Crystal structures of potassium tri­fluorido­(4-meth­oxy­phen­yl)borate and potassium tri­fluorido(4-fluoro­phen­yl)borate

Despite their different compositions and space groups, the irregular KF₈ coordination polyhedra of the potassium cations in these structures are almost identical. The layer stacking sequences are AAA… in the p-methoxy compound and ABAB… in the p-fluoro compound.

Abstract

The title compounds, K⁺·C₇H₇BF₃O⁻, (I), and K⁺·C₆H₄BF₄ ⁻, (II), are mol­ecular salts containing para-substituted phenyl­tri­fluorido­borate anions. In each compound, the B atom adopts a distorted tetra­hedral BCF₃ geometry. Despite their different compositions and space groups, the irregular KF₈ coordination polyhedra of the potassium cations in the structures are almost identical. These polyhedra share faces and edges, generating infinite (010) layers in (I) and infinite (001) layers in (II). In (I), adjacent layers are stacked in an AAA… fashion, whereas in (II), they are stacked in an ABAB… sequence.

Chemical context  

The phenyl­tri­fluorido­borate anion is an inter­esting inter­mediate species between the well-known tetra­fluorido­borate (BF₄ ⁻) and tetra­phenyl­borate [B(C₆H₅)₄ ⁻] ions (Conole et al., 1995 ▸) and may serve as a bulky charge-balancing anion (Quach et al., 2001 ▸; Fei et al., 2010 ▸). As part of our studies in this area, we now describe the syntheses and structures of the para-substituted phenyl­tri­fluorido­borate salts K⁺C₇H₇BF₃O⁻ (I) and K⁺C₆H₄BF₄ ⁻ (II).

Structural commentary  

Compound (I) comprises one cation and one anion in the asymmetric unit (Fig. 1 ▸). In the anion, the C7 atom of the meth­oxy group is close to coplanar with the benzene ring [displacement = 0.048 (2) Å]. The B atom adopts its expected tetra­hedral BF₃C geometry (Conole et al., 1995 ▸) and the C1—B1 bond length of 1.5987 (18) Å is consistent with previous data (Quach et al., 2001 ▸). One of the B—F bonds (to F1) in (I) is notably longer than the other two, which might reflect the different modes of coordination of the fluorine atoms to the potassium ions. The F—B—F bond angles (mean = 105.7°) are significantly smaller than the C—B—F angles (mean = 113.0°). F1 is displaced by −1.427 (2) Å from the plane of the benzene ring and F2 and F3 are displaced in the opposite sense, by 0.715 (2) and 0.252 (2) Å, respectively.

Figure 1.

The asymmetric unit of (I) showing 50% displacement ellipsoids.

The potassium ion in (I) is coordinated by eight fluorine atoms, with one of the K—F bonds substanti­ally longer than the others (Table 1 ▸): the next-nearest F atom is over 4 Å distant. The coordination geometry of the K⁺ ion, which arises from one tridentate, one bidentate and three monodentate BF₃ ⁻ groups, is irregular and highly asymmetric (Fig. 2 ▸), with five of the F atoms forming an approximate plane and the other three (arising from one BF₃ group) lying to one side. The metal ion is displaced by 1.00 Å from the geometric centroid of the eight F atoms. In terms of the F atoms in (I), F1 bonds to three different metal ions (mean K—F = 2.734 Å), generating a distorted FBK₃ tetra­hedron, whereas F2 bonds to two K⁺ ions (mean K—F = 2.755 Å) in an FBK₂ distorted T-shape. If the geometry around F3 is not merely deemed to be irregular, it could be described as an FBK₃ trigonal-based pyramid, with the long K—F bond (Table 1 ▸) as the apex (mean K—F = 2.963 Å). The extended structure in (I) consists of (010) sheets in which the KF₈ polyhedra share faces in the [100] direction and edges in [001]: the shortest K⋯K separation is 4.4523 (4) Å.

Table 1. Selected bond lengths (Å) for (I) .

K1—F3i	2.6156 (10)	K1—F2iv	2.8885 (8)
K1—F2ii	2.6211 (7)	K1—F3iv	3.4886 (9)
K1—F1iii	2.6550 (10)	B1—F3	1.4162 (19)
K1—F1iv	2.7568 (10)	B1—F2	1.4196 (14)
K1—F3	2.7836 (8)	B1—F1	1.4403 (17)
K1—F1	2.7887 (8)

Symmetry codes: (i) ; (ii) ; (iii) ; (iv) .

