organic compounds
4,4,4-Trifluoro-3-hydroxy-3-(trifluoromethyl)butanoic 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
The 5H4F6O3, a polyfluorinated derivative of β-hydroxybutyric acid, comprises two molecules. Intramolecular O—H⋯O hydrogen bonds occur. In the crystal, intermolecular O—H⋯O hydrogen bonds give rise to the formation of carboxylic acid dimers. Along with these hydrogen bonds, C—H⋯O contacts connect the molecules into infinite strands along the a axis.
of the title compound, CRelated literature
For the S)-3-amino-4,4,4-trifluorobutanecarboxylic acid, see: Soloshonok et al. (1993). For the graph-set analysis of hydrogen bonds, see: Etter et al. (1990); Bernstein et al. (1995).
of (Experimental
Crystal data
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Data collection
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Refinement
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Data collection: APEX2 (Bruker, 2010); cell SAINT (Bruker, 2010); 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: SHELXL97 and PLATON (Spek, 2009).
Supporting information
10.1107/S1600536811004764/gk2344sup1.cif
contains datablocks I, global. DOI:Structure factors: contains datablock I. DOI: 10.1107/S1600536811004764/gk2344Isup2.hkl
The structural analysis was done on a single-crystal taken from a commercially obtained (Fluorochem) batch of the title compound.
Carbon-bound H-atoms were placed in calculated positions (C—H 0.99 Å) and were included in the
in the riding model approximation, with U(H) set to 1.2Ueq(C). The H-atoms of the carboxylic acid group as well as 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)), their U(H) invariably set to 1.5Ueq(C)Data collection: APEX2 (Bruker, 2010); cell
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, 1997) and Mercury (Macrae et al., 2006); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008) and PLATON (Spek, 2009).Fig. 1. The asymmetric unit of the title compound with anisotropic displacement ellipsoids drawn at the 50% probability level. | |
Fig. 2. Intermolecular C–H···O contacts and hydrogen bonds in the title compound, viewed along [0 0 - 1]. Intramolecular hydrogen bonds are indicated with green, intermolecular hydrogen bonds with blue dotted lines. The C–H···O contacts are illustrated with yellow dotted lines. Symmetry operators: i -1 + x, y, z; ii = 1 + x, y, z. |
C5H4F6O3 | F(000) = 896 |
Mr = 226.08 | Dx = 1.913 Mg m−3 |
Monoclinic, P21/c | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: -P 2ybc | Cell parameters from 9089 reflections |
a = 5.5031 (2) Å | θ = 2.9–28.3° |
b = 20.5490 (8) Å | µ = 0.24 mm−1 |
c = 14.0342 (6) Å | T = 200 K |
