Acta Cryst. (2008). E64, o1678 [ doi:10.1107/S1600536808024355 ]
The molecule of the title compound, C18H18Cl2N2O2, lies across a crystallographic inversion centre and adopts an E configuration with respect to the azomethine C=N bond. The imino group is coplanar with the aromatic ring. Within the molecule, the planar units are parallel, but extend in opposite directions from the dimethylene bridge. In the crystal structure, the title compound exhibits a layer packing structure via weak ![[pi]](/logos/entities/pi_rmgif.gif)
- stacking interactions [intermolecular plane-to-plane distances between adjacent aromatic rings are 3.461 (3) Å]. Molecules in each layer are linked by intermolecular C-H
O hydrogen-bonding interactions.
2,2'-Dichloro-1,1'-[butane-1,4-diyldioxybis(nitrilomethylidyne)]dibenzene was synthesized according to an analogous method reported earlier (Dong, He et al., 2007; Dong, et al., 2008; Liu, et al., 2008). To an ethanol solution (3 ml) of 2-chloro-benzaldehyde (281.1 mg, 2.00 mmol) was added an ethanol solution (2 ml) of 1, 4-bis(aminooxy)butane (120.2 mg, 1.00 mmol). The mixture solution was stirred at 328 K for 4 h. When cooled to room temperature, the precipitate was filtered, and washed successively with ethanol and hexane, respectively. The product was dried under vacuum and purified with recrystallization from ethanol to yield 219.8 mg of the title compound. Yield, 60.1%. mp. 334–335 K. Anal. Calc. for C18H18Cl2N2O2: C, 59.19; H, 4.97; N, 7.67. Found: C, 59.22; H, 5.03; N, 7.58.
Colorless needle-shaped single crystals suitable for X-ray diffraction studies were obtained after several weeks by slow evaporation from an ethyl-acetate/acetone mixed solution of the title compound.
Non-H atoms were refined anisotropically. H atoms were treated as riding atoms with distances C—H = 0.97 (CH2), 0.93 Å (CH), and Uiso(H) = 1.2 Ueq(C) and 1.5 Ueq(O).
Data collection: SMART (Siemens, 1996); cell refinement: SAINT (Siemens, 1996); data reduction: SAINT (Siemens, 1996); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).
![[Figure 1]](./om2252fig1thm.gif)
| Fig. 1. The molecular structure of the title compound with atom numbering scheme [Symmetry codes: -x, -y + 2, -z + 1]. Displacement ellipsoids for non-hydrogen atoms are drawn at the 30% probability level. |
![[Figure 2]](./om2252fig2thm.gif)
| Fig. 2. The packing diagram of the title compound showing intermolecular hydrogen bonds and π-π stacking interactions. |
| C18H18Cl2N2O2 | F000 = 380 |
| Mr = 365.24 | Dx = 1.351 Mg m−3 |
| Monoclinic, P21/n | Mo Kα radiation λ = 0.71073 Å |
| Hall symbol: -P 2yn | Cell parameters from 2364 reflections |
| a = 4.5296 (5) Å | θ = 3.2–28.2º |
