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

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ISSN: 2056-9890

5-Fluoro­uracil–di­methyl sulfoxide (1/1)

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

(Received 1 September 2004; accepted 8 September 2004; online 18 September 2004)

The title compound, C4H3FN2O2·C2H6OS, crystallizes in the monoclinic space group P21/c, with one mol­ecule of 5-fluoro­uracil and one mol­ecule of di­methyl ­sulfoxide (DMSO) in the asymmetric unit. The crystal structure contains hydrogen-bonded ribbons of alternating 5-fluoro­uracil and DMSO mol­ecules which stack, forming non-interacting layers parallel to the (100) planes.

Comment

In the course of a polymorph screen performed on 5-fluoro­uracil three solvates were discovered; the crystal structure of one of these solvates is reported here. The title compound, (I[link]), crystallizes in the space group P21/c with one mol­ecule of 5-fluoro­uracil and one mol­ecule of di­methyl ­sulfoxide (DMSO) in the asymmetric unit.[link]

[Scheme 1]

The S atom in the DMSO mol­ecule is disordered over two sites, with a 95:5 occupancy ratio. The minor site (S20′) exhib­its the opposite pyrimidisation of the DMSO mol­ecule, compared to the major site (S20). Fig. 1[link] shows the asymmetric unit, with only the major sulfur position shown.

Two conventional hydrogen bonds, of the type N—H⋯O, occur in the structure. The O atom of the DMSO mol­ecule acts as a hydrogen-bond acceptor for two symmetry-related 5-fluoro­uracil mol­ecules (Table 1[link]).

The crystal structure contains hydrogen-bonded ribbons of alternating 5-fluoro­uracil and DMSO mol­ecules (Fig. 2[link]). These ribbons stack, forming form non-interacting layers parallel to the (100) planes.

[Figure 1]
Figure 1
View (Watkin et al., 1996[Watkin, D. J., Prout, C. K. & Pearce, L. J. (1996). CAMERON. Chemical Crystallography Laboratory, Oxford, England.]) of the asymmetric unit of the title compound, with 50% probability displacement ellipsoids. H atoms are drawn as spheres of arbitrary radii.
[Figure 2]
Figure 2
Hydro­gen-bonded ribbon motif, made up of alternating 5-fluoro­uracil and DMSO mol­ecules. Hydro­gen bonds are shown as dashed lines.

Experimental

5-Fluoro­uracil was obtained from the Aldrich Chemical Company Inc. The crystals of the title compound were grown by vapour diffusion of diethyl ether into a saturated solution of 5-fluoro­uracil in DMSO.

Crystal data
  • C4H3FN2O2·C2H6OS

  • Mr = 208.21

  • Monoclinic, P21/c

  • a = 9.8831 (10) Å

  • b = 10.8128 (11) Å

  • c = 8.6842 (9) Å

  • β = 107.397 (2)°

  • V = 885.58 (16) Å3

  • Z = 4

  • Dx = 1.562 Mg m−3

  • Mo Kα radiation

  • Cell parameters from 3031 reflections

  • θ = 2.9–28.0°

  • μ = 0.36 mm−1

  • T = 150 (2) K

  • Block, colourless

  • 0.29 × 0.21 × 0.11 mm

Data collection
  • Bruker SMART APEX diffractometer

  • Narrow-frame ω scans

  • Absorption correction: multi-scan (SADABS; Sheldrick, 1996[Sheldrick, G. M. (1996). SADABS. University of Göttingen, Germany.]) Tmin = 0.903, Tmax = 0.962

  • 7672 measured reflections

  • 2128 independent reflections

  • 1922 reflections with I > 2σ(I)

  • Rint = 0.022

  • θmax = 28.3°

  • h = −13 → 12

  • k = −14 → 14

  • l = −11 → 11

Refinement
  • Refinement on F2

  • R[F2 > 2σ(F2)] = 0.036

  • wR(F2) = 0.090

  • S = 1.07

  • 2127 reflections

  • 140 parameters

  • H atoms treated by a mixture of independent and constrained refinement

  • w = 1/[σ2(Fo2) + (0.0401P)2 + 0.5099P] where P = (Fo2 + 2Fc2)/3

  • (Δ/σ)max < 0.001

  • Δρmax = 0.40 e Å−3

  • Δρmin = −0.54 e Å−3

Table 1
Hydrogen-bonding geometry (Å, °)

D—H⋯A D—H H⋯A DA D—H⋯A
N1—H1⋯O20 0.79 (2) 2.04 (2) 2.838 (2) 175 (2)
N3—H3⋯O20i 0.82 (2) 1.97 (2) 2.790 (2) 173 (2)
N1—H1⋯S20′ 0.79 (2) 2.56 (2) 3.266 (8) 149 (2)
N3—H3⋯S20i 0.82 (2) 2.89 (2) 3.666 (1) 157 (2)
Symmetry code: (i) [1-x,{\script{1\over 2}}+y,{\script{1\over 2}}-z].

