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ISSN: 2056-9890

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

(Received 24 January 2011; accepted 8 February 2011; online 12 February 2011)

The asymmetric unit of the title compound, C5H4F6O3, 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.

Related literature

For the crystal structure of (S)-3-amino-4,4,4-trifluoro­butane­carb­oxy­lic acid, see: Soloshonok et al. (1993[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.]). For the 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
  • C5H4F6O3

  • Mr = 226.08

  • Monoclinic, P 21 /c

  • a = 5.5031 (2) Å

  • b = 20.5490 (8) Å

  • c = 14.0342 (6) Å

  • β = 98.4543 (14)°

  • V = 1569.79 (11) Å3

  • Z = 8

  • Mo Kα radiation

  • μ = 0.24 mm−1

  • T = 200 K

  • 0.59 × 0.45 × 0.33 mm

Data collection
  • Bruker APEXII CCD diffractometer

  • 25936 measured reflections

  • 3897 independent reflections

  • 3469 reflections with I > 2σ(I)

  • Rint = 0.014

Refinement
  • R[F2 > 2σ(F2)] = 0.038

  • wR(F2) = 0.100

  • S = 1.04

  • 3897 reflections

  • 257 parameters

  • H-atom parameters constrained

  • Δρmax = 0.42 e Å−3

  • Δρmin = −0.38 e Å−3

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A D—H H⋯A DA 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.

Data collection: APEX2 (Bruker, 2010[Bruker (2010). APEX2 and SAINT. Bruker AXS Inc., Madison, Wisconsin, USA.]); cell refinement: SAINT (Bruker, 2010[Bruker (2010). APEX2 and SAINT. Bruker AXS Inc., Madison, Wisconsin, 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, 1997[Farrugia, L. J. (1997). J. Appl. Cryst. 30, 565.]) and Mercury (Macrae et al., 2006[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.]); 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. 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).

Related literature top

For the crystal structure of (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).

Experimental top

The structural analysis was done on a single-crystal taken from a commercially obtained (Fluorochem) batch of the title compound.

Refinement top

Carbon-bound H-atoms were placed in calculated positions (C—H 0.99 Å) and were included in the refinement 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)

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, 1997) and Mercury (Macrae et al., 2006); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008) and PLATON (Spek, 2009).

