Acta Cryst. (2009). E65, o1193 [ doi:10.1107/S1600536809015840 ]
The Schiff base, C18H20N2O2, which lies about an inversion centre, adopts a linear conformation. The molecules are packed by C-H
![[pi]](/logos/entities/pi_rmgif.gif)
interactions, forming a two-dimensional supramolecular network.
4,4'-Dimethyl-1,1'-[ethylenedioxybis(nitrilomethylidyne)]dibenzene was synthesized according to an analogous method reported earlier (Dong et al., 2009b). To an ethanol solution (4 ml) of 4-methyl-2-hydroxybenzaldehyde (125.8 mg, 1.05 mmol) was added an ethanol solution (3 ml) of 1,2-bis(aminooxy)ethane (47.7 mg, 0.518 mmol). The reaction mixture was stirred at 328–333 K for 8 h. After cool to room temperature, no precipitate was formed, which was concentrated to about 1 ml under reduced pressure. The precipitate formed was separated by filtration, and washed several times with n-hexane. The product was dried under vacuum to yield 90.0 mg of the title compound. Yield, 58.6%. mp. 359–360 K. Anal. Calcd. for C18H20N2O2: C, 72.95; H, 6.80; N, 9.45. Found: C, 72.66; H, 6.87; N, 9.32.
Colorless needle-like single crystals suitable for X-ray diffraction studies were obtained after about four days by slow evaporation from an diethyl ether 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), C—H = 0.96 (CH3) Å 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]](./ng2575fig1thm.gif)
| Fig. 1. The molecular structure of the title compound with atom numbering scheme [Symmetry codes: -x + 2,-y,-z + 1]. Displacement ellipsoids for non-hydrogen atoms are drawn at the 30% probability level. |
![[Figure 2]](./ng2575fig2thm.gif)
| Fig. 2. Part of the supramolecular structure of the title compound. C—H···π(Ph) interactions are shown as dashed lines. |
| C18H20N2O2 | F000 = 316 |
| Mr = 296.36 | Dx = 1.269 Mg m−3 |
| Monoclinic, P21/c | Mo Kα radiation λ = 0.71073 Å |
| Hall symbol: -P 2ybc | Cell parameters from 1400 reflections |
| a = 13.6946 (12) Å | θ = 3.4–27.7º |
| b = 4.8196 (9) Å | µ = 0.08 mm−1 |
| c = 12.1644 (11) Å | T = 298 K |
| β = 104.936 (1)º | Column, colorless |
| V = 775.75 (17) Å3 | 0.43 × 0.20 × 0.10 mm |
| Z = 2 |
| Siemens SMART 1000 CCD area-detector diffractometer | 1012 reflections with I > 2σ(I) |
| Radiation source: fine-focus sealed tube | Rint = 0.043 |
| Monochromator: graphite | θmax = 25.0º |
| T = 298 K | θmin = 1.5º |
| φ and ω scans | h = −16→15 |
| Absorption correction: None | k = −5→5 |
| 3790 measured reflections | l = −14→13 |
| 1370 independent reflections |
| 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)] = 0.051 | H-atom parameters constrained |
| wR(F2) = 0.158 | w = 1/[σ2(Fo2) + (0.1037P)2] where P = (Fo2 + 2Fc2)/3 |
| S = 1.03 | (Δ/σ)max = 0.001 |
| 1370 reflections | Δρmax = 0.23 e Å−3 |
| 100 parameters | Δρmin = −0.21 e Å−3 |
| Primary atom site location: structure-invariant direct methods | Extinction correction: none |
| C18H20N2O2 | V = 775.75 (17) Å3 |
| Mr = 296.36 | Z = 2 |
| Monoclinic, P21/c | Mo Kα |
| a = 13.6946 (12) Å | µ = 0.08 mm−1 |
| b = 4.8196 (9) Å | T = 298 K |