β = 98.4543 (14)° | Rod, colourless |
V = 1569.79 (11) Å3 | 0.59 × 0.45 × 0.33 mm |
Z = 8 |
Bruker APEXII CCD diffractometer | 3469 reflections with I > 2σ(I) |
Radiation source: fine-focus sealed tube | Rint = 0.014 |
Graphite monochromator | θmax = 28.3°, θmin = 2.5° |
ϕ and ω scans | h = −7→7 |
25936 measured reflections | k = −27→27 |
3897 independent 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)] = 0.038 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.100 | H-atom parameters constrained |
S = 1.04 | w = 1/[σ2(Fo2) + (0.0438P)2 + 0.8289P] where P = (Fo2 + 2Fc2)/3 |
3897 reflections | (Δ/σ)max < 0.001 |
257 parameters | Δρmax = 0.42 e Å−3 |
0 restraints | Δρmin = −0.38 e Å−3 |
C5H4F6O3 | V = 1569.79 (11) Å3 |
Mr = 226.08 | Z = 8 |
Monoclinic, P21/c | Mo Kα radiation |
a = 5.5031 (2) Å | µ = 0.24 mm−1 |
b = 20.5490 (8) Å | T = 200 K |
c = 14.0342 (6) Å | 0.59 × 0.45 × 0.33 mm |
β = 98.4543 (14)° |
Bruker APEXII CCD diffractometer | 3469 reflections with I > 2σ(I) |
25936 measured reflections | Rint = 0.014 |
3897 independent reflections |
R[F2 > 2σ(F2)] = 0.038 | 0 restraints |
wR(F2) = 0.100 | H-atom parameters constrained |
S = 1.04 | Δρmax = 0.42 e Å−3 |
3897 reflections | Δρmin = −0.38 e Å−3 |
257 parameters |
x | y | z | Uiso*/Ueq | ||
O1 | 0.86328 (18) | 0.71888 (5) | 0.08430 (10) | 0.0429 (3) | |
H1 | 0.8645 | 0.6811 | 0.1073 | 0.064* | |
O2 | 0.45964 (17) | 0.70927 (5) | 0.08404 (8) | 0.0326 (2) | |
O3 | 0.17625 (19) | 0.80005 (7) | −0.02218 (11) | 0.0520 (4) | |
H3 | 0.2000 | 0.7657 | 0.0103 | 0.078* | |
O4 | 0.47274 (16) | 0.59040 (4) | 0.16029 (7) | 0.0285 (2) | |
H4 | 0.4717 | 0.6280 | 0.1367 | 0.043* | |
O5 | 0.87553 (17) | 0.59872 (5) | 0.15635 (8) | 0.0337 (2) | |
O6 | 1.13316 (16) | 0.48391 (5) | 0.18383 (8) | 0.0316 (2) | |
H6 | 1.1185 | 0.5241 | 0.1733 | 0.047* | |
C1 | 0.6381 (2) | 0.74043 (6) | 0.06831 (9) | 0.0261 (2) | |
C2 | 0.6189 (2) | 0.80980 (6) | 0.03285 (10) | 0.0281 (3) | |
H2A | 0.7714 | 0.8211 | 0.0069 | 0.034* | |
H2B | 0.6071 | 0.8389 | 0.0882 | 0.034* | |
C3 | 0.3986 (2) | 0.82251 (7) | −0.04523 (10) | 0.0301 (3) | |
C4 | 0.3661 (3) | 0.89678 (8) | −0.05702 (13) | 0.0431 (4) | |
C5 | 0.4440 (4) | 0.79138 (8) | −0.14087 (12) | 0.0477 (4) | |
C6 | 0.6980 (2) | 0.56870 (6) | 0.17642 (9) | 0.0233 (2) | |
C7 | 0.7220 (2) | 0.50386 (6) | 0.22712 (9) | 0.0246 (2) | |
H7A | 0.5583 | 0.4829 | 0.2201 | 0.030* | |
H7B | 0.7761 | 0.5113 | 0.2967 | 0.030* | |
C8 | 0.9032 (2) | 0.45714 (6) | 0.18926 (9) | 0.0237 (2) | |
C9 | 0.9528 (3) | 0.40037 (7) | 0.26098 (11) | 0.0343 (3) | |
C10 | 0.7933 (3) | 0.43236 (7) | 0.08834 (10) | 0.0333 (3) | |