| b = 6.6231 (8) Å | µ = 0.37 mm−1 |
| c = 29.963 (2) Å | T = 298 (2) K |
| β = 92.526 (2)º | Needle, colorless |
| V = 898.02 (16) Å3 | 0.48 × 0.28 × 0.13 mm |
| Z = 2 |
| Bruker SMART 1000 diffractometer | 1531 independent reflections |
| Radiation source: fine-focus sealed tube | 1310 reflections with I > 2σ(I) |
| Monochromator: graphite | Rint = 0.057 |
| T = 298(2) K | θmax = 25.0º |
| φ and ω scans | θmin = 1.4º |
| Absorption correction: multi-scan (SADABS; Sheldrick, 1996) | h = −5→5 |
| Tmin = 0.841, Tmax = 0.953 | k = −7→5 |
| 4304 measured reflections | l = −35→34 |
| Refinement on F2 | Secondary atom site location: difference Fourier map |
| Least-squares matrix: full | Hydrogen site location: inferred from neighbouring sites |
| R[F2 > 2σ(F2)] = 0.074 | H-atom parameters constrained |
| wR(F2) = 0.164 | w = 1/[σ2(Fo2) + (0.0452P)2 + 1.0643P] where P = (Fo2 + 2Fc2)/3 |
| S = 1.10 | (Δ/σ)max = 0.001 |
| 1531 reflections | Δρmax = 0.21 e Å−3 |
| 109 parameters | Δρmin = −0.29 e Å−3 |
| Primary atom site location: structure-invariant direct methods | Extinction correction: none |
| C18H18Cl2N2O2 | V = 898.02 (16) Å3 |
| Mr = 365.24 | Z = 2 |
| Monoclinic, P21/n | Mo Kα |
| a = 4.5296 (5) Å | µ = 0.37 mm−1 |
| b = 6.6231 (8) Å | T = 298 (2) K |
| c = 29.963 (2) Å | 0.48 × 0.28 × 0.13 mm |
| β = 92.526 (2)º |
| Bruker SMART 1000 diffractometer | 1531 independent reflections |
| Absorption correction: multi-scan (SADABS; Sheldrick, 1996) | 1310 reflections with I > 2σ(I) |
| Tmin = 0.841, Tmax = 0.953 | Rint = 0.057 |
| 4304 measured reflections |
| R[F2 > 2σ(F2)] = 0.074 | 109 parameters |
| wR(F2) = 0.164 | H-atom parameters constrained |
| S = 1.10 | Δρmax = 0.21 e Å−3 |
| 1531 reflections | Δρmin = −0.29 e Å−3 |
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 | 0.8257 (3) | 0.7688 (2) | 0.71001 (4) | 0.0939 (5) | |
| N1 | 0.4408 (7) | 0.6370 (5) | 0.57897 (10) | 0.0570 (8) | |
| O1 | 0.2543 (6) | 0.7961 (4) | 0.56512 (8) | 0.0607 (7) | |
| C1 | 0.0979 (8) | 0.7356 (6) | 0.52466 (11) | 0.0598 (9) | |
| H1A | −0.0273 | 0.6204 | 0.5304 | 0.072* | |
| H1B | 0.2370 | 0.6968 | 0.5025 | 0.072* | |
| C2 | −0.0885 (8) | 0.9111 (6) | 0.50759 (13) | 0.0643 (10) | |
| H2A | −0.2160 | 0.8650 | 0.4828 | 0.077* | |
| H2B | −0.2141 | 0.9551 | 0.5311 | 0.077* | |
| C3 | 0.5650 (8) | 0.6708 (6) | 0.61688 (12) | 0.0570 (9) | |
| H3 | 0.5233 | 0.7892 | 0.6321 | 0.068* | |
| C4 | 0.7733 (7) | 0.5252 (5) | 0.63692 (11) | 0.0521 (8) | |
| C5 | 0.9101 (8) | 0.5566 (6) | 0.67866 (12) | 0.0591 (9) | |
| C6 | 1.1129 (9) | 0.4202 (7) | 0.69728 (13) | 0.0697 (11) | |
| H6 | 1.2038 | 0.4454 | 0.7252 | 0.084* | |
