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Acta Crystallogr Sect E Struct Rep Online. 2008 September 1; 64(Pt 9): o1722–o1723.
Published online 2008 August 9. doi:  10.1107/S1600536808024926
PMCID: PMC2960650

N,N′-Bis[2-chloro-5-(trifluoro­meth­yl)benzyl­idene]ethane-1,2-diamine

Abstract

The mol­ecule of the title Schiff base compound, C18H12Cl2F6N2, adopts an E configuration with respect to the azomethine C=N bond. Intra­molecular C—H(...)F (× 2) and C—H(...)Cl (× 2) hydrogen bonds generate S(5) ring motifs. The imino group is coplanar with the aromatic ring. Within the mol­ecule, the planar units are parallel, but extend in opposite directions from the methyl­ene bridge, as indicated by the dihedral angle between the two benzene rings of 3.74 (6)°. The inter­esting features of the crystal structure are weak inter­molecular Cl(...)N and F(...)F inter­actions, with distances of 2.9192 (11) and 3.2714 (10) Å, respectively, which are shorter than the sum of the van der Waals radii of the relevent atoms. These inter­actions link neighbouring mol­ecules into dimers which are stacked down the b axis.

Related literature

For bond-length data, see: Allen et al. (1987 [triangle]). For hydrogen-bond motifs, see: Bernstein et al. (1995 [triangle]). For related structures see, for example: see, for example: Fun, Kargar & Kia (2008 [triangle]); Fun, Kia & Kargar (2008 [triangle]); Fun, Mirkhani et al. (2008a [triangle],b [triangle]); Calligaris & Randaccio (1987 [triangle]). For information on Schiff base complexes and their applications, see, for example: Kia, Mirkhani, Kalman & Deak (2007 [triangle]); Kia, Mirkhani, Harkema & van Hummel (2007 [triangle]); Pal et al. (2005 [triangle]); Hou et al. (2001 [triangle]); Ren et al. (2002 [triangle]).

An external file that holds a picture, illustration, etc.
Object name is e-64-o1722-scheme1.jpg

Experimental

Crystal data

  • C18H12Cl2F6N2
  • M r = 441.20
  • Monoclinic, An external file that holds a picture, illustration, etc.
Object name is e-64-o1722-efi1.jpg
  • a = 35.7299 (8) Å
  • b = 4.6663 (1) Å
  • c = 27.1134 (6) Å
  • β = 127.851 (2)°
  • V = 3569.44 (17) Å3
  • Z = 8
  • Mo Kα radiation
  • μ = 0.43 mm−1
  • T = 100.0 (1) K
  • 0.59 × 0.27 × 0.15 mm

Data collection

  • Bruker SMART APEXII CCD area-detector diffractometer
  • Absorption correction: multi-scan (SADABS; Bruker, 2005 [triangle]) T min = 0.786, T max = 0.938
  • 61787 measured reflections
  • 7964 independent reflections
  • 6400 reflections with I > 2σ(I)
  • R int = 0.036

Refinement

  • R[F 2 > 2σ(F 2)] = 0.039
  • wR(F 2) = 0.111
  • S = 1.10
  • 7964 reflections
  • 253 parameters
  • H-atom parameters constrained
  • Δρmax = 0.49 e Å−3
  • Δρmin = −0.40 e Å−3

Data collection: APEX2 (Bruker, 2005 [triangle]); cell refinement: APEX2; data reduction: SAINT (Bruker, 2005 [triangle]); program(s) used to solve structure: SHELXTL (Sheldrick, 2008 [triangle]); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL and PLATON (Spek, 2003 [triangle]).

Table 1
Hydrogen-bond geometry (Å, °)

Supplementary Material

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536808024926/at2608sup1.cif

Structure factors: contains datablocks I. DOI: 10.1107/S1600536808024926/at2608Isup2.hkl

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

Acknowledgments

HKF and RK thank the Malaysian Government and Universiti Sains Malaysia for the Science Fund grant No. 305/PFIZIK/613312. RK thanks Universiti Sains Malaysia for the award of a post-doctoral research fellowship.

supplementary crystallographic information

Comment

Schiff bases are one of most prevalent mixed-donor ligands in the field of coordination chemistry. There has been growing interest in Schiff base ligands, mainly because of their wide application in the field of biochemistry, synthesis, and catalysis (Kia et al., 2007a,b; Pal et al., 2005; Hou et al., 2001; Ren et al., 2002). Many Schiff base complexes have been structurally characterized, but only a relatively small number of free Schiff bases have been characterized (Calligaris & Randaccio, 1987). As an extension of our work (Fun, Kargar & Kia 2008; Fun, Kia & Kargar 2008; Fun, Mirkhani et al., 2008a,b) on the structural characterization of Schiff base compounds, the title compound (I), is reported here.