Figure 2.

The coordination of the potassium ion in (I). See Table 1 ▸ for symmetry codes.

The asymmetric unit of compound (II) also consists of an ion-pair (Fig. 3 ▸). The geometry of the anion in (II) is very similar to that of the equivalent species in (I): the C1—B1 bond length is 1.590 (2) Å and the mean F—B—F and C—B—F bond angles are 105.5 and 113.2°, respectively. The displace­ments of F1, F2 and F3 from the benzene-ring plane are −1.386 (2), 0.813 (3) and 0.131 (3) Å, respectively. As seen for (I), the B1—F1 bond in (II) is noticeably longer than the B1—F2 and B1—F3 bonds.

Figure 3.

The asymmetric unit of (II) showing 50% displacement ellipsoids.

It is notable that the K⁺ ion in (II) adopts a very similar coordination geometry (Table 2 ▸) to the equivalent species in (I), despite the different space groups. Again, a very asymmetric KF₈ coordination polyhedron (Fig. 4 ▸) arises from one tridentate, one bidentate and three monodentate anions; one K—F bond is much longer than the others and the potassium ion is displaced by 0.98 Å from the geometric centroid of the fluorine atoms.

Table 2. Selected bond lengths (Å) for (II) .

K1—F3i	2.6116 (10)	K1—F2iv	2.8853 (10)
K1—F2ii	2.6159 (9)	K1—F3iv	3.3927 (10)
K1—F1iii	2.6527 (9)	B1—F2	1.4166 (17)
K1—F1iv	2.7612 (10)	B1—F3	1.4182 (19)
K1—F3	2.7732 (9)	B1—F1	1.4393 (18)
K1—F1	2.8050 (9)

Symmetry codes: (i) ; (ii) ; (iii) ; (iv) .

Figure 4.

The coordination of the potassium ion in (II). See Table 2 ▸ for symmetry codes.

The extended structure of (II) consists of (001) sheets [rather than (010) sheets, as seen in (I)] of face- and edge-sharing KF₈ groups with the same topology as in (I): the shortest K⋯K separation is 4.4255 (5) Å.

Supra­molecular features  

In (I) the meth­oxy­phenyl groups lie roughly normal to (010). When the packing is viewed along [101] (Fig. 5 ▸), it may be seen that adjacent benzene ring planes are rotated by 90°, which facilitates the formation of a weak edge-to-face intra-sheet C—H⋯π inter­action (Table 3 ▸). An intra-sheet C2—H2⋯F2 hydrogen bond also occurs. The only possible inter-sheet inter­action in (I) is an extremely weak C—H⋯O hydrogen bond with an H⋯O separation essentially the same as the van der Waals separation of these species. The layer-stacking sequence for (I) is AAA….

Figure 5.

The unit-cell packing in (I) viewed approximately down [101].

Table 3. Hydrogen-bond geometry (Å, °) for (I) .

Cg1 is the centroid of the C1–C6 benzene ring.

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C2—H2⋯F2v	0.95	2.50	3.3359 (17)	147
C7—H7a⋯O1vi	0.98	2.72	3.496 (1)	137
C3—H3⋯Cg1v	0.95	2.85	3.7171 (15)	152

Symmetry codes: (v) ; (vi) .

When the crystal structure of (II) is viewed down [110] (Fig. 6 ▸), adjacent aromatic rings show the same 90° rotation as they do in (I), but the only directional inter­action identified is an intra­layer weak C—H⋯F hydrogen bond (Table 4 ▸) and there are no C—H⋯π inter­actions. There are no identified inter-layer inter­actions and the stacking sequence is ABAB….

Figure 6.

The unit-cell packing in (II) viewed approximately down [110].

Table 4. Hydrogen-bond geometry (Å, °) for (II) .

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C6—H6⋯F2v	0.95	2.53	3.4099 (19)	154

Symmetry code: (v) .

