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Acta Cryst. (2012). E68, o3168    [ doi:10.1107/S1600536812042262 ]

4-Bromo-2-[(E)-{[4-nitro-2-(trifluoromethyl)phenyl]imino}methyl]phenol

M. Akkurt, A. R. Kennedy, S. K. Mohamed, A. A. Abdelhamid and G. J. Miller

Abstract top

Except two F atoms of the -CF3 group, the title compound, C14H8BrF3N2O3, has an almost planar conformation, the dihedral angle between the aromatic rings being 3.60 (16)°. The molecule adopts the enol-imine tautomeric form, with an intramolecular O-H...N hydrogen bond, which generates an S(6) ring motif. In the crystal, face-to-face [pi]-[pi] stacking [centroid-centroid distances = 3.669 (2) and 3.732 (2) Å] between the aromatic rings of the molecules, which lie in sheets parallel to (202), help to establish the packing.

Comment top

A great number of Schiff base complexes with metals have provoked wide interest because they possess a diverse spectrum of biological and pharmaceutical activities, such as antitumor and anti-oxidative activities, as well as the inhibition of lipid peroxidation (Bella et al., 2004; Chandra & Kumar, 2005; Yang et al., 2000). Fluorine can dramatically change the properties of biologically active compounds and can influence the metabolism and distribution of drug molecules in the body (Blair et al., 2000). Recently, SAR studies revealed that the presence of a fluoro group had a marked influence on the antibacterial activity (Chawla et al., 2012). Such facts and further to our studies on synthesis of bio-active molecules we herein report the synthesis and crystal structure of a new potential bio-active fluorinated azomethine compound (I).

Fig. 1 shows the title compound (I) with the enol-imine tautomeric form, which has an intramolecular O— H···N hydrogen bond forming an S(6) motif (Bernstein et al., 1995; Table 1). The C6—O3 single bond of 1.354 (4) Å and the C7N1 double bond of 1.293 (4) Å verify the enol-imine form. These distances and the values of the other geometric parameters are in the normal range and are comparable with those of a similar compound reported previously (Mohamed et al., 2012). The two aromatic rings (C1–C6 and C8–C13) make a dihedral angle of 3.60 (16)° with each other. The C1—C7—N1—C8, O1—N2—C11—C10, O2—N2—C11—C10, C14–C9—C8—N1, C8—N1—C7—C1, C7—C1—C6—O3 and C1—C2—C3—Br1 torsion angles are 178.1 (3), 2.4 (4), 175.8 (3), -1.4 (5), -178.1 (3), 0.0 (6) and 179.2 (3) °, respectively. Therefore, the whole molecule of (I), except the F1 and F3 atoms of the –CF3 group, is almostly planar.

The crystal structure is stabilized by face-to-face π-π stacking interactions [Cg1···Cg2(1 - x, -y, 2 - z) = 3.669 (2) Å and Cg1···Cg2(2 - x, -y, 2 - z) = 3.732 (2) Å] between the Cg1 and Cg2 centroids of the C1–C6 and C8–C13 aromatic rings of the molecules to form two-dimensional sheets parallel to the (202) plane (Fig. 2 & Fig. 3).

Related literature top

For the biological activity of fluorine-containing compounds, see: Blair et al. (2000); Chawla et al. (2012); Bella et al. (2004); Chandra & Kumar (2005); Yang et al. (2000). For the synthesis of a similar azomethine compound, see: Mohamed et al. (2012). For the graph-set analysis of hydrogen bonding, see: Bernstein et al. (1995).

Experimental top

The title compound was unexpectedly obtained from a three component reaction of 0.01 mol 4-nitro-2-(trifluoromethyl)aniline, 0.01 mol 5-bromosalicyaldehyde and 0.01 mol 5-phenyl-1,3-cyclohexanedione in 50 ml ethanol. The reaction mixture was refluxed for 7 h at 350 K. The solid product that obtained on cooling was filtered off, washed with cold ethanol and dried. The crude product was recrystallized from a mixture of ethanol and acetone (10:1 vv) to afford a good quality crystals suitable for X-ray difraction after two days of slow evaporation at room temperature. [Yield 83%; Mp. 511 K].

Refinement top

All H atoms were positioned geometrically [C—H = 0.95 Å and O—H = 0.84 Å] and refined as riding with Uiso(H) = 1.2Ueq(C) for aromatic H and Uiso(H) = 1.5Ueq(O) for hydroxyl H. The components of anisotropic displacement for N1 and C7 atoms were made equal using the EADP constraint.