The molecule of the title compound, (I), (Fig. 1), adopts an E configuration with respect to the azomethine C═N bond. The bond lengths and angles are within normal ranges (Allen et al., 1987). Intramolecular C—H···F (x 2) and C—H···Cl (x 2) hydrogen bonds generate S(5) ring motifs (Bernstein et al., 1995). The two planar units are parallel but extend in opposite directions from the methylene bridge. The dihedral angle between two benzene rings is 3.74 (6)°. The interesting feature of the crystal structure is weak intermolecular Cl···N and F···F interactions with the distances of 2.9192 (11) and 3.2714 (10) Å, which are shorter than the sum of the van der Waals radii of the relevant atoms, respectively (Table 1). These interactions link neighbouring molecules into dimers which are stacked down the b-axis (Fig. 2).

Experimental

The synthetic method has been described earlier (Fun, Mirkhani et al., (2008a,b)). Single crystals suitable for X-ray diffraction were obtained by evaporation of an ethanol solution at room temperature.

Refinement

All of the hydrogen atoms were positioned geometrically with C—H = 0.93 and 0.97 Å, and refined in riding model with Uiso (H) = 1.2 Ueq (C).

Figures

Fig. 1.
The molecular structure of (I) with atom labels and 50% probability ellipsoids for non-H atoms. Intramolecular interactions are shown as dashed lines.
Fig. 2.
The crystal packing of (I), showing stacks of the molecules viewed down the b-axis. Intramolecular and intermolecular interactions are shown as dashed lines.

Crystal data

C18H12Cl2F6N2F000 = 1776
Mr = 441.20Dx = 1.642 Mg m3
Monoclinic, C2/cMo Kα radiation λ = 0.71073 Å
Hall symbol: -C 2ycCell parameters from 9825 reflections
a = 35.7299 (8) Åθ = 3.0–34.6º
b = 4.6663 (1) ŵ = 0.43 mm1
c = 27.1134 (6) ÅT = 100.0 (1) K
β = 127.851 (2)ºBlock, colourless
V = 3569.44 (17) Å30.59 × 0.27 × 0.15 mm
Z = 8

Data collection

Bruker SMART APEXII CCD area-detector diffractometer7964 independent reflections
Radiation source: fine-focus sealed tube6400 reflections with I > 2σ(I)
Monochromator: graphiteRint = 0.037
T = 100.0(1) Kθmax = 35.3º
[var phi] and ω scansθmin = 1.4º
Absorption correction: multi-scan(SADABS; Bruker, 2005)h = −57→57
Tmin = 0.786, Tmax = 0.938k = −7→7
61787 measured reflectionsl = −43→43

Refinement

Refinement on F2Secondary atom site location: difference Fourier map
Least-squares matrix: fullHydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.039H-atom parameters constrained
wR(F2) = 0.111  w = 1/[σ2(Fo2) + (0.0531P)2 + 1.9844P] where P = (Fo2 + 2Fc2)/3
S = 1.10(Δ/σ)max = 0.002
7964 reflectionsΔρmax = 0.49 e Å3
253 parametersΔρmin = −0.40 e Å3
Primary atom site location: structure-invariant direct methodsExtinction correction: none