Database survey  

Compound (I) is closely related to K^+.C₆H₅BF₃ ⁻ (Conole et al., 1995 ▸), (III). Compounds (I) and (III) have the same space group and a similar unit cell, extended in the b-axis direction for (I) to accommodate the meth­oxy group. The potassium ion in (III) has almost the same KF₈ coordination geometry as the equivalent species in (I) and (II) described above. In (III), weak edge-to-face C—H⋯π inter­actions occur between approximately perpendicular aromatic rings, as they do in (I). As already noted, the C₆H₅BF₃ ⁻ anion has found use as a bulky charge-balancing species (Quach et al., 2001 ▸; Fei et al., 2010 ▸).

Synthesis and crystallization  

(I) and (II) were received as commercial samples from Aldrich and recrystallized from ethanol solution, yielding colourless blocks.

Refinement  

The H atoms were placed in idealized positions (C—H = 0.95–0.98 Å) and refined as riding atoms with U _iso(H) = 1.2U _eq(C) or 1.5U _eq(methyl C). The methyl group in (I) was allowed to rotate, but not to tip, to best fit the electron density.. Experimental details are given in Table 5 ▸.

Table 5. Experimental details.

	(I)	(II)
Crystal data
Chemical formula	K+·C7H7BF3O−	K+·C6H4BF4 −
M r	214.04	202.00
Crystal system, space group	Orthorhombic, P c a21	Orthorhombic, P b c a
Temperature (K)	120	100
a, b, c (Å)	7.1347 (2), 17.2819 (7), 7.3289 (3)	7.1317 (5), 7.3757 (5), 29.129 (2)
V (Å3)	903.66 (6)	1532.22 (18)
Z	4	8
Radiation type	Mo Kα	Mo Kα
μ (mm−1)	0.59	0.70
Crystal size (mm)	0.52 × 0.15 × 0.15	0.07 × 0.05 × 0.01
Data collection
Diffractometer	Rigaku CCD	Rigaku CCD
Absorption correction	Multi-scan (SADABS; Bruker, 2012 ▸)	Multi-scan (SADABS; Bruker, 2012 ▸)
T min, T max	0.750, 0.917	0.953, 0.993
No. of measured, independent and observed [I > 2σ(I)] reflections	5789, 1833, 1822	9537, 1726, 1435
R int	0.026	0.037
(sin θ/λ)max (Å−1)	0.649	0.649
Refinement
R[F 2 > 2σ(F 2)], wR(F 2), S	0.021, 0.059, 1.10	0.027, 0.065, 1.06
No. of reflections	1833	1726
No. of parameters	120	109
No. of restraints	1	0
H-atom treatment	H-atom parameters constrained	H-atom parameters constrained
Δρmax, Δρmin (e Å−3)	0.24, −0.20	0.27, −0.23
Absolute structure	Flack (1983 ▸), 712 Friedel pairs	–
Absolute structure parameter	0.02 (3)	–

Computer programs: CrystalClear (Rigaku, 2010 ▸), SHELXS97 and SHELXL97 (Sheldrick, 2008 ▸), ORTEP-3 for Windows (Farrugia, 2012 ▸) and publCIF (Westrip, 2010 ▸).

Supplementary Material

CCDC references: 1004280, 1004281

Additional supporting information: crystallographic information; 3D view; checkCIF report

supplementary crystallographic information

(I) Potassium trifluorido(4-methoxyphenyl)borate. Crystal data

K+·C7H7BF3O−	Dx = 1.573 Mg m−3
Mr = 214.04	Mo Kα radiation, λ = 0.71075 Å
Orthorhombic, Pca21	Cell parameters from 4830 reflections
a = 7.1347 (2) Å	θ = 1.2–27.5°
b = 17.2819 (7) Å	µ = 0.59 mm−1
c = 7.3289 (3) Å	T = 120 K
V = 903.66 (6) Å3	Block, colourless
Z = 4	0.52 × 0.15 × 0.15 mm
F(000) = 432

(I) Potassium trifluorido(4-methoxyphenyl)borate. Data collection

Rigaku CCD diffractometer	1833 independent reflections
Radiation source: fine-focus sealed tube	1822 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.026
ω scans	θmax = 27.5°, θmin = 1.2°
Absorption correction: multi-scan (SADABS; Bruker, 2012)	h = −9→9
Tmin = 0.750, Tmax = 0.917	k = −22→20
5789 measured reflections	l = −8→9

