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

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ISSN: 2056-9890

5-Fluoro­uracil–2,2,2-tri­fluoro­ethanol (1/1)

aChristopher Ingold Laboratory, Department of Chemistry, 20 Gordon Street, London WC1H 0AJ, England
*Correspondence e-mail: a.hulme@ucl.ac.uk

(Received 3 October 2005; accepted 10 October 2005; online 15 October 2005)

The title compound, C4H3FN2O2·C2H3F3O, crystallizes with one 5-fluoro­uracil and one 2,2,2-trifluoro­ethanol mol­ecule in the asymmetric unit. The 5-fluoro­uracil mol­ecules are linked into a chain primarily via N—H⋯O hydrogen bonds, with the 2,2,2-trifluoro­ethanol mol­ecules attached to this via O—H⋯O hydrogen bonds.

Comment

The title compound, (I)[link], is the fourth solvate of 5-fluoro­uracil obtained in the course of a polymorph screen. The previously published structures contained 1,4-dioxane (Hulme & Tocher, 2004a[Hulme, A. T. & Tocher, D. A. (2004a). Acta Cryst. E60, o1781-o1782.]), dimethyl­formamide (Hulme & Tocher, 2004b[Hulme, A. T. & Tocher, D. A. (2004b). Acta Cryst. E60, o1783-o1785.]) and dimethyl­sulfoxide (Hulme & Tocher, 2004c[Hulme, A. T. & Tocher, D. A. (2004c). Acta Cryst. E60, o1786-o1787.]).

[Scheme 1]

One fluoro­uracil mol­ecule and one 2,2,2-trifluoro­ethanol mol­ecule are present in the asymmetric unit of (I)[link] (Fig. 1[link]). This structure bears no similarity to any of the previously reported solvate structures of 5-fluoro­uracil.

The 5-fluoro­uracil mol­ecules of (I)[link] form a ribbon propagated by the screw axis, with trifluoro­ethanol mol­ecules attached to the outer edges of the ribbon. Each 5-fluoro­uracil mol­ecule forms two R22(8) hydrogen bonds with adjacent 5-fluoro­uracil mol­ecules, as shown in Fig. 2[link]; details are given in Table 1[link]. A further hydrogen bond joins the 5-fluoro­uracil carbonyl O atom, unused in forming the ribbon, with the hydroxyl group of the trifluoro­ethanol mol­ecule (Fig. 2[link] and Table 1[link]).

The ribbons stack upon one another parallel to [001] (Fig. 3[link]). Close F⋯F contacts are an inter­esting feature present in this structure. There is a short F⋯F contact within the ribbon, F9⋯F12iv [2.891 (2) Å; symmetry code: (iv) x, y + 1, z], which acts as a weak stabilizing inter­action for the ribbon motif. A short contact is also present between trifluoro­methyl groups in ribbons of adjacent layers, viz. F12⋯F13v [3.001 (2) Å; symmetry code: (v) −x, y[{1\over 2}], −z]. A third short F⋯F contact, F9⋯F13vi [2.906 (2) Å; symmetry code: (vi) 1 − x, [{1\over 2}] + y, −z], also links ribbons in adjacent layers. These inter­layer F⋯F contacts are the only inter­actions between the layers.

[Figure 1]
Figure 1
A view of the asymmetric unit of (I)[link]. Displacement ellipsoids are drawn at the 50% probability level.
[Figure 2]
Figure 2
The structure of the ribbon, showing R22(8) hydrogen-bonded dimers and the hydrogen bonds (dotted lines) between 5-fluoro­uracil and 2,2,2-trifluoro­ethanol.
[Figure 3]
Figure 3
The stacking of the ribbons side-by-side into layers. Hydrogen bonds are shown as dotted lines.

Experimental

Typically, crystals of length 2–5 mm were grown from a solution of 5-fluoro­uracil in 2,2,2-trifluoro­ethanol by solvent evaporation. Attempts to cut crystals to a suitable size for X-ray diffraction led to shattering. Consequently, a large crystal with a longest dimension of 1.49 mm was mounted and used for the experiment.