Special details

Experimental. The low-temperature data was collected with the Oxford Cyrosystem Cobra low-temperature attachment.
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
Cl10.551363 (9)0.32741 (7)0.739234 (12)0.02594 (7)
Cl20.189897 (9)1.19679 (7)0.533622 (12)0.02472 (7)
F10.39316 (3)−0.30228 (17)0.46809 (3)0.02702 (15)
F20.41420 (3)0.04201 (17)0.43779 (3)0.03119 (17)
F30.45421 (3)−0.34947 (19)0.47055 (4)0.03439 (19)
F40.33072 (3)1.47263 (18)0.83440 (3)0.02871 (16)
F50.38418 (2)1.47751 (19)0.82146 (3)0.03130 (18)
F60.34376 (3)1.85581 (16)0.80395 (4)0.03396 (19)
N10.40343 (3)0.5481 (2)0.59973 (4)0.01725 (16)
N20.33501 (3)0.8779 (2)0.64593 (4)0.01823 (16)
C10.51574 (3)0.1868 (2)0.66416 (5)0.01730 (17)
C20.53549 (4)−0.0190 (2)0.64928 (5)0.02017 (19)
H2A0.5667−0.07770.67910.024*
C30.50850 (4)−0.1361 (2)0.58984 (5)0.01883 (18)
H3A0.5214−0.27330.57930.023*
C40.46179 (3)−0.0459 (2)0.54599 (5)0.01615 (17)
C50.44222 (3)0.1577 (2)0.56131 (5)0.01572 (17)
H5A0.41090.21400.53150.019*
C60.46882 (3)0.2794 (2)0.62082 (5)0.01529 (16)
C70.44777 (3)0.5018 (2)0.63563 (5)0.01595 (17)
H7A0.46730.60980.67190.019*
C80.38645 (4)0.7774 (2)0.61797 (5)0.01833 (18)
H8A0.37570.93760.58940.022*
H8B0.41210.84360.65970.022*
C90.34569 (4)0.6674 (2)0.61674 (5)0.01850 (18)
H9A0.31790.63510.57390.022*
H9B0.35450.48690.63910.022*
C100.29330 (3)0.9775 (2)0.61435 (5)0.01680 (17)
H10A0.27050.91460.57360.020*
C110.28058 (3)1.1927 (2)0.64174 (5)0.01518 (16)
C120.23492 (3)1.3059 (2)0.60942 (5)0.01720 (17)
C130.22371 (4)1.5054 (2)0.63682 (5)0.02008 (19)
H13A0.19321.57940.61440.024*
C140.25840 (4)1.5922 (2)0.69772 (5)0.01877 (18)
H14A0.25121.72380.71660.023*
C150.30421 (3)1.4814 (2)0.73076 (5)0.01553 (16)
C160.31517 (3)1.2865 (2)0.70305 (5)0.01529 (16)
H16A0.34591.21660.72540.018*
C170.43124 (4)−0.1644 (2)0.48093 (5)0.01965 (19)
C180.34081 (4)1.5713 (2)0.79726 (5)0.01786 (18)

Atomic displacement parameters (Å2)

