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Acta Crystallogr Sect E Struct Rep Online. 2009 June 1; 65(Pt 6): o1217.
Published online 2009 May 7. doi:  10.1107/S1600536809016468
PMCID: PMC2969748

2,6-Bis(trifluoro­meth­yl)benzoic acid

Abstract

The title compound, C9H4F6O2, contains two mol­ecules in the asymmetric unit, one of which exhibits disorder in both of its trifluoro­methyl groups. The dihedral angles between the benzene ring and the carboxyl group are 71.5 (2) and 99.3 (2)° in the two independent mol­ecules. The compound exhibits a catemeric structure resulting from inter­molecular 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 [triangle]). For a recent example of crystal engineering to promote the formation of dimeric or catemeric structures in benzoic acids, see: Moorthy et al. (2002 [triangle]). For synthesis details, see: Dmowski & Piasecka-Macieiewska (1998 [triangle]).

An external file that holds a picture, illustration, etc.
Object name is e-65-o1217-scheme1.jpg

Experimental

Crystal data

  • C9H4F6O2
  • M r = 258.12
  • Monoclinic, An external file that holds a picture, illustration, etc.
Object name is e-65-o1217-efi1.jpg
  • 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 [triangle]) 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 [triangle]); cell refinement: SAINT (Bruker, 2008 [triangle]); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 [triangle]); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 [triangle]); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997 [triangle]) and Mercury (Macrae et al., 2006 [triangle]); software used to prepare material for publication: SHELXTL (Sheldrick, 2008 [triangle]).

Table 1
Hydrogen-bond geometry (Å, °)

Supplementary Material

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

Acknowledgments

The authors thank Saint Mary’s University for providing funding in the form of initial operating funds (JDM) and student funding through the Summer Employment Experience Program (JMT).

supplementary crystallographic information

Comment

The title molecule crystallizes in a catemer motif, a relatively rare form compared to the typical dimeric motif exhibited by benzoic acids resulting from intermolecular hydrogen bonding between the carboxylic acid groups (Moorthy et al., 2002). The sterically bulky o-CF3 groups result in the carboxylic acid fragments being twisted with respect to the aryl ring. This results in dihedral angles between the aryl ring and carboxylic acid fragments of C7—C2—C1—O1 = 71.5 (2)° and C12—C11—C10—O4 = 99.3 (2)°.

Experimental

The title compound was prepared following the literature methods (Dmowski & Piasecka-Macieiewska, 1998) with a slight modification. The compound crystallized from the oily reaction mixture that remained after acidification of the potassium benzoate salt with concentrated HCl, extraction of the organic components with toluene, drying of the organic fraction with magnesium sulfate and concentration by rotary evaporation.

Refinement

H atoms were placed in geometrically idealized positions with C—H = 0.93 Å and O—H = 0.82 Å and constrained to ride on the parent atom with Uiso(H) = 1.2 Ueq(C) or 1.5 Ueq(O). The trifluoromethyl groups belonging to C17 and C18 were modeled with a two-site disorder of the F atoms with refined site occupancy factors of 0.569 (5):0.431 (5) and 0.689 (5):0.311 (5), respectively.

Figures

Fig. 1.
The two molecules in the asymmetric unit with displacement ellipsoids shown at 50% probability for non-H atoms. For the disordered CF3 groups, both disorder components are shown.
Fig. 2.
Ball and stick representation featuring the catemeric structure formed through O—H···O hydrogen bonding. H atoms not involved in H-bonding and the CF3 groups have been omitted for clarity.

Crystal data

C9H4F6O2F(000) = 1024
Mr = 258.12Dx = 1.738 Mg m3
Monoclinic, P21/cMo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybcCell parameters from 6970 reflections
a = 10.873 (2) Åθ = 2.3–28.0°
b = 15.755 (3) ŵ = 0.20 mm1
c = 11.561 (2) ÅT = 296 K
β = 94.961 (2)°Block, colorless
V = 1973.0 (6) Å30.39 × 0.31 × 0.26 mm
Z = 8

Data collection

Bruker APEXII CCD diffractometer3438 independent reflections
Radiation source: fine-focus sealed tube2889 reflections with I > 2σ(I)
graphiteRint = 0.021
[var phi] and ω scansθmax = 25.0°, θmin = 2.2°
Absorption correction: multi-scan (SADABS; Bruker, 2008)h = −12→12
Tmin = 0.834, Tmax = 0.951k = −18→18
12904 measured reflectionsl = −13→11

Refinement

Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.039Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.112H-atom parameters constrained
S = 1.02w = 1/[σ2(Fo2) + (0.058P)2 + 0.5224P] where P = (Fo2 + 2Fc2)/3
3438 reflections(Δ/σ)max < 0.001
331 parametersΔρmax = 0.21 e Å3
0 restraintsΔρmin = −0.23 e Å3

