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Acta Crystallogr Sect E Struct Rep Online. 2010 August 1; 66(Pt 8): o1948–o1949.
Published online 2010 July 7. doi:  10.1107/S1600536810026036
PMCID: PMC3007318

3,5-Bis(4-fluoro­phen­yl)-1-phenyl-4,5-dihydro-1H-pyrazole

Abstract

In the title compound, C21H16F2N2, the dihedral angle between the fluoro­phenyl groups is 66.34 (8)°, and the dihedral angle between the envelope-configured pyrazole group (N/N/C/C/C) and the benzene ring is 11.50 (9)°. The dihedral angles between the benzene and the two fluoro-substituted phenyl groups are 77.7 (6) and 16.7 (5)°. Weak C—H(...)π interactions contribute to the stability of the crystal structure.

Related literature

For background to the chemistry and biological activity of pyrazolines, see: Amir et al. (2008 [triangle]); Bhaskarreddy et al. (1997 [triangle]); Fustero et al. (2009 [triangle]); Hes et al. (1978 [triangle]); Klimova et al. (1999 [triangle]); Regaila et al. (1979 [triangle]); Sarojini et al. (2010 [triangle]); Wiley et al. (1958 [triangle]); Spek (2009 [triangle]). For related structures, see: Butcher et al. (2007 [triangle]); Fun, Quah et al. (2009 [triangle]); Fun, Yeap et al. (2009 [triangle]); Fun et al. (2010 [triangle]); Guo et al. (2006 [triangle], 2007 [triangle]); Li (2007a [triangle],b [triangle]); Loh et al. (2010 [triangle]); Yathirajan et al. (2007a [triangle],b [triangle]).

An external file that holds a picture, illustration, etc.
Object name is e-66-o1948-scheme1.jpg

Experimental

Crystal data

  • C21H16F2N2
  • M r = 334.36
  • Monoclinic, An external file that holds a picture, illustration, etc.
Object name is e-66-o1948-efi1.jpg
  • a = 12.2880 (3) Å
  • b = 13.1678 (3) Å
  • c = 11.3245 (3) Å
  • β = 112.661 (3)°
  • V = 1690.91 (7) Å3
  • Z = 4
  • Cu Kα radiation
  • μ = 0.77 mm−1
  • T = 100 K
  • 0.28 × 0.24 × 0.23 mm

Data collection

  • Oxford Diffraction Xcalibur diffractometer with a Ruby (Gemini Cu) detector
  • Absorption correction: multi-scan (CrysAlis RED; Oxford Diffraction, 2007 [triangle]) T min = 0.774, T max = 1.000
  • 7737 measured reflections
  • 3541 independent reflections
  • 2740 reflections with I > 2σ(I)
  • R int = 0.016

Refinement

  • R[F 2 > 2σ(F 2)] = 0.039
  • wR(F 2) = 0.116
  • S = 1.05
  • 3541 reflections
  • 226 parameters
  • H-atom parameters constrained
  • Δρmax = 0.15 e Å−3
  • Δρmin = −0.16 e Å−3

Data collection: CrysAlis PRO (Oxford Diffraction, 2007 [triangle]); cell refinement: CrysAlis RED (Oxford Diffraction, 2007 [triangle]); data reduction: CrysAlis RED; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 [triangle]); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 [triangle]); molecular graphics: SHELXTL (Sheldrick, 2008 [triangle]); software used to prepare material for publication: SHELXTL and PLATON (Spek, 2009 [triangle]).

Table 1
YX(...)Cg π ring inter­actions (Å, °)

Supplementary Material

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536810026036/tk2686sup1.cif

Structure factors: contains datablocks I. DOI: 10.1107/S1600536810026036/tk2686Isup2.hkl

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

Acknowledgments

SS thanks Mangalore University for research facilities and HSY thanks the University of Mysore for sabbatical leave. JPJ thanks Dr Ray Butcher and Howard University for assistance with the data collection.

supplementary crystallographic information

Comment

Pyrazolines are well known as important nitrogen-containing five-membered heterocyclic compounds and various methods have been worked out for their synthesis (Fustero et al., 2009). The pyrazoline function is quite stable and has inspired chemists to utilize this stable fragment in bioactive moieties to synthesize new compounds possessing biological activities, and the presence of fluorine in the molecules at strategic positions alters their activity. Several pyrazoline derivatives have been found to possess considerable biological activities, which stimulated research activity in this field. In particular, they are used as antitumor, antibacterial, antifungal, antiviral, anti-parasitic, anti-tubercular and insecticidal agents (Hes et al., 1978; Amir et al., 2008). Some of these compounds have also anti-inflammatory, anti-diabetic, anaesthetic and analgesic properties (Sarojini et al., 2010; Regaila et al., 1979). Several 1,3,5-triaryl-2 -pyrazolines were also used as scintillation solutes (Wiley et al., 1958). In addition, pyrazolines have played a crucial part in the development of theory in heterocyclic chemistry and also used extensively in organic synthesis (Klimova et al., 1999; Bhaskarreddy et al., 1997).

