic name: 1,3-dioxolan-2-one) molecules, BF₃H₂O·2OC(OCH₂)₂, was determined by low-temperature single-crystal X-ray diffraction. The co-crystal crystallizes in the orthorhombic space group P2₁2₁2₁ with four formula units per unit cell. The asymmetric unit consists of an aquatrifluoridoboron molecule and two ethylene carbonate molecules, connected by O—H⋯O=C hydrogen bonds. This crystal structure is an interesting example of a superacidic BF₃H₂O species co-crystallized with an organic carbonate.

Keywords: aquatrifluoridoboron; ethylene carbonate; co-crystal; crystal structure.

CCDC reference: 2237804

Structure description

Adducts synthesized from boron trifluoride and various organic carbonates have been reported as potential functional electrolyte additives for secondary (rechargeable) lithium-ion batteries (Eisele et al., 2020 ), and have been shown to modify the electrode surfaces, resulting in reduced cell resistance and better capacity retention at high current rates. Recently, the use of BF₃-based additives has been extended to divalent-metal batteries, namely calcium-ion batteries (Forero-Saboya et al., 2021 ; Bodin et al., 2023 ), where their decomposition into boron-crosslinked polymeric matrices in the passivation layer was found to be crucial for calcium plating and stripping. Such BF₃ adducts are moisture sensitive and readily hydrolyze to form BF₃H₂O (Simonov et al., 1996 ; Fonari et al., 1997 ). The title co-crystal formed from the boron trifluoride–ethylene carbonate (1/1) adduct, BF₃·OC(OCH₂)₂, upon exposure to moisture.

The BF₃H₂O·2OC(OCH₂)₂ co-crystal crystallizes in the orthorhombic Sohncke space group P2₁2₁2₁ with one aquatrifluoridoboron and two ethylene carbonate molecules in the asymmetric unit (Fig. 1). The two OC(OCH₂)₂ molecules have an essentially identical molecular shape (slightly twisted), which also agrees well with the crystal structure determination of 1,3-dioxolan-2-one (Atterberry & Bond, 2019 ). The B—O and B—F bond lengths [1.5236 (18) Å and 1.3718 (18)–1.3760 (17) Å, respectively] in the BF₃H₂O molecule of the title co-crystal are similar to those found in BF₃H₂O (Mootz & Steffen, 1981a ), BF₃H₂O·H₂O (Mootz & Steffen, 1981b ), BF₃H₂O·C₄H₈O₂ (Barthen & Frank, 2019 ), or adducts of BF₃ and organic carbonates (Bodin et al., 2023). The F—B—F angles [110.75 (12)–112.57 (12)°] are larger than the O—B—F angles, with the angle involving F1 [109.23 (11)°] being significantly larger than the other two angles [105.47 (11)° and 106.41 (12)°]. The hydrogen atoms of the H₂O moiety in the BF₃H₂O adduct are inclined toward the F1 atom, with the angle between the B—O bond and the plane defined by the water atoms being 128 (2)°. The overall shape of the BF₃ moiety in BF₃H₂O in terms of bond lengths and angles is similar to that of the BF₄⁻ anion (Lozinšek, 2021 ).

Figure 1
The asymmetric unit and the atom-labelling scheme of the BF₃H₂O·2OC(OCH₂)₂ co-crystal. Anisotropic displacement ellipsoids are drawn at the 50% probability level, hydrogen atoms are depicted as spheres of arbitrary radius, and hydrogen bonds are indicated by blue dashed lines.

Aquatrifluoridoboron is stabilized in the solid state by hydrogen-bonding interactions with oxygen hydrogen-bond acceptors, such as 1,4-dioxane (Barthen & Frank, 2019) or crown ethers (Bott et al., 1991 ; Simonov et al., 1996; Fonari et al., 1997; Gelmboldt et al., 2012 ). In the present case, the BF₃H₂O molecule is hydrogen-bonded to the carbonyl oxygen atoms of the two ethylene carbonate molecules, forming a C=O⋯H—O—H⋯O=C fragment with a D²₂(5) graph-set motif (Etter, 1990 ) and O⋯O distances of 2.5637 (15) Å and 2.5985 (15) Å (Table 1, Figs. 1 and 2). A similar hydrogen-bonding motif was observed in the crystal structure of the BF₃H₂O·2Ph₃PO co-crystal (Chekhlov, 2005 ).