| c = 12.1644 (11) Å | 0.43 × 0.20 × 0.10 mm |
| β = 104.936 (1)º |
| Siemens SMART 1000 CCD area-detector diffractometer | 1370 independent reflections |
| Absorption correction: None | 1012 reflections with I > 2σ(I) |
| 3790 measured reflections | Rint = 0.043 |
| R[F2 > 2σ(F2)] = 0.051 | 100 parameters |
| wR(F2) = 0.158 | H-atom parameters constrained |
| S = 1.03 | Δρmax = 0.23 e Å−3 |
| 1370 reflections | Δρmin = −0.21 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 | ||
| N1 | 0.87170 (11) | 0.4357 (3) | 0.55939 (12) | 0.0389 (4) | |
| O1 | 0.95570 (9) | 0.2523 (3) | 0.58336 (10) | 0.0424 (4) | |
| C1 | 0.95420 (13) | 0.0920 (4) | 0.48465 (15) | 0.0381 (5) | |
| H1A | 0.9568 | 0.2120 | 0.4214 | 0.046* | |
| H1B | 0.8931 | −0.0187 | 0.4631 | 0.046* | |
| C2 | 0.86877 (13) | 0.5688 (4) | 0.64775 (16) | 0.0386 (5) | |
| H2 | 0.9180 | 0.5342 | 0.7148 | 0.046* | |
| C3 | 0.79062 (13) | 0.7762 (4) | 0.64868 (15) | 0.0366 (5) | |
| C4 | 0.71621 (13) | 0.8512 (4) | 0.55207 (15) | 0.0417 (5) | |
| H4 | 0.7148 | 0.7693 | 0.4825 | 0.050* | |
| C5 | 0.64425 (14) | 1.0474 (4) | 0.55907 (16) | 0.0439 (5) | |
| H5 | 0.5956 | 1.0971 | 0.4934 | 0.053* | |
| C6 | 0.64272 (13) | 1.1717 (4) | 0.66137 (17) | 0.0434 (5) | |
| C7 | 0.71769 (15) | 1.0973 (4) | 0.75725 (16) | 0.0457 (5) | |
| H7 | 0.7189 | 1.1784 | 0.8270 | 0.055* | |
| C8 | 0.79055 (14) | 0.9047 (4) | 0.75058 (15) | 0.0424 (5) | |
| H8 | 0.8406 | 0.8602 | 0.8158 | 0.051* | |
| C9 | 0.56330 (16) | 1.3823 (4) | 0.6689 (2) | 0.0577 (6) | |
| H9A | 0.5911 | 1.5656 | 0.6709 | 0.086* | |
| H9B | 0.5417 | 1.3507 | 0.7369 | 0.086* | |
| H9C | 0.5065 | 1.3647 | 0.6038 | 0.086* |
| U11 | U22 | U33 | U12 | U13 | U23 | |
| N1 | 0.0315 (8) | 0.0384 (9) | 0.0465 (9) | 0.0052 (7) | 0.0093 (6) | 0.0011 (7) |
| O1 | 0.0343 (8) | 0.0455 (8) | 0.0446 (8) | 0.0100 (6) | 0.0052 (6) | −0.0053 (6) |
| C1 | 0.0335 (10) | 0.0397 (10) | 0.0405 (10) | 0.0010 (8) | 0.0084 (8) | −0.0035 (8) |
| C2 | 0.0349 (10) | 0.0398 (11) | 0.0396 (10) | 0.0016 (8) | 0.0072 (8) | 0.0006 (8) |
| C3 | 0.0324 (10) | 0.0365 (10) | 0.0414 (10) | −0.0013 (7) | 0.0104 (8) | 0.0016 (8) |
| C4 | 0.0393 (10) | 0.0446 (11) | 0.0415 (10) | −0.0007 (9) | 0.0108 (8) | −0.0032 (8) |
| C5 | 0.0366 (10) | 0.0462 (11) | 0.0473 (11) | 0.0040 (8) | 0.0080 (8) | 0.0058 (9) |
| C6 | 0.0398 (11) | 0.0342 (10) | 0.0604 (12) | 0.0000 (9) | 0.0204 (9) | 0.0036 (9) |
| C7 | 0.0537 (12) | 0.0417 (11) | 0.0452 (11) | 0.0029 (9) | 0.0189 (9) | −0.0056 (9) |
| C8 | 0.0452 (11) | 0.0419 (11) | 0.0388 (10) | 0.0018 (9) | 0.0085 (8) | 0.0006 (8) |
| C9 | 0.0510 (12) | 0.0461 (12) | 0.0816 (17) | 0.0075 (10) | 0.0276 (11) | 0.0031 (12) |
| N1—C2 | 1.261 (2) | C4—H4 | 0.9300 |
| N1—O1 | 1.4203 (18) | C5—C6 | 1.386 (3) |
| O1—C1 | 1.424 (2) | C5—H5 | 0.9300 |
| C1—C1i | 1.503 (3) | C6—C7 | 1.388 (3) |
| C1—H1A | 0.9700 | C6—C9 | 1.508 (3) |
| C1—H1B | 0.9700 | C7—C8 | 1.380 (3) |
| C2—C3 | 1.466 (2) | C7—H7 | 0.9300 |
| C2—H2 | 0.9300 | C8—H8 | 0.9300 |
| C3—C8 | 1.386 (2) | C9—H9A | 0.9600 |
| C3—C4 | 1.390 (3) | C9—H9B | 0.9600 |