The crystal structures of some substituted 4,5-dihydro N– phenyl pyrazoles viz., 6-chloro-3-[5-(4-fluorophenyl)-1-phenyl-4,5- dihydro-1H-pyrazol-3-yl]-2-methyl-4-phenyl quinoline (Loh et al., 2010), 6-chloro-3-[5-(3-methoxy-8-methyl-4- quinolyl)-1-phenyl-4,5-dihydro-1H-pyrazol-3-yl]-2-methyl-4-phenyl quinoline (Fun et al., 2009a), 6-chloro-2-methyl-4-phenyl- 3-[1-phenyl-5-(2-thienyl)-4,5-dihydro-1H-pyrazol-3-yl] quinoline (Fun et al., 2009b), 3-(4-fluorophenyl)-1,5-diphenyl-2-pyrazoline (Guo et al., 2006), 3-(4-bromophenyl)-5- (2-chlorophenyl)-1-phenyl-2-pyrazoline, (Guo et al., 2007), 5-(p-fluorophenyl)-1,3-diphenyl-2-pyrazoline, 3-(4-bromophenyl)-5 -(4-fluorophenyl)-1-phenyl-4,5-dihydro-1H-pyrazole (Li, 2007a,b) have been reported. In continuation of our work on pyrazoline derivatives (Fun et al., 2010; Yathirajan et al., 2007a,b; Butcher et al., 2007) and in view of the importance of these derivatives, the title compound C21H15N2F2 (I) was synthesized and its crystal structure is reported here.

The title compound (I) contains two p-florophenyl groups and a benzene ring attached to an envelope configured pyrazole ring (Fig. 1). The dihedral angle between the two flourophenyl groups is 66.34 (8)° and the dihedral angle between the pyrazole and benzene rings is 11.50 (9) °. Also, the dihedral angles between the benzene ring and the two fluoro-substituted phenyl groups are 77.7 (6) and 16.7 (5) °, respectively. Two C–H···π interactions (Table 1) contribute to the stability of the crystal structure (Fig. 2).

Experimental

A mixture of (2E)-1,3-bis(4-fluorophenyl)prop-2-en-1-one (2.44 g, 0.01 mol) and phenyl hydrazine (1.08 g, 0.01 mol) in ethanol (20 ml) in the presence of glacial acetic acid (5 ml) was refluxed for 5 h. The reaction mixture was cooled and poured into ice-cold water (50 ml). The precipitate was collected by filtration and purified by recrystallization from ethanol. The single-crystal was grown from toluene by the slow evaporation method. The yield of the compound was 84%; m.pt. 387 K. Analytical data: Found (Calculated): C %: 67.86 (67.99); H %: 4.62 (4.70); N %: 9.29 (9.33).

Refinement

All of the H atoms were placed in their calculated positions and then refined using the riding model approximation with C—H = 0.93–0.98 Å, and with Uiso(H) = 1.19–1.30Ueq(C).

Figures

Fig. 1.
Molecular structure of (I), with 50% probability displacement ellipsoids.
Fig. 2.
Packing diagram for (I), viewed down the c axis.

Crystal data

C21H16F2N2F(000) = 696
Mr = 334.36Dx = 1.313 Mg m3
Monoclinic, P21/cCu Kα radiation, λ = 1.54184 Å
Hall symbol: -P 2ybcCell parameters from 3839 reflections
a = 12.2880 (3) Åθ = 4.5–77.2°
b = 13.1678 (3) ŵ = 0.77 mm1
c = 11.3245 (3) ÅT = 100 K
β = 112.661 (3)°Block, colorless
V = 1690.91 (7) Å30.28 × 0.24 × 0.23 mm
Z = 4

