2,4-Difluoro­phenyl­boronic acid

Rodríguez-Cuamatzi, P.; Tlahuext, H.; Höpfl, H.

doi:10.1107/S1600536808040646

organic compounds

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ISSN: 2056-9890

Volume 65| Part 1| January 2009| Pages o44-o45

doi:10.1107/S1600536808040646

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2,4-Difluorophenylboronic acid

Patricia Rodríguez-Cuamatzi,^a Hugo Tlahuext ^b and Herbert Höpfl ^b ^*

^aUniversidad Politécnica de Tlaxcala, Carretera Federal Tlaxcala-Puebla Km 9.5, Tepeyanco, Tlaxcala, Mexico, and ^bCentro de Investigaciones Químicas, Universidad Autónoma del Estado de Morelos. Av. Universidad 1001 Col., Chamilpa, CP 62209, Cuernavaca Mor., Mexico
^*Correspondence e-mail: hhopfl@uaem.mx

(Received 24 November 2008; accepted 3 December 2008; online 10 December 2008)

The molecular structure of the title compound, C₆H₅BF₂O₂, is essentially planar (mean deviation = 0.019 Å), indicating electronic delocalization between the dihydroxyboryl group and the aromatic ring. In the crystal structure, inversion dimers linked by two O—H⋯O hydrogen bonds arise. An intramolecular O—H⋯F hydrogen bond reinforces the conformation and the same H atom is also involved in an intermolecular O—H⋯F link, leading to molecular sheets in the crystal.

Related literature

For general backround to boronic acids, see: Hall (2005 ); Höpfl (2002 ); Fujita et al. (2008 ); Soloway et al. (1998 ). For hydrogen-bond motifs, see: Bernstein et al. (1995 ); Desiraju (2002 ). For related structures, see: Wu et al. (2006 ); Bradley et al. (1996 ); Horton et al. (2004 ). For crystal engineering, see: Fournier et al. (2003 ); Rodríguez-Cuamatzi et al. (2004 , 2005 ).

Experimental

Crystal data

C₆H₅BF₂O₂
M_r = 157.91
Monoclinic, P 2₁ /n
a = 3.7617 (11) Å
b = 12.347 (4) Å
c = 14.620 (4) Å
β = 95.450 (5)°
V = 676.0 (3) Å³
Z = 4
Mo Kα radiation
μ = 0.15 mm⁻¹
T = 293 (2) K
0.37 × 0.35 × 0.22 mm

Data collection

Bruker SMART APEX CCD area-detector diffractometer
Absorption correction: multi-scan (SADABS; Sheldrick, 1996 ) T_min = 0.947, T_max = 0.968
3196 measured reflections
1190 independent reflections
1012 reflections with I > 2σ(I)
R_int = 0.028

Refinement

R[F² > 2σ(F²)] = 0.056
wR(F²) = 0.127
S = 1.15
1190 reflections
106 parameters
2 restraints
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.14 e Å⁻³
Δρ_min = −0.18 e Å⁻³

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O1—H1⋯F1	0.841 (15)	2.16 (3)	2.799 (3)	133 (2)
O1—H1⋯F2ⁱ	0.841 (15)	2.39 (2)	3.086 (3)	140 (3)
O2—H2⋯O1ⁱⁱ	0.841 (19)	1.97 (2)	2.809 (3)	174 (3)
Symmetry codes: (i) $[x-{\script{1\over 2}}, -y+{\script{1\over 2}}, z-{\script{1\over 2}}]$ ; (ii) -x+1, -y+1, -z+1.

Data collection: SMART (Bruker, 2000 ); cell refinement: SAINT-Plus-NT (Bruker, 2001 ); data reduction: SAINT-Plus-NT; program(s) used to solve structure: SHELXTL-NT (Sheldrick, 2008 ); program(s) used to refine structure: SHELXTL-NT; molecular graphics: CAMERON (Watkin et al., 1996 ); software used to prepare material for publication: PLATON (Spek, 2003 ) and publCIF (Westrip, 2009 ).