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O1—H1A⋯O2	0.90 (3)	1.67 (3)	2.5637 (15)	175 (3)
O1—H1B⋯O5	0.82 (3)	1.79 (3)	2.5985 (15)	166 (2)

Figure 2
Crystal packing of BF₃H₂O·2OC(OCH₂)₂ viewed along [100]. Hydrogen bonds are indicated by blue dashed lines.

Synthesis and crystallization

Single crystals of the BF₃H₂O·2OC(OCH₂)₂ co-crystal were discovered when a crystalline sample of the air-sensitive BF₃·OC(OCH₂)₂ adduct was examined under a protective cold nitrogen stream at about −50 °C. The BF₃·OC(OCH₂)₂ compound was synthesized from dry ethylene carbonate and BF₃ gas under anhydrous conditions, as described previously (Bodin et al., 2023). Platelet-shaped co-crystals of BF₃H₂O·2OC(OCH₂)₂ were located in a droplet at the tip of the aluminium trough (Veith & Bärnighausen, 1974 ) of the low-temperature crystal mounting apparatus, which likely formed by an inadvertent introduction of a small amount of moisture. Selected crystals were mounted on the diffractometer employing a previously described procedure for mounting crystals at low temperatures (Lozinšek et al., 2021 ). The crystals melted and turned into droplets when exposed to air at room temperature.

Refinement

Crystal data, data collection, and structure refinement details are summarized in Table 2. Positions and isotropic thermal displacement parameters of hydrogen atoms were freely refined (Cooper et al., 2010 ).

Table 2
Experimental details

Crystal data
Chemical formula	2C₃H₄O₃·H₂BF₃O
M_r	261.95
Crystal system, space group	Orthorhombic, P2₁2₁2₁
Temperature (K)	150
a, b, c (Å)	5.44197 (4), 13.09134 (8), 14.36102 (9)
V (Å³)	1023.12 (1)
Z	4
Radiation type	Cu Kα
μ (mm⁻¹)	1.65
Crystal size (mm)	0.18 × 0.08 × 0.05

Data collection
Diffractometer	XtaLAB Synergy, Dualflex, Eiger2 R CdTe 1M
Absorption correction	Gaussian (CrysAlis PRO; Rigaku OD, 2022 )
T_min, T_max	0.663, 1.000
No. of measured, independent and observed [I > 2σ(I)] reflections	34542, 2134, 2100
R_int	0.038
(sin θ/λ)_max (Å⁻¹)	0.630

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.019, 0.050, 1.04
No. of reflections	2134
No. of parameters	195
H-atom treatment	All H-atom parameters refined
Δρ_max, Δρ_min (e Å⁻³)	0.11, −0.13
Absolute structure	Flack x determined using 853 quotients [(I⁺)−(I⁻)]/[(I⁺)+(I⁻)] (Parsons et al., 2013 )
Absolute structure parameter	−0.05 (3)
Computer programs: CrysAlis PRO (Rigaku OD, 2022), SHELXT (Sheldrick, 2015a ), SHELXL (Sheldrick, 2015b ), OLEX2 (Dolomanov et al., 2009 ), DIAMOND (Brandenburg, 2005 ) and publCIF (Westrip, 2010 ).

Structural data

CCDC reference: 2237804

Crystal structure: contains datablock I. DOI: https://doi.org/10.1107/S2414314623000627/wm4182sup1.cif

Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S2414314623000627/wm4182Isup2.hkl

checkCIF report

Computing details top

Data collection: CrysAlis PRO (Rigaku OD, 2022); cell refinement: CrysAlis PRO (Rigaku OD, 2022); data reduction: CrysAlis PRO (Rigaku OD, 2022); program(s) used to solve structure: SHELXT (Sheldrick, 2015a); program(s) used to refine structure: SHELXL (Sheldrick, 2015b); molecular graphics: Olex2 (Dolomanov et al., 2009), DIAMOND (Brandenburg, 2005); software used to prepare material for publication: publCIF (Westrip, 2010).