(I) Potassium trifluorido(4-methoxyphenyl)borate. Refinement

Refinement on F2	Hydrogen site location: inferred from neighbouring sites
Least-squares matrix: full	H-atom parameters constrained
R[F2 > 2σ(F2)] = 0.021	w = 1/[σ2(Fo2) + (0.035P)2 + 0.1245P] where P = (Fo2 + 2Fc2)/3
wR(F2) = 0.059	(Δ/σ)max < 0.001
S = 1.10	Δρmax = 0.24 e Å−3
1833 reflections	Δρmin = −0.20 e Å−3
120 parameters	Extinction correction: SHELXL97 (Sheldrick, 2008), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
1 restraint	Extinction coefficient: 0.0115 (14)
Primary atom site location: structure-invariant direct methods	Absolute structure: Flack (1983), 712 Friedel pairs
Secondary atom site location: difference Fourier map	Absolute structure parameter: 0.02 (3)

(I) Potassium trifluorido(4-methoxyphenyl)borate. Special details

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 F2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F2, conventional R-factors R are based on F, with F set to zero for negative F2. The threshold expression of F2 > σ(F2) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F2 are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger.

(I) Potassium trifluorido(4-methoxyphenyl)borate. Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
K1	0.93636 (3)	0.577078 (16)	0.49116 (4)	0.01659 (9)
C1	0.48663 (17)	0.69908 (7)	0.3989 (2)	0.0159 (3)
C2	0.36313 (18)	0.72309 (8)	0.2628 (2)	0.0195 (3)
H2	0.2718	0.6875	0.2199	0.023*
C3	0.36757 (18)	0.79722 (8)	0.1867 (2)	0.0223 (3)
H3	0.2813	0.8114	0.0938	0.027*
C4	0.5004 (2)	0.84983 (8)	0.2493 (2)	0.0208 (3)
C5	0.62439 (19)	0.82828 (8)	0.3880 (2)	0.0233 (3)
H5	0.7139	0.8643	0.4324	0.028*
C6	0.61673 (19)	0.75407 (8)	0.4608 (2)	0.0206 (3)
H6	0.7018	0.7402	0.5549	0.025*
C7	0.3970 (3)	0.94712 (11)	0.0422 (3)	0.0393 (5)
H7A	0.4278	1.0000	0.0044	0.059*
H7B	0.2674	0.9454	0.0865	0.059*
H7C	0.4105	0.9121	−0.0622	0.059*
B1	0.48502 (18)	0.61227 (8)	0.4743 (2)	0.0153 (3)
F1	0.57562 (10)	0.55930 (5)	0.35081 (13)	0.01754 (18)
F2	0.30347 (10)	0.58074 (4)	0.50165 (17)	0.02096 (19)
F3	0.58402 (11)	0.60460 (5)	0.64078 (13)	0.02023 (19)
O1	0.52053 (18)	0.92364 (6)	0.1842 (2)	0.0297 (3)

(I) Potassium trifluorido(4-methoxyphenyl)borate. Atomic displacement parameters (Ų)

	U11	U22	U33	U12	U13	U23
K1	0.01225 (13)	0.02391 (15)	0.01361 (16)	0.00081 (8)	0.00031 (12)	0.00042 (12)
C1	0.0132 (5)	0.0193 (6)	0.0152 (6)	0.0009 (5)	0.0007 (5)	−0.0009 (5)
C2	0.0199 (6)	0.0204 (6)	0.0183 (7)	−0.0015 (5)	−0.0044 (5)	−0.0014 (6)
C3	0.0233 (6)	0.0229 (6)	0.0206 (7)	0.0011 (5)	−0.0043 (5)	0.0017 (6)
C4	0.0234 (6)	0.0167 (6)	0.0222 (7)	0.0007 (5)	0.0007 (6)	0.0011 (6)
C5	0.0223 (6)	0.0200 (6)	0.0277 (8)	−0.0036 (5)	−0.0054 (5)	−0.0028 (6)
C6	0.0181 (5)	0.0211 (6)	0.0226 (8)	0.0002 (5)	−0.0046 (5)	−0.0010 (6)
C7	0.0421 (9)	0.0273 (7)	0.0484 (13)	0.0011 (7)	−0.0085 (8)	0.0167 (9)
B1	0.0121 (5)	0.0185 (6)	0.0153 (7)	0.0000 (4)	0.0002 (6)	0.0008 (6)
F1	0.0182 (4)	0.0196 (4)	0.0148 (5)	0.0031 (3)	0.0025 (3)	−0.0007 (4)
F2	0.0129 (3)	0.0209 (3)	0.0291 (5)	−0.0015 (2)	0.0028 (4)	−0.0004 (3)
F3	0.0204 (3)	0.0271 (4)	0.0132 (5)	−0.0004 (3)	−0.0022 (3)	0.0025 (4)
O1	0.0352 (5)	0.0176 (5)	0.0362 (8)	−0.0009 (4)	−0.0037 (6)	0.0052 (5)

