Sodium penta­fluoro­phenyl­borate

The crystal structure of the title compound, Na[(C₆F₅)BH₃], is composed of discrete anions and cations. The sodium cations are surrounded by four anions with three short Na⋯B [2.848 (8), 2.842 (7) and 2.868 (8) Å] and two short Na⋯F contacts [2.348 (5) and 2.392 (5) Å], forming a three-dimensional network. The anion is the first structural example of a pentafluorophenyl ring carrying a BH₃ group.

Related literature

For synthetic background, see: Schnurr et al. (2011). For a description of the Cambridge Structural Database, see: Allen (2002).

Experimental

Crystal data

• Na⁺·C₆H₃BF₅⁻

• M_r = 203.88

• Monoclinic, P 2₁

• a = 4.6813 (10) Å

• b = 6.1986 (16) Å

• c = 12.993 (3) Å

• β = 92.995 (17)°

• V = 376.51 (15) ų

• Z = 2

• Mo Kα radiation

• μ = 0.24 mm⁻¹

• T = 173 K

• 0.21 × 0.18 × 0.03 mm

Data collection

• STOE IPDS II two-circle-diffractometer

• Absorption correction: multi-scan (MULABS; Spek, 2009 and Blessing, 1995) T_min = 0.951, T_max = 0.993

• 2267 measured reflections

• 775 independent reflections

• 601 reflections with I > 2σ(I)

• R_int = 0.116

Refinement

• R[F² > 2σ(F²)] = 0.058

• wR(F²) = 0.138

• S = 1.01

• 775 reflections

• 119 parameters

• 1 restraint

• H-atom parameters constrained

• Δρ_max = 0.37 e Å⁻³

• Δρ_min = −0.45 e Å⁻³

Data collection: X-AREA (Stoe & Cie, 2001); cell refinement: X-AREA; data reduction: X-AREA; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: XP in SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXL97.

Supporting information

S1. Comment

The hydridoborates [(C₆F₅)BH₃]^- and [(C₆F₅)₂BH₂]^- are convenient starting materials for the in situ generation of the boranes (C₆F₅)BH₂ and (C₆F₅)₂BH (Schnurr et al., 2011). In this paper we report the crystal structure of Na[(C₆F₅)BH₃] which was obtained from the reaction mixture of (C₆F₅)B(OMe)₂ and Li[AlH₄] by a cation exchange with NaOH (Fig. 1).

The title compound (Fig. 2) is composed of discrete anions and cations. The sodium cations are surrounded by four anions with three short Na···B [Na1···B1 2.848 (8) Å, Na1···B1ⁱ 2.842 (7) Å, Na1···B1ⁱⁱ 2.868 (8) Å; symmetry operators: (i) -x + 2, y - 1/2, -z + 1, (ii) -x + 1, y - 1/2, -z + 1] and two short Na···F [Na1···F6ⁱⁱ 2.348 (5) Å, Na1···F2ⁱⁱ 2.392 (5) Å] contacts (Fig. 3).

It is remarkable that this is the first structure with an pentafluorophenyl ring carrying a BH₃ group. A search in the Cambridge Crystallographic Database (CSD, Version 5.33 of November 2011, plus three updates (Allen, (2002). Acta Cryst. B58, 380–388) yielded no hit at all for this fragment.

Related literature

For synthetic background, see: Schnurr et al. (2011). For a description of the Cambridge Structural Database, see: Allen (2002).

S2. Experimental

In a round bottom flask (C₆F₅)B(OMe)₂ (0.16 g, 0.65 mmol) was dissolved in 10 ml diethyl ether. Under stirring a 1 m solution of Li[AlH₄] in diethyl ether (1.2 mmol, 1.1 ml) was added via canula. A brown slurry was obtained which was treated with 3 ml aqueous NaOH (3 mmol) and 15 ml benzene. Insoluble material was removed by filtration from the organic layer. Single crystals of the title compound were obtained of the concentrated benzene solution (5 ml). Yield 20%.

S3. Refinement

Due to the absence of anomalous scatterers, the absolute structure could not be determined and 414 Friedel pairs were merged. H atoms were located in a difference map, but geometrically positioned and refined using a riding model with fixed individual displacement parameters [U(H) = 1.5 U_eq(B)] and with B—H = 0.98 Å. The BH₃ group was allowed to rotate but not to tip.

