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Acta Cryst. (2009). E65, o663    [ doi:10.1107/S1600536809007120 ]

1-[2-(2,4-Dichlorophenyl)pentyl]-1H-1,2,4-triazole

C. Rizzoli, E. Marku and L. Greci

Abstract top

The title compound, C13H15Cl2N3, also known as penconazole, crystallizes as a racemate. The dihedral angle between the benzene and triazole rings is 24.96 (13)°. In the crystal structure, molecules are linked into chains running parallel to the c axis by intermolecular C-H...N hydrogen-bonding interactions.

Comment top

The synthesis of the title compound, I, commonly known as penconazole, was described years ago (Maier et al., 1987). Due to its ability to inhibit the development of fungi by interfering with sterol biosynthesis of their cell membranes, this product was introduced as an agriculture systemic fungicide affecting cucurbits, grapes, pome fruits and vegetables. The advantages of this compound is its low toxicity: acute oral dose (LD50) of 2125 mg/kg for rats (Worthing, 1987). More recently, penconazole was prepared by condensation of 2-(2,4-dichlorophenyl)-1-pentanole with 1,2,4-triazole (Tao et al., 2003), but this method also leads to the formation of 1-(1H-1,3,4-triazol-1-yl)-2-(2,4-dichlorophenyl)-pentane (II) as a by-product. In repeating this reaction, our purpose was the determination of the crystal structure of the desired compound I and the evaluation of the percentage of the by-product II.

The title compound (Fig. 1) crystallizes as a racemate. The triazole ring is substantially planar (maximum deviation from planarity 0.006 (3) Å for atom C2) and forms a dihedral angle of 24.96 (13)° with the benzene ring. The N—N (1.351 (3) Å) and C—N (mean value 1.328 (4) Å) bond lengths within the triazole ring are comparable with those observed in 6-[(4-chlorophenyl)(1H-1,2,4-triazol-1-yl)methyl]-1-methyl-1H-benzotriazole (vorozole; Peeters et al., 1993) and suggest electron delocalization over the ring. In the crystal structure, an intermolecular C—H···N hydrogen bonding interaction (Table 1) link the molecules into chains running parallel to the c axis (Fig. 2).

Related literature top

For the synthesis and toxicity of the title compound, see: Maier et al. (1987); Worthing (1987); Tao et al. (2003). For the crystal structure of a related compound, see: Peeters et al. (1993).

Experimental top

The title compound was prepared according to the literature reports (Tao et al., 2003). This method afforded compounds I and II in a 93:3 ratio. The two compounds were separated by chromatography on SiO2 column eluting with cyclohexane/ethyl acetate (9:1 v/v). Crystals of the title compound suitable for X-ray analysis were obtained on slow evaporation of an n-pentane solution (m. p. 60–61°C). IR data, ν, cm-1: 3060, 1597, 1448, 760, 746, 700. 1H-NMR, δ in CDCL3: 0.87 (t, 3H, –CH2CH3), 1.23 (sextet, 2H, -CH2CH3), 2.6–2.8 (m,2H, –CHCH2CH2CH3), 3.78 (1H, quintet, –CH2CHCH2-), 4.34 (d, -CH2CH<), 7.23 (1H, speudo-q, H-5, J=8.3 Hz, J=2.2 Hz), 7.38 (1H, d, H-3, J=2.2 Hz), 7.71 (s, 1H, triazolyl-H-3), 7.89 (s,1H, triazolyl-H-5). MS, Calcd for C13H15Cl2N3, 284.2; Found. M (%): 250 (12.72), 248 (36.93), 161 (63.69), 159 (100); no molecular ion peak was observed; the highest peaks are those corresponding to the loss of a chlorine atom. The 1H-NMR spectrum of compound II shows a singlet at δ = 7.89 corresponding to the two equivalent H atoms of the 1,3,4-triazol-1-yl ring, the other part of the spectrum is strictly similar to that of compound I. Melting points were determined by an electrochemical apparatus and were uncorrected. 1H-NMR spectra were recorded on a Varian Gemini 200 MHz. IR spectra were recorded in the solid state with a Perkin-Elmer MGX1 spectrophotometer equipped with Spectra Tech. Mass spectra were recorded with a Carlo Erba QMD 1000 mass spectrometer in positive EI mode.