Supporting information

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536808040646/hb2865sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536808040646/hb2865Isup2.hkl

checkCIF report

Comment top

Boronic acids, RB(OH)₂ with R = alkyl and aryl, have applications in organic synthesis (Hall, 2005), host–guest chemistry (Höpfl, 2002), the molecular recognition of biochemically active molecules (Fujita et al., 2008) and in medicine as antibiotics, inhibitors and for the treatment of tumors (Soloway et al., 1998). Similar to carboxylic acids they are capable to form hydrogen-bonded dimeric units and, therefore, boronic acids have been used recently as new building blocks in crystal engineering (Fournier et al., 2003; Rodríguez-Cuamatzi et al., 2004; Rodríguez-Cuamatzi et al., 2005). Previously, the structures of 3-fluorophenylboronic acid (Wu et al., 2006), 2,6-difluoroboronic acid (Bradley et al., 1996) and pentafluoroboronic acid (Horton et al., 2004) had been reported. We now present the crystal structure of (I).

The molecular structure is essentially planar, O1—B1—C1—C2 = 4.4 (4)°, indicating that there is a π···π interaction between the dihydroxyboryl group and the aromatic ring, to which it is attached (Fig. 1). This interaction is also evidenced by the B—C bond length of 1.566 (3) Å, which is significantly shorter than that observed in boronates containing tetra-coordinate boron atoms (Höpfl, 2002). The crystal structure is stabilized by strong O2—H2···O1 hydrogen-bonding interactions, forming R₂²(8) motifs (Bernstein et al., 1995), as well as, O1—H1···F1 and O1—H1···F2 bifurcated hydrogen bonds (Fig. 2; Table 1) (Desiraju, 2002). Due to these interactions each boronic acid homodimer is linked to two neighboring homodimeric units, thus creating a two-dimensional hydrogen-bonded network, in which fluorine is therefore an essential structural component.

Related literature top

For general backround to boronic acids, see: Hall (2005); Höpfl (2002); Fujita et al. (2008); Soloway et al. (1998);. For hydrogen-bond motifs, see: Bernstein et al. (1995); Desiraju (2002). For related structures, see: Wu et al. (2006); Bradley et al. (1996); Horton et al. (2004). For crystal engineering, see: Fournier et al. (2003); Rodríguez-Cuamatzi et al. (2004, 2005).

Experimental top

2,4-Difluorophenylboronic acid was purchased from Aldrich and crystallized from water to yield colourless blocks of (I).

Computing details top

Data collection: SMART (Bruker, 2000); cell refinement: SAINT-Plus-NT (Bruker, 2001); data reduction: SAINT-Plus-NT (Bruker, 2001); program(s) used to solve structure: SHELXTL-NT (Sheldrick, 2008); program(s) used to refine structure: SHELXTL-NT (Sheldrick, 2008); molecular graphics: CAMERON (Watkin et al., 1996); software used to prepare material for publication: PLATON (Spek, 2003) and publCIF (Westrip, 2009).

Figures top

	Fig. 1. The molecular structure of (I) with displacement ellipsoids drawn at the 30% probability level and H atoms shown as small spheres of arbitrary radius.
	Fig. 2. View of the packing arrangement of the two-dimensional network of (I)(I).

2,4-Difluorophenylboronic acid top

Crystal data top

C₆H₅BF₂O₂	F(000) = 320
M_r = 157.91	D_x = 1.552 Mg m⁻³
Monoclinic, P2₁/n	Melting point = 521–522 K
Hall symbol: -P 2yn	Mo Kα radiation, λ = 0.71073 Å
a = 3.7617 (11) Å	Cell parameters from 1052 reflections
b = 12.347 (4) Å	θ = 2.3–26.2°
c = 14.620 (4) Å	µ = 0.15 mm⁻¹
β = 95.450 (5)°	T = 293 K
V = 676.0 (3) Å³	Block, colorless
Z = 4	0.37 × 0.35 × 0.22 mm

Data collection top

Bruker SMART APEX CCD area-detector diffractometer	1190 independent reflections
Radiation source: fine-focus sealed tube	1012 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.028
Detector resolution: 8.3 pixels mm^-1	θ_max = 25.0°, θ_min = 2.2°
ϕ and ω scans	h = −3→4
Absorption correction: multi-scan (SADABS; Sheldrick, 1996)	k = −14→12
T_min = 0.947, T_max = 0.968	l = −17→17
3196 measured reflections