Crystal data
  • C4H3FN2O2·C2H3F3O

  • Mr = 230.13

  • Monoclinic, P 21

  • a = 5.3976 (6) Å

  • b = 6.7062 (8) Å

  • c = 12.1098 (14) Å

  • β = 102.807 (2)°

  • V = 427.44 (9) Å3

  • Z = 2

  • Dx = 1.788 Mg m−3

  • Mo Kα radiation

  • Cell parameters from 2027 reflections

  • θ = 3.5–28.1°

  • μ = 0.19 mm−1

  • T = 150 (2) K

  • Lath, colourless

  • 1.49 × 0.34 × 0.17 mm

Data collection
  • Bruker SMART APEX diffractometer

  • ω rotation scans with narrow frames

  • Absorption correction: multi-scan(SADABS; Sheldrick, 1996[Sheldrick, G. M. (1996). SADABS. University of Göttingen, Germany.])Tmin = 0.760, Tmax = 0.968

  • 2634 measured reflections

  • 1090 independent reflections

  • 1060 reflections with I > 2σ(I)

  • Rint = 0.017

  • θmax = 28.2°

  • h = −7 → 6

  • k = −8 → 8

  • l = −15 → 15

Refinement
  • Refinement on F2

  • R[F2 > 2σ(F2)] = 0.028

  • wR(F2) = 0.074

  • S = 1.04

  • 1090 reflections

  • 160 parameters

  • All H-atom parameters refined

  • w = 1/[σ2(Fo2) + (0.0503P)2 + 0.0688P] where P = (Fo2 + 2Fc2)/3

  • (Δ/σ)max < 0.001

  • Δρmax = 0.31 e Å−3

  • Δρmin = −0.24 e Å−3

Table 1
Hydrogen-bond geometry (Å, °)[link]

D—H⋯A D—H H⋯A DA D—H⋯A
N3—H3⋯O7i 0.87 (3) 1.92 (3) 2.786 (2) 173 (2)
N1—H1⋯O7ii 0.82 (3) 2.20 (3) 2.924 (2) 147 (2)
N1—H1⋯O11iii 0.82 (3) 2.43 (3) 3.037 (2) 132 (2)
O11—H11⋯O8 0.76 (3) 2.00 (3) 2.7507 (19) 171 (3)
Symmetry codes: (i) [-x+3, y-{\script{1\over 2}}, -z+1]; (ii) [-x+3, y+{\script{1\over 2}}, -z+1]; (iii) x+1, y+1, z.

All H atoms were located in a difference map and were refined isotropically, with C—H distances between 0.89 (3) and 0.97 (2) Å. See Table 1[link] for N—H and O—H bond distances.

Data collection: SMART (Bruker, 1998[Bruker (1998). SMART and SAINT. Bruker AXS Inc., Madison, Wisconsin, USA.]); cell refinement: SAINT (Bruker, 1998[Bruker (1998). SMART and SAINT. Bruker AXS Inc., Madison, Wisconsin, USA.]); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997[Sheldrick, G. M. (1997). SHELXS97 and SHELXL97. University of Göttingen, Germany.]); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997[Sheldrick, G. M. (1997). SHELXS97 and SHELXL97. University of Göttingen, Germany.]); molecular graphics: CAMERON (Watkin et al., 1996[Watkin, D. J., Prout, C. K. & Pearce, L. J. (1996). CAMERON. Chemical Crystallography Laboratory, University of Oxford, England.]); software used to prepare material for publication: SHELXL97.

Supporting information


Computing details top

Data collection: SMART (Bruker, 1998); cell refinement: SAINT (Bruker, 1998); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: CAMERON (Watkin et al., 1996); software used to prepare material for publication: SHELXL97.

5-fluorouracil–2,2,2-trifluoroethanol (1/1) top
Crystal data top
C4H3FN2O2·C2H3F3OF(000) = 232
Mr = 230.13Dx = 1.788 Mg m3
Monoclinic, P21Mo Kα radiation, λ = 0.71073 Å
Hall symbol: P2ybCell parameters from 2027 reflections
a = 5.3976 (6) Åθ = 3.5–28.1°
b = 6.7062 (8) ŵ = 0.19 mm1
c = 12.1098 (14) ÅT = 150 K
β = 102.807 (2)°Plate, colourless
V = 427.44 (9) Å31.49 × 0.34 × 0.17 mm
Z = 2
Data collection top
Bruker SMART APEX
diffractometer
1090 independent reflections
Radiation source: fine-focus sealed tube1060 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.017
ω rotation with narrow frames scansθmax = 28.2°, θmin = 1.7°
Absorption correction: multi-scan
(SADABS; Sheldrick, 1996)
h = 76
Tmin = 0.760, Tmax = 0.968k = 88
2634 measured reflectionsl = 1515
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)] = 0.028Hydrogen site location: difference Fourier map
wR(F2) = 0.074All H-atom parameters refined
S = 1.04 w = 1/[σ2(Fo2) + (0.0503P)2 + 0.0688P]
where P = (Fo2 + 2Fc2)/3
1090 reflections(Δ/σ)max < 0.001
160 parametersΔρmax = 0.31 e Å3
1 restraintΔρmin = 0.24 e Å3
Special details top

