organic compounds\(\def\hfill{\hskip 5em}\def\hfil{\hskip 3em}\def\eqno#1{\hfil {#1}}\)

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3,3,3-Tri­fluoro-2-hydr­­oxy-2-(tri­fluoro­meth­yl)propionic acid

aNelson Mandela Metropolitan University, Summerstrand Campus, Department of Chemistry, University Way, Summerstrand, PO Box 77000, Port Elizabeth, 6031, South Africa
*Correspondence e-mail: richard.betz@webmail.co.za

(Received 29 January 2013; accepted 30 January 2013; online 2 February 2013)

In the title perfluorinated hy­droxy­isobutyric acid derivative, C4H2F6O3, the mol­ecule shows approximately Cs symmetry. The carb­oxy group is nearly coplanar with the C—OH moiety and the O=C—C—O(H) torsion angle is 5.5 (2)°. An intra­molecular O—H⋯O hydrogen bond occurs. In the crystal, O—H⋯O hydrogen bonds connect the mol­ecules into supra­molecular chains along the a-axis direction.

Related literature

For the crystal structure of 2-hy­droxy-2-(trifluoro­meth­yl)proprionic acid, see: Soloshonok et al. (2007[Soloshonok, V. A., Ueki, H., Yasumoto, M., Mekala, S., Hirschi, J. S. & Singleton, D. A. (2007). J. Am. Chem. Soc. 129, 12112-?-12113.]). For background to chelate ligands, see: Gade (1998[Gade, L. H. (1998). Koordinationschemie, 1. Auflage, Weinheim: Wiley-VCH.]). For graph-set analysis of hydrogen bonds, see: Etter et al. (1990[Etter, M. C., MacDonald, J. C. & Bernstein, J. (1990). Acta Cryst. B46, 256-262.]); Bernstein et al. (1995[Bernstein, J., Davis, R. E., Shimoni, L. & Chang, N.-L. (1995). Angew. Chem. Int. Ed. Engl. 34, 1555-1573.]).

[Scheme 1]

Experimental

Crystal data
  • C4H2F6O3

  • Mr = 212.06

  • Orthorhombic, P 21 21 21

  • a = 5.9949 (2) Å

  • b = 6.4007 (2) Å

  • c = 18.5642 (6) Å

  • V = 712.34 (4) Å3

  • Z = 4

  • Mo Kα radiation

  • μ = 0.26 mm−1

  • T = 200 K

  • 0.53 × 0.53 × 0.34 mm

Data collection
  • Bruker APEXII CCD diffractometer

  • Absorption correction: multi-scan (SADABS; Bruker, 2008[Bruker (2008). SADABS. Bruker AXS Inc., Madison, Wisconsin, USA.]) Tmin = 0.908, Tmax = 1.000

  • 3824 measured reflections

  • 1052 independent reflections

  • 1024 reflections with I > 2σ(I)

  • Rint = 0.010

Refinement
  • R[F2 > 2σ(F2)] = 0.029

  • wR(F2) = 0.076

  • S = 1.05

  • 1052 reflections

  • 120 parameters

  • H-atom parameters constrained

  • Δρmax = 0.31 e Å−3

  • Δρmin = −0.18 e Å−3

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A D—H H⋯A DA D—H⋯A
O3—H3⋯O2 0.84 2.13 2.6274 (17) 118
O1—H1⋯O3i 0.84 1.91 2.7170 (17) 160
O3—H3⋯O2ii 0.84 2.06 2.7186 (17) 135
Symmetry codes: (i) x-1, y, z; (ii) [x+{\script{1\over 2}}, -y+{\script{1\over 2}}, -z].

