2,6-Bis(trifluoro-meth-yl)benzoic acid.

The title compound, C(9)H(4)F(6)O(2), contains two mol-ecules in the asymmetric unit, one of which exhibits disorder in both of its trifluoro-methyl groups. The dihedral angles between the benzene ring and the carboxyl group are 71.5 (2) and 99.3 (2)° in the two independent mol-ecules. The compound exhibits a catemeric structure resulting from inter-molecular O-H⋯O hydrogen bonding between the carboxyl groups.

Related literature

There is only one example in the literature of a crystallographically characterized benzoic acid with trifluoro­methyl groups in the ortho position, namely 2-trifluoro­methyl-3-pyrrole benzoic acid (see Faigl et al., 1999 ▶). For a recent example of crystal engineering to promote the formation of dimeric or catemeric structures in benzoic acids, see: Moorthy et al. (2002 ▶). For synthesis details, see: Dmowski & Piasecka-Macieiewska (1998 ▶).

Experimental

Crystal data

C9H4F6O2

M = 258.12

Monoclinic,

a = 10.873 (2) Å

b = 15.755 (3) Å

c = 11.561 (2) Å

β = 94.961 (2)°

V = 1973.0 (6) Å3

Z = 8

Mo Kα radiation

μ = 0.20 mm−1

T = 296 K

0.39 × 0.31 × 0.26 mm

Data collection

Bruker APEXII CCD diffractometer

Absorption correction: multi-scan (SADABS; Bruker, 2008 ▶) T min = 0.834, T max = 0.951

12904 measured reflections

3438 independent reflections

2889 reflections with I > 2σ(I)

R int = 0.021

Refinement

R[F 2 > 2σ(F 2)] = 0.039

wR(F 2) = 0.112

S = 1.02

3438 reflections

331 parameters

H-atom parameters constrained

Δρmax = 0.21 e Å−3

Δρmin = −0.23 e Å−3

Data collection: APEX2 (Bruker, 2008 ▶); cell refinement: SAINT (Bruker, 2008 ▶); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997 ▶) and Mercury (Macrae et al., 2006 ▶); software used to prepare material for publication: SHELXTL (Sheldrick, 2008 ▶).

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536809016468/bi2369sup1.cif

Structure factors: contains datablocks I. DOI: 10.1107/S1600536809016468/bi2369Isup2.hkl

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

C9H4F6O2	F(000) = 1024
Mr = 258.12	Dx = 1.738 Mg m−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybc	Cell parameters from 6970 reflections
a = 10.873 (2) Å	θ = 2.3–28.0°
b = 15.755 (3) Å	µ = 0.20 mm−1
c = 11.561 (2) Å	T = 296 K
β = 94.961 (2)°	Block, colorless
V = 1973.0 (6) Å3	0.39 × 0.31 × 0.26 mm
Z = 8

Bruker APEXII CCD diffractometer	3438 independent reflections
Radiation source: fine-focus sealed tube	2889 reflections with I > 2σ(I)
graphite	Rint = 0.021
φ and ω scans	θmax = 25.0°, θmin = 2.2°
Absorption correction: multi-scan (SADABS; Bruker, 2008)	h = −12→12
Tmin = 0.834, Tmax = 0.951	k = −18→18
12904 measured reflections	l = −13→11

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)] = 0.039	Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.112	H-atom parameters constrained
S = 1.02	w = 1/[σ2(Fo2) + (0.058P)2 + 0.5224P] where P = (Fo2 + 2Fc2)/3
3438 reflections	(Δ/σ)max < 0.001
331 parameters	Δρmax = 0.21 e Å−3
0 restraints	Δρmin = −0.23 e Å−3