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) top
xyzUiso*/Ueq
F90.57881 (18)0.57165 (18)0.24396 (9)0.0274 (3)
O71.5295 (2)0.59410 (19)0.49255 (11)0.0208 (3)
O80.8249 (2)0.2336 (2)0.34213 (11)0.0248 (3)
N11.1899 (3)0.7582 (2)0.38580 (12)0.0209 (3)
H11.271 (5)0.862 (5)0.393 (2)0.037 (7)*
N31.1724 (3)0.4198 (2)0.41781 (12)0.0191 (3)
H31.254 (4)0.313 (4)0.446 (2)0.020 (5)*
C21.3099 (3)0.5927 (3)0.43551 (13)0.0176 (3)
C40.9293 (3)0.3969 (3)0.35374 (13)0.0186 (3)
C50.8192 (3)0.5820 (3)0.30489 (14)0.0200 (3)
C60.9461 (3)0.7542 (3)0.32056 (14)0.0216 (3)
H60.881 (4)0.870 (4)0.2910 (18)0.017 (5)*
F110.5628 (3)0.0249 (3)0.08309 (13)0.0571 (5)
F120.2214 (3)0.1821 (2)0.08921 (13)0.0506 (4)
F130.2185 (3)0.0332 (3)0.04178 (11)0.0533 (4)
O110.3333 (3)0.1118 (2)0.25622 (11)0.0299 (3)
H110.466 (5)0.155 (5)0.275 (2)0.033 (7)*
C110.2408 (4)0.1569 (3)0.14144 (16)0.0289 (4)
H120.056 (5)0.155 (4)0.126 (2)0.030 (6)*
H130.316 (5)0.277 (5)0.121 (2)0.041 (7)*
C120.3116 (4)0.0040 (4)0.06811 (17)0.0323 (4)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
F90.0195 (5)0.0296 (6)0.0290 (5)0.0011 (5)0.0037 (4)0.0016 (5)
O70.0193 (5)0.0154 (5)0.0257 (6)0.0009 (5)0.0005 (4)0.0018 (5)
O80.0202 (6)0.0184 (6)0.0335 (6)0.0034 (5)0.0009 (5)0.0011 (5)
N10.0224 (7)0.0126 (7)0.0267 (7)0.0009 (6)0.0034 (5)0.0009 (6)
N30.0192 (6)0.0140 (6)0.0226 (6)0.0014 (5)0.0015 (5)0.0019 (6)
C20.0199 (7)0.0144 (7)0.0181 (7)0.0015 (7)0.0038 (5)0.0022 (6)
C40.0189 (7)0.0174 (8)0.0192 (7)0.0004 (6)0.0036 (6)0.0015 (6)
C50.0179 (7)0.0217 (8)0.0194 (7)0.0020 (7)0.0020 (6)0.0005 (6)
C60.0226 (8)0.0187 (8)0.0227 (7)0.0041 (7)0.0031 (6)0.0042 (7)
F110.0388 (7)0.0803 (13)0.0542 (9)0.0108 (8)0.0149 (6)0.0146 (8)
F120.0700 (10)0.0305 (7)0.0444 (8)0.0085 (7)0.0023 (7)0.0050 (6)
F130.0697 (9)0.0655 (11)0.0216 (6)0.0002 (8)0.0032 (6)0.0015 (6)
O110.0266 (6)0.0391 (8)0.0227 (6)0.0110 (6)0.0026 (5)0.0024 (6)
C110.0284 (8)0.0287 (10)0.0270 (8)0.0003 (8)0.0003 (7)0.0012 (8)
C120.0347 (9)0.0361 (10)0.0242 (8)0.0000 (9)0.0025 (7)0.0022 (8)
Geometric parameters (Å, º) top
F9—C51.3448 (19)C5—C61.335 (3)
O7—C21.233 (2)C6—H60.89 (3)
O8—C41.225 (2)F11—C121.335 (3)
N1—C21.357 (2)F12—C121.336 (3)
N1—C61.377 (2)F13—C121.338 (2)
N1—H10.82 (3)O11—C111.402 (2)
N3—C21.368 (2)O11—H110.76 (3)
N3—C41.377 (2)C11—C121.500 (3)
N3—H30.87 (3)C11—H120.97 (2)