| C7 | 1.1776 (10) | 0.2505 (8) | 0.67465 (16) | 0.0820 (13) | |
| H7 | 1.3133 | 0.1587 | 0.6871 | 0.098* | |
| C8 | 1.0431 (11) | 0.2122 (7) | 0.63302 (16) | 0.0826 (13) | |
| H8 | 1.0867 | 0.0946 | 0.6177 | 0.099* | |
| C9 | 0.8444 (9) | 0.3496 (6) | 0.61452 (12) | 0.0636 (10) | |
| H9 | 0.7562 | 0.3241 | 0.5865 | 0.076* |
| U11 | U22 | U33 | U12 | U13 | U23 | |
| Cl1 | 0.1045 (9) | 0.1019 (10) | 0.0731 (7) | 0.0144 (8) | −0.0213 (6) | −0.0275 (7) |
| N1 | 0.0621 (18) | 0.0562 (17) | 0.0522 (17) | 0.0094 (15) | −0.0026 (14) | 0.0042 (14) |
| O1 | 0.0694 (16) | 0.0559 (15) | 0.0555 (14) | 0.0125 (12) | −0.0105 (12) | −0.0013 (12) |
| C1 | 0.063 (2) | 0.064 (2) | 0.0514 (19) | −0.0040 (19) | −0.0059 (15) | 0.0049 (18) |
| C2 | 0.056 (2) | 0.075 (3) | 0.061 (2) | −0.0034 (19) | −0.0106 (17) | 0.018 (2) |
| C3 | 0.064 (2) | 0.057 (2) | 0.0498 (19) | 0.0071 (18) | −0.0003 (16) | −0.0012 (16) |
| C4 | 0.0524 (19) | 0.060 (2) | 0.0436 (17) | 0.0034 (17) | 0.0046 (14) | 0.0085 (16) |
| C5 | 0.059 (2) | 0.073 (2) | 0.0451 (18) | −0.0021 (19) | 0.0045 (15) | 0.0073 (18) |
| C6 | 0.061 (2) | 0.092 (3) | 0.055 (2) | 0.003 (2) | −0.0034 (17) | 0.020 (2) |
| C7 | 0.074 (3) | 0.089 (3) | 0.083 (3) | 0.022 (3) | 0.000 (2) | 0.033 (3) |
| C8 | 0.097 (3) | 0.071 (3) | 0.080 (3) | 0.030 (3) | 0.011 (2) | 0.013 (2) |
| C9 | 0.074 (2) | 0.069 (2) | 0.0483 (19) | 0.010 (2) | 0.0036 (17) | 0.0047 (18) |
| Cl1—C5 | 1.742 (4) | C3—H3 | 0.9300 |
| N1—C3 | 1.265 (4) | C4—C5 | 1.387 (5) |
| N1—O1 | 1.402 (4) | C4—C9 | 1.387 (5) |
| O1—C1 | 1.434 (4) | C5—C6 | 1.388 (5) |
| C1—C2 | 1.513 (5) | C6—C7 | 1.351 (6) |
| C1—H1A | 0.9700 | C6—H6 | 0.9300 |
| C1—H1B | 0.9700 | C7—C8 | 1.387 (7) |
| C2—C2i | 1.506 (8) | C7—H7 | 0.9300 |
| C2—H2A | 0.9700 | C8—C9 | 1.379 (5) |
| C2—H2B | 0.9700 | C8—H8 | 0.9300 |
| C3—C4 | 1.460 (5) | C9—H9 | 0.9300 |
| C3—N1—O1 | 111.8 (3) | C5—C4—C3 | 121.8 (3) |
| N1—O1—C1 | 108.0 (3) | C9—C4—C3 | 121.0 (3) |
| O1—C1—C2 | 108.6 (3) | C4—C5—C6 | 121.7 (4) |
| O1—C1—H1A | 110.0 | C4—C5—Cl1 | 120.5 (3) |
| C2—C1—H1A | 110.0 | C6—C5—Cl1 | 117.8 (3) |
| O1—C1—H1B | 110.0 | C7—C6—C5 | 119.6 (4) |
| C2—C1—H1B | 110.0 | C7—C6—H6 | 120.2 |
| H1A—C1—H1B | 108.4 | C5—C6—H6 | 120.2 |
| C2i—C2—C1 | 114.0 (4) | C6—C7—C8 | 120.4 (4) |
| C2i—C2—H2A | 108.8 | C6—C7—H7 | 119.8 |
| C1—C2—H2A | 108.8 | C8—C7—H7 | 119.8 |
| C2i—C2—H2B | 108.8 | C9—C8—C7 | 119.6 (4) |
| C1—C2—H2B | 108.8 | C9—C8—H8 | 120.2 |
| H2A—C2—H2B | 107.7 | C7—C8—H8 | 120.2 |
| N1—C3—C4 | 120.4 (3) | C8—C9—C4 | 121.3 (4) |
| N1—C3—H3 | 119.8 | C8—C9—H9 | 119.3 |
| C4—C3—H3 | 119.8 | C4—C9—H9 | 119.3 |
| C5—C4—C9 | 117.3 (3) | ||
| C3—N1—O1—C1 | −173.4 (3) | C3—C4—C5—Cl1 | 2.6 (5) |