Computing details

Data collection: X-AREA (Stoe & Cie, 2001); cell refinement: X-AREA (Stoe & Cie, 2001); data reduction: X-AREA (Stoe & Cie, 2001); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: XP in SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008).

Figures

	Fig. 1. Reaction scheme for obtaining the title compound.
	Fig. 2. Perspective view of the title compound. Displacement ellipsoids are drawn at the 30% probability level.
	Fig. 3. Environment of a sodium cation.

Sodium pentafluorophenylborate

Crystal data

Na^+·C6H3BF5^−	F(000) = 200
Mr = 203.88	Dx = 1.798 Mg m^−3
Monoclinic, P21	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: P 2yb	Cell parameters from 1888 reflections
a = 4.6813 (10) Å	θ = 3.7–25.5°
b = 6.1986 (16) Å	µ = 0.24 mm^−1
c = 12.993 (3) Å	T = 173 K
β = 92.995 (17)°	Plate, colourless
V = 376.51 (15) Å^3	0.21 × 0.18 × 0.03 mm
Z = 2

Data collection

STOE IPDS II two-circle- diffractometer	775 independent reflections
Radiation source: fine-focus sealed tube	601 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.116
ω scans	θmax = 25.6°, θmin = 3.6°
Absorption correction: multi-scan (MULABS; Spek, 2009 and Blessing, 1995)	h = −5→5
Tmin = 0.951, Tmax = 0.993	k = −6→7
2267 measured reflections	l = −15→15

Refinement

Refinement on F^2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.058	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.138	H-atom parameters constrained
S = 1.01	w = 1/[σ^2(Fo^2) + (0.0711P)^2] where P = (Fo^2 + 2Fc^2)/3
775 reflections	(Δ/σ)max < 0.001
119 parameters	Δρmax = 0.37 e Å^−3
1 restraint	Δρmin = −0.45 e Å^−3

Special details

Experimental. ;

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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
Na1	0.8015 (5)	0.5576 (5)	0.5911 (2)	0.0289 (6)
B1	0.7013 (14)	0.7940 (13)	0.4048 (5)	0.0245 (15)
H1A	0.6928	0.9477	0.3873	0.037*
H1B	0.8948	0.7573	0.4316	0.037*
H1C	0.5643	0.7628	0.4573	0.037*
C1	0.6218 (11)	0.6519 (12)	0.3025 (5)	0.0228 (13)
C2	0.7487 (11)	0.4581 (11)	0.2778 (5)	0.0258 (14)
C3	0.6739 (13)	0.3361 (12)	0.1908 (5)	0.0297 (15)
C4	0.4582 (12)	0.4078 (14)	0.1233 (5)	0.0325 (16)
C5	0.3237 (12)	0.6030 (13)	0.1438 (5)	0.0316 (18)
C6	0.4083 (12)	0.7149 (12)	0.2310 (5)	0.0275 (15)
F2	0.9668 (7)	0.3764 (7)	0.3429 (3)	0.0351 (10)
F3	0.8099 (8)	0.1482 (7)	0.1730 (3)	0.0420 (11)
F4	0.3794 (9)	0.2917 (10)	0.0395 (3)	0.0495 (13)
F5	0.1147 (7)	0.6743 (8)	0.0784 (3)	0.0426 (12)
F6	0.2667 (7)	0.9043 (7)	0.2468 (3)	0.0351 (10)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Na1	0.0223 (10)	0.0281 (14)	0.0361 (14)	−0.0006 (11)	−0.0003 (9)	0.0047 (13)
B1	0.020 (3)	0.028 (4)	0.026 (3)	−0.002 (3)	0.000 (3)	0.002 (4)
C1	0.015 (2)	0.025 (3)	0.028 (3)	−0.005 (2)	0.001 (2)	0.004 (3)
C2	0.017 (2)	0.028 (3)	0.032 (4)	0.003 (3)	−0.005 (2)	0.007 (3)
C3	0.028 (3)	0.025 (4)	0.037 (4)	0.001 (3)	0.008 (3)	−0.006 (3)
C4	0.023 (3)	0.044 (4)	0.029 (3)	−0.002 (3)	−0.002 (3)	−0.006 (3)
C5	0.018 (2)	0.047 (5)	0.028 (4)	0.001 (3)	−0.002 (2)	0.003 (3)
C6	0.018 (3)	0.039 (4)	0.027 (3)	0.007 (3)	0.007 (2)	0.007 (3)
F2	0.0276 (18)	0.031 (2)	0.045 (2)	0.0079 (18)	−0.0124 (16)	0.003 (2)
F3	0.040 (2)	0.033 (2)	0.052 (3)	0.012 (2)	0.0000 (18)	−0.009 (2)
F4	0.039 (2)	0.066 (3)	0.043 (3)	0.006 (2)	−0.0056 (18)	−0.022 (3)
F5	0.0262 (17)	0.068 (3)	0.033 (2)	0.015 (2)	−0.0083 (15)	0.005 (2)
F6	0.0262 (17)	0.044 (3)	0.035 (2)	0.0156 (18)	−0.0050 (15)	−0.002 (2)

