Acta Cryst. (2008). E64, o2285 [ doi:10.1107/S1600536808035745 ]
The molecule of the title Schiff base compound, C19H18Cl4N2, has crystallographic twofold rotation symmetry, with one C atom lying on the rotation axis. The dihedral angle between the two symmetry-related benzene rings is 84.70 (2)°. The plane of the -C=N-C- group is twisted away from the benzene ring by 7.5 (1)°. In the crystal structure, weak intermolecular Cl
Cl [3.4851 (3) Å] contacts link neighbouring molecules into a two-dimensional network parallel to the bc plane.
The synthetic method has been described earlier (Fun et al., 2008). Single crystals suitable for X-ray diffraction were obtained by evaporation of an ethanol solution at room temperature.
H atoms were positioned geometrically and refined using a riding model, with C—H = 0.93 Å for aromatic and 0.97 Å for methylene and 0.96 Å for methyl H atoms.
Data collection: APEX2 (Bruker, 2005); cell refinement: APEX2 (Bruker, 2005); data reduction: SAINT (Bruker, 2005); program(s) used to solve structure: SHELXTL (Sheldrick, 2008); program(s) used to refine structure: SHELXTL (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL (Sheldrick, 2008) and PLATON (Spek, 2003).
![[Figure 1]](./ci2702fig1thm.gif)
| Fig. 1. The molecular structure of the title compound, with atom labels and 50% probability ellipsoids for non-H atoms. Atoms labelled with the suffix A are generated by the symmetry operation (1/2 - x, 2 - y, z). |
![[Figure 2]](./ci2702fig2thm.gif)
| Fig. 2. Part of the crystal structure of the title compound, viewed down the b-axis. Dashed lines indicate intermolecular Cl···Cl interactions. |
| C19H18Cl4N2 | F(000) = 856 |
| Mr = 416.15 | Dx = 1.452 Mg m−3 |
| Orthorhombic, Pcca | Mo Kα radiation, λ = 0.71073 Å |
| Hall symbol: -P 2a 2ac | Cell parameters from 9929 reflections |
| a = 30.7633 (4) Å | θ = 3.6–41.1° |
| b = 5.4012 (1) Å | µ = 0.63 mm−1 |
| c = 11.4532 (1) Å | T = 100 K |
| V = 1903.05 (5) Å3 | Block, colourless |
| Z = 4 | 0.43 × 0.25 × 0.23 mm |
| Bruker SMART APEXII CCD area-detector diffractometer | 6565 independent reflections |
| Radiation source: fine-focus sealed tube | 5678 reflections with I > 2σ(I) |
| graphite | Rint = 0.028 |
| φ and ω scans | θmax = 42.5°, θmin = 1.3° |
| Absorption correction: multi-scan (SADABS; Bruker, 2005) | h = −52→57 |
| Tmin = 0.774, Tmax = 0.872 | k = −9→10 |
| 86683 measured reflections | l = −20→20 |
| Refinement on F2 | Primary atom site location: structure-invariant direct methods |
| Least-squares matrix: full | Secondary atom site location: difference Fourier map |
| R[F2 > 2σ(F2)] = 0.030 | Hydrogen site location: inferred from neighbouring sites |
| wR(F2) = 0.099 | H-atom parameters constrained |
| S = 1.19 | w = 1/[σ2(Fo2) + (0.0454P)2 + 0.5965P] where P = (Fo2 + 2Fc2)/3 |
| 4992 reflections | (Δ/σ)max = 0.001 |
| 115 parameters | Δρmax = 0.51 e Å−3 |
| 0 restraints | Δρmin = −0.30 e Å−3 |
| C19H18Cl4N2 | V = 1903.05 (5) Å3 |
| Mr = 416.15 | Z = 4 |
| Orthorhombic, Pcca | Mo Kα radiation |
| a = 30.7633 (4) Å | µ = 0.63 mm−1 |
| b = 5.4012 (1) Å | T = 100 K |
| c = 11.4532 (1) Å | 0.43 × 0.25 × 0.23 mm |
