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Acta Cryst. (2009). E65, o2377    [ doi:10.1107/S1600536809035624 ]

1-Methyl-3-trifluoromethyl-1H-pyrazol-5-ol

J. Xu, W. Cheng, J. Yan and G. Quan

Abstract top

In the title compound, C5H5F3N2O, the F atoms are disordered over two sets of sites in a 0.64 (3):0.36 (3) ratio. In the crystal structure, O-H...N hydrogen bonds link the molecules into chains and a short C-H...F contact also occurs.

Comment top

As part of the ongoing study of polyfluorinated heterocycles (Marcos & Martins, 2003), we report herein the crystal structure of the title compound.

In the molecule of the title compound (Fig 1), the bond lengths (Allen et al., 1987) and angles are within normal ranges. Ring A (C4-C9) is, of course, planar. The intramolecular C-H···O hydrogen bond (Table 1) results in the formation of a five-membered ring B (O1/C1-C3/H1A), having envelope conformation with C2 atom displaced by -0.668 (3) Å from the plane of the other ring atoms.

In the crystal structure, intermolecular O—H···N hydrogen bonds (Table 1) link the molecules (Fig. 2), in which they may be effective in the stabilization of the structure.

Related literature top

For background on fluorinated heterocycles, see: Marcos & Martins (2003). For bond-length data, see: Allen et al. (1987).

For related literature, see: Farrugia (1997).

Experimental top

4,4-Diethoxy-1,1,1-trifluorobut-3-en-2-one (2 mmol) was added to a stirred solution of hydrazine (2.2 mmol) at room temperature in ethanol (15 ml). The mixture was stirred under reflux for 24 h. The solvent was evaporated and to the residue was added H2O (10 ml) and the organic phase were extract with dichloromethane (15 ml). The organic extract was dried (Na2SO4) and the solvent was removed under reduced pressure to obtain the title compound (yield; 25%, m.p. 446 K). Colourless blocks of (I) were obtained by slow evaporation of an ethyl acetate solution.

Refinement top

H atoms were positioned geometrically, with C—H = 0.93, 0.97 and 0.96 Å for aromatic, methylene and methyl H, respectively, and constrained to ride on their parent atoms, with Uiso(H) = xUeq(C), where x = 1.5 for methyl H and x = 1.2 for all other H atoms.

Computing details top

Data collection: CAD-4 EXPRESS (Enraf–Nonius, 1994); cell refinement: CAD-4 EXPRESS (Enraf–Nonius, 1994); data reduction: XCAD4 (Harms & Wocadlo, 1995); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: PLATON (Spek, 2009).

Figures top
[Figure 1] Fig. 1. The molecular structure of (I).
[Figure 2] Fig. 2. A partial packing diagram of (I). Hydrogen bonds are shown as dashed lines.
1-Methyl-3-trifluoromethyl-1H-pyrazol-5-ol top
Crystal data top
C5H5F3N2OF(000) = 336
Mr = 166.11Dx = 1.591 Mg m−3
Monoclinic, P21/cMelting point: 446 K
Hall symbol: -P 2ybcMo Kα radiation, λ = 0.71073 Å
a = 7.5500 (15) ÅCell parameters from 25 reflections
b = 8.3530 (17) Åθ = 9–13°
c = 11.371 (2) ŵ = 0.17 mm−1
β = 104.72 (3)°T = 293 K
V = 693.6 (2) Å3Block, colourless
Z = 40.20 × 0.10 × 0.10 mm
Data collection top
Enraf–Nonius CAD-4
diffractometer		856 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tubeRint = 0.041
graphiteθmax = 25.3°, θmin = 2.8°
ω/2θ scansh = 0→9
Absorption correction: ψ scan
(North et al., 1968)		k = 0→10
Tmin = 0.968, Tmax = 0.984l = −13→13
1357 measured reflections3 standard reflections every 200 reflections
1259 independent reflections intensity decay: 1%
Refinement top
Refinement on F2Secondary atom site location: difference Fourier map
Least-squares matrix: fullHydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.050H-atom parameters constrained
wR(F2) = 0.168 w = 1/[σ2(Fo2) + (0.1P)2 + 0.12P]
where P = (Fo2 + 2Fc2)/3
S = 1.00(Δ/σ)max < 0.001
1259 reflectionsΔρmax = 0.20 e Å−3
130 parametersΔρmin = −0.21 e Å−3
36 restraintsExtinction correction: SHELXL97 (Sheldrick, 2008), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
Primary atom site location: structure-invariant direct methodsExtinction coefficient: 0.062 (13)
Crystal data top
C5H5F3N2OV = 693.6 (2) Å3
Mr = 166.11Z = 4
Monoclinic, P21/cMo Kα radiation
a = 7.5500 (15) ŵ = 0.17 mm−1
b = 8.3530 (17) ÅT = 293 K
c = 11.371 (2) Å0.20 × 0.10 × 0.10 mm
β = 104.72 (3)°
Data collection top
Enraf–Nonius CAD-4
diffractometer		856 reflections with I > 2σ(I)
Absorption correction: ψ scan
(North et al., 1968)		Rint = 0.041
Tmin = 0.968, Tmax = 0.984θmax = 25.3°
1357 measured reflections3 standard reflections every 200 reflections
1259 independent reflections intensity decay: 1%
Refinement top
R[F2 > 2σ(F2)] = 0.050H-atom parameters constrained
wR(F2) = 0.168Δρmax = 0.20 e Å−3
S = 1.00Δρmin = −0.21 e Å−3
1259 reflectionsAbsolute structure: ?
130 parametersFlack parameter: ?
36 restraintsRogers parameter: ?
Special details top

Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds 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 > 2sigma(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)
O0.6146 (3)0.1822 (3)0.22551 (16)0.0812 (8)
H0A0.57350.19880.28740.097*
N10.4722 (3)0.2582 (3)−0.08398 (18)0.0562 (7)
C10.1757 (5)0.3877 (5)−0.1412 (3)0.0701 (9)
N20.5857 (3)0.2020 (3)0.02028 (18)0.0549 (7)
C20.3341 (4)0.3246 (3)−0.0489 (2)0.0540 (8)
C30.3563 (4)0.3122 (4)0.0765 (2)0.0609 (8)
H3A0.27830.34920.12200.073*
C40.5184 (4)0.2333 (4)0.1169 (2)0.0585 (8)
C50.7551 (4)0.1216 (5)0.0201 (3)0.0697 (9)
H5A0.80430.07230.09780.105*
H5B0.84140.19810.00460.105*
H5C0.73230.0411−0.04220.105*
F10.0666 (15)0.2656 (12)−0.1980 (10)0.117 (3)0.64 (3)
F20.2287 (15)0.4689 (17)−0.2294 (11)0.107 (3)0.64 (3)
F30.057 (2)0.458 (3)−0.0997 (12)0.093 (5)0.36 (3)
F3'0.1113 (17)0.5237 (14)−0.0992 (8)0.103 (2)0.64 (3)
F2'0.202 (2)0.412 (2)−0.2461 (11)0.077 (4)0.36 (3)
F1'0.0325 (19)0.309 (3)−0.157 (2)0.105 (5)0.36 (3)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
O0.0761 (14)0.143 (2)0.0277 (11)0.0173 (14)0.0192 (9)0.0057 (11)
N10.0633 (14)0.0805 (17)0.0266 (11)−0.0061 (12)0.0150 (10)−0.0014 (10)
C10.075 (2)0.089 (2)0.0477 (18)0.003 (2)0.0183 (16)0.0058 (16)
N20.0585 (13)0.0824 (16)0.0266 (11)−0.0018 (12)0.0162 (9)−0.0031 (10)
C20.0632 (17)0.0676 (18)0.0346 (13)−0.0069 (14)0.0190 (12)−0.0019 (12)
C30.0642 (17)0.090 (2)0.0338 (14)−0.0021 (16)0.0221 (12)−0.0070 (13)
C40.0606 (17)0.090 (2)0.0277 (13)−0.0054 (16)0.0164 (12)−0.0050 (13)
C50.0675 (18)0.100 (2)0.0454 (16)0.0037 (18)0.0219 (14)−0.0017 (15)
F10.096 (4)0.120 (4)0.104 (5)−0.001 (3)−0.033 (3)−0.017 (3)
F20.118 (4)0.122 (6)0.076 (4)−0.003 (4)0.016 (3)0.042 (4)
F30.088 (6)0.120 (10)0.074 (4)0.036 (6)0.027 (4)−0.009 (6)
F3'0.112 (5)0.099 (5)0.095 (3)0.028 (4)0.020 (3)0.000 (3)
F2'0.091 (6)0.114 (8)0.030 (3)0.019 (5)0.024 (3)0.011 (4)
F1'0.073 (5)0.114 (9)0.110 (8)−0.029 (5)−0.008 (5)0.014 (6)
Geometric parameters (Å, °) top
O—C41.334 (3)C1—C21.474 (4)
O—H0A0.8501N2—C41.348 (3)
N1—C21.328 (3)N2—C51.445 (4)
N1—N21.358 (3)C2—C31.397 (4)
C1—F1'1.238 (13)C3—C41.363 (4)
C1—F31.257 (12)C3—H3A0.9300
C1—F2'1.274 (12)C5—H5A0.9600
C1—F21.352 (10)C5—H5B0.9600
C1—F11.366 (9)C5—H5C0.9600