(I) Potassium trifluorido(4-methoxyphenyl)borate. Geometric parameters (Å, º)

K1—F3i	2.6156 (10)	C4—C5	1.398 (2)
K1—F2ii	2.6211 (7)	C5—C6	1.390 (2)
K1—F1iii	2.6550 (10)	C5—H5	0.9500
K1—F1iv	2.7568 (10)	C6—H6	0.9500
K1—F3	2.7836 (8)	C7—O1	1.423 (2)
K1—F1	2.7887 (8)	C7—H7A	0.9800
K1—F2iv	2.8885 (8)	C7—H7B	0.9800
K1—F3iv	3.4886 (9)	C7—H7C	0.9800
C1—C2	1.3940 (19)	B1—F3	1.4162 (19)
C1—C6	1.4036 (18)	B1—F2	1.4196 (14)
C1—B1	1.5987 (18)	B1—F1	1.4403 (17)
C2—C3	1.398 (2)	B1—K1v	3.2930 (14)
C2—K1i	3.5183 (15)	F1—K1i	2.6550 (10)
C2—H2	0.9500	F1—K1v	2.7568 (10)
C3—C4	1.3910 (19)	F2—K1vi	2.6211 (7)
C3—H3	0.9500	F2—K1v	2.8885 (8)
C4—O1	1.3696 (17)	F3—K1iii	2.6157 (10)
F3i—K1—F2ii	94.59 (3)	O1—C4—C5	115.78 (13)
F3i—K1—F1iii	173.67 (3)	C3—C4—C5	119.79 (13)
F2ii—K1—F1iii	90.34 (3)	C6—C5—C4	119.99 (13)
F3i—K1—F1iv	79.00 (3)	C6—C5—H5	120.0
F2ii—K1—F1iv	70.82 (2)	C4—C5—H5	120.0
F1iii—K1—F1iv	106.45 (2)	C5—C6—C1	121.78 (14)
F3i—K1—F3	107.78 (2)	C5—C6—H6	119.1
F2ii—K1—F3	152.47 (3)	C1—C6—H6	119.1
F1iii—K1—F3	66.40 (3)	O1—C7—H7A	109.5
F1iv—K1—F3	128.21 (2)	O1—C7—H7B	109.5
F3i—K1—F1	66.83 (3)	H7A—C7—H7B	109.5
F2ii—K1—F1	159.35 (3)	O1—C7—H7C	109.5
F1iii—K1—F1	108.89 (2)	H7A—C7—H7C	109.5
F1iv—K1—F1	95.79 (2)	H7B—C7—H7C	109.5
F3—K1—F1	47.98 (3)	F3—B1—F2	107.30 (13)
F3i—K1—F2iv	100.35 (3)	F3—B1—F1	104.95 (10)
F2ii—K1—F2iv	110.489 (19)	F2—B1—F1	104.73 (10)
F1iii—K1—F2iv	81.59 (3)	F3—B1—C1	112.45 (11)
F1iv—K1—F2iv	47.24 (3)	F2—B1—C1	114.56 (11)
F3—K1—F2iv	81.63 (2)	F1—B1—C1	112.10 (12)
F1—K1—F2iv	66.60 (3)	B1—F1—K1i	122.39 (8)
C2—C1—C6	116.59 (12)	B1—F1—K1v	98.47 (7)
C2—C1—B1	121.46 (12)	K1i—F1—K1v	117.24 (3)
C6—C1—B1	121.90 (12)	B1—F1—K1	96.46 (7)
C1—C2—C3	122.95 (12)	K1i—F1—K1	112.53 (3)
C1—C2—K1i	86.24 (8)	K1v—F1—K1	106.81 (3)
C3—C2—K1i	114.99 (10)	B1—F2—K1vi	156.48 (8)
C1—C2—H2	118.5	B1—F2—K1v	93.39 (6)
C3—C2—H2	118.5	K1vi—F2—K1v	107.73 (2)
K1i—C2—H2	68.1	B1—F3—K1iii	146.64 (8)
C4—C3—C2	118.88 (13)	B1—F3—K1	97.29 (7)
C4—C3—H3	120.6	K1iii—F3—K1	113.95 (3)
C2—C3—H3	120.6	C4—O1—C7	117.09 (13)
O1—C4—C3	124.43 (14)
C6—C1—C2—C3	1.2 (2)	C2—C1—C6—C5	−1.1 (2)
B1—C1—C2—C3	−176.35 (14)	B1—C1—C6—C5	176.46 (14)
C6—C1—C2—K1i	118.72 (12)	C2—C1—B1—F3	−164.66 (12)
B1—C1—C2—K1i	−58.84 (12)	C6—C1—B1—F3	17.90 (18)
C1—C2—C3—C4	−0.2 (2)	C2—C1—B1—F2	−41.81 (19)
K1i—C2—C3—C4	−102.69 (14)	C6—C1—B1—F2	140.76 (15)
C2—C3—C4—O1	179.10 (14)	C2—C1—B1—F1	77.36 (16)
C2—C3—C4—C5	−0.9 (2)	C6—C1—B1—F1	−100.07 (15)
O1—C4—C5—C6	−178.99 (14)	C3—C4—O1—C7	−0.4 (2)
C3—C4—C5—C6	1.0 (2)	C5—C4—O1—C7	179.62 (15)
C4—C5—C6—C1	0.0 (2)