| Bruker SMART APEXII CCD area-detector diffractometer | 6565 independent reflections |
| Absorption correction: multi-scan (SADABS; Bruker, 2005) | 5678 reflections with I > 2σ(I) |
| Tmin = 0.774, Tmax = 0.872 | Rint = 0.028 |
| 86683 measured reflections | θmax = 42.5° |
| R[F2 > 2σ(F2)] = 0.030 | H-atom parameters constrained |
| wR(F2) = 0.099 | Δρmax = 0.51 e Å−3 |
| S = 1.19 | Δρmin = −0.30 e Å−3 |
| 4992 reflections | Absolute structure: ? |
| 115 parameters | Flack parameter: ? |
| 0 restraints | Rogers parameter: ? |
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. |
| x | y | z | Uiso*/Ueq | ||
| Cl1 | 0.053693 (7) | 1.12278 (4) | 0.346996 (17) | 0.01671 (5) | |
| Cl2 | 0.046757 (8) | 0.37440 (4) | 0.653936 (18) | 0.02040 (6) | |
| N1 | 0.19231 (2) | 0.96758 (14) | 0.31674 (6) | 0.01660 (12) | |
| C1 | 0.08049 (2) | 0.88739 (14) | 0.42126 (6) | 0.01301 (12) | |
| C2 | 0.05625 (3) | 0.74765 (14) | 0.49989 (6) | 0.01467 (12) | |
| H2A | 0.0270 | 0.7822 | 0.5127 | 0.018* | |
| C3 | 0.07667 (3) | 0.55568 (15) | 0.55865 (7) | 0.01504 (12) | |
| C4 | 0.12041 (3) | 0.50138 (16) | 0.54095 (7) | 0.01807 (13) | |
| H4A | 0.1336 | 0.3713 | 0.5807 | 0.022* | |
| C5 | 0.14395 (3) | 0.64492 (16) | 0.46298 (8) | 0.01748 (13) | |
| H5A | 0.1732 | 0.6098 | 0.4510 | 0.021* | |
| C6 | 0.12480 (2) | 0.84188 (14) | 0.40166 (7) | 0.01397 (12) | |
| C7 | 0.15133 (2) | 0.99635 (15) | 0.32244 (7) | 0.01527 (12) | |
| H7A | 0.1379 | 1.1157 | 0.2763 | 0.018* | |
| C8 | 0.21668 (3) | 1.13674 (14) | 0.24238 (7) | 0.01553 (13) | |
| H8A | 0.2317 | 1.2566 | 0.2909 | 0.019* | |
| H8B | 0.1966 | 1.2262 | 0.1925 | 0.019* | |
| C9 | 0.2500 | 1.0000 | 0.16598 (9) | 0.01351 (16) | |
| C18 | 0.22667 (3) | 0.81059 (16) | 0.08866 (7) | 0.01774 (13) | |
| H18A | 0.2044 | 0.8922 | 0.0443 | 0.027* | |
| H18B | 0.2138 | 0.6850 | 0.1368 | 0.027* | |
| H18C | 0.2472 | 0.7358 | 0.0364 | 0.027* |
| U11 | U22 | U33 | U12 | U13 | U23 | |
| Cl1 | 0.01438 (9) | 0.01789 (9) | 0.01786 (9) | 0.00404 (6) | 0.00073 (5) | 0.00121 (5) |
| Cl2 | 0.02045 (10) | 0.02338 (10) | 0.01738 (9) | −0.00623 (7) | 0.00240 (6) | 0.00349 (6) |
| N1 | 0.0117 (3) | 0.0205 (3) | 0.0176 (3) | −0.0015 (2) | 0.0016 (2) | 0.0025 (2) |
| C1 | 0.0116 (3) | 0.0143 (3) | 0.0131 (3) | 0.0006 (2) | 0.0001 (2) | −0.0008 (2) |
| C2 | 0.0117 (3) | 0.0175 (3) | 0.0149 (3) | −0.0002 (2) | 0.0016 (2) | −0.0010 (2) |
| C3 | 0.0143 (3) | 0.0170 (3) | 0.0139 (3) | −0.0031 (2) | 0.0004 (2) | 0.0006 (2) |
| C4 | 0.0136 (3) | 0.0197 (3) | 0.0209 (3) | −0.0004 (2) | −0.0016 (2) | 0.0046 (3) |
| C5 | 0.0108 (3) | 0.0207 (3) | 0.0209 (3) | 0.0005 (2) | −0.0002 (2) | 0.0044 (3) |
| C6 | 0.0102 (3) | 0.0168 (3) | 0.0149 (3) | −0.0004 (2) | 0.0005 (2) | 0.0009 (2) |
| C7 | 0.0120 (3) | 0.0178 (3) | 0.0160 (3) | −0.0004 (2) | 0.0010 (2) | 0.0015 (2) |
| C8 | 0.0120 (3) | 0.0163 (3) | 0.0183 (3) | −0.0012 (2) | 0.0021 (2) | 0.0009 (2) |
| C9 | 0.0113 (4) | 0.0144 (4) | 0.0148 (4) | −0.0023 (3) | 0.000 | 0.000 |
| C18 | 0.0169 (3) | 0.0176 (3) | 0.0187 (3) | −0.0033 (3) | −0.0036 (2) | −0.0008 (2) |
| Cl1—C1 | 1.7376 (8) | C5—H5A | 0.93 |
| Cl2—C3 | 1.7311 (8) | C6—C7 | 1.4783 (11) |
| N1—C7 | 1.2720 (10) | C7—H7A | 0.93 |