The S atom in the DMSO mol­ecule is disordered over two sites and was modelled anisotropically, with site occupancy 95:5. The S—O and S—C distances in the major and minor components were restrained to be equal within [\pm]0.01 Å. All H atoms on 5-fluoro­uracil were located in a difference map and were refined isotropically; N—H = 0.79 (2) and 0.82 (2) Å, and C—H = 0.94 (2) Å. The H-atom positions on the methyl group were idealized and refined using a riding model [C—H = 0.96 Å and Uiso(H) = 1.5Ueq(C)].

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, 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 Dimethylsulfoxide (1/1) top
Crystal data top
C2H6OS·C4H3FN2O2F(000) = 432
Mr = 208.21Dx = 1.562 Mg m3
Monoclinic, P21/cMo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybcCell parameters from 3031 reflections
a = 9.8831 (10) Åθ = 2.9–28.0°
b = 10.8128 (11) ŵ = 0.36 mm1
c = 8.6842 (9) ÅT = 150 K
β = 107.397 (2)°Block, colourless
V = 885.58 (16) Å30.29 × 0.21 × 0.11 mm
Z = 4
Data collection top
Bruker SMART APEX
diffractometer
2128 independent reflections
Radiation source: sealed tube1922 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.022
ω rotation with narrow frames scansθmax = 28.3°, θmin = 2.2°
Absorption correction: multi-scan
(SADABS; Sheldrick, 1996)
h = 1312
Tmin = 0.903, Tmax = 0.962k = 1414
7672 measured reflectionsl = 1111
Refinement top
Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: found from delta F
R[F2 > 2σ(F2)] = 0.036Hydrogen site location: found from delta F
wR(F2) = 0.090H atoms treated by a mixture of independent and constrained refinement
S = 1.07 w = 1/[σ2(Fo2) + (0.0401P)2 + 0.5099P]
where P = (Fo2 + 2Fc2)/3
2127 reflections(Δ/σ)max < 0.001
140 parametersΔρmax = 0.40 e Å3
7 restraintsΔρmin = 0.54 e Å3
Special details top

Experimental. The sulfur atom in the DMSO molecule is disordered and is modelled anisotropically, with site occupancy 95:5.