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

(I) Potassium trifluorido(4-methoxyphenyl)borate. Hydrogen-bond geometry (Å, º)

Cg1 is the centroid of the C1–C6 benzene ring.

D—H···A	D—H	H···A	D···A	D—H···A
C2—H2···F2vii	0.95	2.50	3.3359 (17)	147
C7—H7a···O1viii	0.98	2.72	3.496 (1)	137
C3—H3···Cg1vii	0.95	2.85	3.7171 (15)	152

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

(II) Potassium trifluorido(4-fluorophenyl)borate. Crystal data

K+·C6H4BF4−	F(000) = 800
Mr = 202.00	Dx = 1.751 Mg m−3
Orthorhombic, Pbca	Mo Kα radiation, λ = 0.71075 Å
Hall symbol: -P 2ac 2ab	Cell parameters from 8210 reflections
a = 7.1317 (5) Å	θ = 3.2–27.5°
b = 7.3757 (5) Å	µ = 0.70 mm−1
c = 29.129 (2) Å	T = 100 K
V = 1532.22 (18) Å3	Block, colourless
Z = 8	0.07 × 0.05 × 0.01 mm

(II) Potassium trifluorido(4-fluorophenyl)borate. Data collection

Rigaku CCD diffractometer	1726 independent reflections
Radiation source: fine-focus sealed tube	1435 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.037
ω scans	θmax = 27.5°, θmin = 3.2°
Absorption correction: multi-scan (SADABS; Bruker, 2012)	h = −9→8
Tmin = 0.953, Tmax = 0.993	k = −9→7
9537 measured reflections	l = −32→37

(II) Potassium trifluorido(4-fluorophenyl)borate. Refinement

Refinement on F2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.027	Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.065	H-atom parameters constrained
S = 1.06	w = 1/[σ2(Fo2) + (0.0274P)2 + 0.6658P] where P = (Fo2 + 2Fc2)/3
1726 reflections	(Δ/σ)max = 0.001
109 parameters	Δρmax = 0.27 e Å−3
0 restraints	Δρmin = −0.23 e Å−3

(II) Potassium trifluorido(4-fluorophenyl)borate. Special details

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 F2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F2, conventional R-factors R are based on F, with F set to zero for negative F2. The threshold expression of F2 > σ(F2) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F2 are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger.