Data collection: APEX2 (Bruker, 2010[Bruker (2010). APEX2 and SAINT. Bruker AXS Inc., Madison, USA.]); cell refinement: SAINT (Bruker, 2010[Bruker (2010). APEX2 and SAINT. Bruker AXS Inc., Madison, USA.]); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]); molecular graphics: ORTEP-3 for Windows (Farrugia, 2012[Farrugia, L. J. (2012). J. Appl. Cryst. 45, 849-854.]) and Mercury (Macrae et al., 2008[Macrae, C. F., Bruno, I. J., Chisholm, J. A., Edgington, P. R., McCabe, P., Pidcock, E., Rodriguez-Monge, L., Taylor, R., van de Streek, J. & Wood, P. A. (2008). J. Appl. Cryst. 41, 466-470.]); software used to prepare material for publication: SHELXL97 and PLATON (Spek, 2009[Spek, A. L. (2009). Acta Cryst. D65, 148-155.]).

Supporting information


Comment top

Chelate ligands have found widespread use in coordination chemistry due to the increased stability of coordination compounds they can form in comparison to monodentate ligands (Gade, 1998). Hydroxycarboxylic acids are particularily interesting in this aspect as they offer two hydroxyl groups of markedly different acidity as potential bonding partners. Upon varying the substitution pattern on the hydrocarbon backbone, the acidity of the respective hydroxyl groups can be finetuned over a wide range and they may, thus, serve as probes for establishing the rules in which pKa range coordination to various central atoms can be observed. To allow for comparisons of metrical parameters of the carboxylic-acid-derived ligand in envisioned coordination compounds, the crystal and molecular structure of the free ligand was determined. The crystal structure of a related compound, 2-hydroxy-2-(trifluoromethyl)proprionic acid, is apparent in the literature (Soloshonok et al., 2007).

The carboxyl group is nearly in plane with the C–OH moiety. The respective OC–C–O(H) torsion angle was found to be only 5.5 (2)°. This common plane also acts as internal mirror plane for the compound which shows approximately Cs symmetry (Fig. 1).

In the crystal, intermolecular hydrogen bonds can be observed. These are established between the carboxylic acid group as donor and the hydroxyl group as acceptor. The latter group itself, at the same time, acts as donor towards the double-bonded oxygen atom of the carboxyl group. The small dihedral angle among the OC–C–O(H) moiety may be indicative of an intramolecular hydrogen bond as well, denoting the alcoholic hydroxyl group to give rise to a bifurcated hydrogen bond. Metrical parameters as well as information about the symmetry of these hydrogen bonds is summarized in Table 1. In terms of graph-set analysis (Etter et al., 1990; Bernstein et al., 1995), the descriptor for the hydrogen bonds is S(5)C11(5)C11(5) on the unary level (Fig. 2).

The packing of the title compound in the crystal structure is shown in Fig. 3.

Related literature top

For the crystal structure of 2-hydroxy-2-(trifluoromethyl)proprionic acid, see: Soloshonok et al. (2007). For background to chelate ligands, see: Gade (1998). For graph-set analysis of hydrogen bonds, see: Etter et al. (1990); Bernstein et al. (1995).

Experimental top

The compound was obtained from Alfa Aesar. Crystals suitable for the diffraction study were taken directly from the provided product.

Refinement top

The H atoms of the hydroxyl groups were allowed to rotate with a fixed angle around the C—O bond to best fit the experimental electron density (HFIX 147 in the SHELX program suite (Sheldrick, 2008), with O—H = 0.84 Å, and with U(H) = 1.5Ueq(O).

Computing details top

Data collection: APEX2 (Bruker, 2010); cell refinement: SAINT (Bruker, 2010); data reduction: SAINT (Bruker, 2010); 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, 2012) and Mercury (Macrae et al., 2008); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008) and PLATON (Spek, 2009).