Geometric parameters (Å, º)

Na1—F6^i	2.348 (5)	C2—C3	1.389 (10)
Na1—F2^ii	2.392 (5)	C3—F3	1.353 (9)
Na1—B1^iii	2.842 (7)	C3—C4	1.376 (10)
Na1—B1^i	2.868 (8)	C4—F4	1.342 (9)
B1—C1	1.621 (10)	C4—C5	1.396 (11)
B1—H1A	0.9800	C5—F5	1.337 (7)
B1—H1B	0.9800	C5—C6	1.370 (10)
B1—H1C	0.9800	C6—F6	1.369 (8)
C1—C6	1.385 (9)	F2—Na1^iii	2.392 (5)
C1—C2	1.385 (10)	F6—Na1^iv	2.348 (5)
C2—F2	1.387 (7)
F6^i—Na1—F2^ii	95.35 (17)	F2—C2—C1	119.1 (6)
F6^i—Na1—B1^iii	84.3 (2)	C3—C2—C1	124.6 (6)
F2^ii—Na1—B1^iii	96.5 (2)	F3—C3—C4	120.3 (7)
F6^i—Na1—B1^i	66.57 (18)	F3—C3—C2	120.5 (6)
F2^ii—Na1—B1^i	145.2 (2)	C4—C3—C2	119.2 (6)
B1^iii—Na1—B1^i	110.1 (3)	F4—C4—C3	120.4 (7)
C1—B1—H1A	109.5	F4—C4—C5	120.8 (6)
C1—B1—H1B	109.5	C3—C4—C5	118.8 (6)
H1A—B1—H1B	109.5	F5—C5—C6	121.9 (7)
C1—B1—H1C	109.5	F5—C5—C4	119.2 (6)
H1A—B1—H1C	109.5	C6—C5—C4	118.9 (6)
H1B—B1—H1C	109.5	F6—C6—C5	115.9 (6)
C6—C1—C2	113.1 (6)	F6—C6—C1	118.6 (6)
C6—C1—B1	121.6 (6)	C5—C6—C1	125.4 (6)
C2—C1—B1	125.3 (6)	C2—F2—Na1^iii	145.7 (4)
F2—C2—C3	116.3 (6)	C6—F6—Na1^iv	124.9 (4)
C6—C1—C2—F2	179.8 (5)	F4—C4—C5—C6	179.2 (6)
B1—C1—C2—F2	−1.5 (8)	C3—C4—C5—C6	−0.9 (9)
C6—C1—C2—C3	−0.1 (8)	F5—C5—C6—F6	−0.3 (9)
B1—C1—C2—C3	178.6 (6)	C4—C5—C6—F6	−179.6 (6)
F2—C2—C3—F3	0.2 (9)	F5—C5—C6—C1	179.8 (6)
C1—C2—C3—F3	−179.9 (6)	C4—C5—C6—C1	0.5 (9)
F2—C2—C3—C4	179.7 (6)	C2—C1—C6—F6	−179.9 (5)
C1—C2—C3—C4	−0.4 (9)	B1—C1—C6—F6	1.4 (8)
F3—C3—C4—F4	0.4 (10)	C2—C1—C6—C5	0.0 (9)
C2—C3—C4—F4	−179.2 (6)	B1—C1—C6—C5	−178.7 (6)
F3—C3—C4—C5	−179.6 (6)	C3—C2—F2—Na1^iii	−30.8 (9)
C2—C3—C4—C5	0.9 (9)	C1—C2—F2—Na1^iii	149.3 (5)
F4—C4—C5—F5	−0.2 (9)	C5—C6—F6—Na1^iv	151.8 (4)
C3—C4—C5—F5	179.7 (6)	C1—C6—F6—Na1^iv	−28.2 (7)

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