Refinement top

All H atoms were positioned geometrically with C—H = 0.93–0.98 Å, and refined using a riding model approximation with Uiso(H) = 1.2 Ueq(C) or 1.5 Ueq(C) for methyl H atoms.

Computing details top

Data collection: AED (Belletti et al., 1993); cell refinement: AED (Belletti et al., 1993); data reduction: AED (Belletti et al., 1993); 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 SCHAKAL (Keller, 1997); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008) and PARST95 (Nardelli, 1995).

Figures top
[Figure 1] Fig. 1. The molecular structure of the title compound. Displacement ellipsoids are drawn at the 50% probability level.
[Figure 2] Fig. 2. Crystal packing of the title compound viewed approximately along the b axis. Intermolecular C—H···N hydrogen bonds are shown as dashed lines.
[Figure 3] Fig. 3. The structures of (I) and (II).
1-[2-(2,4-Dichlorophenyl)pentyl]-1H-1,2,4-triazole top
Crystal data top
C13H15Cl2N3F(000) = 1184
Mr = 284.18Dx = 1.296 Mg m−3
Monoclinic, C2/cCu Kα radiation, λ = 1.54178 Å
Hall symbol: -C 2ycCell parameters from 48 reflections
a = 25.083 (8) Åθ = 18.4–42.5°
b = 10.763 (2) ŵ = 3.89 mm−1
c = 11.206 (3) ÅT = 297 K
β = 105.654 (3)°Block, colourless
V = 2913.1 (13) Å30.23 × 0.20 × 0.16 mm
Z = 8
Data collection top
Siemens AED
diffractometer		1183 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tubeRint = 0.060
graphiteθmax = 67.9°, θmin = 3.7°
θ/2θ scansh = −29→28
Absorption correction: empirical (using intensity measurements)
(DIFABS; Walker & Stuart, 1983)		k = −2→12
Tmin = 0.432, Tmax = 0.538l = −5→13
2737 measured reflections3 standard reflections every 100 reflections
2611 independent reflections intensity decay: 0.01%
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)] = 0.056Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.127H-atom parameters constrained
S = 0.99 w = 1/[σ2(Fo2) + (0.0456P)2]
where P = (Fo2 + 2Fc2)/3
2611 reflections(Δ/σ)max < 0.001
163 parametersΔρmax = 0.34 e Å−3
0 restraintsΔρmin = −0.27 e Å−3
Crystal data top
C13H15Cl2N3V = 2913.1 (13) Å3
Mr = 284.18Z = 8
Monoclinic, C2/cCu Kα radiation
a = 25.083 (8) ŵ = 3.89 mm−1
b = 10.763 (2) ÅT = 297 K
c = 11.206 (3) Å0.23 × 0.20 × 0.16 mm
β = 105.654 (3)°
Data collection top
Siemens AED
diffractometer		1183 reflections with I > 2σ(I)
Absorption correction: empirical (using intensity measurements)
(DIFABS; Walker & Stuart, 1983)		Rint = 0.060
Tmin = 0.432, Tmax = 0.538θmax = 67.9°
2737 measured reflections3 standard reflections every 100 reflections
2611 independent reflections intensity decay: 0.01%
Refinement top
R[F2 > 2σ(F2)] = 0.056H-atom parameters constrained
wR(F2) = 0.127Δρmax = 0.34 e Å−3
S = 0.99Δρmin = −0.27 e Å−3
2611 reflectionsAbsolute structure: ?
163 parametersFlack parameter: ?
0 restraintsRogers parameter: ?
Special details top