U11U22U33U12U13U23
Cl10.01659 (11)0.03460 (15)0.01714 (11)0.00362 (10)0.00552 (9)−0.00367 (10)
Cl20.01410 (11)0.03396 (15)0.01727 (11)0.00410 (9)0.00514 (9)−0.00528 (10)
F10.0227 (3)0.0324 (4)0.0215 (3)−0.0075 (3)0.0113 (3)−0.0041 (3)
F20.0443 (4)0.0263 (4)0.0198 (3)0.0003 (3)0.0181 (3)0.0034 (3)
F30.0314 (4)0.0401 (5)0.0311 (4)0.0075 (3)0.0189 (3)−0.0113 (3)
F40.0281 (4)0.0420 (4)0.0175 (3)−0.0100 (3)0.0147 (3)−0.0003 (3)
F50.0142 (3)0.0474 (5)0.0236 (3)−0.0012 (3)0.0072 (3)−0.0106 (3)
F60.0474 (5)0.0173 (3)0.0210 (3)−0.0056 (3)0.0127 (3)−0.0035 (3)
N10.0159 (4)0.0195 (4)0.0181 (4)0.0028 (3)0.0113 (3)0.0004 (3)
N20.0155 (4)0.0207 (4)0.0203 (4)0.0015 (3)0.0119 (3)−0.0020 (3)
C10.0134 (4)0.0203 (4)0.0162 (4)0.0010 (3)0.0081 (3)0.0004 (3)
C20.0133 (4)0.0225 (5)0.0226 (5)0.0040 (3)0.0099 (4)0.0018 (4)
C30.0173 (4)0.0184 (4)0.0241 (5)0.0029 (3)0.0144 (4)0.0005 (4)
C40.0154 (4)0.0172 (4)0.0178 (4)0.0009 (3)0.0111 (3)0.0005 (3)
C50.0141 (4)0.0172 (4)0.0169 (4)0.0020 (3)0.0101 (3)0.0014 (3)
C60.0128 (4)0.0171 (4)0.0167 (4)0.0017 (3)0.0094 (3)0.0012 (3)
C70.0158 (4)0.0166 (4)0.0172 (4)0.0011 (3)0.0110 (3)0.0003 (3)
C80.0186 (4)0.0171 (4)0.0233 (5)0.0024 (3)0.0149 (4)−0.0002 (3)
C90.0155 (4)0.0200 (4)0.0217 (4)0.0007 (3)0.0122 (4)−0.0031 (4)
C100.0145 (4)0.0192 (4)0.0167 (4)0.0002 (3)0.0096 (3)−0.0019 (3)
C110.0132 (4)0.0166 (4)0.0164 (4)0.0012 (3)0.0094 (3)0.0000 (3)
C120.0127 (4)0.0208 (4)0.0152 (4)0.0011 (3)0.0071 (3)−0.0012 (3)
C130.0147 (4)0.0240 (5)0.0197 (4)0.0040 (4)0.0096 (4)−0.0012 (4)
C140.0174 (4)0.0199 (4)0.0202 (4)0.0022 (4)0.0122 (4)−0.0013 (4)
C150.0152 (4)0.0158 (4)0.0158 (4)−0.0007 (3)0.0096 (3)−0.0002 (3)
C160.0131 (4)0.0168 (4)0.0163 (4)0.0005 (3)0.0091 (3)0.0002 (3)
C170.0212 (4)0.0203 (5)0.0195 (4)0.0018 (4)0.0135 (4)−0.0005 (4)
C180.0181 (4)0.0184 (4)0.0174 (4)−0.0021 (3)0.0110 (4)−0.0008 (3)

Geometric parameters (Å, °)