Refinement top

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)] = 0.056	Hydrogen site location: inferred from neighbouring sites
wR(F²) = 0.127	H atoms treated by a mixture of independent and constrained refinement
S = 1.15	w = 1/[σ²(F_o²) + (0.0442P)² + 0.2673P] where P = (F_o² + 2F_c²)/3
1190 reflections	(Δ/σ)_max < 0.001
106 parameters	Δρ_max = 0.14 e Å⁻³
2 restraints	Δρ_min = −0.18 e Å⁻³

Crystal data top

C₆H₅BF₂O₂	V = 676.0 (3) Å³
M_r = 157.91	Z = 4
Monoclinic, P2₁/n	Mo Kα radiation
a = 3.7617 (11) Å	µ = 0.15 mm⁻¹
b = 12.347 (4) Å	T = 293 K
c = 14.620 (4) Å	0.37 × 0.35 × 0.22 mm
β = 95.450 (5)°

Data collection top

Bruker SMART APEX CCD area-detector diffractometer	1190 independent reflections
Absorption correction: multi-scan (SADABS; Sheldrick, 1996)	1012 reflections with I > 2σ(I)
T_min = 0.947, T_max = 0.968	R_int = 0.028
3196 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.056	2 restraints
wR(F²) = 0.127	H atoms treated by a mixture of independent and constrained refinement
S = 1.15	Δρ_max = 0.14 e Å⁻³
1190 reflections	Δρ_min = −0.18 e Å⁻³
106 parameters

Special details top

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 (Å²) top

	x	y	z	U_iso*/U_eq
B1	0.7704 (8)	0.4548 (2)	0.62567 (18)	0.0452 (7)
O1	0.6825 (6)	0.38623 (15)	0.55419 (13)	0.0695 (6)
H1	0.748 (9)	0.3215 (9)	0.562 (2)	0.104*
O2	0.6880 (6)	0.55977 (14)	0.61557 (12)	0.0630 (6)
H2	0.593 (8)	0.577 (3)	0.5632 (10)	0.094*
F1	1.0385 (5)	0.23728 (11)	0.67473 (11)	0.0768 (6)
F2	1.4329 (5)	0.33016 (14)	0.97634 (10)	0.0822 (6)
C1	0.9591 (6)	0.41789 (18)	0.72069 (15)	0.0424 (6)
C2	1.0796 (7)	0.31430 (18)	0.74175 (16)	0.0470 (6)
C3	1.2380 (7)	0.2819 (2)	0.82553 (17)	0.0539 (7)
H3	1.3138	0.2109	0.8363	0.065*
C4	1.2785 (7)	0.3593 (2)	0.89223 (17)	0.0547 (7)
C5	1.1696 (8)	0.4640 (2)	0.87828 (17)	0.0586 (7)
H5	1.2013	0.5150	0.9251	0.070*
C6	1.0119 (7)	0.49169 (19)	0.79282 (16)	0.0498 (6)
H6	0.9371	0.5628	0.7827	0.060*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
B1	0.0451 (16)	0.0425 (15)	0.0471 (16)	−0.0009 (12)	−0.0005 (12)	0.0033 (12)
O1	0.1000 (17)	0.0484 (11)	0.0540 (11)	0.0158 (10)	−0.0241 (10)	−0.0009 (9)
O2	0.0850 (15)	0.0441 (10)	0.0552 (11)	0.0087 (9)	−0.0172 (10)	0.0048 (8)
F1	0.1192 (15)	0.0456 (9)	0.0602 (10)	0.0151 (9)	−0.0187 (9)	−0.0046 (7)
F2	0.1070 (14)	0.0804 (12)	0.0527 (10)	−0.0120 (10)	−0.0262 (9)	0.0181 (8)
C1	0.0383 (13)	0.0412 (13)	0.0473 (13)	−0.0039 (10)	0.0019 (10)	0.0048 (10)
C2	0.0523 (16)	0.0410 (13)	0.0467 (13)	−0.0017 (11)	0.0001 (11)	0.0008 (10)
C3	0.0584 (17)	0.0449 (14)	0.0564 (15)	0.0002 (12)	−0.0053 (13)	0.0124 (12)
C4	0.0579 (17)	0.0613 (17)	0.0426 (13)	−0.0099 (13)	−0.0075 (12)	0.0135 (12)
C5	0.0696 (19)	0.0552 (16)	0.0489 (14)	−0.0109 (13)	−0.0058 (13)	−0.0020 (12)
C6	0.0559 (16)	0.0399 (13)	0.0522 (14)	−0.0011 (11)	−0.0011 (12)	0.0029 (11)