Data collection

Oxford Diffraction Xcalibur diffractometer with a Ruby (Gemini Cu) detector3541 independent reflections
Radiation source: fine-focus sealed tube2740 reflections with I > 2σ(I)
graphiteRint = 0.016
Detector resolution: 10.5081 pixels mm-1θmax = 77.4°, θmin = 5.2°
ω scansh = −11→15
Absorption correction: multi-scan (CrysAlis RED; Oxford Diffraction, 2007)k = −16→14
Tmin = 0.774, Tmax = 1.000l = −13→14
7737 measured reflections

Refinement

Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.039Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.116H-atom parameters constrained
S = 1.05w = 1/[σ2(Fo2) + (0.060P)2 + 0.1618P] where P = (Fo2 + 2Fc2)/3
3541 reflections(Δ/σ)max < 0.001
226 parametersΔρmax = 0.15 e Å3
0 restraintsΔρmin = −0.16 e Å3

Special details

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)

xyzUiso*/Ueq
F10.14722 (10)0.03973 (7)0.26845 (11)0.0891 (3)
F20.03475 (11)0.92804 (9)0.61215 (12)0.0958 (4)
N10.27887 (10)0.60196 (9)0.37791 (11)0.0583 (3)
N20.31295 (11)0.50566 (9)0.35601 (11)0.0594 (3)
C10.11598 (14)0.67082 (12)0.57694 (14)0.0649 (4)
H10.10900.60620.60640.078*
C20.06799 (15)0.75266 (13)0.61618 (15)0.0710 (4)
H20.02880.74370.67120.085*
C30.07946 (15)0.84700 (12)0.57224 (15)0.0682 (4)
C40.13479 (15)0.86269 (12)0.48921 (17)0.0725 (4)
H40.13980.92760.45930.087*
C50.18302 (14)0.78039 (12)0.45068 (15)0.0643 (4)
H50.22150.79020.39510.077*
C60.17452 (12)0.68283 (10)0.49427 (12)0.0549 (3)
C70.22462 (12)0.59450 (11)0.45457 (12)0.0554 (3)
C80.21469 (15)0.48688 (11)0.49360 (15)0.0644 (4)
H8A0.13530.46080.45050.077*
H8B0.23740.48120.58540.077*
C90.30233 (13)0.43192 (10)0.44948 (13)0.0563 (3)
H90.37850.42650.52180.068*
C100.26207 (11)0.32735 (10)0.39674 (12)0.0515 (3)
C110.18963 (13)0.31090 (11)0.26960 (13)0.0603 (3)
H110.16650.36540.21320.072*
C120.15145 (14)0.21357 (13)0.22594 (14)0.0658 (4)
H120.10390.20200.14050.079*
C130.18527 (14)0.13539 (11)0.31124 (15)0.0632 (4)
C140.25607 (15)0.14782 (11)0.43752 (15)0.0662 (4)
H140.27750.09290.49340.079*
C150.29473 (14)0.24498 (11)0.47929 (14)0.0605 (3)
H150.34370.25530.56460.073*
C160.39681 (12)0.49799 (11)0.30110 (13)0.0567 (3)
C170.46147 (13)0.40957 (13)0.31169 (15)0.0660 (4)
H170.45260.35560.36020.079*
C180.53935 (14)0.40141 (15)0.25016 (18)0.0769 (5)
H180.58180.34170.25730.092*
C190.55439 (16)0.48058 (17)0.17879 (18)0.0853 (5)
H190.60600.47450.13690.102*
C200.49212 (17)0.56887 (17)0.17010 (18)0.0838 (5)
H200.50320.62310.12320.101*
C210.41337 (15)0.57872 (13)0.22966 (15)0.0679 (4)
H210.37160.63890.22220.081*

Atomic displacement parameters (Å2)