C1—F3'1.369 (9)
C4—O—H0A119.2F1—C1—C2110.6 (5)
C2—N1—N2104.6 (2)F3'—C1—C2110.2 (5)
F1'—C1—F368 (2)C4—N2—N1111.1 (2)
F1'—C1—F2'106.6 (10)C4—N2—C5127.5 (2)
F3—C1—F2'124.7 (11)N1—N2—C5121.5 (2)
F1'—C1—F2124.7 (8)N1—C2—C3112.1 (3)
F3—C1—F2114.7 (14)N1—C2—C1119.5 (2)
F2'—C1—F223.0 (8)C3—C2—C1128.2 (3)
F1'—C1—F130.3 (9)C4—C3—C2104.2 (2)
F3—C1—F197.0 (17)C4—C3—H3A127.9
F2'—C1—F184.1 (8)C2—C3—H3A127.9
F2—C1—F1106.3 (6)O—C4—N2117.6 (3)
F1'—C1—F3'96.6 (18)O—C4—C3134.3 (2)
F3—C1—F3'29.9 (8)N2—C4—C3108.1 (2)
F2'—C1—F3'110.2 (11)N2—C5—H5A109.5
F2—C1—F3'92.4 (11)N2—C5—H5B109.5
F1—C1—F3'124.0 (11)H5A—C5—H5B109.5
F1'—C1—C2115.8 (7)N2—C5—H5C109.5
F3—C1—C2115.2 (6)H5A—C5—H5C109.5
F2'—C1—C2115.7 (7)H5B—C5—H5C109.5
F2—C1—C2111.6 (5)
C2—N1—N2—C40.0 (3)F2'—C1—C2—C3168.0 (11)
C2—N1—N2—C5−179.4 (3)F2—C1—C2—C3143.2 (8)
N2—N1—C2—C3−0.1 (3)F1—C1—C2—C3−98.6 (8)
N2—N1—C2—C1−175.2 (3)F3'—C1—C2—C342.1 (8)
F1'—C1—C2—N1108.2 (15)N1—C2—C3—C40.1 (3)
F3—C1—C2—N1−175.6 (14)C1—C2—C3—C4174.7 (3)
F2'—C1—C2—N1−17.7 (11)N1—N2—C4—O178.9 (3)
F2—C1—C2—N1−42.5 (8)C5—N2—C4—O−1.7 (5)
F1—C1—C2—N175.7 (8)N1—N2—C4—C30.0 (3)
F3'—C1—C2—N1−143.6 (7)C5—N2—C4—C3179.4 (3)
F1'—C1—C2—C3−66.1 (16)C2—C3—C4—O−178.7 (4)
F3—C1—C2—C310.1 (15)C2—C3—C4—N20.0 (3)
Hydrogen-bond geometry (Å, °) top
D—H···AD—HH···AD···AD—H···A
O—H0A···N1i0.851.852.698 (3)176
C5—H5B···F3'ii0.962.553.185 (12)124
Symmetry codes: (i) x, −y+1/2, z+1/2; (ii) −x+1, −y+1, −z.
Table 1
Hydrogen-bond geometry (Å, °) top
D—H···AD—HH···AD···AD—H···A
O—H0A···N1i0.851.852.698 (3)176
C5—H5B···F3'ii0.962.553.185 (12)124
Symmetry codes: (i) x, −y+1/2, z+1/2; (ii) −x+1, −y+1, −z.
Acknowledgements top

no

references
References top

Allen, F. H., Kennard, O., Watson, D. G., Brammer, L., Orpen, A. G. & Taylor, R. (1987). J. Chem. Soc. Perkin Trans. 2, pp. S1–19.

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Farrugia, L. J. (1997). J. Appl. Cryst. 30, 565.

Harms, K. & Wocadlo, S. (1995). XCAD4. University of Marburg, Germany.

Marcos, A. P. & Martins, X. X. (2003). J. Fluorine Chem. 123, 261–265.

North, A. C. T., Phillips, D. C. & Mathews, F. S. (1968). Acta Cryst. A24, 351–359.

Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122.

Spek, A. L. (2009). Acta Cryst. D65, 148–155.