Computing details top

Data collection: CrysAlis PRO (Oxford Diffraction, 2010); cell refinement: CrysAlis PRO (Oxford Diffraction, 2010); data reduction: CrysAlis PRO (Oxford Diffraction, 2010); 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); software used to prepare material for publication: WinGX (Farrugia, 1999) and PLATON (Spek, 2009).

Figures top
[Figure 1] Fig. 1. The title compound with the atom numbering scheme. Displacement ellipsoids for non-H atoms are drawn at the 50% probability level.
[Figure 2] Fig. 2. View of the packing and hydrogen bonding of (I) down a axis. H atoms not involved in hydrogen bonding have been omitted for clarity.
[Figure 3] Fig. 3. View of the packing and hydrogen bonding of (I) down b axis. H atoms not involved in hydrogen bonding have been omitted for clarity.
4-Bromo-2-[(E)-{[4-nitro-2-(trifluoromethyl)phenyl]imino}methyl]phenol top
Crystal data top
C14H8BrF3N2O3F(000) = 768
Mr = 389.12Dx = 1.902 Mg m3
Monoclinic, P21/nMo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ynCell parameters from 1836 reflections
a = 7.3596 (5) Åθ = 3.2–29.0°
b = 16.4625 (10) ŵ = 3.08 mm1
c = 11.2599 (6) ÅT = 123 K
β = 94.955 (5)°Cut rod, yellow
V = 1359.12 (14) Å30.20 × 0.18 × 0.18 mm
Z = 4
Data collection top
Oxford Diffraction Xcalibur Eos
diffractometer
3149 independent reflections
Radiation source: Enhance (Mo) X-ray Source2165 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.043
Detector resolution: 16.0727 pixels mm-1θmax = 29.0°, θmin = 3.2°
ω scansh = 98
Absorption correction: multi-scan
(CrysAlis PRO; Oxford Diffraction, 2010)
k = 1822
Tmin = 0.546, Tmax = 0.575l = 1415
6329 measured reflections
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)] = 0.050Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.090H-atom parameters constrained
S = 1.02 w = 1/[σ2(Fo2) + (0.0233P)2]
where P = (Fo2 + 2Fc2)/3
3149 reflections(Δ/σ)max < 0.001
203 parametersΔρmax = 0.51 e Å3
1 restraintΔρmin = 0.59 e Å3
Crystal data top
C14H8BrF3N2O3V = 1359.12 (14) Å3
Mr = 389.12Z = 4
Monoclinic, P21/nMo Kα radiation
a = 7.3596 (5) ŵ = 3.08 mm1
b = 16.4625 (10) ÅT = 123 K
c = 11.2599 (6) Å0.20 × 0.18 × 0.18 mm
β = 94.955 (5)°
Data collection top
Oxford Diffraction Xcalibur Eos
diffractometer
3149 independent reflections
Absorption correction: multi-scan
(CrysAlis PRO; Oxford Diffraction, 2010)
2165 reflections with I > 2σ(I)
Tmin = 0.546, Tmax = 0.575Rint = 0.043
6329 measured reflectionsθmax = 29.0°
Refinement top
R[F2 > 2σ(F2)] = 0.050H-atom parameters constrained
wR(F2) = 0.090Δρmax = 0.51 e Å3
S = 1.02Δρmin = 0.59 e Å3
3149 reflectionsAbsolute structure: ?
203 parametersFlack parameter: ?
1 restraintRogers parameter: ?
Special details top

Geometry. Bond distances, angles etc. have been calculated using the rounded fractional coordinates. All su's are estimated from the variances of the (full) variance-covariance matrix. The cell e.s.d.'s are taken into account in the estimation of distances, angles and torsion angles