C4—C51.445 (2)C11—H130.96 (3)
C2—N1—C6122.69 (16)C5—C6—H6123.5 (14)
C2—N1—H1118 (2)N1—C6—H6116.9 (14)
C6—N1—H1119.7 (19)C11—O11—H11108 (2)
C2—N3—C4126.78 (15)O11—C11—C12110.50 (17)
C2—N3—H3115.3 (16)O11—C11—H12108.0 (15)
C4—N3—H3117.7 (16)C12—C11—H12105.2 (16)
O7—C2—N1123.20 (16)O11—C11—H13111.0 (17)
O7—C2—N3121.01 (16)C12—C11—H13106.0 (18)
N1—C2—N3115.79 (14)H12—C11—H13116 (2)
O8—C4—N3121.37 (16)F11—C12—F12106.4 (2)
O8—C4—C5125.73 (15)F11—C12—F13107.51 (17)
N3—C4—C5112.90 (15)F12—C12—F13106.53 (18)
C6—C5—F9121.65 (16)F11—C12—C11112.29 (18)
C6—C5—C4122.26 (14)F12—C12—C11112.26 (17)
F9—C5—C4116.08 (15)F13—C12—C11111.48 (18)
C5—C6—N1119.57 (16)
C6—N1—C2—O7178.79 (15)O8—C4—C5—F91.7 (2)
C6—N1—C2—N30.6 (2)N3—C4—C5—F9178.07 (13)
C4—N3—C2—O7178.17 (15)F9—C5—C6—N1178.49 (14)
C4—N3—C2—N11.2 (2)C4—C5—C6—N10.4 (2)
C2—N3—C4—O8178.87 (15)C2—N1—C6—C50.2 (2)
C2—N3—C4—C51.3 (2)O11—C11—C12—F1161.2 (2)
O8—C4—C5—C6179.36 (17)O11—C11—C12—F1258.7 (2)
N3—C4—C5—C60.8 (2)O11—C11—C12—F13178.12 (16)
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
N3—H3···O7i0.87 (3)1.92 (3)2.786 (2)173 (2)
N1—H1···O7ii0.82 (3)2.20 (3)2.924 (2)147 (2)
N1—H1···O11iii0.82 (3)2.43 (3)3.037 (2)132 (2)
O11—H11···O80.76 (3)2.00 (3)2.7507 (19)171 (3)
Symmetry codes: (i) x+3, y1/2, z+1; (ii) x+3, y+1/2, z+1; (iii) x+1, y+1, z.
 

Acknowledgements

The authors acknowledge the EPSRC's UK Basic Technology Programme for supporting `Control and Prediction of the Organic Solid State'.

References

First citationBruker (1998). SMART and SAINT. Bruker AXS Inc., Madison, Wisconsin, USA.
First citationHulme, A. T. & Tocher, D. A. (2004a). Acta Cryst. E60, o1781–o1782. Web of Science CSD CrossRef IUCr Journals
First citationHulme, A. T. & Tocher, D. A. (2004b). Acta Cryst. E60, o1783–o1785. Web of Science CSD CrossRef IUCr Journals
First citationHulme, A. T. & Tocher, D. A. (2004c). Acta Cryst. E60, o1786–o1787. Web of Science CSD CrossRef IUCr Journals
First citationSheldrick, G. M. (1996). SADABS. University of Göttingen, Germany.
First citationSheldrick, G. M. (1997). SHELXS97 and SHELXL97. University of Göttingen, Germany.
First citationWatkin, D. J., Prout, C. K. & Pearce, L. J. (1996). CAMERON. Chemical Crystallography Laboratory, University of Oxford, England.

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