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	Occ. (<1)
C1	0.25273 (16)	0.14562 (11)	0.00186 (14)	0.0532 (4)
C2	0.34011 (15)	0.08652 (10)	0.07069 (14)	0.0490 (4)
C3	0.43893 (16)	0.11687 (12)	0.14433 (16)	0.0564 (4)
C4	0.51596 (17)	0.06028 (14)	0.20807 (17)	0.0666 (5)
H4A	0.5807	0.0808	0.2581	0.080*
C5	0.49740 (19)	−0.02557 (14)	0.19783 (18)	0.0689 (5)
H5A	0.5498	−0.0629	0.2405	0.083*
C6	0.40178 (18)	−0.05640 (12)	0.12489 (16)	0.0614 (5)
H6A	0.3900	−0.1147	0.1175	0.074*
C7	0.32257 (15)	−0.00131 (10)	0.06209 (14)	0.0508 (4)
C8	0.46743 (19)	0.20978 (14)	0.1562 (2)	0.0756 (6)
F1	0.5244 (2)	0.22865 (11)	0.25885 (18)	0.1361 (7)
F2	0.53907 (15)	0.23619 (9)	0.07602 (19)	0.1232 (7)
F3	0.36850 (12)	0.25931 (8)	0.14440 (14)	0.0893 (4)
C9	0.21830 (18)	−0.03876 (12)	−0.01534 (17)	0.0632 (5)
F4	0.11518 (12)	−0.04286 (10)	0.03733 (13)	0.0975 (4)
F5	0.19338 (14)	0.00483 (8)	−0.11254 (11)	0.0911 (4)
F6	0.24344 (13)	−0.11707 (8)	−0.04877 (12)	0.0906 (4)
C10	0.10257 (17)	0.15284 (11)	0.30263 (15)	0.0545 (4)
C11	0.07034 (16)	0.13002 (10)	0.42282 (14)	0.0514 (4)
C12	−0.04150 (17)	0.15569 (11)	0.46310 (15)	0.0561 (4)
C13	−0.0643 (2)	0.14110 (13)	0.57757 (18)	0.0711 (5)
H13A	−0.1380	0.1593	0.6045	0.085*
C14	0.0220 (2)	0.09977 (15)	0.65140 (18)	0.0801 (6)
H14A	0.0066	0.0906	0.7283	0.096*
C15	0.1301 (2)	0.07212 (14)	0.61252 (17)	0.0730 (6)
H15A	0.1869	0.0430	0.6626	0.088*
C16	0.15558 (18)	0.08709 (12)	0.49899 (16)	0.0603 (5)
O1	0.14736 (11)	0.15753 (8)	0.02411 (10)	0.0606 (3)
O2	0.30404 (14)	0.18036 (9)	−0.08444 (12)	0.0751 (4)
H2A	0.2549	0.2129	−0.1192	0.113*
O3	0.05615 (13)	0.10397 (9)	0.22093 (11)	0.0684 (4)
H3A	0.0818	0.1182	0.1592	0.103*
O4	0.16936 (19)	0.21110 (11)	0.28586 (13)	0.0999 (6)
C17	−0.13950 (10)	0.19782 (8)	0.38373 (10)	0.0726 (5)
F7A	−0.09321 (12)	0.25255 (8)	0.31618 (10)	0.1010 (13)	0.569 (5)
F8A	−0.19164 (10)	0.13805 (10)	0.31178 (10)	0.0901 (11)	0.569 (5)
F9A	−0.22489 (10)	0.23045 (8)	0.43893 (12)	0.139 (2)	0.569 (5)
F7B	−0.17175 (10)	0.16347 (9)	0.28614 (11)	0.144 (3)	0.431 (5)
F9B	−0.10986 (11)	0.28028 (10)	0.35381 (9)	0.1164 (19)	0.431 (5)
F8B	−0.24254 (11)	0.21614 (8)	0.43317 (12)	0.0970 (19)	0.431 (5)
C18	0.27540 (10)	0.05569 (8)	0.46034 (11)	0.0751 (6)
F10A	0.26369 (10)	0.01894 (8)	0.35789 (13)	0.0877 (11)	0.689 (5)
F11A	0.36230 (10)	0.11205 (10)	0.46284 (11)	0.1163 (14)	0.689 (5)
F12A	0.32020 (9)	−0.01015 (9)	0.52898 (13)	0.1142 (11)	0.689 (5)
F10B	0.33236 (9)	0.12165 (10)	0.40107 (11)	0.108 (2)	0.311 (5)
F12B	0.35672 (10)	0.03614 (8)	0.54011 (13)	0.125 (3)	0.311 (5)
F11B	0.26173 (10)	0.00490 (9)	0.37781 (12)	0.154 (5)	0.311 (5)