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
Cl10.08070 (6)0.51687 (9)0.93474 (12)0.1422 (6)
Cl20.08744 (5)0.18168 (11)1.28987 (10)0.1305 (5)
N10.22774 (10)0.3780 (2)0.7443 (2)0.0595 (7)
N20.24356 (12)0.3032 (2)0.6633 (2)0.0757 (8)
N30.25582 (12)0.5043 (2)0.6210 (3)0.0815 (9)
C10.25951 (15)0.3839 (3)0.5932 (3)0.0808 (10)
H10.27280.35910.52700.097*
C20.23549 (13)0.4960 (3)0.7196 (3)0.0714 (9)
H20.22790.56340.76440.086*
C30.20829 (13)0.3285 (3)0.8460 (3)0.0638 (8)
H3A0.22300.37900.91920.077*
H3B0.22260.24490.86460.077*
C40.14554 (13)0.3253 (3)0.8180 (3)0.0666 (8)
H40.13130.40860.79210.080*
C50.13060 (12)0.2927 (3)0.9380 (3)0.0648 (8)
C60.10164 (15)0.3713 (3)0.9946 (3)0.0807 (10)
C70.08852 (16)0.3387 (3)1.1047 (4)0.0927 (11)
H70.06950.39371.14240.111*
C80.10441 (15)0.2235 (4)1.1558 (3)0.0790 (10)
C90.13257 (14)0.1450 (3)1.1013 (3)0.0787 (10)
H90.14350.06801.13720.094*
C100.14543 (13)0.1774 (3)0.9930 (3)0.0724 (9)
H100.16430.12110.95620.087*
C110.11930 (14)0.2323 (3)0.7113 (3)0.0830 (10)
H11A0.13150.25370.63890.100*
H11B0.13260.14920.73680.100*
C120.05814 (16)0.2321 (4)0.6773 (3)0.1057 (13)
H12A0.04500.31520.65140.127*
H12B0.04600.21150.75010.127*
C130.03234 (16)0.1433 (4)0.5764 (4)0.1191 (15)
H131−0.00720.14820.55890.179*
H1320.04420.06040.60200.179*
H1330.04340.16400.50320.179*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Cl10.2339 (15)0.0687 (6)0.1461 (10)0.0447 (8)0.0895 (10)0.0118 (7)
Cl20.1620 (11)0.1516 (11)0.0905 (7)−0.0169 (8)0.0558 (7)0.0066 (7)
N10.0728 (18)0.0384 (12)0.0602 (15)−0.0030 (12)0.0061 (13)−0.0050 (12)
N20.103 (2)0.0486 (14)0.0760 (18)−0.0110 (15)0.0248 (16)−0.0087 (14)
N30.101 (2)0.0588 (17)0.081 (2)−0.0131 (15)0.0183 (18)0.0088 (15)
C10.111 (3)0.0566 (19)0.075 (2)−0.016 (2)0.026 (2)−0.0020 (18)
C20.084 (3)0.0447 (17)0.079 (2)−0.0054 (16)0.0105 (19)−0.0048 (17)
C30.076 (2)0.0485 (16)0.0612 (19)−0.0073 (15)0.0083 (16)0.0029 (15)
C40.072 (2)0.0545 (18)0.067 (2)0.0001 (16)0.0072 (17)0.0065 (16)
C50.064 (2)0.0564 (18)0.066 (2)−0.0038 (16)0.0049 (16)−0.0013 (16)
C60.105 (3)0.057 (2)0.082 (2)−0.003 (2)0.027 (2)−0.0030 (19)
C70.109 (3)0.079 (3)0.094 (3)−0.006 (2)0.035 (2)−0.019 (2)
C80.086 (3)0.089 (3)0.064 (2)−0.015 (2)0.0244 (19)0.002 (2)
C90.079 (2)0.074 (2)0.079 (2)−0.0020 (19)0.014 (2)0.019 (2)