Figures top
[Figure 1] Fig. 1. The asymmetric unit of the title compound with anisotropic displacement ellipsoids drawn at the 50% probability level.
[Figure 2] 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.
4,4,4-Trifluoro-3-hydroxy-3-(trifluoromethyl)butanoic acid top
Crystal data top
C5H4F6O3F(000) = 896
Mr = 226.08Dx = 1.913 Mg m3
Monoclinic, P21/cMo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybcCell parameters from 9089 reflections
a = 5.5031 (2) Åθ = 2.9–28.3°
b = 20.5490 (8) ŵ = 0.24 mm1
c = 14.0342 (6) ÅT = 200 K
β = 98.4543 (14)°Rod, colourless
V = 1569.79 (11) Å30.59 × 0.45 × 0.33 mm
Z = 8
Data collection top
Bruker APEXII CCD
diffractometer
3469 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tubeRint = 0.014
Graphite monochromatorθmax = 28.3°, θmin = 2.5°
ϕ and ω scansh = 77
25936 measured reflectionsk = 2727
3897 independent reflectionsl = 1818
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)] = 0.038Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.100H-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 parametersΔρmax = 0.42 e Å3
0 restraintsΔρmin = 0.38 e Å3
Crystal data top
C5H4F6O3V = 1569.79 (11) Å3
Mr = 226.08Z = 8
Monoclinic, P21/cMo Kα radiation
a = 5.5031 (2) ŵ = 0.24 mm1
b = 20.5490 (8) ÅT = 200 K
c = 14.0342 (6) Å0.59 × 0.45 × 0.33 mm
β = 98.4543 (14)°
Data collection top
Bruker APEXII CCD
diffractometer
3469 reflections with I > 2σ(I)
25936 measured reflectionsRint = 0.014
3897 independent reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0380 restraints
wR(F2) = 0.100H-atom parameters constrained
S = 1.04Δρmax = 0.42 e Å3
3897 reflectionsΔρmin = 0.38 e Å3
257 parameters
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
O10.86328 (18)0.71888 (5)0.08430 (10)0.0429 (3)
H10.86450.68110.10730.064*
O20.45964 (17)0.70927 (5)0.08404 (8)0.0326 (2)
O30.17625 (19)0.80005 (7)0.02218 (11)0.0520 (4)
H30.20000.76570.01030.078*
O40.47274 (16)0.59040 (4)0.16029 (7)0.0285 (2)
H40.47170.62800.13670.043*
O50.87553 (17)0.59872 (5)0.15635 (8)0.0337 (2)
O61.13316 (16)0.48391 (5)0.18383 (8)0.0316 (2)
H61.11850.52410.17330.047*
C10.6381 (2)0.74043 (6)0.06831 (9)0.0261 (2)
C20.6189 (2)0.80980 (6)0.03285 (10)0.0281 (3)
H2A0.77140.82110.00690.034*
H2B0.60710.83890.08820.034*
C30.3986 (2)0.82251 (7)0.04523 (10)0.0301 (3)
C40.3661 (3)0.89678 (8)0.05702 (13)0.0431 (4)
C50.4440 (4)0.79138 (8)0.14087 (12)0.0477 (4)
C60.6980 (2)0.56870 (6)0.17642 (9)0.0233 (2)
C70.7220 (2)0.50386 (6)0.22712 (9)0.0246 (2)
H7A0.55830.48290.22010.030*
H7B0.77610.51130.29670.030*
C80.9032 (2)0.45714 (6)0.18926 (9)0.0237 (2)
C90.9528 (3)0.40037 (7)0.26098 (11)0.0343 (3)
C100.7933 (3)0.43236 (7)0.08834 (10)0.0333 (3)
F10.1814 (3)0.91197 (7)0.12449 (13)0.0885 (5)
F20.5634 (2)0.92505 (5)0.08100 (10)0.0611 (3)
F30.3264 (3)0.92357 (6)0.02449 (11)0.0842 (5)
F40.2561 (3)0.79879 (8)0.21017 (9)0.0852 (5)
F50.6404 (2)0.81581 (6)0.17319 (8)0.0595 (3)
F60.4835 (4)0.72803 (6)0.12768 (9)0.0885 (5)
F70.74664 (19)0.36955 (5)0.27353 (8)0.0483 (2)
F81.1068 (2)0.35676 (5)0.23401 (9)0.0582 (3)
F91.05355 (19)0.42287 (5)0.34686 (7)0.0486 (3)
F100.75894 (18)0.48279 (5)0.02779 (6)0.0430 (2)
F110.9385 (2)0.39072 (6)0.05224 (8)0.0601 (3)
F120.57504 (19)0.40413 (5)0.08745 (7)0.0503 (3)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
O10.0233 (5)0.0342 (5)0.0710 (8)0.0020 (4)0.0066 (5)0.0233 (5)
O20.0239 (4)0.0293 (5)0.0446 (6)0.0004 (4)0.0053 (4)0.0128 (4)
O30.0223 (5)0.0557 (7)0.0775 (9)0.0007 (5)0.0055 (5)0.0399 (7)
O40.0201 (4)0.0232 (4)0.0421 (5)0.0019 (3)0.0042 (4)0.0057 (4)
O50.0215 (4)0.0276 (5)0.0525 (6)0.0005 (4)0.0068 (4)0.0101 (4)
O60.0181 (4)0.0299 (5)0.0474 (6)0.0013 (3)0.0061 (4)0.0051 (4)
C10.0243 (6)0.0250 (6)0.0284 (6)0.0002 (5)0.0021 (5)0.0039 (5)
C20.0260 (6)0.0232 (6)0.0343 (6)0.0023 (5)0.0020 (5)0.0039 (5)
C30.0252 (6)0.0282 (6)0.0368 (7)0.0012 (5)0.0042 (5)0.0117 (5)
C40.0451 (8)0.0333 (7)0.0536 (9)0.0100 (6)0.0162 (7)0.0177 (7)
C50.0688 (11)0.0382 (8)0.0333 (8)0.0069 (8)0.0022 (7)0.0056 (6)
C60.0215 (5)0.0224 (5)0.0258 (6)0.0009 (4)0.0026 (4)0.0009 (4)