Geometric parameters (Å, º) top

B1—O2	1.338 (3)	C1—C6	1.394 (3)
B1—O1	1.361 (3)	C2—C3	1.370 (3)
B1—C1	1.566 (3)	C3—C4	1.363 (4)
O1—H1	0.841 (15)	C3—H3	0.93
O2—H2	0.841 (15)	C4—C5	1.366 (4)
F1—C2	1.364 (3)	C5—C6	1.374 (3)
F2—C4	1.358 (3)	C5—H5	0.93
C1—C2	1.382 (3)	C6—H6	0.93

O2—B1—O1	118.7 (2)	C4—C3—H3	121.8
O2—B1—C1	117.4 (2)	C2—C3—H3	121.8
O1—B1—C1	123.8 (2)	F2—C4—C3	118.1 (2)
B1—O1—H1	116 (2)	F2—C4—C5	118.8 (2)
B1—O2—H2	115 (2)	C3—C4—C5	123.0 (2)
C2—C1—C6	114.6 (2)	C4—C5—C6	117.9 (2)
C2—C1—B1	125.3 (2)	C4—C5—H5	121.0
C6—C1—B1	120.1 (2)	C6—C5—H5	121.0
F1—C2—C3	116.7 (2)	C5—C6—C1	122.9 (2)
F1—C2—C1	118.2 (2)	C5—C6—H6	118.5
C3—C2—C1	125.1 (2)	C1—C6—H6	118.5
C4—C3—C2	116.4 (2)

O2—B1—C1—C2	−176.5 (2)	C1—C2—C3—C4	−0.3 (4)
O1—B1—C1—C2	4.5 (4)	C2—C3—C4—F2	179.7 (2)
O2—B1—C1—C6	4.6 (4)	C2—C3—C4—C5	0.0 (4)
O1—B1—C1—C6	−174.5 (2)	F2—C4—C5—C6	−179.6 (2)
C6—C1—C2—F1	−179.9 (2)	C3—C4—C5—C6	0.1 (4)
B1—C1—C2—F1	1.1 (4)	C4—C5—C6—C1	0.0 (4)
C6—C1—C2—C3	0.4 (4)	C2—C1—C6—C5	−0.3 (4)
B1—C1—C2—C3	−178.6 (2)	B1—C1—C6—C5	178.8 (2)
F1—C2—C3—C4	180.0 (2)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
O1—H1···F1	0.84 (2)	2.16 (3)	2.799 (3)	133 (2)
O1—H1···F2ⁱ	0.84 (2)	2.39 (2)	3.086 (3)	140 (3)
O2—H2···O1ⁱⁱ	0.84 (2)	1.97 (2)	2.809 (3)	174 (3)

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

Experimental details

Crystal data
Chemical formula	C₆H₅BF₂O₂
M_r	157.91
Crystal system, space group	Monoclinic, P2₁/n
Temperature (K)	293
a, b, c (Å)	3.7617 (11), 12.347 (4), 14.620 (4)
β (°)	95.450 (5)
V (Å³)	676.0 (3)
Z	4
Radiation type	Mo Kα
µ (mm⁻¹)	0.15
Crystal size (mm)	0.37 × 0.35 × 0.22

Data collection
Diffractometer	Bruker SMART APEX CCD area-detector diffractometer
Absorption correction	Multi-scan (SADABS; Sheldrick, 1996)
T_min, T_max	0.947, 0.968
No. of measured, independent and observed [I > 2σ(I)] reflections	3196, 1190, 1012
R_int	0.028
(sin θ/λ)_max (Å⁻¹)	0.594

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.056, 0.127, 1.15
No. of reflections	1190
No. of parameters	106
No. of restraints	2
H-atom treatment	H atoms treated by a mixture of independent and constrained refinement
Δρ_max, Δρ_min (e Å⁻³)	0.14, −0.18

Computer programs: SMART (Bruker, 2000), SAINT-Plus-NT (Bruker, 2001), SHELXTL-NT (Sheldrick, 2008), CAMERON (Watkin et al., 1996), PLATON (Spek, 2003) and publCIF (Westrip, 2009).