F1 | 0.1814 (3) | 0.91197 (7) | −0.12449 (13) | 0.0885 (5) | |
F2 | 0.5634 (2) | 0.92505 (5) | −0.08100 (10) | 0.0611 (3) | |
F3 | 0.3264 (3) | 0.92357 (6) | 0.02449 (11) | 0.0842 (5) | |
F4 | 0.2561 (3) | 0.79879 (8) | −0.21017 (9) | 0.0852 (5) | |
F5 | 0.6404 (2) | 0.81581 (6) | −0.17319 (8) | 0.0595 (3) | |
F6 | 0.4835 (4) | 0.72803 (6) | −0.12768 (9) | 0.0885 (5) | |
F7 | 0.74664 (19) | 0.36955 (5) | 0.27353 (8) | 0.0483 (2) | |
F8 | 1.1068 (2) | 0.35676 (5) | 0.23401 (9) | 0.0582 (3) | |
F9 | 1.05355 (19) | 0.42287 (5) | 0.34686 (7) | 0.0486 (3) | |
F10 | 0.75894 (18) | 0.48279 (5) | 0.02779 (6) | 0.0430 (2) | |
F11 | 0.9385 (2) | 0.39072 (6) | 0.05224 (8) | 0.0601 (3) | |
F12 | 0.57504 (19) | 0.40413 (5) | 0.08745 (7) | 0.0503 (3) |
U11 | U22 | U33 | U12 | U13 | U23 | |
O1 | 0.0233 (5) | 0.0342 (5) | 0.0710 (8) | 0.0020 (4) | 0.0066 (5) | 0.0233 (5) |
O2 | 0.0239 (4) | 0.0293 (5) | 0.0446 (6) | 0.0004 (4) | 0.0053 (4) | 0.0128 (4) |
O3 | 0.0223 (5) | 0.0557 (7) | 0.0775 (9) | −0.0007 (5) | 0.0055 (5) | 0.0399 (7) |
O4 | 0.0201 (4) | 0.0232 (4) | 0.0421 (5) | 0.0019 (3) | 0.0042 (4) | 0.0057 (4) |
O5 | 0.0215 (4) | 0.0276 (5) | 0.0525 (6) | 0.0005 (4) | 0.0068 (4) | 0.0101 (4) |
O6 | 0.0181 (4) | 0.0299 (5) | 0.0474 (6) | 0.0013 (3) | 0.0061 (4) | 0.0051 (4) |
C1 | 0.0243 (6) | 0.0250 (6) | 0.0284 (6) | −0.0002 (5) | 0.0021 (5) | 0.0039 (5) |
C2 | 0.0260 (6) | 0.0232 (6) | 0.0343 (6) | −0.0023 (5) | 0.0020 (5) | 0.0039 (5) |
C3 | 0.0252 (6) | 0.0282 (6) | 0.0368 (7) | −0.0012 (5) | 0.0042 (5) | 0.0117 (5) |
C4 | 0.0451 (8) | 0.0333 (7) | 0.0536 (9) | 0.0100 (6) | 0.0162 (7) | 0.0177 (7) |
C5 | 0.0688 (11) | 0.0382 (8) | 0.0333 (8) | −0.0069 (8) | −0.0022 (7) | 0.0056 (6) |
C6 | 0.0215 (5) | 0.0224 (5) | 0.0258 (6) | 0.0009 (4) | 0.0026 (4) | −0.0009 (4) |
C7 | 0.0223 (5) | 0.0241 (6) | 0.0284 (6) | 0.0026 (4) | 0.0069 (4) | 0.0039 (5) |
C8 | 0.0205 (5) | 0.0223 (5) | 0.0284 (6) | 0.0016 (4) | 0.0042 (4) | 0.0024 (4) |
C9 | 0.0363 (7) | 0.0283 (6) | 0.0384 (7) | 0.0067 (5) | 0.0058 (6) | 0.0077 (5) |
C10 | 0.0377 (7) | 0.0301 (7) | 0.0320 (7) | −0.0014 (5) | 0.0050 (5) | −0.0032 (5) |
F1 | 0.0713 (9) | 0.0650 (8) | 0.1198 (13) | 0.0159 (7) | −0.0168 (8) | 0.0530 (8) |
F2 | 0.0698 (7) | 0.0310 (5) | 0.0890 (9) | −0.0065 (5) | 0.0329 (6) | 0.0162 (5) |
F3 | 0.1413 (14) | 0.0428 (6) | 0.0828 (9) | 0.0398 (7) | 0.0640 (9) | 0.0165 (6) |
F4 | 0.0932 (10) | 0.1107 (12) | 0.0420 (6) | −0.0324 (9) | −0.0229 (6) | 0.0152 (7) |
F5 | 0.0693 (7) | 0.0685 (7) | 0.0459 (6) | 0.0097 (6) | 0.0255 (5) | 0.0052 (5) |
F6 | 0.1863 (17) | 0.0330 (6) | 0.0454 (6) | −0.0033 (8) | 0.0140 (8) | −0.0057 (5) |
F7 | 0.0554 (6) | 0.0367 (5) | 0.0539 (6) | −0.0085 (4) | 0.0122 (5) | 0.0157 (4) |