| N1—C8 | 1.4566 (10) | C8—C9 | 1.5369 (10) |
| C1—C2 | 1.3917 (11) | C8—H8A | 0.97 |
| C1—C6 | 1.4033 (11) | C8—H8B | 0.97 |
| C2—C3 | 1.3866 (11) | C9—C18 | 1.5316 (10) |
| C2—H2A | 0.93 | C9—C18i | 1.5316 (10) |
| C3—C4 | 1.3917 (11) | C9—C8i | 1.5369 (10) |
| C4—C5 | 1.3869 (12) | C18—H18A | 0.96 |
| C4—H4A | 0.93 | C18—H18B | 0.96 |
| C5—C6 | 1.4043 (11) | C18—H18C | 0.96 |
| C7—N1—C8 | 117.61 (7) | N1—C7—H7A | 119.7 |
| C2—C1—C6 | 121.94 (7) | C6—C7—H7A | 119.7 |
| C2—C1—Cl1 | 117.35 (6) | N1—C8—C9 | 112.00 (6) |
| C6—C1—Cl1 | 120.71 (6) | N1—C8—H8A | 109.2 |
| C3—C2—C1 | 118.49 (7) | C9—C8—H8A | 109.2 |
| C3—C2—H2A | 120.8 | N1—C8—H8B | 109.2 |
| C1—C2—H2A | 120.8 | C9—C8—H8B | 109.2 |
| C2—C3—C4 | 121.66 (7) | H8A—C8—H8B | 107.9 |
| C2—C3—Cl2 | 119.21 (6) | C18—C9—C18i | 109.36 (9) |
| C4—C3—Cl2 | 119.12 (6) | C18—C9—C8i | 108.71 (4) |
| C5—C4—C3 | 118.74 (8) | C18i—C9—C8i | 109.73 (4) |
| C5—C4—H4A | 120.6 | C18—C9—C8 | 109.73 (4) |
| C3—C4—H4A | 120.6 | C18i—C9—C8 | 108.71 (4) |
| C4—C5—C6 | 121.76 (7) | C8i—C9—C8 | 110.59 (9) |
| C4—C5—H5A | 119.1 | C9—C18—H18A | 109.5 |
| C6—C5—H5A | 119.1 | C9—C18—H18B | 109.5 |
| C1—C6—C5 | 117.40 (7) | H18A—C18—H18B | 109.5 |
| C1—C6—C7 | 122.39 (7) | C9—C18—H18C | 109.5 |
| C5—C6—C7 | 120.19 (7) | H18A—C18—H18C | 109.5 |
| N1—C7—C6 | 120.65 (7) | H18B—C18—H18C | 109.5 |
| C6—C1—C2—C3 | −1.08 (11) | Cl1—C1—C6—C7 | 2.99 (11) |
| Cl1—C1—C2—C3 | 178.81 (6) | C4—C5—C6—C1 | −0.64 (13) |
| C1—C2—C3—C4 | 0.20 (12) | C4—C5—C6—C7 | 177.81 (8) |
| C1—C2—C3—Cl2 | −178.30 (6) | C8—N1—C7—C6 | −176.18 (7) |
| C2—C3—C4—C5 | 0.42 (13) | C1—C6—C7—N1 | 172.02 (8) |
| Cl2—C3—C4—C5 | 178.92 (7) | C5—C6—C7—N1 | −6.36 (12) |
| C3—C4—C5—C6 | −0.19 (13) | C7—N1—C8—C9 | −134.46 (8) |
| C2—C1—C6—C5 | 1.29 (11) | N1—C8—C9—C18 | 59.07 (9) |
| Cl1—C1—C6—C5 | −178.59 (6) | N1—C8—C9—C18i | 178.63 (7) |
| C2—C1—C6—C7 | −177.13 (7) | N1—C8—C9—C8i | −60.85 (5) |
| Symmetry codes: (i) −x+1/2, −y+2, z. |
HKF and RK thanks the Malaysian Government and Universiti sains Malaysia for the Science Fund grant No. 305/PFIZIK/613312. RK thanks Universiti Sains Malaysia for a post-doctoral research fellowship. HK thanks PNU for financial support.
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Schiff bases are one of most prevalent mixed-donor ligands in the field of coordination chemistry. They play an important role in the development of coordination chemistry related to catalysis and enzymatic reactions, magnetism, and supramolecular architectures. Crystal structures of Schiff bases derived from substituted benzaldehydes and closely related to the title compound have been reported earlier (Li et al., 2005; Bomfim et al., 2005; Glidewell et al., 2005, 2006; Sun et al., 2004; Fun et al., 2008).
The molecule of the title Schiff base compound has crystallographic twofold rotation symmetry (Fig. 1). Bond lengths are within normal ranges (Allen et al., 1987). The plane of the –C═N—C– group is twisted away from the benzene ring by 7.5 (1)°.
In the crystal structure, weak intermolecular Cl···Cl contacts [Cl1···Cl2(x,1 - y,-1/2 + z) = 3.4851 (3) Å] link neighbouring molecules into a two-dimensional network parallel to the bc plane (Fig.2).