	U11	U22	U33	U12	U13	U23
C1	0.0618 (10)	0.0542 (9)	0.0442 (9)	0.0104 (7)	0.0085 (7)	0.0040 (7)
C2	0.0497 (8)	0.0552 (9)	0.0428 (8)	0.0073 (7)	0.0077 (7)	0.0041 (7)
C3	0.0508 (9)	0.0623 (10)	0.0566 (10)	0.0011 (8)	0.0089 (8)	−0.0018 (8)
C4	0.0507 (10)	0.0864 (14)	0.0607 (11)	0.0064 (9)	−0.0062 (8)	−0.0020 (10)
C5	0.0631 (11)	0.0776 (13)	0.0641 (12)	0.0199 (10)	−0.0061 (9)	0.0105 (10)
C6	0.0689 (11)	0.0567 (10)	0.0582 (11)	0.0113 (8)	0.0025 (9)	0.0077 (8)
C7	0.0535 (9)	0.0551 (9)	0.0436 (9)	0.0056 (7)	0.0044 (7)	0.0031 (7)
C8	0.0608 (11)	0.0702 (12)	0.0965 (16)	−0.0044 (10)	0.0112 (11)	−0.0113 (11)
F1	0.1536 (16)	0.0987 (11)	0.1447 (15)	−0.0163 (10)	−0.0518 (13)	−0.0361 (10)
F2	0.1085 (11)	0.0773 (9)	0.1956 (19)	−0.0172 (8)	0.0813 (12)	−0.0035 (10)
F3	0.0828 (8)	0.0627 (7)	0.1245 (12)	0.0037 (6)	0.0221 (8)	−0.0124 (7)
C9	0.0672 (11)	0.0597 (11)	0.0615 (11)	0.0030 (9)	−0.0013 (9)	0.0003 (9)
F4	0.0628 (7)	0.1270 (12)	0.1024 (10)	−0.0164 (7)	0.0050 (7)	−0.0162 (9)
F5	0.1201 (11)	0.0832 (8)	0.0628 (7)	−0.0013 (7)	−0.0338 (7)	0.0035 (6)
F6	0.1079 (10)	0.0632 (7)	0.0972 (10)	0.0013 (6)	−0.0118 (8)	−0.0186 (6)
C10	0.0609 (10)	0.0574 (10)	0.0454 (9)	−0.0107 (8)	0.0059 (7)	−0.0075 (7)
C11	0.0640 (10)	0.0495 (9)	0.0408 (8)	−0.0136 (7)	0.0046 (7)	−0.0079 (7)
C12	0.0679 (11)	0.0526 (9)	0.0486 (9)	−0.0112 (8)	0.0089 (8)	−0.0117 (7)
C13	0.0839 (13)	0.0731 (12)	0.0591 (12)	−0.0128 (10)	0.0231 (10)	−0.0126 (10)