Figures top
[Figure 1] Fig. 1. The molecular structure of the title compound, with atom labels and anisotropic displacement ellipsoids (drawn at 50% probability level).
[Figure 2] Fig. 2. Intermolecular contacts, viewed along [0 0 - 1]. Blue dashed lines indicate intermolecular hydrogen bonds, yellow dashed lines indicate intramolecular hydrogen bonds. Symmetry operators: i x - 1, y, z; ii x - 1/2, -y + 1/2, -z; iii x + 1/2, -y + 1/2, -z; iv x + 1x, y, z.
[Figure 3] Fig. 3. Molecular packing of the title compound, viewed along [0 1 0] (anisotropic displacement ellipsoids drawn at 50% probability level).
3,3,3-Trifluoro-2-hydroxy-2-(trifluoromethyl)propionic acid top
Crystal data top
C4H2F6O3F(000) = 416
Mr = 212.06Dx = 1.977 Mg m3
Orthorhombic, P212121Mo Kα radiation, λ = 0.71073 Å
Hall symbol: P 2ac 2abCell parameters from 2971 reflections
a = 5.9949 (2) Åθ = 4.4–28.3°
b = 6.4007 (2) ŵ = 0.26 mm1
c = 18.5642 (6) ÅT = 200 K
V = 712.34 (4) Å3Block, colourless
Z = 40.53 × 0.53 × 0.34 mm
Data collection top
Bruker APEXII CCD
diffractometer
1052 independent reflections
Radiation source: fine-focus sealed tube1024 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.010
ϕ and ω scansθmax = 28.3°, θmin = 3.4°
Absorption correction: multi-scan
(SADABS; Bruker, 2008)
h = 58
Tmin = 0.908, Tmax = 1.000k = 68
3824 measured reflectionsl = 2224
Refinement top
Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.029Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.076H-atom parameters constrained
S = 1.05 w = 1/[σ2(Fo2) + (0.0385P)2 + 0.2376P]
where P = (Fo2 + 2Fc2)/3
1052 reflections(Δ/σ)max < 0.001
120 parametersΔρmax = 0.31 e Å3
0 restraintsΔρmin = 0.18 e Å3
Crystal data top
C4H2F6O3V = 712.34 (4) Å3
Mr = 212.06Z = 4
Orthorhombic, P212121Mo Kα radiation
a = 5.9949 (2) ŵ = 0.26 mm1
b = 6.4007 (2) ÅT = 200 K
c = 18.5642 (6) Å0.53 × 0.53 × 0.34 mm
Data collection top
Bruker APEXII CCD
diffractometer
1052 independent reflections
Absorption correction: multi-scan
(SADABS; Bruker, 2008)
1024 reflections with I > 2σ(I)
Tmin = 0.908, Tmax = 1.000Rint = 0.010
3824 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0290 restraints
wR(F2) = 0.076H-atom parameters constrained
S = 1.05Δρmax = 0.31 e Å3
1052 reflectionsΔρmin = 0.18 e Å3
120 parameters
Special details top