Refinement. Refinement on F2 for ALL reflections except those flagged by the user for potential systematic errors. Weighted R-factors wR and all goodnesses of fit S are based on F2, conventional R-factors R are based on F, with F set to zero for negative F2. The observed criterion of F2 > σ(F2) is used only for calculating -R-factor-obs 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
Br10.40760 (6)0.10935 (3)0.52512 (3)0.0305 (2)
F10.7671 (3)0.08414 (14)1.28090 (17)0.0313 (8)
F21.0022 (3)0.05148 (15)1.39501 (17)0.0404 (9)
F31.0339 (3)0.09587 (14)1.21958 (18)0.0321 (8)
O11.1326 (3)0.22498 (18)1.4389 (2)0.0299 (9)
O21.0746 (4)0.31205 (17)1.2960 (2)0.0286 (9)
O30.7242 (4)0.17073 (17)1.02757 (19)0.0262 (9)
N10.7788 (4)0.01384 (19)1.0499 (2)0.0168 (7)
N21.0692 (4)0.2434 (2)1.3380 (3)0.0231 (11)
C10.6384 (5)0.0741 (2)0.8725 (3)0.0160 (11)
C20.5635 (4)0.0613 (2)0.7551 (3)0.0185 (11)
C30.5065 (5)0.1256 (3)0.6850 (3)0.0192 (11)
C40.5184 (5)0.2040 (3)0.7277 (3)0.0220 (12)
C50.5917 (5)0.2182 (2)0.8437 (3)0.0210 (12)
C60.6520 (5)0.1540 (2)0.9156 (3)0.0176 (11)
C70.6997 (4)0.0045 (2)0.9437 (3)0.0168 (7)
C80.8434 (4)0.0537 (2)1.1180 (3)0.0145 (11)
C90.9215 (5)0.0375 (2)1.2358 (3)0.0158 (11)
C100.9916 (4)0.1002 (2)1.3070 (3)0.0185 (11)
C110.9869 (4)0.1777 (2)1.2628 (3)0.0165 (11)
C120.9119 (5)0.1958 (2)1.1491 (3)0.0194 (12)
C130.8421 (5)0.1338 (2)1.0781 (3)0.0190 (11)
C140.9282 (5)0.0480 (3)1.2828 (3)0.0225 (12)
H1O0.757200.127301.062200.0390*
H20.552300.007600.724400.0220*
H40.476700.248100.678200.0260*
H50.600300.272200.873600.0250*
H70.681600.048700.912100.0200*
H101.042600.089701.385900.0220*
H120.908800.250201.120800.0230*
H130.791500.145700.999600.0230*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Br10.0418 (3)0.0288 (3)0.0189 (2)0.0038 (2)0.0083 (2)0.0014 (2)
F10.0389 (14)0.0225 (14)0.0323 (13)0.0074 (12)0.0023 (10)0.0076 (11)
F20.0708 (18)0.0249 (16)0.0215 (12)0.0036 (15)0.0195 (11)0.0031 (11)
F30.0407 (14)0.0180 (14)0.0370 (13)0.0091 (12)0.0002 (10)0.0010 (11)
O10.0367 (17)0.0287 (18)0.0221 (14)0.0014 (15)0.0098 (11)0.0078 (14)
O20.0364 (17)0.0168 (17)0.0325 (15)0.0032 (15)0.0019 (12)0.0047 (13)
O30.0387 (17)0.0174 (16)0.0206 (14)0.0006 (15)0.0082 (11)0.0014 (12)
N10.0190 (12)0.0145 (13)0.0168 (11)0.0024 (11)0.0008 (9)0.0019 (11)
N20.0215 (18)0.023 (2)0.0249 (18)0.0009 (17)0.0021 (13)0.0074 (16)
C10.0146 (19)0.017 (2)0.0164 (18)0.0012 (17)0.0015 (14)0.0063 (17)
C20.0190 (19)0.015 (2)0.021 (2)0.0019 (18)0.0007 (14)0.0029 (17)
C30.0156 (19)0.024 (2)0.0178 (19)0.0020 (18)0.0004 (14)0.0031 (17)
C40.020 (2)0.023 (2)0.023 (2)0.0011 (19)0.0022 (15)0.0039 (18)
C50.025 (2)0.013 (2)0.025 (2)0.0003 (18)0.0022 (15)0.0016 (17)
C60.0170 (19)0.016 (2)0.0198 (19)0.0017 (18)0.0014 (14)0.0005 (17)
C70.0190 (12)0.0145 (13)0.0168 (11)0.0024 (11)0.0008 (9)0.0019 (11)
C80.0136 (18)0.016 (2)0.0139 (18)0.0001 (17)0.0015 (13)0.0036 (16)
C90.0169 (19)0.016 (2)0.0144 (18)0.0003 (17)0.0015 (14)0.0020 (16)
C100.0168 (19)0.025 (2)0.0136 (18)0.0014 (19)0.0009 (13)0.0002 (17)