C14	0.1122 (18)	0.0860 (15)	0.0440 (10)	−0.0135 (13)	0.0171 (11)	0.0010 (10)
C15	0.0927 (15)	0.0781 (13)	0.0473 (10)	−0.0043 (11)	0.0009 (10)	0.0031 (9)
C16	0.0698 (11)	0.0606 (10)	0.0499 (10)	−0.0094 (9)	0.0017 (8)	−0.0042 (8)
O1	0.0575 (7)	0.0753 (8)	0.0490 (7)	0.0156 (6)	0.0041 (5)	0.0077 (6)
O2	0.0858 (9)	0.0756 (9)	0.0677 (8)	0.0301 (7)	0.0294 (7)	0.0303 (7)
O3	0.0850 (9)	0.0783 (9)	0.0420 (6)	−0.0259 (7)	0.0064 (6)	−0.0103 (6)
O4	0.1505 (15)	0.0963 (11)	0.0575 (9)	−0.0706 (11)	0.0357 (9)	−0.0223 (8)
C17	0.0723 (13)	0.0783 (14)	0.0675 (13)	0.0023 (11)	0.0087 (10)	−0.0092 (11)
F7A	0.115 (2)	0.088 (2)	0.099 (2)	0.0095 (16)	0.0008 (17)	0.0347 (18)
F8A	0.0718 (17)	0.0977 (19)	0.095 (2)	−0.0026 (14)	−0.0251 (14)	−0.0169 (16)
F9A	0.153 (4)	0.144 (3)	0.121 (4)	0.087 (3)	0.022 (3)	−0.030 (3)
F7B	0.156 (5)	0.187 (5)	0.079 (3)	0.090 (4)	−0.040 (3)	−0.064 (3)
F9B	0.100 (3)	0.097 (3)	0.151 (4)	0.009 (2)	0.005 (3)	0.039 (3)
F8B	0.055 (2)	0.146 (4)	0.092 (4)	0.006 (3)	0.018 (2)	0.007 (3)
C18	0.0736 (13)	0.0807 (15)	0.0699 (14)	−0.0014 (11)	0.0001 (11)	−0.0030 (11)
F10A	0.082 (2)	0.116 (2)	0.0655 (15)	0.0210 (16)	0.0119 (13)	−0.0152 (16)
F11A	0.0730 (14)	0.115 (2)	0.161 (3)	−0.0229 (14)	0.0114 (17)	−0.033 (2)
F12A	0.1041 (18)	0.130 (2)	0.107 (2)	0.0381 (17)	−0.0002 (15)	0.0232 (16)
F10B	0.076 (3)	0.109 (4)	0.146 (6)	0.006 (3)	0.039 (3)	0.029 (4)
F12B	0.084 (3)	0.204 (9)	0.081 (4)	0.039 (5)	−0.020 (3)	0.023 (4)
F11B	0.099 (7)	0.145 (7)	0.222 (11)	−0.022 (5)	0.038 (6)	−0.109 (7)