F8 | 0.0696 (7) | 0.0405 (5) | 0.0674 (7) | 0.0310 (5) | 0.0197 (6) | 0.0141 (5) |
F9 | 0.0552 (6) | 0.0490 (6) | 0.0369 (5) | 0.0086 (5) | −0.0084 (4) | 0.0121 (4) |
F10 | 0.0524 (5) | 0.0473 (5) | 0.0275 (4) | −0.0056 (4) | 0.0000 (4) | 0.0059 (4) |
F11 | 0.0746 (8) | 0.0577 (7) | 0.0495 (6) | 0.0186 (6) | 0.0140 (5) | −0.0199 (5) |
F12 | 0.0496 (6) | 0.0501 (6) | 0.0485 (6) | −0.0230 (5) | −0.0022 (4) | −0.0053 (4) |
O1—C1 | 1.3042 (16) | C7—C8 | 1.5347 (16) |
O1—H1 | 0.8400 | C7—H7A | 0.9900 |
O2—C1 | 1.2192 (16) | C7—H7B | 0.9900 |
O3—C3 | 1.3896 (16) | C8—C9 | 1.5387 (18) |
O3—H3 | 0.8400 | C8—C10 | 1.5425 (19) |
O4—C6 | 1.3055 (15) | F1—C4 | 1.321 (2) |
O4—H4 | 0.8400 | F2—C4 | 1.3183 (19) |
O5—C6 | 1.2228 (15) | F3—C4 | 1.316 (2) |
O6—C8 | 1.3920 (14) | F4—C5 | 1.320 (2) |
O6—H6 | 0.8400 | F5—C5 | 1.330 (2) |
C1—C2 | 1.5084 (17) | F6—C5 | 1.328 (2) |
C2—C3 | 1.5325 (18) | F7—C9 | 1.3336 (18) |
C2—H2A | 0.9900 | F8—C9 | 1.3259 (17) |
C2—H2B | 0.9900 | F9—C9 | 1.3330 (19) |
C3—C5 | 1.540 (2) | F10—C10 | 1.3359 (17) |
C3—C4 | 1.543 (2) | F11—C10 | 1.3213 (17) |
C7—C6 | 1.5073 (17) | F12—C10 | 1.3323 (17) |
O1—C1—C2 | 113.34 (11) | C8—C7—H7A | 108.8 |
O2—C1—O1 | 124.10 (12) | C8—C7—H7B | 108.8 |
O2—C1—C2 | 122.48 (11) | C9—C8—C10 | 111.00 (11) |
O3—C3—C2 | 114.09 (11) | F1—C4—C3 | 112.06 (16) |
O3—C3—C4 | 105.15 (12) | F2—C4—C3 | 112.11 (13) |
O3—C3—C5 | 109.04 (13) | F2—C4—F1 | 106.79 (14) |
O4—C6—C7 | 113.50 (10) | F3—C4—C3 | 110.61 (13) |
O5—C6—O4 | 123.94 (11) | F3—C4—F1 | 108.40 (16) |
O5—C6—C7 | 122.50 (11) | F3—C4—F2 | 106.61 (16) |
O6—C8—C7 | 114.46 (10) | F4—C5—C3 | 112.59 (17) |
O6—C8—C9 | 105.08 (10) | F4—C5—F5 | 107.03 (14) |
O6—C8—C10 | 108.49 (10) | F4—C5—F6 | 108.05 (16) |
C1—O1—H1 | 109.5 | F5—C5—C3 | 112.62 (14) |
C1—C2—C3 | 113.99 (11) | F6—C5—C3 | 109.26 (13) |
C1—C2—H2A | 108.8 | F6—C5—F5 | 107.04 (18) |
C1—C2—H2B | 108.8 | F7—C9—C8 | 111.95 (11) |
C2—C3—C4 | 108.21 (12) | F8—C9—C8 | 112.64 (12) |
C2—C3—C5 | 109.85 (12) | F8—C9—F7 | 107.96 (13) |
C3—O3—H3 | 109.5 | F8—C9—F9 | 107.12 (12) |
C3—C2—H2A | 108.8 | F9—C9—C8 | 109.80 (12) |
C3—C2—H2B | 108.8 | F9—C9—F7 | 107.10 (12) |
C5—C3—C4 | 110.40 (12) | F10—C10—C8 | 109.13 (11) |
C6—O4—H4 | 109.5 | F11—C10—C8 | 112.85 (12) |
C6—C7—C8 | 113.94 (10) | F11—C10—F10 | 107.19 (12) |
C6—C7—H7A | 108.8 | F11—C10—F12 | 108.03 (13) |
C6—C7—H7B | 108.8 | F12—C10—C8 | 112.56 (11) |
C7—C8—C9 | 108.03 (10) | F12—C10—F10 | 106.78 (12) |
C7—C8—C10 | 109.71 (10) | H2A—C2—H2B | 107.6 |
C8—O6—H6 | 109.5 | H7A—C7—H7B | 107.7 |
O1—C1—C2—C3 | 140.99 (13) | C4—C3—C5—F4 | −63.00 (18) |
O2—C1—C2—C3 | −41.98 (19) | C4—C3—C5—F5 | 58.14 (18) |