Refinement. Due to the absence of a strong anomalous scatterer, the Flack parameter is meaningless. Thus, Friedel opposites (636 pairs) have been merged and the item was removed from the CIF.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
F110.7286 (3)0.2280 (3)0.20540 (9)0.0635 (5)
F120.6570 (2)0.0851 (3)0.23660 (7)0.0670 (5)
F130.99402 (19)0.0068 (3)0.21779 (6)0.0464 (3)
F210.7614 (3)0.2907 (3)0.02996 (9)0.0702 (5)
F220.6292 (3)0.3692 (2)0.13324 (12)0.0747 (6)
F230.9814 (2)0.3310 (2)0.11960 (9)0.0527 (4)
O10.37188 (19)0.0103 (3)0.11897 (8)0.0403 (4)
H10.25410.03800.10100.060*
O20.5456 (2)0.1808 (2)0.03438 (8)0.0372 (3)
O30.94390 (19)0.0739 (2)0.08055 (7)0.0338 (3)
H30.89670.14640.04610.051*
C10.5428 (3)0.0629 (3)0.08432 (9)0.0260 (3)
C20.7654 (3)0.0219 (3)0.11475 (8)0.0223 (3)
C30.7855 (3)0.0308 (4)0.19560 (10)0.0340 (4)
C40.7833 (4)0.2590 (3)0.10055 (12)0.0382 (4)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
F110.0602 (10)0.0626 (9)0.0677 (9)0.0226 (9)0.0209 (8)0.0336 (7)
F120.0487 (8)0.1198 (14)0.0326 (6)0.0194 (10)0.0099 (6)0.0174 (8)
F130.0276 (5)0.0770 (9)0.0347 (5)0.0062 (7)0.0112 (4)0.0026 (7)
F210.0736 (10)0.0738 (10)0.0632 (8)0.0260 (10)0.0204 (8)0.0368 (8)
F220.0546 (9)0.0326 (6)0.1368 (17)0.0094 (7)0.0194 (11)0.0087 (9)
F230.0412 (7)0.0433 (7)0.0735 (9)0.0204 (6)0.0056 (7)0.0015 (7)
O10.0129 (5)0.0608 (9)0.0473 (7)0.0005 (6)0.0007 (5)0.0171 (8)
O20.0213 (5)0.0479 (8)0.0424 (7)0.0020 (6)0.0061 (5)0.0185 (6)
O30.0133 (5)0.0512 (8)0.0368 (6)0.0008 (6)0.0012 (5)0.0206 (6)
C10.0142 (7)0.0332 (8)0.0305 (7)0.0003 (7)0.0022 (6)0.0021 (7)
C20.0127 (6)0.0287 (7)0.0254 (6)0.0005 (6)0.0014 (5)0.0054 (6)
C30.0223 (8)0.0501 (11)0.0295 (8)0.0020 (9)0.0016 (6)0.0007 (8)
C40.0301 (9)0.0329 (9)0.0517 (11)0.0049 (8)0.0019 (9)0.0029 (9)
Geometric parameters (Å, º) top
F11—C31.320 (3)O1—H10.8400
F12—C31.313 (3)O2—C11.196 (2)
F13—C31.325 (2)O3—C21.3870 (19)
F21—C41.332 (3)O3—H30.8400
F22—C41.312 (3)C1—C21.547 (2)
F23—C41.322 (2)C2—C31.543 (2)
O1—C11.297 (2)C2—C41.544 (3)
C1—O1—H1109.5F12—C3—F13107.93 (17)
C2—O3—H3109.5F11—C3—F13108.19 (19)
O2—C1—O1128.59 (16)F12—C3—C2113.24 (17)
O2—C1—C2119.48 (15)F11—C3—C2108.83 (17)
O1—C1—C2111.93 (13)F13—C3—C2110.55 (15)
O3—C2—C3106.75 (14)F22—C4—F23108.76 (18)
O3—C2—C4107.61 (15)F22—C4—F21107.7 (2)
C3—C2—C4112.06 (15)F23—C4—F21107.36 (18)
O3—C2—C1110.08 (12)F22—C4—C2113.62 (17)
C3—C2—C1110.23 (14)F23—C4—C2111.08 (17)
C4—C2—C1110.02 (15)F21—C4—C2108.10 (17)
F12—C3—F11107.96 (19)
O2—C1—C2—O35.5 (2)O3—C2—C3—F1344.9 (2)
O1—C1—C2—O3174.76 (17)C4—C2—C3—F1372.7 (2)
O2—C1—C2—C3123.00 (19)C1—C2—C3—F13164.42 (16)
O1—C1—C2—C357.3 (2)O3—C2—C4—F22176.80 (17)
O2—C1—C2—C4112.92 (19)C3—C2—C4—F2259.8 (2)
O1—C1—C2—C466.81 (19)C1—C2—C4—F2263.3 (2)
O3—C2—C3—F12166.13 (17)O3—C2—C4—F2353.8 (2)
C4—C2—C3—F1248.6 (2)C3—C2—C4—F2363.2 (2)
C1—C2—C3—F1274.3 (2)C1—C2—C4—F23173.74 (15)
O3—C2—C3—F1173.80 (18)O3—C2—C4—F2163.7 (2)
C4—C2—C3—F11168.63 (17)C3—C2—C4—F21179.21 (16)
C1—C2—C3—F1145.7 (2)C1—C2—C4—F2156.2 (2)
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
O3—H3···O20.842.132.6274 (17)118
O1—H1···O3i0.841.912.7170 (17)160
O3—H3···O2ii0.842.062.7186 (17)135
Symmetry codes: (i) x1, y, z; (ii) x+1/2, y+1/2, z.