C70.0223 (5)0.0241 (6)0.0284 (6)0.0026 (4)0.0069 (4)0.0039 (5)
C80.0205 (5)0.0223 (5)0.0284 (6)0.0016 (4)0.0042 (4)0.0024 (4)
C90.0363 (7)0.0283 (6)0.0384 (7)0.0067 (5)0.0058 (6)0.0077 (5)
C100.0377 (7)0.0301 (7)0.0320 (7)0.0014 (5)0.0050 (5)0.0032 (5)
F10.0713 (9)0.0650 (8)0.1198 (13)0.0159 (7)0.0168 (8)0.0530 (8)
F20.0698 (7)0.0310 (5)0.0890 (9)0.0065 (5)0.0329 (6)0.0162 (5)
F30.1413 (14)0.0428 (6)0.0828 (9)0.0398 (7)0.0640 (9)0.0165 (6)
F40.0932 (10)0.1107 (12)0.0420 (6)0.0324 (9)0.0229 (6)0.0152 (7)
F50.0693 (7)0.0685 (7)0.0459 (6)0.0097 (6)0.0255 (5)0.0052 (5)
F60.1863 (17)0.0330 (6)0.0454 (6)0.0033 (8)0.0140 (8)0.0057 (5)
F70.0554 (6)0.0367 (5)0.0539 (6)0.0085 (4)0.0122 (5)0.0157 (4)
F80.0696 (7)0.0405 (5)0.0674 (7)0.0310 (5)0.0197 (6)0.0141 (5)
F90.0552 (6)0.0490 (6)0.0369 (5)0.0086 (5)0.0084 (4)0.0121 (4)
F100.0524 (5)0.0473 (5)0.0275 (4)0.0056 (4)0.0000 (4)0.0059 (4)
F110.0746 (8)0.0577 (7)0.0495 (6)0.0186 (6)0.0140 (5)0.0199 (5)
F120.0496 (6)0.0501 (6)0.0485 (6)0.0230 (5)0.0022 (4)0.0053 (4)
Geometric parameters (Å, º) top
O1—C11.3042 (16)C7—C81.5347 (16)
O1—H10.8400C7—H7A0.9900
O2—C11.2192 (16)C7—H7B0.9900
O3—C31.3896 (16)C8—C91.5387 (18)
O3—H30.8400C8—C101.5425 (19)
O4—C61.3055 (15)F1—C41.321 (2)
O4—H40.8400F2—C41.3183 (19)
O5—C61.2228 (15)F3—C41.316 (2)
O6—C81.3920 (14)F4—C51.320 (2)
O6—H60.8400F5—C51.330 (2)
C1—C21.5084 (17)F6—C51.328 (2)
C2—C31.5325 (18)F7—C91.3336 (18)
C2—H2A0.9900F8—C91.3259 (17)
C2—H2B0.9900F9—C91.3330 (19)
C3—C51.540 (2)F10—C101.3359 (17)
C3—C41.543 (2)F11—C101.3213 (17)
C7—C61.5073 (17)F12—C101.3323 (17)
O1—C1—C2113.34 (11)C8—C7—H7A108.8
O2—C1—O1124.10 (12)C8—C7—H7B108.8
O2—C1—C2122.48 (11)C9—C8—C10111.00 (11)
O3—C3—C2114.09 (11)F1—C4—C3112.06 (16)
O3—C3—C4105.15 (12)F2—C4—C3112.11 (13)
O3—C3—C5109.04 (13)F2—C4—F1106.79 (14)
O4—C6—C7113.50 (10)F3—C4—C3110.61 (13)
O5—C6—O4123.94 (11)F3—C4—F1108.40 (16)
O5—C6—C7122.50 (11)F3—C4—F2106.61 (16)
O6—C8—C7114.46 (10)F4—C5—C3112.59 (17)
O6—C8—C9105.08 (10)F4—C5—F5107.03 (14)
O6—C8—C10108.49 (10)F4—C5—F6108.05 (16)
C1—O1—H1109.5F5—C5—C3112.62 (14)
C1—C2—C3113.99 (11)F6—C5—C3109.26 (13)
C1—C2—H2A108.8F6—C5—F5107.04 (18)
C1—C2—H2B108.8F7—C9—C8111.95 (11)
C2—C3—C4108.21 (12)F8—C9—C8112.64 (12)
C2—C3—C5109.85 (12)F8—C9—F7107.96 (13)
C3—O3—H3109.5F8—C9—F9107.12 (12)
C3—C2—H2A108.8F9—C9—C8109.80 (12)
C3—C2—H2B108.8F9—C9—F7107.10 (12)
C5—C3—C4110.40 (12)F10—C10—C8109.13 (11)
C6—O4—H4109.5F11—C10—C8112.85 (12)
C6—C7—C8113.94 (10)F11—C10—F10107.19 (12)
C6—C7—H7A108.8F11—C10—F12108.03 (13)
C6—C7—H7B108.8F12—C10—C8112.56 (11)
C7—C8—C9108.03 (10)F12—C10—F10106.78 (12)
C7—C8—C10109.71 (10)H2A—C2—H2B107.6
C8—O6—H6109.5H7A—C7—H7B107.7
O1—C1—C2—C3140.99 (13)C4—C3—C5—F463.00 (18)
O2—C1—C2—C341.98 (19)C4—C3—C5—F558.14 (18)
O3—C3—C4—F158.76 (18)C4—C3—C5—F6176.95 (16)
O3—C3—C4—F2178.84 (14)C5—C3—C4—F158.71 (18)
O3—C3—C4—F362.33 (18)C5—C3—C4—F261.37 (19)
O3—C3—C5—F452.05 (17)C5—C3—C4—F3179.80 (15)
O3—C3—C5—F5173.18 (13)C6—C7—C8—O650.77 (14)
O3—C3—C5—F668.01 (19)C6—C7—C8—C9167.43 (11)
O6—C8—C9—F7179.87 (11)C6—C7—C8—C1071.45 (13)
O6—C8—C9—F857.98 (15)C7—C8—C9—F757.53 (15)
O6—C8—C9—F961.31 (14)C7—C8—C9—F8179.43 (12)
O6—C8—C10—F1063.45 (14)C7—C8—C9—F961.29 (14)
O6—C8—C10—F1155.60 (15)C7—C8—C10—F1062.26 (14)
O6—C8—C10—F12178.20 (11)C7—C8—C10—F11178.69 (12)
C1—C2—C3—O350.06 (17)C7—C8—C10—F1256.09 (15)
C1—C2—C3—C572.71 (15)C8—C7—C6—O4139.87 (11)
C1—C2—C3—C4166.70 (12)C8—C7—C6—O542.93 (17)
C2—C3—C4—F1178.96 (14)C9—C8—C10—F10178.42 (11)
C2—C3—C4—F258.88 (18)C9—C8—C10—F1159.37 (15)
C2—C3—C4—F359.96 (18)C9—C8—C10—F1263.22 (15)
C2—C3—C5—F4177.75 (13)C10—C8—C9—F762.79 (15)
C2—C3—C5—F561.12 (17)C10—C8—C9—F859.10 (16)
C2—C3—C5—F657.69 (19)C10—C8—C9—F9178.39 (11)
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
O1—H1···O50.841.832.6653 (14)178
O3—H3···O20.842.012.7296 (14)144
O3—H3···O1i0.842.452.9561 (15)120
O4—H4···O20.841.822.6635 (13)178
O6—H6···O50.842.032.7502 (13)144
O6—H6···O4ii0.842.412.9276 (13)121
C2—H2A···O3ii0.992.363.2773 (16)153
C7—H7A···O6i0.992.323.2340 (14)153
Symmetry codes: (i) x1, y, z; (ii) x+1, y, z.