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*/UeqOcc. (<1)
S200.15779 (4)0.27388 (4)0.05029 (5)0.01947 (14)0.9452 (19)
S20'0.1956 (8)0.3387 (7)0.0775 (10)0.047 (3)0.0548 (19)
O200.27984 (12)0.22286 (10)0.08812 (14)0.0242 (3)
C200.02017 (18)0.30934 (19)0.0348 (2)0.0310 (4)
H20A0.01870.23400.06210.047*0.9452 (19)
H20B0.05300.35490.04200.047*0.9452 (19)
H20C0.05760.35830.13030.047*0.9452 (19)
H20D0.00330.25920.11840.047*0.0548 (19)
H20E0.01380.26710.06670.047*0.0548 (19)
H20F0.02890.38670.02890.047*0.0548 (19)
C210.20530 (19)0.42683 (17)0.0857 (2)0.0296 (4)
H21A0.28120.42460.13350.044*0.9452 (19)
H21B0.23560.47100.01470.044*0.9452 (19)
H21C0.12490.46780.15760.044*0.9452 (19)
H21D0.30410.44450.06720.044*0.0548 (19)
H21E0.15410.50290.09040.044*0.0548 (19)
H21F0.16910.38330.18600.044*0.0548 (19)
C60.57652 (17)0.24074 (15)0.4738 (2)0.0203 (3)
F90.76106 (11)0.21144 (9)0.71240 (12)0.0274 (2)
O70.48751 (13)0.49901 (12)0.21670 (14)0.0288 (3)
O80.84328 (13)0.45295 (12)0.68615 (15)0.0300 (3)
N10.50578 (15)0.31511 (13)0.34764 (17)0.0202 (3)
N30.66006 (14)0.47552 (13)0.45536 (16)0.0195 (3)
C20.54651 (16)0.43374 (15)0.33165 (18)0.0194 (3)
C40.73994 (16)0.40891 (15)0.58632 (19)0.0197 (3)
C50.68843 (17)0.28387 (14)0.58802 (19)0.0199 (3)
H10.439 (2)0.2926 (18)0.276 (2)0.019 (5)*
H30.685 (2)0.548 (2)0.448 (2)0.027 (5)*
H60.5414 (19)0.1598 (18)0.474 (2)0.020 (5)*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
S200.0212 (2)0.0176 (2)0.0164 (2)0.00214 (15)0.00069 (16)0.00209 (14)
S20'0.066 (7)0.043 (6)0.032 (5)0.012 (5)0.014 (5)0.003 (4)
O200.0213 (6)0.0183 (6)0.0276 (6)0.0039 (4)0.0006 (5)0.0006 (4)
C200.0207 (8)0.0428 (11)0.0277 (9)0.0050 (7)0.0044 (7)0.0087 (8)
C210.0272 (9)0.0267 (9)0.0331 (10)0.0027 (7)0.0064 (7)0.0094 (7)
C60.0245 (8)0.0151 (7)0.0226 (8)0.0018 (6)0.0091 (7)0.0008 (6)
F90.0293 (5)0.0233 (5)0.0253 (5)0.0022 (4)0.0017 (4)0.0084 (4)
O70.0295 (6)0.0268 (6)0.0237 (6)0.0024 (5)0.0019 (5)0.0068 (5)
O80.0273 (6)0.0261 (6)0.0280 (7)0.0053 (5)0.0048 (5)0.0013 (5)
N10.0190 (7)0.0211 (7)0.0173 (7)0.0046 (5)0.0007 (5)0.0029 (5)
N30.0211 (7)0.0140 (6)0.0212 (7)0.0032 (5)0.0029 (5)0.0001 (5)
C20.0195 (7)0.0206 (7)0.0176 (7)0.0001 (6)0.0050 (6)0.0008 (6)
C40.0194 (7)0.0199 (7)0.0190 (7)0.0005 (6)0.0043 (6)0.0004 (6)
C50.0223 (7)0.0180 (7)0.0188 (7)0.0020 (6)0.0050 (6)0.0033 (6)
Geometric parameters (Å, º) top
S20—O201.5288 (12)C21—H21D0.96
S20—C211.7710 (18)C21—H21E0.96
S20—C201.7729 (18)C21—H21F0.96
S20'—O201.492 (7)C6—C51.330 (2)
S20'—C201.691 (7)C6—N11.371 (2)
S20'—C211.734 (7)C6—H60.94 (2)
C20—H20A0.96F9—C51.3534 (18)
C20—H20B0.96O7—C21.2192 (19)
C20—H20C0.96O8—C41.2215 (19)
C20—H20D0.96N1—C21.364 (2)
C20—H20E0.96N1—H10.79 (2)
C20—H20F0.96N3—C21.377 (2)
C21—H21A0.96N3—C41.378 (2)
C21—H21B0.96N3—H30.82 (2)
C21—H21C0.96C4—C51.446 (2)
O20—S20—C21106.60 (8)C2—N1—C6122.53 (14)
O20—S20—C20105.89 (8)C2—N1—H1114.2 (14)
C21—S20—C2098.44 (9)C6—N1—H1123.3 (14)
O20—S20—H20E126.7C2—N3—C4127.20 (14)
C21—S20—H20E110.1C2—N3—H3116.1 (14)
O20—S20—H21F126.7C4—N3—H3116.6 (14)
C20—S20—H21F110.9O7—C2—N1122.98 (15)
H20E—S20—H21F104.4O7—C2—N3121.84 (15)
O20—S20'—C20111.9 (5)N1—C2—N3115.18 (14)
O20—S20'—C21110.2 (4)O8—C4—N3122.22 (15)
C20—S20'—C21103.2 (4)O8—C4—C5125.40 (15)
S20'—C20—H20C66.5N3—C4—C5112.37 (13)
C5—C6—N1120.15 (15)C6—C5—F9121.11 (14)
C5—C6—H6123.3 (12)C6—C5—C4122.48 (14)
N1—C6—H6116.6 (12)F9—C5—C4116.41 (14)
C5—C6—N1—C20.9 (2)N1—C6—C5—F9179.01 (14)
C6—N1—C2—O7177.16 (15)N1—C6—C5—C40.5 (2)
C6—N1—C2—N32.8 (2)O8—C4—C5—C6178.74 (17)
C4—N3—C2—O7176.16 (16)N3—C4—C5—C60.2 (2)
C4—N3—C2—N13.8 (2)O8—C4—C5—F90.8 (2)
C2—N3—C4—O8176.46 (16)N3—C4—C5—F9179.76 (13)
C2—N3—C4—C52.5 (2)
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
N1—H1···O200.79 (2)2.04 (2)2.838 (2)175 (2)
N3—H3···O20i0.82 (2)1.97 (2)2.790 (2)173 (2)
N1—H1···S200.79 (2)2.56 (2)3.266 (8)149 (2)
N3—H3···S20i0.82 (2)2.89 (2)3.666 (1)157 (2)
Symmetry code: (i) x+1, y+1/2, z+1/2.
 

Acknowledgements

The authors acknowledge the Research Councils 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.  Google Scholar
First citationSheldrick, G. M. (1997). SHELXS97 and SHELXL97. University of Göttingen, Germany.  Google Scholar
First citationSheldrick, G. M. (1996). SADABS. University of Göttingen, Germany.  Google Scholar
First citationWatkin, D. J., Prout, C. K. & Pearce, L. J. (1996). CAMERON. Chemical Crystallography Laboratory, Oxford, England.  Google Scholar

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ISSN: 2056-9890
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