C100.073 (2)0.066 (2)0.076 (2)0.0035 (17)0.0154 (18)0.0082 (18)
C110.084 (3)0.094 (3)0.060 (2)−0.011 (2)0.0009 (18)−0.0074 (19)
C120.096 (3)0.121 (3)0.091 (3)−0.026 (3)0.011 (2)−0.011 (3)
C130.095 (3)0.140 (4)0.100 (3)−0.016 (3)−0.013 (2)−0.030 (3)
Geometric parameters (Å, °) top
Cl1—C61.729 (3)C5—C101.391 (4)
Cl2—C81.728 (3)C6—C71.404 (5)
N1—C21.326 (3)C7—C81.379 (4)
N1—N21.351 (3)C7—H70.9300
N1—C31.457 (3)C8—C91.348 (4)
N2—C11.304 (4)C9—C101.382 (4)
N3—C21.339 (4)C9—H90.9300
N3—C11.342 (4)C10—H100.9300
C1—H10.9300C11—C121.478 (4)
C2—H20.9300C11—H11A0.9700
C3—C41.520 (4)C11—H11B0.9700
C3—H3A0.9700C12—C131.488 (5)
C3—H3B0.9700C12—H12A0.9700
C4—C51.530 (4)C12—H12B0.9700
C4—C111.562 (4)C13—H1310.9600
C4—H40.9800C13—H1320.9600
C5—C61.377 (4)C13—H1330.9600
C2—N1—N2110.2 (3)C8—C7—H7120.7
C2—N1—C3127.8 (3)C6—C7—H7120.7
N2—N1—C3122.0 (2)C9—C8—C7120.2 (3)
C1—N2—N1101.6 (2)C9—C8—Cl2120.9 (3)
C2—N3—C1101.1 (3)C7—C8—Cl2118.9 (3)
N2—C1—N3116.8 (3)C8—C9—C10121.0 (3)
N2—C1—H1121.6C8—C9—H9119.5
N3—C1—H1121.6C10—C9—H9119.5
N1—C2—N3110.2 (3)C9—C10—C5121.1 (3)
N1—C2—H2124.9C9—C10—H10119.5
N3—C2—H2124.9C5—C10—H10119.5
N1—C3—C4113.2 (2)C12—C11—C4113.1 (3)
N1—C3—H3A108.9C12—C11—H11A109.0
C4—C3—H3A108.9C4—C11—H11A109.0
N1—C3—H3B108.9C12—C11—H11B109.0
C4—C3—H3B108.9C4—C11—H11B109.0
H3A—C3—H3B107.8H11A—C11—H11B107.8
C3—C4—C5108.0 (2)C11—C12—C13113.9 (3)
C3—C4—C11111.8 (3)C11—C12—H12A108.8
C5—C4—C11111.9 (2)C13—C12—H12A108.8
C3—C4—H4108.3C11—C12—H12B108.8
C5—C4—H4108.3C13—C12—H12B108.8
C11—C4—H4108.3H12A—C12—H12B107.7
C6—C5—C10117.1 (3)C12—C13—H131109.5
C6—C5—C4123.3 (3)C12—C13—H132109.5
C10—C5—C4119.6 (3)H131—C13—H132109.5
C5—C6—C7122.0 (3)C12—C13—H133109.5
C5—C6—Cl1121.4 (3)H131—C13—H133109.5
C7—C6—Cl1116.7 (3)H132—C13—H133109.5
C8—C7—C6118.7 (3)
Hydrogen-bond geometry (Å, °) top
D—H···AD—HH···AD···AD—H···A
C3—H3A···N3i0.972.523.489 (4)174
Symmetry codes: (i) x, −y+1, z+1/2.
Table 1
Hydrogen-bond geometry (Å, °) top
D—H···AD—HH···AD···AD—H···A
C3—H3A···N3i0.972.523.489 (4)174
Symmetry codes: (i) x, −y+1, z+1/2.
Acknowledgements top

Financial support from the Universitá Politecnica delle Marche and the Universitá degli Studi di Parma is gratefully acknowledged.

references
References top

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