2,6-Difluoro-benzoic acid.

In the title compound, C(7)H(4)F(2)O(2), the dihedral angle between the benzene ring and the carboxyl-ate group is 33.70 (14)°. In the crystal structure, inversion dimers linked by pairs of O-H⋯O hydro-gren bonds occur, generating R(2) (2)(8) loops. The dimers are linked into sheets lying parallel to (102) by C-H⋯F hydrogen bonds.

Related literature

For general background to 2,6-diflorobenzyl­chloride derivatives, see: Beavo (1995 ▶); Beavo & Reifsnyder (1990 ▶); Nicholson et al. (1991 ▶). For the stability of the temperature controller used in the data collection, see: Cosier & Glazer (1986 ▶).

Experimental

Crystal data

C7H4F2O2

M = 158.10

Monoclinic,

a = 3.6517 (4) Å

b = 14.1214 (15) Å

c = 12.2850 (13) Å

β = 95.651 (3)°

V = 630.42 (12) Å3

Z = 4

Mo Kα radiation

μ = 0.16 mm−1

T = 100 K

0.73 × 0.19 × 0.09 mm

Data collection

Bruker APEXII DUO CCD diffractometer

Absorption correction: multi-scan (SADABS; Bruker, 2009 ▶) T min = 0.841, T max = 0.986

6112 measured reflections

2190 independent reflections

1895 reflections with I > 2σ(I)

R int = 0.029

Refinement

R[F 2 > 2σ(F 2)] = 0.049

wR(F 2) = 0.143

S = 1.12

2190 reflections

116 parameters

All H-atom parameters refined

Δρmax = 0.47 e Å−3

Δρmin = −0.31 e Å−3

Data collection: APEX2 (Bruker, 2009 ▶); cell refinement: SAINT (Bruker, 2009 ▶); data reduction: SAINT; program(s) used to solve structure: SHELXTL (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL and PLATON (Spek, 2009 ▶).

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536810028758/hb5558sup1.cif

Structure factors: contains datablocks I. DOI: 10.1107/S1600536810028758/hb5558Isup2.hkl

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

C7H4F2O2	F(000) = 320
Mr = 158.10	Dx = 1.666 Mg m−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybc	Cell parameters from 3166 reflections
a = 3.6517 (4) Å	θ = 3.3–32.1°
b = 14.1214 (15) Å	µ = 0.16 mm−1
c = 12.2850 (13) Å	T = 100 K
β = 95.651 (3)°	Needle, colourless
V = 630.42 (12) Å3	0.73 × 0.19 × 0.09 mm
Z = 4

Bruker APEXII DUO CCD diffractometer	2190 independent reflections
Radiation source: fine-focus sealed tube	1895 reflections with I > 2σ(I)
graphite	Rint = 0.029
φ and ω scans	θmax = 32.1°, θmin = 2.2°
Absorption correction: multi-scan (SADABS; Bruker, 2009)	h = −5→5
Tmin = 0.841, Tmax = 0.986	k = −20→20
6112 measured reflections	l = −18→18

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)] = 0.049	Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.143	All H-atom parameters refined
S = 1.12	w = 1/[σ2(Fo2) + (0.0668P)2 + 0.3079P] where P = (Fo2 + 2Fc2)/3
2190 reflections	(Δ/σ)max < 0.001
116 parameters	Δρmax = 0.47 e Å−3
0 restraints	Δρmin = −0.31 e Å−3

Experimental. The crystal was placed in the cold stream of an Oxford Cryosystems Cobra open-flow nitrogen cryostat (Cosier & Glazer, 1986) operating at 100.0 (1) K.

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.

	x	y	z	Uiso*/Ueq
F1	0.0410 (3)	−0.01635 (6)	0.16839 (7)	0.0312 (2)
F2	0.2348 (3)	0.26707 (6)	0.36896 (7)	0.0285 (2)
O2	0.2287 (3)	0.09843 (7)	0.46658 (7)	0.0238 (2)
O3	0.4751 (3)	−0.00746 (7)	0.35958 (8)	0.0222 (2)
C1	0.0163 (4)	0.07830 (9)	0.17659 (9)	0.0194 (2)
C2	−0.1413 (4)	0.12763 (10)	0.08679 (10)	0.0228 (3)
C3	−0.1734 (4)	0.22519 (10)	0.09441 (10)	0.0234 (3)
C4	−0.0482 (4)	0.27250 (10)	0.19005 (11)	0.0230 (3)
C5	0.1044 (4)	0.22003 (9)	0.27793 (9)	0.0184 (2)
C6	0.1398 (3)	0.12160 (8)	0.27576 (9)	0.0160 (2)
C7	0.2939 (3)	0.06665 (8)	0.37288 (9)	0.0156 (2)
H2	−0.221 (7)	0.0927 (16)	0.0182 (18)	0.038 (6)*
H3	−0.285 (6)	0.2599 (15)	0.0302 (17)	0.035 (5)*
H4	−0.074 (6)	0.3406 (16)	0.1979 (18)	0.035 (5)*
H1O2	0.341 (11)	0.062 (3)	0.526 (3)	0.098 (12)*