(II) Potassium trifluorido(4-fluorophenyl)borate. Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
K1	0.06924 (4)	0.02356 (5)	0.205013 (12)	0.01668 (10)
C1	0.5118 (2)	0.1023 (2)	0.13156 (5)	0.0161 (3)
C2	0.3892 (2)	0.0245 (2)	0.09978 (6)	0.0213 (3)
H2	0.3130	−0.0745	0.1091	0.026*
C3	0.3750 (2)	0.0869 (2)	0.05506 (6)	0.0245 (4)
H3	0.2905	0.0324	0.0339	0.029*
C4	0.4867 (2)	0.2301 (2)	0.04213 (5)	0.0236 (4)
C5	0.6112 (2)	0.3121 (2)	0.07145 (6)	0.0250 (4)
H5	0.6871	0.4105	0.0616	0.030*
C6	0.6226 (2)	0.2463 (2)	0.11604 (6)	0.0207 (3)
H6	0.7085	0.3011	0.1367	0.025*
B1	0.5200 (2)	0.0373 (2)	0.18355 (6)	0.0147 (3)
F1	0.43225 (11)	0.16564 (12)	0.21396 (3)	0.0178 (2)
F2	0.70288 (11)	0.01321 (13)	0.20154 (3)	0.0210 (2)
F3	0.42107 (11)	−0.12680 (12)	0.19106 (3)	0.0193 (2)
F4	0.47218 (15)	0.29343 (14)	−0.00157 (3)	0.0327 (3)

(II) Potassium trifluorido(4-fluorophenyl)borate. Atomic displacement parameters (Ų)

	U11	U22	U33	U12	U13	U23
K1	0.01228 (15)	0.01386 (17)	0.02390 (18)	0.00022 (12)	0.00079 (12)	0.00020 (13)
C1	0.0143 (6)	0.0139 (7)	0.0200 (8)	0.0019 (6)	0.0007 (6)	−0.0006 (6)
C2	0.0214 (7)	0.0201 (8)	0.0225 (8)	−0.0029 (7)	−0.0016 (6)	0.0002 (7)
C3	0.0268 (8)	0.0256 (9)	0.0211 (9)	−0.0019 (7)	−0.0056 (7)	−0.0016 (7)
C4	0.0306 (9)	0.0243 (9)	0.0160 (8)	0.0046 (7)	0.0013 (6)	0.0020 (7)
C5	0.0296 (9)	0.0221 (9)	0.0234 (9)	−0.0056 (7)	0.0052 (6)	0.0014 (7)
C6	0.0222 (7)	0.0189 (8)	0.0211 (8)	−0.0050 (7)	0.0007 (6)	−0.0014 (7)
B1	0.0116 (7)	0.0130 (8)	0.0194 (8)	0.0014 (6)	0.0006 (6)	−0.0008 (6)
F1	0.0184 (4)	0.0152 (5)	0.0198 (5)	0.0027 (4)	0.0027 (3)	−0.0012 (4)
F2	0.0125 (4)	0.0295 (5)	0.0209 (5)	0.0032 (4)	−0.0024 (3)	−0.0012 (4)
F3	0.0205 (4)	0.0125 (5)	0.0247 (5)	−0.0017 (4)	0.0003 (4)	0.0026 (4)
F4	0.0474 (6)	0.0332 (6)	0.0174 (5)	−0.0013 (5)	−0.0007 (5)	0.0061 (4)

(II) Potassium trifluorido(4-fluorophenyl)borate. Geometric parameters (Å, º)