Experimental details

Crystal data
Chemical formulaC5H4F6O3
Mr226.08
Crystal system, space groupMonoclinic, P21/c
Temperature (K)200
a, b, c (Å)5.5031 (2), 20.5490 (8), 14.0342 (6)
β (°) 98.4543 (14)
V3)1569.79 (11)
Z8
Radiation typeMo Kα
µ (mm1)0.24
Crystal size (mm)0.59 × 0.45 × 0.33
Data collection
DiffractometerBruker APEXII CCD
diffractometer
Absorption correction
No. of measured, independent and
observed [I > 2σ(I)] reflections
25936, 3897, 3469
Rint0.014
(sin θ/λ)max1)0.667
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.038, 0.100, 1.04
No. of reflections3897
No. of parameters257
H-atom treatmentH-atom parameters constrained
Δρmax, Δρmin (e Å3)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).

Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
O1—H1···O50.841.832.6653 (14)178
O3—H3···O20.842.012.7296 (14)144
O3—H3···O1i0.842.452.9561 (15)120
O4—H4···O20.841.822.6635 (13)178
O6—H6···O50.842.032.7502 (13)144
O6—H6···O4ii0.842.412.9276 (13)121
C2—H2A···O3ii0.992.363.2773 (16)153
C7—H7A···O6i0.992.323.2340 (14)153
Symmetry codes: (i) x1, y, z; (ii) x+1, y, z.
 

Acknowledgements

The authors thank Mr Eddie Nelson for helpful discussions.

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