U11U22U33U12U13U23
F10.1227 (8)0.0572 (5)0.1070 (7)−0.0245 (5)0.0660 (7)−0.0303 (5)
F20.1130 (8)0.0748 (7)0.1084 (8)0.0252 (6)0.0524 (7)−0.0023 (6)
N10.0659 (6)0.0496 (6)0.0595 (6)−0.0020 (5)0.0243 (5)0.0031 (5)
N20.0710 (7)0.0487 (6)0.0649 (6)−0.0046 (5)0.0332 (6)0.0029 (5)
C10.0796 (9)0.0579 (8)0.0594 (8)0.0042 (7)0.0292 (7)0.0100 (6)
C20.0806 (10)0.0748 (11)0.0610 (8)0.0123 (8)0.0309 (7)0.0080 (7)
C30.0734 (9)0.0615 (9)0.0660 (8)0.0099 (7)0.0226 (7)−0.0019 (7)
C40.0819 (10)0.0501 (8)0.0846 (10)0.0001 (7)0.0310 (8)0.0051 (7)
C50.0739 (9)0.0559 (8)0.0653 (8)−0.0043 (7)0.0294 (7)0.0037 (6)
C60.0608 (7)0.0511 (7)0.0482 (6)−0.0024 (6)0.0160 (5)0.0006 (5)
C70.0637 (7)0.0505 (7)0.0492 (6)−0.0054 (6)0.0186 (6)0.0013 (5)
C80.0879 (10)0.0489 (7)0.0653 (8)−0.0086 (7)0.0392 (8)−0.0038 (6)
C90.0655 (7)0.0490 (7)0.0521 (7)−0.0080 (6)0.0199 (6)0.0009 (5)
C100.0568 (7)0.0468 (6)0.0521 (6)−0.0041 (5)0.0224 (5)−0.0005 (5)
C110.0666 (8)0.0574 (8)0.0536 (7)−0.0053 (6)0.0193 (6)0.0030 (6)
C120.0689 (8)0.0707 (9)0.0574 (8)−0.0129 (7)0.0238 (7)−0.0140 (7)
C130.0790 (9)0.0481 (7)0.0783 (9)−0.0110 (7)0.0479 (8)−0.0148 (7)
C140.0893 (10)0.0472 (7)0.0713 (9)0.0007 (7)0.0409 (8)0.0036 (6)
C150.0748 (8)0.0518 (7)0.0532 (7)−0.0019 (6)0.0229 (6)0.0018 (6)
C160.0554 (7)0.0578 (8)0.0543 (7)−0.0101 (6)0.0183 (6)−0.0038 (6)
C170.0608 (7)0.0643 (9)0.0730 (9)−0.0073 (7)0.0260 (7)0.0002 (7)
C180.0634 (8)0.0789 (11)0.0888 (11)−0.0029 (8)0.0296 (8)−0.0106 (9)
C190.0762 (10)0.1065 (15)0.0854 (11)−0.0113 (10)0.0445 (9)−0.0060 (11)
C200.0886 (11)0.0945 (13)0.0772 (11)−0.0122 (10)0.0420 (9)0.0117 (9)
C210.0735 (9)0.0678 (9)0.0649 (8)−0.0065 (7)0.0295 (7)0.0055 (7)

Geometric parameters (Å, °)