	U11	U22	U33	U12	U13	U23
F1	0.0518 (6)	0.0183 (4)	0.0219 (4)	0.0019 (4)	−0.0044 (4)	−0.0039 (3)
F2	0.0459 (6)	0.0169 (4)	0.0210 (4)	−0.0010 (4)	−0.0048 (4)	−0.0018 (3)
O2	0.0340 (6)	0.0238 (5)	0.0135 (4)	0.0038 (4)	0.0014 (4)	0.0013 (3)
O3	0.0269 (5)	0.0179 (4)	0.0216 (4)	0.0056 (4)	0.0012 (4)	0.0030 (3)
C1	0.0238 (6)	0.0181 (5)	0.0162 (5)	0.0001 (4)	0.0014 (4)	0.0003 (4)
C2	0.0242 (6)	0.0289 (6)	0.0150 (5)	−0.0002 (5)	−0.0006 (4)	0.0019 (4)
C3	0.0224 (6)	0.0289 (6)	0.0184 (5)	0.0037 (5)	−0.0001 (4)	0.0078 (4)
C4	0.0272 (6)	0.0193 (6)	0.0225 (6)	0.0041 (5)	0.0016 (5)	0.0062 (4)
C5	0.0210 (5)	0.0174 (5)	0.0166 (5)	0.0004 (4)	0.0012 (4)	0.0011 (4)
C6	0.0182 (5)	0.0160 (5)	0.0137 (4)	0.0009 (4)	0.0014 (4)	0.0019 (3)
C7	0.0174 (5)	0.0148 (5)	0.0148 (4)	−0.0006 (4)	0.0020 (4)	0.0012 (3)

F1—C1	1.3442 (15)	C2—H2	0.99 (2)
F2—C5	1.3467 (14)	C3—C4	1.3892 (19)
O2—C7	1.2794 (14)	C3—H3	0.98 (2)
O2—H1O2	0.96 (4)	C4—C5	1.3807 (17)
O3—C7	1.2574 (15)	C4—H4	0.97 (2)
C1—C2	1.3815 (17)	C5—C6	1.3965 (17)
C1—C6	1.3976 (16)	C6—C7	1.4866 (15)
C2—C3	1.387 (2)
C7—O2—H1O2	113 (2)	C5—C4—H4	119.3 (13)
F1—C1—C2	117.86 (11)	C3—C4—H4	122.2 (13)
F1—C1—C6	118.83 (11)	F2—C5—C4	117.84 (11)
C2—C1—C6	123.29 (12)	F2—C5—C6	118.74 (10)
C1—C2—C3	118.58 (12)	C4—C5—C6	123.38 (11)
C1—C2—H2	119.4 (13)	C5—C6—C1	115.44 (10)
C3—C2—H2	122.0 (13)	C5—C6—C7	122.18 (10)
C2—C3—C4	120.79 (11)	C1—C6—C7	122.37 (11)
C2—C3—H3	118.2 (13)	O3—C7—O2	123.76 (11)
C4—C3—H3	121.0 (13)	O3—C7—C6	119.51 (10)
C5—C4—C3	118.49 (12)	O2—C7—C6	116.72 (10)
F1—C1—C2—C3	179.13 (13)	C4—C5—C6—C7	−177.92 (12)
C6—C1—C2—C3	1.2 (2)	F1—C1—C6—C5	−179.87 (12)
C1—C2—C3—C4	0.3 (2)	C2—C1—C6—C5	−1.92 (19)
C2—C3—C4—C5	−0.9 (2)	F1—C1—C6—C7	−0.65 (19)
C3—C4—C5—F2	178.01 (12)	C2—C1—C6—C7	177.31 (12)
C3—C4—C5—C6	0.0 (2)	C5—C6—C7—O3	−147.25 (13)
F2—C5—C6—C1	−176.65 (11)	C1—C6—C7—O3	33.57 (18)
C4—C5—C6—C1	1.31 (19)	C5—C6—C7—O2	33.33 (17)
F2—C5—C6—C7	4.12 (18)	C1—C6—C7—O2	−145.84 (13)

D—H···A	D—H	H···A	D···A	D—H···A
O2—H1O2···O3i	0.95 (4)	1.68 (4)	2.6318 (14)	174 (4)
C3—H3···F2ii	0.98 (2)	2.54 (2)	3.3428 (16)	138.7 (16)

Table 1

Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O2—H1O2⋯O3i	0.95 (4)	1.68 (4)	2.6318 (14)	174 (4)
C3—H3⋯F2ii	0.98 (2)	2.54 (2)	3.3428 (16)	138.7 (16)

Symmetry codes: (i) ; (ii) .