K1—F3i	2.6116 (10)	C4—F4	1.3597 (18)
K1—F2ii	2.6159 (9)	C4—C5	1.373 (2)
K1—F1iii	2.6527 (9)	C5—C6	1.389 (2)
K1—F1iv	2.7612 (10)	C5—H5	0.9500
K1—F3	2.7732 (9)	C6—H6	0.9500
K1—F1	2.8050 (9)	B1—F2	1.4166 (17)
K1—F2iv	2.8853 (10)	B1—F3	1.4182 (19)
K1—F3iv	3.3927 (10)	B1—F1	1.4393 (18)
C1—C2	1.397 (2)	B1—K1v	3.2665 (18)
C1—C6	1.399 (2)	F1—K1i	2.6527 (9)
C1—B1	1.590 (2)	F1—K1v	2.7612 (9)
C2—C3	1.385 (2)	F2—K1vi	2.6159 (9)
C2—H2	0.9500	F2—K1v	2.8852 (10)
C3—C4	1.375 (2)	F3—K1iii	2.6116 (10)
C3—H3	0.9500	F3—K1v	3.3928 (10)
F3i—K1—F2ii	92.82 (3)	F4—C4—C3	118.44 (15)
F3i—K1—F1iii	176.44 (3)	C5—C4—C3	122.87 (16)
F2ii—K1—F1iii	88.32 (3)	C4—C5—C6	117.74 (16)
F3i—K1—F1iv	76.56 (3)	C4—C5—H5	121.1
F2ii—K1—F1iv	71.99 (3)	C6—C5—H5	121.1
F1iii—K1—F1iv	107.00 (2)	C5—C6—C1	122.34 (15)
F3i—K1—F3	110.37 (2)	C5—C6—H6	118.8
F2ii—K1—F3	152.42 (3)	C1—C6—H6	118.8
F1iii—K1—F3	67.67 (3)	F2—B1—F3	107.08 (12)
F1iv—K1—F3	126.67 (3)	F2—B1—F1	104.80 (12)
F3i—K1—F1	67.74 (3)	F3—B1—F1	104.48 (11)
F2ii—K1—F1	159.45 (3)	F2—B1—C1	115.08 (12)
F1iii—K1—F1	111.49 (2)	F3—B1—C1	112.70 (13)
F1iv—K1—F1	96.05 (2)	F1—B1—C1	111.86 (12)
F3—K1—F1	47.78 (3)	F2—B1—K1v	61.95 (7)
F3i—K1—F2iv	99.45 (3)	F3—B1—K1v	82.74 (8)
F2ii—K1—F2iv	111.45 (2)	F1—B1—K1v	57.03 (7)
F1iii—K1—F2iv	83.24 (3)	C1—B1—K1v	163.77 (11)
F1iv—K1—F2iv	47.18 (2)	F2—B1—K1	145.97 (10)
F3—K1—F2iv	80.14 (3)	F3—B1—K1	57.04 (6)
F1—K1—F2iv	67.51 (3)	F1—B1—K1	58.42 (6)
F3i—K1—F3iv	118.03 (3)	C1—B1—K1	98.93 (9)
F2ii—K1—F3iv	73.38 (3)	K1v—B1—K1	85.12 (4)
F1iii—K1—F3iv	65.53 (2)	B1—F1—K1i	126.56 (8)
F1iv—K1—F3iv	41.51 (2)	B1—F1—K1v	97.04 (8)
F3—K1—F3iv	106.37 (3)	K1i—F1—K1v	117.58 (3)
F1—K1—F3iv	109.07 (3)	B1—F1—K1	95.66 (8)
F2iv—K1—F3iv	41.62 (2)	K1i—F1—K1	111.04 (3)
C2—C1—C6	116.82 (15)	K1v—F1—K1	105.32 (3)
C2—C1—B1	122.05 (14)	B1—F2—K1vi	158.46 (9)
C6—C1—B1	121.08 (14)	B1—F2—K1v	92.38 (8)
C3—C2—C1	122.18 (15)	K1vi—F2—K1v	107.01 (3)
C3—C2—H2	118.9	B1—F3—K1iii	148.62 (8)
C1—C2—H2	118.9	B1—F3—K1	97.55 (8)
C4—C3—C2	118.06 (15)	K1iii—F3—K1	113.33 (3)
C4—C3—H3	121.0	B1—F3—K1v	72.76 (8)
C2—C3—H3	121.0	K1iii—F3—K1v	100.12 (3)
F4—C4—C5	118.69 (15)	K1—F3—K1v	91.16 (3)
C6—C1—C2—C3	−0.7 (2)	C2—C1—C6—C5	0.8 (2)
B1—C1—C2—C3	176.65 (15)	B1—C1—C6—C5	−176.56 (15)
C1—C2—C3—C4	0.1 (3)	C2—C1—B1—F2	135.24 (15)
C2—C3—C4—F4	−179.32 (15)	C6—C1—B1—F2	−47.6 (2)
C2—C3—C4—C5	0.4 (3)	C2—C1—B1—F3	12.0 (2)
F4—C4—C5—C6	179.43 (15)	C6—C1—B1—F3	−170.75 (13)
C3—C4—C5—C6	−0.3 (3)	C2—C1—B1—F1	−105.32 (17)
C4—C5—C6—C1	−0.3 (3)	C6—C1—B1—F1	71.88 (18)

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

(II) Potassium trifluorido(4-fluorophenyl)borate. Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
C6—H6···F2vii	0.95	2.53	3.4099 (19)	154

Symmetry code: (vii) −x+3/2, y+1/2, z.