Aquatrifluoridoboron–1,3-dioxolan-2-one (1/2) top

Crystal data top

2C₃H₄O₃·H₂BF₃O	D_x = 1.701 Mg m⁻³
M_r = 261.95	Cu Kα radiation, λ = 1.54184 Å
Orthorhombic, P2₁2₁2₁	Cell parameters from 24984 reflections
a = 5.44197 (4) Å	θ = 4.6–75.5°
b = 13.09134 (8) Å	µ = 1.65 mm⁻¹
c = 14.36102 (9) Å	T = 150 K
V = 1023.12 (1) Å³	Plate, clear colourless
Z = 4	0.18 × 0.08 × 0.05 mm
F(000) = 536

Data collection top

XtaLAB Synergy, Dualflex, Eiger2 R CdTe 1M diffractometer	2134 independent reflections
Radiation source: micro-focus sealed X-ray tube, PhotonJet (Cu) X-ray Source	2100 reflections with I > 2σ(I)
Mirror monochromator	R_int = 0.038
Detector resolution: 13.3333 pixels mm^-1	θ_max = 76.1°, θ_min = 4.6°
ω scans	h = −6→6
Absorption correction: gaussian (CrysAlisPro; Rigaku OD, 2022)	k = −15→16
T_min = 0.663, T_max = 1.000	l = −18→18
34542 measured reflections

Refinement top

Refinement on F²	All H-atom parameters refined
Least-squares matrix: full	w = 1/[σ²(F_o²) + (0.0311P)² + 0.1146P] where P = (F_o² + 2F_c²)/3
R[F² > 2σ(F²)] = 0.019	(Δ/σ)_max < 0.001
wR(F²) = 0.050	Δρ_max = 0.11 e Å⁻³
S = 1.04	Δρ_min = −0.13 e Å⁻³
2134 reflections	Extinction correction: SHELXL (Sheldrick, 2015b), F_c^* = kF_c[1+0.001xF_c²λ³/sin(2θ)]^–1/4
195 parameters	Extinction coefficient: 0.0035 (5)
0 restraints	Absolute structure: Flack x determined using 853 quotients [(I⁺)–(I^–)]/[(I⁺)+(I^–)] (Parsons et al., 2013)
Primary atom site location: dual	Absolute structure parameter: −0.05 (3)
Hydrogen site location: difference Fourier map