C110.0138 (19)0.018 (2)0.0177 (18)0.0029 (17)0.0018 (14)0.0057 (17)
C120.022 (2)0.012 (2)0.024 (2)0.0020 (18)0.0015 (15)0.0028 (17)
C130.028 (2)0.014 (2)0.0139 (18)0.0011 (18)0.0037 (15)0.0018 (16)
C140.029 (2)0.017 (2)0.020 (2)0.001 (2)0.0071 (16)0.0025 (17)
Geometric parameters (Å, º) top
Br1—C31.902 (3)C4—C51.389 (5)
F1—C141.325 (5)C5—C61.381 (5)
F2—C141.333 (4)C8—C131.393 (5)
F3—C141.352 (5)C8—C91.425 (5)
O1—N21.228 (4)C9—C101.379 (5)
O2—N21.227 (4)C9—C141.503 (6)
O3—C61.354 (4)C10—C111.369 (5)
O3—H1O0.8400C11—C121.382 (5)
N1—C71.293 (4)C12—C131.369 (5)
N1—C81.410 (4)C2—H20.9500
N2—C111.471 (5)C4—H40.9500
C1—C61.403 (5)C5—H50.9500
C1—C71.448 (5)C7—H70.9500
C1—C21.404 (5)C10—H100.9500
C2—C31.365 (5)C12—H120.9500
C3—C41.378 (7)C13—H130.9500
C6—O3—H1O109.00N2—C11—C10118.7 (3)
C7—N1—C8120.9 (3)C10—C11—C12122.2 (3)
O1—N2—C11117.1 (3)N2—C11—C12119.1 (3)
O2—N2—C11118.7 (3)C11—C12—C13118.7 (3)
O1—N2—O2124.2 (3)C8—C13—C12121.7 (3)
C2—C1—C7118.8 (3)F1—C14—F3106.5 (3)
C6—C1—C7122.8 (3)F1—C14—C9114.4 (3)
C2—C1—C6118.5 (3)F1—C14—F2106.7 (3)
C1—C2—C3120.3 (3)F2—C14—C9111.9 (3)
Br1—C3—C2120.8 (3)F3—C14—C9111.3 (3)
Br1—C3—C4118.0 (3)F2—C14—F3105.5 (3)
C2—C3—C4121.2 (3)C1—C2—H2120.00
C3—C4—C5119.6 (4)C3—C2—H2120.00
C4—C5—C6120.1 (3)C3—C4—H4120.00
O3—C6—C5118.1 (3)C5—C4—H4120.00
C1—C6—C5120.3 (3)C4—C5—H5120.00
O3—C6—C1121.6 (3)C6—C5—H5120.00
N1—C7—C1120.8 (3)N1—C7—H7120.00
N1—C8—C13125.4 (3)C1—C7—H7120.00
C9—C8—C13117.9 (3)C9—C10—H10120.00
N1—C8—C9116.7 (3)C11—C10—H10120.00
C8—C9—C14120.1 (3)C11—C12—H12121.00
C10—C9—C14119.8 (3)C13—C12—H12121.00
C8—C9—C10120.1 (3)C8—C13—H13119.00
C9—C10—C11119.3 (3)C12—C13—H13119.00
C8—N1—C7—C1178.1 (3)C4—C5—C6—C10.5 (6)
C7—N1—C8—C9177.4 (3)N1—C8—C9—C10178.5 (3)
C7—N1—C8—C134.8 (5)N1—C8—C9—C141.4 (5)
O1—N2—C11—C102.4 (4)C13—C8—C9—C100.5 (5)
O1—N2—C11—C12179.2 (3)C13—C8—C9—C14179.3 (3)
O2—N2—C11—C10175.8 (3)N1—C8—C13—C12178.3 (3)
O2—N2—C11—C122.5 (5)C9—C8—C13—C120.5 (5)
C6—C1—C2—C30.3 (5)C8—C9—C10—C110.7 (5)
C7—C1—C2—C3179.2 (3)C14—C9—C10—C11179.2 (3)
C2—C1—C6—O3179.5 (3)C8—C9—C14—F157.2 (4)
C2—C1—C6—C50.4 (5)C8—C9—C14—F2178.7 (3)
C7—C1—C6—O30.0 (6)C8—C9—C14—F363.6 (4)
C7—C1—C6—C5179.9 (3)C10—C9—C14—F1122.9 (3)
C2—C1—C7—N1176.1 (3)C10—C9—C14—F21.5 (5)
C6—C1—C7—N13.4 (5)C10—C9—C14—F3116.3 (4)
C1—C2—C3—Br1179.2 (3)C9—C10—C11—N2177.4 (3)
C1—C2—C3—C40.9 (5)C9—C10—C11—C120.8 (5)
Br1—C3—C4—C5179.3 (3)N2—C11—C12—C13177.5 (3)
C2—C3—C4—C50.8 (6)C10—C11—C12—C130.8 (5)
C3—C4—C5—C60.1 (6)C11—C12—C13—C80.6 (5)
C4—C5—C6—O3179.3 (3)
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
O3—H1O···N10.841.882.623 (4)146
C10—H10···F20.952.352.685 (4)100
C13—H13···O1i0.952.503.134 (4)125
Symmetry code: (i) x1/2, y1/2, z1/2.
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
O3—H1O···N10.841.882.623 (4)146.
Acknowledgements top

Manchester Metropolitan University, Erciyes University and the University of Strathclyde are gratefully acknowledged for supporting this study.

references
References top

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