| N1—O1—C1—C2 | −176.2 (3) | C4—C5—C6—C7 | −0.9 (6) |
| O1—C1—C2—C2i | 66.7 (5) | Cl1—C5—C6—C7 | 178.0 (3) |
| O1—N1—C3—C4 | −178.7 (3) | C5—C6—C7—C8 | 0.1 (7) |
| N1—C3—C4—C5 | −179.1 (4) | C6—C7—C8—C9 | 0.7 (7) |
| N1—C3—C4—C9 | 1.5 (6) | C7—C8—C9—C4 | −0.7 (7) |
| C9—C4—C5—C6 | 0.8 (5) | C5—C4—C9—C8 | −0.1 (6) |
| C3—C4—C5—C6 | −178.6 (3) | C3—C4—C9—C8 | 179.4 (4) |
| C9—C4—C5—Cl1 | −178.0 (3) |
| Symmetry codes: (i) −x, −y+2, −z+1. |
| D—H···A | D—H | H···A | D···A | D—H···A |
| C8—H8···O1ii | 0.93 | 2.66 | 3.581 (5) | 171 |
| Symmetry codes: (ii) x+1, y−1, z. |
| D—H···A | D—H | H···A | D···A | D—H···A |
| C8—H8···O1i | 0.93 | 2.66 | 3.581 (5) | 171 |
| Symmetry codes: (i) x+1, y−1, z. |
This work was supported by the Foundation of the Education Department of Gansu Province (No. 0604–01) and the 'Qing Lan' Talent Engineering Funds of Lanzhou Jiaotong University (No. QL-03–01 A), which are gratefully acknowledged.
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Schiff bases are an important class of compounds which can be used in a variety of studies such as organic synthesis, catalyst, drug design, material science and life science and so on (Collison, et al., 1996; Mandal, et al., 1996). In the past decades, a continuing attention has been drawn to the Schiff bases derived from benzaldehyde or salicylaldehyde and their metal complexes for the investigation of luminescent properties which could be finely tuned by different substituent groups bonded to the phenolic ring (Lu et al., 2006; Yu et al., 2007; Yu et al., 2008). Here, in continuation of our previous studies (Dong, Duan et al., 2007; Shi, et al., 2007), we report the synthesis and X-ray structure of a new Schiff base bisoxime compound 2,2'-dichloro-1,1'-[butane-1,4-diyldioxybis(nitrilomethylidyne)]dibenzene.
The crystal structure of the title compound is built up by only the C18H18Cl2N2O2 molecules, in which all bond lengths are in normal ranges. The molecule, as shown in Fig. 1, lies across a crystallographic inversion centre (symmetry code: -x, -y, -z) and adopts an E configuration with respect to the azomethine C=N bond. The imino group is coplanar with the aromatic ring. Within the molecule, the planar units are parallel, with the distance 1.480 (4) Å [intra-molecular plane-to-plane distance], but extend in opposite directions from the dimethylene bridge. In the crystal structure, (Fig. 2) the title compound exhibits a layer packing structure via weak π-π stacking interactions [inter-molecular plane-to-plane distances between adjacent aromatic rings is 3.461 (3) Å]. Molecules in each layer are linked by intermolecular C8—H8···O1 hydrogen bonding interactions [C8···O1, 3.581 (5) Å].