O3—C3—C4—F1 | −58.76 (18) | C4—C3—C5—F6 | 176.95 (16) |
O3—C3—C4—F2 | −178.84 (14) | C5—C3—C4—F1 | 58.71 (18) |
O3—C3—C4—F3 | 62.33 (18) | C5—C3—C4—F2 | −61.37 (19) |
O3—C3—C5—F4 | 52.05 (17) | C5—C3—C4—F3 | 179.80 (15) |
O3—C3—C5—F5 | 173.18 (13) | C6—C7—C8—O6 | 50.77 (14) |
O3—C3—C5—F6 | −68.01 (19) | C6—C7—C8—C9 | 167.43 (11) |
O6—C8—C9—F7 | −179.87 (11) | C6—C7—C8—C10 | −71.45 (13) |
O6—C8—C9—F8 | −57.98 (15) | C7—C8—C9—F7 | 57.53 (15) |
O6—C8—C9—F9 | 61.31 (14) | C7—C8—C9—F8 | 179.43 (12) |
O6—C8—C10—F10 | −63.45 (14) | C7—C8—C9—F9 | −61.29 (14) |
O6—C8—C10—F11 | 55.60 (15) | C7—C8—C10—F10 | 62.26 (14) |
O6—C8—C10—F12 | 178.20 (11) | C7—C8—C10—F11 | −178.69 (12) |
C1—C2—C3—O3 | 50.06 (17) | C7—C8—C10—F12 | −56.09 (15) |
C1—C2—C3—C5 | −72.71 (15) | C8—C7—C6—O4 | 139.87 (11) |
C1—C2—C3—C4 | 166.70 (12) | C8—C7—C6—O5 | −42.93 (17) |
C2—C3—C4—F1 | 178.96 (14) | C9—C8—C10—F10 | −178.42 (11) |
C2—C3—C4—F2 | 58.88 (18) | C9—C8—C10—F11 | −59.37 (15) |
C2—C3—C4—F3 | −59.96 (18) | C9—C8—C10—F12 | 63.22 (15) |
C2—C3—C5—F4 | 177.75 (13) | C10—C8—C9—F7 | −62.79 (15) |
C2—C3—C5—F5 | −61.12 (17) | C10—C8—C9—F8 | 59.10 (16) |
C2—C3—C5—F6 | 57.69 (19) | C10—C8—C9—F9 | 178.39 (11) |
D—H···A | D—H | H···A | D···A | D—H···A |
O1—H1···O5 | 0.84 | 1.83 | 2.6653 (14) | 178 |
O3—H3···O2 | 0.84 | 2.01 | 2.7296 (14) | 144 |
O3—H3···O1i | 0.84 | 2.45 | 2.9561 (15) | 120 |
O4—H4···O2 | 0.84 | 1.82 | 2.6635 (13) | 178 |
O6—H6···O5 | 0.84 | 2.03 | 2.7502 (13) | 144 |
O6—H6···O4ii | 0.84 | 2.41 | 2.9276 (13) | 121 |
C2—H2A···O3ii | 0.99 | 2.36 | 3.2773 (16) | 153 |
C7—H7A···O6i | 0.99 | 2.32 | 3.2340 (14) | 153 |
Symmetry codes: (i) x−1, y, z; (ii) x+1, y, z. |
Experimental details
Crystal data | |
Chemical formula | C5H4F6O3 |
Mr | 226.08 |
Crystal system, space group | Monoclinic, P21/c |
Temperature (K) | 200 |
a, b, c (Å) | 5.5031 (2), 20.5490 (8), 14.0342 (6) |
β (°) | 98.4543 (14) |
V (Å3) | 1569.79 (11) |
Z | 8 |
Radiation type | Mo Kα |
µ (mm−1) | 0.24 |
Crystal size (mm) | 0.59 × 0.45 × 0.33 |
Data collection | |
Diffractometer | Bruker APEXII CCD diffractometer |
Absorption correction | – |
No. of measured, independent and observed [I > 2σ(I)] reflections | 25936, 3897, 3469 |
Rint | 0.014 |
(sin θ/λ)max (Å−1) | 0.667 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.038, 0.100, 1.04 |
No. of reflections | 3897 |
No. of parameters | 257 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 0.42, −0.38 |
Computer programs: APEX2 (Bruker, 2010), SAINT (Bruker, 2010), SHELXS97 (Sheldrick, 2008), ORTEP-3 for Windows (Farrugia, 1997) and Mercury (Macrae et al., 2006), SHELXL97 (Sheldrick, 2008) and PLATON (Spek, 2009).