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

	x	y	z	U_iso*/U_eq
F1	0.05387 (16)	0.46158 (7)	0.69151 (6)	0.0345 (2)
F2	0.31541 (19)	0.57475 (6)	0.75716 (6)	0.0347 (2)
F3	0.35784 (17)	0.40399 (6)	0.78723 (6)	0.0320 (2)
O1	0.4683 (2)	0.46651 (8)	0.64281 (7)	0.0283 (2)
H1A	0.518 (5)	0.404 (2)	0.6252 (19)	0.071 (8)*
H1B	0.432 (5)	0.5005 (19)	0.5968 (17)	0.052 (6)*
O2	0.6234 (2)	0.29312 (8)	0.58425 (7)	0.0312 (2)
O3	0.29867 (18)	0.19871 (7)	0.62526 (7)	0.0266 (2)
O4	0.59130 (18)	0.13169 (7)	0.53775 (7)	0.0255 (2)
C1	0.5104 (2)	0.21312 (10)	0.58256 (9)	0.0232 (3)
C2	0.2189 (3)	0.09379 (11)	0.61128 (10)	0.0267 (3)
H2A	0.062 (4)	0.0949 (14)	0.5867 (13)	0.033 (5)*
H2B	0.220 (3)	0.0629 (13)	0.6729 (12)	0.025 (4)*
C3	0.4125 (3)	0.04997 (10)	0.54606 (10)	0.0249 (3)
H3A	0.349 (4)	0.0354 (14)	0.4844 (13)	0.031 (4)*
H3B	0.497 (4)	−0.0097 (15)	0.5697 (12)	0.030 (5)*
B1	0.2884 (3)	0.47702 (12)	0.72354 (11)	0.0252 (3)
O5	0.3601 (2)	0.59963 (8)	0.51501 (8)	0.0359 (3)
O6	0.60783 (19)	0.63618 (7)	0.39559 (7)	0.0280 (2)
O7	0.31353 (19)	0.74337 (7)	0.43534 (6)	0.0266 (2)
C4	0.4246 (3)	0.65572 (10)	0.45246 (9)	0.0240 (3)
C5	0.6409 (3)	0.72193 (11)	0.33235 (10)	0.0305 (3)
H5B	0.793 (4)	0.7521 (16)	0.3486 (14)	0.040 (5)*
H5A	0.649 (4)	0.6923 (14)	0.2694 (14)	0.038 (5)*
C6	0.4207 (3)	0.78959 (11)	0.35281 (10)	0.0291 (3)
H6B	0.470 (3)	0.8616 (15)	0.3687 (13)	0.032 (4)*
H6A	0.296 (4)	0.7853 (15)	0.3028 (14)	0.040 (5)*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
F1	0.0260 (4)	0.0419 (5)	0.0356 (4)	−0.0012 (4)	−0.0027 (3)	0.0046 (4)
F2	0.0475 (5)	0.0265 (4)	0.0300 (4)	0.0037 (4)	−0.0046 (4)	−0.0043 (3)
F3	0.0379 (5)	0.0309 (4)	0.0273 (4)	0.0026 (4)	−0.0013 (4)	0.0085 (3)
O1	0.0324 (5)	0.0254 (5)	0.0271 (5)	0.0034 (4)	0.0049 (4)	0.0046 (4)
O2	0.0325 (5)	0.0237 (4)	0.0373 (5)	−0.0033 (4)	0.0051 (5)	−0.0004 (4)
O3	0.0256 (5)	0.0243 (4)	0.0299 (5)	0.0006 (4)	0.0066 (4)	−0.0026 (4)
O4	0.0236 (5)	0.0243 (4)	0.0285 (5)	0.0008 (4)	0.0043 (4)	−0.0025 (4)
C1	0.0240 (6)	0.0236 (6)	0.0220 (6)	0.0025 (5)	0.0007 (5)	0.0016 (5)
C2	0.0243 (7)	0.0258 (6)	0.0300 (7)	−0.0032 (5)	0.0023 (6)	−0.0027 (5)
C3	0.0236 (6)	0.0234 (6)	0.0275 (6)	−0.0009 (5)	−0.0003 (5)	−0.0010 (5)
B1	0.0282 (8)	0.0253 (7)	0.0220 (7)	0.0020 (6)	−0.0007 (6)	0.0015 (5)
O5	0.0459 (6)	0.0315 (5)	0.0303 (5)	−0.0073 (5)	−0.0016 (5)	0.0098 (4)
O6	0.0299 (5)	0.0225 (4)	0.0314 (5)	0.0031 (4)	0.0017 (4)	−0.0006 (4)
O7	0.0303 (5)	0.0240 (4)	0.0255 (4)	0.0035 (4)	0.0055 (4)	0.0024 (4)
C4	0.0278 (7)	0.0212 (6)	0.0229 (6)	−0.0023 (5)	−0.0024 (5)	0.0002 (5)
C5	0.0343 (8)	0.0271 (7)	0.0302 (7)	−0.0041 (6)	0.0083 (6)	0.0000 (6)
C6	0.0355 (8)	0.0244 (7)	0.0273 (6)	0.0000 (6)	0.0034 (6)	0.0069 (5)

Geometric parameters (Å, º) top

F1—B1	1.3718 (18)	C2—C3	1.522 (2)
F2—B1	1.3753 (17)	C3—H3A	0.969 (19)
F3—B1	1.3760 (17)	C3—H3B	0.97 (2)
O1—H1A	0.90 (3)	O5—C4	1.2122 (17)
O1—H1B	0.82 (3)	O6—C4	1.3139 (18)
O1—B1	1.5236 (18)	O6—C5	1.4550 (17)
O2—C1	1.2147 (17)	O7—C4	1.3200 (16)
O3—C1	1.3187 (16)	O7—C6	1.4530 (17)
O3—C2	1.4545 (16)	C5—H5B	0.95 (2)
O4—C1	1.3208 (16)	C5—H5A	0.98 (2)
O4—C3	1.4512 (17)	C5—C6	1.519 (2)
C2—H2A	0.92 (2)	C6—H6B	1.01 (2)
C2—H2B	0.972 (18)	C6—H6A	0.99 (2)