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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2)

xyzUiso*/UeqOcc. (<1)
C10.25273 (16)0.14562 (11)0.00186 (14)0.0532 (4)
C20.34011 (15)0.08652 (10)0.07069 (14)0.0490 (4)
C30.43893 (16)0.11687 (12)0.14433 (16)0.0564 (4)
C40.51596 (17)0.06028 (14)0.20807 (17)0.0666 (5)
H4A0.58070.08080.25810.080*
C50.49740 (19)−0.02557 (14)0.19783 (18)0.0689 (5)
H5A0.5498−0.06290.24050.083*
C60.40178 (18)−0.05640 (12)0.12489 (16)0.0614 (5)
H6A0.3900−0.11470.11750.074*
C70.32257 (15)−0.00131 (10)0.06209 (14)0.0508 (4)
C80.46743 (19)0.20978 (14)0.1562 (2)0.0756 (6)
F10.5244 (2)0.22865 (11)0.25885 (18)0.1361 (7)
F20.53907 (15)0.23619 (9)0.07602 (19)0.1232 (7)
F30.36850 (12)0.25931 (8)0.14440 (14)0.0893 (4)
C90.21830 (18)−0.03876 (12)−0.01534 (17)0.0632 (5)
F40.11518 (12)−0.04286 (10)0.03733 (13)0.0975 (4)
F50.19338 (14)0.00483 (8)−0.11254 (11)0.0911 (4)
F60.24344 (13)−0.11707 (8)−0.04877 (12)0.0906 (4)
C100.10257 (17)0.15284 (11)0.30263 (15)0.0545 (4)
C110.07034 (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−0.13800.15930.60450.085*
C140.0220 (2)0.09977 (15)0.65140 (18)0.0801 (6)
H14A0.00660.09060.72830.096*
C150.1301 (2)0.07212 (14)0.61252 (17)0.0730 (6)
H15A0.18690.04300.66260.088*
C160.15558 (18)0.08709 (12)0.49899 (16)0.0603 (5)
O10.14736 (11)0.15753 (8)0.02411 (10)0.0606 (3)
O20.30404 (14)0.18036 (9)−0.08444 (12)0.0751 (4)
H2A0.25490.2129−0.11920.113*
O30.05615 (13)0.10397 (9)0.22093 (11)0.0684 (4)
H3A0.08180.11820.15920.103*
O40.16936 (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)
C180.27540 (10)0.05569 (8)0.46034 (11)0.0751 (6)
F10A0.26369 (10)0.01894 (8)0.35789 (13)0.0877 (11)0.689 (5)
F11A0.36230 (10)0.11205 (10)0.46284 (11)0.1163 (14)0.689 (5)
F12A0.32020 (9)−0.01015 (9)0.52898 (13)0.1142 (11)0.689 (5)
F10B0.33236 (9)0.12165 (10)0.40107 (11)0.108 (2)0.311 (5)
F12B0.35672 (10)0.03614 (8)0.54011 (13)0.125 (3)0.311 (5)
F11B0.26173 (10)0.00490 (9)0.37781 (12)0.154 (5)0.311 (5)

Atomic displacement parameters (Å2)