D—H···A | D—H | H···A | D···A | D—H···A |
O1—H1···O5 | 0.84 | 1.83 | 2.6653 (14) | 178 |
O3—H3···O2 | 0.84 | 2.01 | 2.7296 (14) | 144 |
O3—H3···O1i | 0.84 | 2.45 | 2.9561 (15) | 120 |
O4—H4···O2 | 0.84 | 1.82 | 2.6635 (13) | 178 |
O6—H6···O5 | 0.84 | 2.03 | 2.7502 (13) | 144 |
O6—H6···O4ii | 0.84 | 2.41 | 2.9276 (13) | 121 |
C2—H2A···O3ii | 0.99 | 2.36 | 3.2773 (16) | 153 |
C7—H7A···O6i | 0.99 | 2.32 | 3.2340 (14) | 153 |
Symmetry codes: (i) x−1, y, z; (ii) x+1, y, z. |
Acknowledgements
The authors thank Mr Eddie Nelson for helpful discussions.
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
Bruker (2010). APEX2 and SAINT. Bruker AXS Inc., Madison, Wisconsin, USA. Google Scholar
Etter, M. C., MacDonald, J. C. & Bernstein, J. (1990). Acta Cryst. B46, 256–262. CrossRef CAS Web of Science IUCr Journals Google Scholar
Farrugia, L. J. (1997). J. Appl. Cryst. 30, 565. CrossRef IUCr Journals Google Scholar
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. Web of Science CrossRef CAS IUCr Journals Google Scholar
Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. Web of Science CrossRef CAS IUCr Journals Google Scholar
Soloshonok, V. A., Svedas, V. K., Kukhar, V. P., Kirilenko, A. G., Rybakova, A. V., Solodenko, V. A., Fokina, N. A., Kogut, O. V., Galaev, I. Y., Kozlova, E. V., Shishkina, I. P. & Galushko, S. V. (1993). Synlett, pp. 339–341. CSD CrossRef Google Scholar
Spek, A. L. (2009). Acta Cryst. D65, 148–155. Web of Science CrossRef CAS IUCr Journals Google Scholar
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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. Most work in this field has been done with chelate ligands capable of forming five-, six- and seven-membered chelate rings. The coordination behaviour of such ligands with respect to reaction products formed (e.g. the coordination number of the central atom) is a function of electronic as well as steric factors. In a larger study aimed at elucidating the coordination chemistry of multiply-fluorinated carboxylic acid derivatives, the structure of the title compound was determined to enable comparisons with reaction products obtained.
The title compound is a symmetric, polyhalogenated derivative of β-hydroxypropanecarboxylic acid which bears two trifluoromethyl-groups at the alcoholic carbon atom. The asymmetric unit (Fig. 1) comprises two molecules of the title compound.
In the crystal structure, intra- as well as intermolecular hydrogen bonds are present. While the intramolecular hydrogen bonds are formed between the alcoholic hydroxyl group and the carbonylic O-atom of the carboxylic group, intermolecular hydrogen bonds can be observed between the carboxylic acid groups' OH-groups and carbonylic O-atoms. The latter interaction connects both molecules of the asymmetric unit to dimers. In terms of graph-set analysis, the descriptor for the intramolecular hydrogen bonds is S(6)S(6) on the unitary level while the intermolecular hydrogen bonds necessitate a R22(8) descriptor on the binary level. For the intramolecular hydrogen bond, a bifurcation could be discussed applying the O-atom of another hydroxyl group as acceptor. This would render it a mixed intra-intermolecular hydrogen bond, however, the D–H···A angle of only around 120° for the intermolecular hydrogen bond is comparatively small.
Apart from these hydrogen bonds, C–H···O contacts are present in the crystal structure whose ranges fall more than 0.2 Å below the sum of van-der-Waals radii of the respective atoms. These contacts can be observed between one of the H-atoms of the methylene group and the O-atom of a neighbouring hydroxyl group. Like the possible, bifurcated hydrogen bond mentioned above, these C–H···O contacts connect the molecules to infinite strands along the crystallographic a axis (Fig. 3). The descriptor for the C–H···O contacts on the unitary level is C11(4)C11(4).