Cl1—C11.7362 (11)C5—H5A0.9300
Cl2—C121.7358 (10)C6—C71.4746 (14)
F1—C171.3433 (13)C7—H7A0.9300
F2—C171.3389 (13)C8—C91.5253 (15)
F3—C171.3348 (13)C8—H8A0.9700
F4—C181.3419 (12)C8—H8B0.9700
F5—C181.3325 (13)C9—H9A0.9700
F6—C181.3354 (13)C9—H9B0.9700
N1—C71.2693 (13)C10—C111.4771 (14)
N1—C81.4580 (13)C10—H10A0.9300
N2—C101.2663 (13)C11—C121.3977 (14)
N2—C91.4517 (13)C11—C161.4004 (14)
C1—C21.3901 (15)C12—C131.3944 (14)
C1—C61.4000 (14)C13—C141.3839 (15)
C2—C31.3853 (15)C13—H13A0.9300
C2—H2A0.9300C14—C151.3963 (14)
C3—C41.3933 (14)C14—H14A0.9300
C3—H3A0.9300C15—C161.3803 (14)
C4—C51.3858 (14)C15—C181.4979 (14)
C4—C171.4989 (15)C16—H16A0.9300
C5—C61.3955 (14)
Cl···Ni3.2714 (10)F···Fii2.9192 (11)
C7—N1—C8116.62 (9)H9A—C9—H9B108.3
C10—N2—C9118.26 (9)N2—C10—C11120.47 (9)
C2—C1—C6121.96 (9)N2—C10—H10A119.8
C2—C1—Cl1117.63 (8)C11—C10—H10A119.8
C6—C1—Cl1120.41 (8)C12—C11—C16117.82 (9)
C3—C2—C1119.69 (9)C12—C11—C10122.86 (9)
C3—C2—H2A120.2C16—C11—C10119.32 (9)
C1—C2—H2A120.2C13—C12—C11121.63 (9)
C2—C3—C4119.18 (9)C13—C12—Cl2117.78 (8)
C2—C3—H3A120.4C11—C12—Cl2120.58 (8)
C4—C3—H3A120.4C14—C13—C12119.43 (9)
C5—C4—C3120.80 (9)C14—C13—H13A120.3
C5—C4—C17117.96 (9)C12—C13—H13A120.3
C3—C4—C17121.24 (9)C13—C14—C15119.74 (9)
C4—C5—C6120.96 (9)C13—C14—H14A120.1
C4—C5—H5A119.5C15—C14—H14A120.1
C6—C5—H5A119.5C16—C15—C14120.47 (9)
C5—C6—C1117.39 (9)C16—C15—C18120.66 (9)
C5—C6—C7120.12 (9)C14—C15—C18118.84 (9)
C1—C6—C7122.47 (9)C15—C16—C11120.89 (9)
N1—C7—C6121.08 (9)C15—C16—H16A119.6
N1—C7—H7A119.5C11—C16—H16A119.6
C6—C7—H7A119.5F3—C17—F2106.87 (9)
N1—C8—C9109.64 (9)F3—C17—F1106.95 (9)
N1—C8—H8A109.7F2—C17—F1105.83 (9)
C9—C8—H8A109.7F3—C17—C4112.89 (9)
N1—C8—H8B109.7F2—C17—C4112.02 (9)
C9—C8—H8B109.7F1—C17—C4111.84 (8)
H8A—C8—H8B108.2F5—C18—F6106.77 (9)
N2—C9—C8109.09 (9)F5—C18—F4106.53 (9)
N2—C9—H9A109.9F6—C18—F4105.93 (9)
C8—C9—H9A109.9F5—C18—C15113.15 (9)
N2—C9—H9B109.9F6—C18—C15112.32 (9)
C8—C9—H9B109.9F4—C18—C15111.66 (9)
C6—C1—C2—C30.55 (17)C16—C11—C12—Cl2−179.14 (8)
Cl1—C1—C2—C3−179.64 (9)C10—C11—C12—Cl2−0.15 (15)
C1—C2—C3—C4−0.30 (16)C11—C12—C13—C14−0.63 (17)
C2—C3—C4—C5−0.22 (16)Cl2—C12—C13—C14178.44 (9)
C2—C3—C4—C17179.54 (10)C12—C13—C14—C150.58 (17)
C3—C4—C5—C60.51 (15)C13—C14—C15—C160.18 (16)
C17—C4—C5—C6−179.26 (9)C13—C14—C15—C18−178.10 (10)
C4—C5—C6—C1−0.27 (15)C14—C15—C16—C11−0.92 (15)
C4—C5—C6—C7178.24 (9)C18—C15—C16—C11177.33 (9)
C2—C1—C6—C5−0.26 (15)C12—C11—C16—C150.86 (15)
Cl1—C1—C6—C5179.93 (8)C10—C11—C16—C15−178.16 (9)
C2—C1—C6—C7−178.73 (10)C5—C4—C17—F3177.37 (9)
Cl1—C1—C6—C71.46 (14)C3—C4—C17—F3−2.39 (15)
C8—N1—C7—C6−178.56 (9)C5—C4—C17—F256.68 (13)
C5—C6—C7—N113.43 (15)C3—C4—C17—F2−123.09 (11)
C1—C6—C7—N1−168.13 (10)C5—C4—C17—F1−61.95 (13)
C7—N1—C8—C9−129.40 (10)C3—C4—C17—F1118.28 (11)
C10—N2—C9—C8122.57 (11)C16—C15—C18—F58.87 (14)
N1—C8—C9—N2169.41 (8)C14—C15—C18—F5−172.85 (10)
C9—N2—C10—C11−179.84 (9)C16—C15—C18—F6129.85 (11)
N2—C10—C11—C12−178.81 (10)C14—C15—C18—F6−51.87 (13)
N2—C10—C11—C160.17 (15)C16—C15—C18—F4−111.31 (11)
C16—C11—C12—C13−0.09 (16)C14—C15—C18—F466.97 (13)
C10—C11—C12—C13178.90 (10)

Symmetry codes: (i) −x+1/2, −y+3/2, −z+1; (ii) −x+1/2, y−3/2, −z+1/2.

Hydrogen-bond geometry (Å, °)

D—H···AD—HH···AD···AD—H···A
C3—H3A···F30.932.432.7415 (14)100
C7—H7A···Cl10.932.713.0811 (12)105
C10—H10A···Cl20.932.723.0925 (13)105
C16—H16A···F50.932.402.7325 (13)101

Footnotes

Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: AT2608).

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