U11U22U33U12U13U23
C10.0618 (10)0.0542 (9)0.0442 (9)0.0104 (7)0.0085 (7)0.0040 (7)
C20.0497 (8)0.0552 (9)0.0428 (8)0.0073 (7)0.0077 (7)0.0041 (7)
C30.0508 (9)0.0623 (10)0.0566 (10)0.0011 (8)0.0089 (8)−0.0018 (8)
C40.0507 (10)0.0864 (14)0.0607 (11)0.0064 (9)−0.0062 (8)−0.0020 (10)
C50.0631 (11)0.0776 (13)0.0641 (12)0.0199 (10)−0.0061 (9)0.0105 (10)
C60.0689 (11)0.0567 (10)0.0582 (11)0.0113 (8)0.0025 (9)0.0077 (8)
C70.0535 (9)0.0551 (9)0.0436 (9)0.0056 (7)0.0044 (7)0.0031 (7)
C80.0608 (11)0.0702 (12)0.0965 (16)−0.0044 (10)0.0112 (11)−0.0113 (11)
F10.1536 (16)0.0987 (11)0.1447 (15)−0.0163 (10)−0.0518 (13)−0.0361 (10)
F20.1085 (11)0.0773 (9)0.1956 (19)−0.0172 (8)0.0813 (12)−0.0035 (10)
F30.0828 (8)0.0627 (7)0.1245 (12)0.0037 (6)0.0221 (8)−0.0124 (7)
C90.0672 (11)0.0597 (11)0.0615 (11)0.0030 (9)−0.0013 (9)0.0003 (9)
F40.0628 (7)0.1270 (12)0.1024 (10)−0.0164 (7)0.0050 (7)−0.0162 (9)
F50.1201 (11)0.0832 (8)0.0628 (7)−0.0013 (7)−0.0338 (7)0.0035 (6)
F60.1079 (10)0.0632 (7)0.0972 (10)0.0013 (6)−0.0118 (8)−0.0186 (6)
C100.0609 (10)0.0574 (10)0.0454 (9)−0.0107 (8)0.0059 (7)−0.0075 (7)
C110.0640 (10)0.0495 (9)0.0408 (8)−0.0136 (7)0.0046 (7)−0.0079 (7)
C120.0679 (11)0.0526 (9)0.0486 (9)−0.0112 (8)0.0089 (8)−0.0117 (7)
C130.0839 (13)0.0731 (12)0.0591 (12)−0.0128 (10)0.0231 (10)−0.0126 (10)
C140.1122 (18)0.0860 (15)0.0440 (10)−0.0135 (13)0.0171 (11)0.0010 (10)
C150.0927 (15)0.0781 (13)0.0473 (10)−0.0043 (11)0.0009 (10)0.0031 (9)
C160.0698 (11)0.0606 (10)0.0499 (10)−0.0094 (9)0.0017 (8)−0.0042 (8)
O10.0575 (7)0.0753 (8)0.0490 (7)0.0156 (6)0.0041 (5)0.0077 (6)
O20.0858 (9)0.0756 (9)0.0677 (8)0.0301 (7)0.0294 (7)0.0303 (7)
O30.0850 (9)0.0783 (9)0.0420 (6)−0.0259 (7)0.0064 (6)−0.0103 (6)
O40.1505 (15)0.0963 (11)0.0575 (9)−0.0706 (11)0.0357 (9)−0.0223 (8)
C170.0723 (13)0.0783 (14)0.0675 (13)0.0023 (11)0.0087 (10)−0.0092 (11)
F7A0.115 (2)0.088 (2)0.099 (2)0.0095 (16)0.0008 (17)0.0347 (18)
F8A0.0718 (17)0.0977 (19)0.095 (2)−0.0026 (14)−0.0251 (14)−0.0169 (16)
F9A0.153 (4)0.144 (3)0.121 (4)0.087 (3)0.022 (3)−0.030 (3)
F7B0.156 (5)0.187 (5)0.079 (3)0.090 (4)−0.040 (3)−0.064 (3)
F9B0.100 (3)0.097 (3)0.151 (4)0.009 (2)0.005 (3)0.039 (3)
F8B0.055 (2)0.146 (4)0.092 (4)0.006 (3)0.018 (2)0.007 (3)
C180.0736 (13)0.0807 (15)0.0699 (14)−0.0014 (11)0.0001 (11)−0.0030 (11)
F10A0.082 (2)0.116 (2)0.0655 (15)0.0210 (16)0.0119 (13)−0.0152 (16)
F11A0.0730 (14)0.115 (2)0.161 (3)−0.0229 (14)0.0114 (17)−0.033 (2)
F12A0.1041 (18)0.130 (2)0.107 (2)0.0381 (17)−0.0002 (15)0.0232 (16)
F10B0.076 (3)0.109 (4)0.146 (6)0.006 (3)0.039 (3)0.029 (4)
F12B0.084 (3)0.204 (9)0.081 (4)0.039 (5)−0.020 (3)0.023 (4)
F11B0.099 (7)0.145 (7)0.222 (11)−0.022 (5)0.038 (6)−0.109 (7)

Geometric parameters (Å, °)