Experimental details

Crystal data
Chemical formulaC4H2F6O3
Mr212.06
Crystal system, space groupOrthorhombic, P212121
Temperature (K)200
a, b, c (Å)5.9949 (2), 6.4007 (2), 18.5642 (6)
V3)712.34 (4)
Z4
Radiation typeMo Kα
µ (mm1)0.26
Crystal size (mm)0.53 × 0.53 × 0.34
Data collection
DiffractometerBruker APEXII CCD
diffractometer
Absorption correctionMulti-scan
(SADABS; Bruker, 2008)
Tmin, Tmax0.908, 1.000
No. of measured, independent and
observed [I > 2σ(I)] reflections
3824, 1052, 1024
Rint0.010
(sin θ/λ)max1)0.667
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.029, 0.076, 1.05
No. of reflections1052
No. of parameters120
H-atom treatmentH-atom parameters constrained
Δρmax, Δρmin (e Å3)0.31, 0.18

Computer programs: APEX2 (Bruker, 2010), SAINT (Bruker, 2010), SHELXS97 (Sheldrick, 2008), ORTEP-3 for Windows (Farrugia, 2012) and Mercury (Macrae et al., 2008), SHELXL97 (Sheldrick, 2008) and PLATON (Spek, 2009).

Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
O3—H3···O20.842.132.6274 (17)118
O1—H1···O3i0.841.912.7170 (17)160
O3—H3···O2ii0.842.062.7186 (17)135
Symmetry codes: (i) x1, y, z; (ii) x+1/2, y+1/2, z.
 

Acknowledgements

The authors thank Mr Jamie Haner for helpful discussions.

References

First citationBernstein, J., Davis, R. E., Shimoni, L. & Chang, N.-L. (1995). Angew. Chem. Int. Ed. Engl. 34, 1555–1573.  CrossRef CAS Web of Science
First citationBruker (2008). SADABS. Bruker AXS Inc., Madison, Wisconsin, USA.
First citationBruker (2010). APEX2 and SAINT. Bruker AXS Inc., Madison, USA.
First citationEtter, M. C., MacDonald, J. C. & Bernstein, J. (1990). Acta Cryst. B46, 256–262.  CrossRef CAS Web of Science IUCr Journals
First citationFarrugia, L. J. (2012). J. Appl. Cryst. 45, 849–854.  Web of Science CrossRef CAS IUCr Journals
First citationGade, L. H. (1998). Koordinationschemie, 1. Auflage, Weinheim: Wiley-VCH.
First citationMacrae, C. F., Bruno, I. J., Chisholm, J. A., Edgington, P. R., McCabe, P., Pidcock, E., Rodriguez-Monge, L., Taylor, R., van de Streek, J. & Wood, P. A. (2008). J. Appl. Cryst. 41, 466–470.  Web of Science CrossRef CAS IUCr Journals
First citationSheldrick, G. M. (2008). Acta Cryst. A64, 112–122.  Web of Science CrossRef CAS IUCr Journals
First citationSoloshonok, V. A., Ueki, H., Yasumoto, M., Mekala, S., Hirschi, J. S. & Singleton, D. A. (2007). J. Am. Chem. Soc. 129, 12112–?-12113.
First citationSpek, A. L. (2009). Acta Cryst. D65, 148–155.  Web of Science CrossRef CAS IUCr Journals

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