F1—C131.3658 (16)C9—H90.9800
F2—C31.3551 (19)C10—C151.3865 (19)
N1—C71.2859 (19)C10—C111.3873 (19)
N1—N21.3875 (17)C11—C121.389 (2)
N2—C161.3973 (19)C11—H110.9300
N2—C91.4787 (17)C12—C131.363 (2)
C1—C21.382 (2)C12—H120.9300
C1—C61.392 (2)C13—C141.367 (2)
C1—H10.9300C14—C151.383 (2)
C2—C31.366 (2)C14—H140.9300
C2—H20.9300C15—H150.9300
C3—C41.372 (3)C16—C171.388 (2)
C4—C51.384 (2)C16—C211.398 (2)
C4—H40.9300C17—C181.388 (2)
C5—C61.395 (2)C17—H170.9300
C5—H50.9300C18—C191.374 (3)
C6—C71.465 (2)C18—H180.9300
C7—C81.503 (2)C19—C201.374 (3)
C8—C91.532 (2)C19—H190.9300
C8—H8A0.9700C20—C211.382 (3)
C8—H8B0.9700C20—H200.9300
C9—C101.5066 (18)C21—H210.9300
C7—N1—N2108.75 (11)C15—C10—C11118.74 (13)
N1—N2—C16118.08 (11)C15—C10—C9118.83 (12)
N1—N2—C9110.87 (11)C11—C10—C9122.38 (12)
C16—N2—C9123.69 (12)C10—C11—C12120.48 (13)
C2—C1—C6121.53 (15)C10—C11—H11119.8
C2—C1—H1119.2C12—C11—H11119.8
C6—C1—H1119.2C13—C12—C11118.43 (13)
C3—C2—C1118.40 (16)C13—C12—H12120.8
C3—C2—H2120.8C11—C12—H12120.8
C1—C2—H2120.8C12—C13—F1118.43 (14)
F2—C3—C2118.86 (16)C12—C13—C14123.25 (13)
F2—C3—C4118.80 (15)F1—C13—C14118.31 (14)
C2—C3—C4122.34 (15)C13—C14—C15117.69 (14)
C3—C4—C5118.93 (15)C13—C14—H14121.2
C3—C4—H4120.5C15—C14—H14121.2
C5—C4—H4120.5C14—C15—C10121.40 (13)
C4—C5—C6120.67 (15)C14—C15—H15119.3
C4—C5—H5119.7C10—C15—H15119.3
C6—C5—H5119.7C17—C16—N2121.18 (13)
C1—C6—C5118.12 (14)C17—C16—C21118.80 (14)
C1—C6—C7120.21 (13)N2—C16—C21119.97 (14)
C5—C6—C7121.67 (13)C18—C17—C16120.26 (16)
N1—C7—C6122.33 (13)C18—C17—H17119.9
N1—C7—C8113.11 (13)C16—C17—H17119.9
C6—C7—C8124.52 (13)C19—C18—C17120.75 (18)
C7—C8—C9101.68 (12)C19—C18—H18119.6
C7—C8—H8A111.4C17—C18—H18119.6
C9—C8—H8A111.4C20—C19—C18119.11 (17)
C7—C8—H8B111.4C20—C19—H19120.4
C9—C8—H8B111.4C18—C19—H19120.4
H8A—C8—H8B109.3C19—C20—C21121.30 (17)
N2—C9—C10114.99 (11)C19—C20—H20119.4
N2—C9—C8100.96 (11)C21—C20—H20119.4
C10—C9—C8113.34 (11)C20—C21—C16119.77 (17)
N2—C9—H9109.1C20—C21—H21120.1
C10—C9—H9109.1C16—C21—H21120.1
C8—C9—H9109.1
C7—N1—N2—C16−164.89 (12)N2—C9—C10—C15153.43 (13)
C7—N1—N2—C9−13.70 (16)C8—C9—C10—C15−91.13 (16)
C6—C1—C2—C3−0.2 (2)N2—C9—C10—C11−29.19 (19)
C1—C2—C3—F2−178.70 (14)C8—C9—C10—C1186.26 (17)
C1—C2—C3—C41.2 (3)C15—C10—C11—C12−0.5 (2)
F2—C3—C4—C5178.47 (14)C9—C10—C11—C12−177.88 (13)
C2—C3—C4—C5−1.4 (3)C10—C11—C12—C131.0 (2)
C3—C4—C5—C60.7 (2)C11—C12—C13—F1179.67 (13)
C2—C1—C6—C5−0.5 (2)C11—C12—C13—C14−0.8 (2)
C2—C1—C6—C7179.91 (14)C12—C13—C14—C15−0.1 (2)
C4—C5—C6—C10.2 (2)F1—C13—C14—C15179.47 (14)
C4—C5—C6—C7179.85 (14)C13—C14—C15—C100.7 (2)
N2—N1—C7—C6−178.39 (12)C11—C10—C15—C14−0.4 (2)
N2—N1—C7—C8−0.60 (16)C9—C10—C15—C14177.09 (14)
C1—C6—C7—N1179.65 (13)N1—N2—C16—C17160.01 (13)
C5—C6—C7—N10.0 (2)C9—N2—C16—C1712.8 (2)
C1—C6—C7—C82.1 (2)N1—N2—C16—C21−22.60 (19)
C5—C6—C7—C8−177.51 (14)C9—N2—C16—C21−169.85 (13)
N1—C7—C8—C913.51 (16)N2—C16—C17—C18176.23 (14)
C6—C7—C8—C9−168.75 (12)C21—C16—C17—C18−1.2 (2)
N1—N2—C9—C10143.41 (12)C16—C17—C18—C190.5 (2)
C16—N2—C9—C10−67.31 (17)C17—C18—C19—C200.7 (3)
N1—N2—C9—C821.03 (14)C18—C19—C20—C21−1.2 (3)
C16—N2—C9—C8170.31 (12)C19—C20—C21—C160.5 (3)
C7—C8—C9—N2−19.28 (13)C17—C16—C21—C200.7 (2)
C7—C8—C9—C10−142.80 (12)N2—C16—C21—C20−176.72 (15)

Table 1 Y-X···Cg π ring interactions, Cg4 is the centroid of ring C16-C21, and Cg2 is the centroid of the ring C1-C6. [Symmetry codes: (i) 1-x,1-y,1-z ; (ii) -x,-1/2+y,1/2-z]

XH···CgX (Å)X···Cg, (Å)H···CgX···Perp (Å)
C9–H9···Cg4i3.6677 (16)2.822.76
C12–H12···Cg223.6061 (18)2.88-2.79

Footnotes

Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: TK2686).

References

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