C1—O11.210 (2)C11—C121.399 (3)
C1—O21.305 (2)C12—C131.387 (3)
C1—C21.507 (2)C12—C171.500 (2)
C2—C31.396 (2)C13—C141.376 (3)
C2—C71.399 (2)C13—H13A0.930
C3—C41.390 (3)C14—C151.365 (3)
C3—C81.500 (3)C14—H14A0.930
C4—C51.371 (3)C15—C161.385 (3)
C4—H4A0.930C15—H15A0.930
C5—C61.370 (3)C16—C181.498 (2)
C5—H5A0.930O2—H2A0.820
C6—C71.383 (2)O3—H3A0.820
C6—H6A0.930C17—F7B1.2729 (11)
C7—C91.503 (3)C17—F9A1.2791 (11)
C8—F11.324 (3)C17—F7A1.2941 (11)
C8—F31.326 (3)C17—F8B1.3326 (12)
C8—F21.328 (3)C17—F8A1.3485 (12)
C9—F41.323 (2)C17—F9B1.3895 (12)
C9—F51.325 (2)C18—F11B1.2443 (10)
C9—F61.328 (2)C18—F12B1.2593 (11)
C10—O41.197 (2)C18—F11A1.2952 (11)
C10—O31.287 (2)C18—F10A1.3146 (11)
C10—C111.506 (2)C18—F12A1.3697 (11)
C11—C161.397 (3)C18—F10B1.4165 (12)
O1—C1—O2124.93 (16)C13—C12—C17118.76 (16)
O1—C1—C2123.28 (15)C11—C12—C17121.09 (14)
O2—C1—C2111.78 (14)C14—C13—C12120.1 (2)
C3—C2—C7118.36 (15)C14—C13—H13A119.9
C3—C2—C1121.80 (15)C12—C13—H13A119.9
C7—C2—C1119.84 (15)C15—C14—C13120.45 (19)
C4—C3—C2120.00 (17)C15—C14—H14A119.8
C4—C3—C8117.85 (18)C13—C14—H14A119.8
C2—C3—C8122.14 (17)C14—C15—C16120.4 (2)
C5—C4—C3120.63 (18)C14—C15—H15A119.8
C5—C4—H4A119.7C16—C15—H15A119.8
C3—C4—H4A119.7C15—C16—C11120.24 (19)
C6—C5—C4120.08 (17)C15—C16—C18118.50 (17)
C6—C5—H5A120.0C11—C16—C18121.25 (15)
C4—C5—H5A120.0C1—O2—H2A109.5
C5—C6—C7120.36 (18)C10—O3—H3A109.5
C5—C6—H6A119.8F9A—C17—F7A111.7
C7—C6—H6A119.8F7B—C17—F8B107.2
C6—C7—C2120.55 (16)F9A—C17—F8A107.7
C6—C7—C9118.00 (16)F7A—C17—F8A104.9
C2—C7—C9121.45 (15)F7B—C17—F9B103.2
F1—C8—F3105.80 (19)F8B—C17—F9B97.2
F1—C8—F2107.3 (2)F7B—C17—C12118.73 (8)
F3—C8—F2105.3 (2)F9A—C17—C12112.38 (8)
F1—C8—C3112.2 (2)F7A—C17—C12111.79 (8)
F3—C8—C3113.92 (17)F8B—C17—C12114.37 (8)
F2—C8—C3111.77 (18)F8A—C17—C12107.87 (8)
F4—C9—F5107.23 (17)F9B—C17—C12113.47 (8)
F4—C9—F6107.01 (17)F11B—C18—F12B115.7
F5—C9—F6105.48 (16)F11A—C18—F10A109.6
F4—C9—C7111.76 (16)F11A—C18—F12A106.5
F5—C9—C7112.95 (16)F10A—C18—F12A101.0
F6—C9—C7111.98 (16)F11B—C18—F10B97.4
O4—C10—O3123.01 (17)F12B—C18—F10B103.0
O4—C10—C11121.71 (15)F11B—C18—C16113.07 (8)
O3—C10—C11115.25 (15)F12B—C18—C16115.85 (8)
C16—C11—C12118.60 (16)F11A—C18—C16114.75 (8)
C16—C11—C10120.19 (16)F10A—C18—C16113.29 (8)
C12—C11—C10121.10 (16)F12A—C18—C16110.63 (9)
C13—C12—C11120.14 (18)F10B—C18—C16109.27 (9)
C7—C2—C1—O171.5 (2)C12—C11—C10—O499.3 (2)

Hydrogen-bond geometry (Å, °)

D—H···AD—HH···AD···AD—H···A
O2—H2A···O4i0.821.822.6340 (19)169
O3—H3A···O10.821.882.6951 (18)176

Symmetry codes: (i) x, −y+1/2, z−1/2.

Footnotes

Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: BI2369).

References

  • Bruker (2008). APEX2, SAINT and SADABS Bruker AXS Inc., Madison, Wisconsin, USA.
  • Dmowski, W. & Piasecka-Macieiewska, K. (1998). Tetrahedron, 54, 6781–6792.
  • Faigl, F., Fogassy, K., Szűcs, E., Kovács, K., Keserű, G. M., Harmat, V., Böcski, Z. & Tőke, L. (1999). Tetrahedron, 55, 7881–7892.
  • Farrugia, L. J. (1997). J. Appl. Cryst.30, 565.
  • Macrae, C. F., Edgington, P. R., McCabe, P., Pidcock, E., Shields, G. P., Taylor, R., Towler, M. & van de Streek, J. (2006). J. Appl. Cryst.39, 453–457.
  • Moorthy, J. N., Natarajan, R., Mal, P. & Venugopalan, P. (2002). J. Am. Chem. Soc.124, 6530–6531. [PubMed]
  • Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. [PubMed]

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