C1—O1	1.210 (2)	C11—C12	1.399 (3)
C1—O2	1.305 (2)	C12—C13	1.387 (3)
C1—C2	1.507 (2)	C12—C17	1.500 (2)
C2—C3	1.396 (2)	C13—C14	1.376 (3)
C2—C7	1.399 (2)	C13—H13A	0.930
C3—C4	1.390 (3)	C14—C15	1.365 (3)
C3—C8	1.500 (3)	C14—H14A	0.930
C4—C5	1.371 (3)	C15—C16	1.385 (3)
C4—H4A	0.930	C15—H15A	0.930
C5—C6	1.370 (3)	C16—C18	1.498 (2)
C5—H5A	0.930	O2—H2A	0.820
C6—C7	1.383 (2)	O3—H3A	0.820
C6—H6A	0.930	C17—F7B	1.2729 (11)
C7—C9	1.503 (3)	C17—F9A	1.2791 (11)
C8—F1	1.324 (3)	C17—F7A	1.2941 (11)
C8—F3	1.326 (3)	C17—F8B	1.3326 (12)
C8—F2	1.328 (3)	C17—F8A	1.3485 (12)
C9—F4	1.323 (2)	C17—F9B	1.3895 (12)
C9—F5	1.325 (2)	C18—F11B	1.2443 (10)
C9—F6	1.328 (2)	C18—F12B	1.2593 (11)
C10—O4	1.197 (2)	C18—F11A	1.2952 (11)
C10—O3	1.287 (2)	C18—F10A	1.3146 (11)
C10—C11	1.506 (2)	C18—F12A	1.3697 (11)
C11—C16	1.397 (3)	C18—F10B	1.4165 (12)
O1—C1—O2	124.93 (16)	C13—C12—C17	118.76 (16)
O1—C1—C2	123.28 (15)	C11—C12—C17	121.09 (14)
O2—C1—C2	111.78 (14)	C14—C13—C12	120.1 (2)
C3—C2—C7	118.36 (15)	C14—C13—H13A	119.9
C3—C2—C1	121.80 (15)	C12—C13—H13A	119.9
C7—C2—C1	119.84 (15)	C15—C14—C13	120.45 (19)
C4—C3—C2	120.00 (17)	C15—C14—H14A	119.8
C4—C3—C8	117.85 (18)	C13—C14—H14A	119.8
C2—C3—C8	122.14 (17)	C14—C15—C16	120.4 (2)
C5—C4—C3	120.63 (18)	C14—C15—H15A	119.8
C5—C4—H4A	119.7	C16—C15—H15A	119.8
C3—C4—H4A	119.7	C15—C16—C11	120.24 (19)
C6—C5—C4	120.08 (17)	C15—C16—C18	118.50 (17)
C6—C5—H5A	120.0	C11—C16—C18	121.25 (15)
C4—C5—H5A	120.0	C1—O2—H2A	109.5
C5—C6—C7	120.36 (18)	C10—O3—H3A	109.5
C5—C6—H6A	119.8	F9A—C17—F7A	111.7
C7—C6—H6A	119.8	F7B—C17—F8B	107.2
C6—C7—C2	120.55 (16)	F9A—C17—F8A	107.7
C6—C7—C9	118.00 (16)	F7A—C17—F8A	104.9
C2—C7—C9	121.45 (15)	F7B—C17—F9B	103.2
F1—C8—F3	105.80 (19)	F8B—C17—F9B	97.2
F1—C8—F2	107.3 (2)	F7B—C17—C12	118.73 (8)
F3—C8—F2	105.3 (2)	F9A—C17—C12	112.38 (8)
F1—C8—C3	112.2 (2)	F7A—C17—C12	111.79 (8)
F3—C8—C3	113.92 (17)	F8B—C17—C12	114.37 (8)
F2—C8—C3	111.77 (18)	F8A—C17—C12	107.87 (8)
F4—C9—F5	107.23 (17)	F9B—C17—C12	113.47 (8)
F4—C9—F6	107.01 (17)	F11B—C18—F12B	115.7
F5—C9—F6	105.48 (16)	F11A—C18—F10A	109.6
F4—C9—C7	111.76 (16)	F11A—C18—F12A	106.5
F5—C9—C7	112.95 (16)	F10A—C18—F12A	101.0
F6—C9—C7	111.98 (16)	F11B—C18—F10B	97.4
O4—C10—O3	123.01 (17)	F12B—C18—F10B	103.0
O4—C10—C11	121.71 (15)	F11B—C18—C16	113.07 (8)
O3—C10—C11	115.25 (15)	F12B—C18—C16	115.85 (8)
C16—C11—C12	118.60 (16)	F11A—C18—C16	114.75 (8)
C16—C11—C10	120.19 (16)	F10A—C18—C16	113.29 (8)
C12—C11—C10	121.10 (16)	F12A—C18—C16	110.63 (9)
C13—C12—C11	120.14 (18)	F10B—C18—C16	109.27 (9)
C7—C2—C1—O1	71.5 (2)	C12—C11—C10—O4	99.3 (2)

D—H···A	D—H	H···A	D···A	D—H···A
O2—H2A···O4i	0.82	1.82	2.6340 (19)	169
O3—H3A···O1	0.82	1.88	2.6951 (18)	176

Table 1

Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O2—H2A⋯O4i	0.82	1.82	2.6340 (19)	169
O3—H3A⋯O1	0.82	1.88	2.6951 (18)	176

Symmetry code: (i) .