H1A—O1—H1B	110 (2)	F1—B1—O1	109.23 (11)
B1—O1—H1A	119.4 (18)	F2—B1—F3	112.57 (12)
B1—O1—H1B	114.2 (17)	F2—B1—O1	106.41 (12)
C1—O3—C2	109.38 (10)	F3—B1—O1	105.47 (11)
C1—O4—C3	109.35 (10)	C4—O6—C5	109.37 (11)
O2—C1—O3	123.81 (12)	C4—O7—C6	109.27 (11)
O2—C1—O4	122.46 (12)	O5—C4—O6	124.23 (13)
O3—C1—O4	113.73 (12)	O5—C4—O7	122.13 (14)
O3—C2—H2A	108.3 (12)	O6—C4—O7	113.64 (11)
O3—C2—H2B	105.4 (10)	O6—C5—H5B	106.1 (13)
O3—C2—C3	103.55 (11)	O6—C5—H5A	105.9 (11)
H2A—C2—H2B	110.9 (16)	O6—C5—C6	103.38 (11)
C3—C2—H2A	114.2 (12)	H5B—C5—H5A	110.5 (17)
C3—C2—H2B	113.6 (11)	C6—C5—H5B	113.6 (13)
O4—C3—C2	103.71 (11)	C6—C5—H5A	116.3 (12)
O4—C3—H3A	108.0 (11)	O7—C6—C5	103.40 (11)
O4—C3—H3B	107.7 (11)	O7—C6—H6B	108.2 (11)
C2—C3—H3A	112.9 (12)	O7—C6—H6A	107.1 (12)
C2—C3—H3B	114.7 (11)	C5—C6—H6B	112.2 (11)
H3A—C3—H3B	109.3 (16)	C5—C6—H6A	111.6 (11)
F1—B1—F2	110.75 (12)	H6B—C6—H6A	113.6 (15)
F1—B1—F3	112.08 (13)

O3—C2—C3—O4	5.22 (14)	O6—C5—C6—O7	9.38 (14)
C1—O3—C2—C3	−4.14 (14)	C4—O6—C5—C6	−7.83 (15)
C1—O4—C3—C2	−4.81 (14)	C4—O7—C6—C5	−8.29 (15)
C2—O3—C1—O2	−178.23 (13)	C5—O6—C4—O5	−177.25 (14)
C2—O3—C1—O4	1.26 (15)	C5—O6—C4—O7	2.92 (16)
C3—O4—C1—O2	−178.06 (13)	C6—O7—C4—O5	−176.09 (13)
C3—O4—C1—O3	2.44 (15)	C6—O7—C4—O6	3.74 (16)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
O1—H1A···O2	0.90 (3)	1.67 (3)	2.5637 (15)	175 (3)
O1—H1B···O5	0.82 (3)	1.79 (3)	2.5985 (15)	166 (2)
C3—H3B···F3ⁱ	0.97 (2)	2.474 (19)	3.3085 (16)	144.2 (14)
C6—H6B···F1ⁱⁱ	1.01 (2)	2.51 (2)	3.3974 (17)	146.4 (14)

Symmetry codes: (i) −x+1, y−1/2, −z+3/2; (ii) x+1/2, −y+3/2, −z+1.

Funding information

Funding for this research was provided by: European Research Council (ERC) (StG HiPeR-F and StG CAMBAT) (grant agreement Nos. 950625 and 715087); Marie Skłodowska-Curie Actions (COFUND-2016 DOC-FAM) under the European Union's Horizon 2020 research and innovation programme (grant No. 754397); Jožef Stefan Institute Director's Fund; Slovenian Research Agency (grant No. N1-0189); Spanish Ministry for Economy, Industry and Competitiveness Severo Ochoa Programme for Centres of Excellence in R&D (contract No. CEX2019-000917-S).

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