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
O1—H1···F1	0.841 (15)	2.16 (3)	2.799 (3)	133 (2)
O1—H1···F2ⁱ	0.841 (15)	2.39 (2)	3.086 (3)	140 (3)
O2—H2···O1ⁱⁱ	0.841 (19)	1.97 (2)	2.809 (3)	174 (3)

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

Acknowledgements

This work was supported by Consejo Nacional de Ciencia y Tecnología (CIAM-59213 for HH).

References

Bernstein, J., Davis, R. E., Shimoni, L. & Chang, N.-L. (1995). Angew. Chem. Int. Ed. Engl. 34, 1555–1573. CrossRef CAS Web of Science Google Scholar
Bradley, D. C., Harding, I. S., Keefe, A. D., Motevalli, M. & Zheng, D. H. (1996). J. Chem. Soc. Dalton Trans. pp. 3931–3936. CSD CrossRef Web of Science Google Scholar
Bruker (2000). SMART. Bruker AXS Inc., Madison, Wisconsin, USA. Google Scholar
Bruker (2001). SAINT-Plus NT. Bruker AXS Inc., Madison, Wisconsin, USA. Google Scholar
Desiraju, G. R. (2002). Acc. Chem. Res. 35, 565–573. Web of Science CrossRef PubMed CAS Google Scholar
Fournier, J.-H., Maris, T., Wuest, J. D., Guo, W. & Galoppini, E. (2003). J. Am. Chem. Soc. 125, 1002–1006. Web of Science CSD CrossRef PubMed CAS Google Scholar
Fujita, N., Shinkai, S. & James, T. D. (2008). Chem. Asian J. 3, 1076–1091. Web of Science CrossRef PubMed CAS Google Scholar
Hall, D. G. (2005). Boronic Acids: Preparation, Applications in Organic Synthesis and Medicine. Weinheim: Wiley-VCH. Google Scholar
Höpfl, H. (2002). Structure and Bonding, edited by H. W. Roesky & D. A. Atwood, Vol. 103, pp. 1-56. Berlin: Springer Verlag. Google Scholar
Horton, P. N., Hursthouse, M. B., Beckett, M. A. & Rugen-Hankey, M. P. (2004). Acta Cryst. E60, o2204–o2206. Web of Science CSD CrossRef IUCr Journals Google Scholar
Rodríguez-Cuamatzi, P., Arillo-Flores, O. I., Bernal-Uruchurtu, M. I. & Höpfl, H. (2005). Cryst. Growth Des. 5, 167–175. Google Scholar
Rodríguez-Cuamatzi, P., Vargas-Díaz, G. & Höpfl, H. (2004). Angew. Chem. Int. Ed. 43, 3041–3044. Web of Science CSD CrossRef Google Scholar
Sheldrick, G. M. (1996). SADABS. University of Göttingen, Germany. Google Scholar
Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. Web of Science CrossRef CAS IUCr Journals Google Scholar
Soloway, A. H., Tjarks, W., Barnum, B. A., Rong, R.-A., Barth, R. F., Codogni, I. M. & Wilson, J. G. (1998). Chem. Rev. 98, 1515–1562. Web of Science CrossRef PubMed CAS Google Scholar
Spek, A. L. (2003). J. Appl. Cryst. 36, 7–13. Web of Science CrossRef CAS IUCr Journals Google Scholar
Watkin, D. J., Prout, C. K. & Pearce, L. J. (1996). CAMERON. Chemical Crystallography Laboratory Oxford, Oxford, England. Google Scholar
Westrip, S. P. (2009). publCIF. In preparation. Google Scholar
Wu, Y.-M., Dong, C.-C., Liu, S., Zhu, H.-J. & Wu, Y.-Z. (2006). Acta Cryst. E62, o4236–o4237. Web of Science CSD CrossRef IUCr Journals Google Scholar