| C4—C5 | 1.384 (2) | C9—H9C | 0.9600 |
| C2—N1—O1 | 110.10 (14) | C4—C5—H5 | 119.1 |
| N1—O1—C1 | 109.26 (12) | C6—C5—H5 | 119.1 |
| O1—C1—C1i | 106.32 (17) | C5—C6—C7 | 117.62 (17) |
| O1—C1—H1A | 110.5 | C5—C6—C9 | 121.59 (19) |
| C1i—C1—H1A | 110.5 | C7—C6—C9 | 120.78 (19) |
| O1—C1—H1B | 110.5 | C8—C7—C6 | 120.92 (18) |
| C1i—C1—H1B | 110.5 | C8—C7—H7 | 119.5 |
| H1A—C1—H1B | 108.7 | C6—C7—H7 | 119.5 |
| N1—C2—C3 | 122.47 (17) | C7—C8—C3 | 121.35 (17) |
| N1—C2—H2 | 118.8 | C7—C8—H8 | 119.3 |
| C3—C2—H2 | 118.8 | C3—C8—H8 | 119.3 |
| C8—C3—C4 | 118.06 (17) | C6—C9—H9A | 109.5 |
| C8—C3—C2 | 118.70 (17) | C6—C9—H9B | 109.5 |
| C4—C3—C2 | 123.24 (17) | H9A—C9—H9B | 109.5 |
| C5—C4—C3 | 120.27 (17) | C6—C9—H9C | 109.5 |
| C5—C4—H4 | 119.9 | H9A—C9—H9C | 109.5 |
| C3—C4—H4 | 119.9 | H9B—C9—H9C | 109.5 |
| C4—C5—C6 | 121.76 (17) | ||
| C2—N1—O1—C1 | 176.47 (14) | C4—C5—C6—C7 | 1.4 (3) |
| N1—O1—C1—C1i | 178.87 (16) | C4—C5—C6—C9 | −179.11 (16) |
| O1—N1—C2—C3 | 179.41 (14) | C5—C6—C7—C8 | −0.5 (3) |
| N1—C2—C3—C8 | 177.36 (16) | C9—C6—C7—C8 | −179.96 (17) |
| N1—C2—C3—C4 | −2.7 (3) | C6—C7—C8—C3 | −0.9 (3) |
| C8—C3—C4—C5 | −0.5 (3) | C4—C3—C8—C7 | 1.4 (3) |
| C2—C3—C4—C5 | 179.58 (16) | C2—C3—C8—C7 | −178.65 (16) |
| C3—C4—C5—C6 | −0.9 (3) |
| Symmetry codes: (i) −x+2, −y, −z+1. |
| D—H···A | D—H | H···A | D···A | D—H···A |
| C9—H9A···Cg1 | 0.96 | 2.66 | 3.578 (2) | 160 |
The authors acknowledge finanical support from the `Jing Lan' Talent Engineering Funds of Lanzhou Jiaotong University.
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Siemens (1996). SMART and SAINT. Siemens Analytical X-ray Instruments Inc., Madison, Wisconsin, USA.
Yamada, S. (1999). Coord. Chem. Rev. 190, 537–555.
Schiff bases and their bis-oxime analogues are a significant class of compounds which can be used in a variety of studies such as organic synthesis, catalyst, drug design and life science and so on (Yamada, 1999; Akine et al., 2005; Dong et al., 2009a). In order to extend our work (Dong et al., 2008) on structural characterization of bisoxime compounds, we report the synthesis and the X-ray structure of 4,4'-dimethyl-1,1'-[ethylenedioxybis(nitrilomethylidyne)]dibenzene in this paper (Fig. 1).
The molecule of the title compound is disposed about a crystallographic inversion centre (Symmetry codes: -x, -y,-z) and twofold screw axis (symmetry code: -x, 1/2 + y, 1/2 - z). The oxime, methyl groups and benzene rings have anti-conformation. The two benzene rings of the molecule are parallel, and the methyl and oxime (–CH2—O—N=C–) functional groups are coplanar with the benzene ring in each half of the molecule.
The molecule adopts a linear-shaped configuration with respect to the oxime C=N bonds, which is different from our previous reported bisoxime of 3,3'-dibromo-1,1'-[ethylenedioxybis(nitrilomethylidyne)]dibenzene in which the molecule assumes an E configuration (Dong et al., 2008). The packing of the molecule is controlled by C—H···π(Ph) interactions linking molecules into infinite supramolecular structure along b axis (Fig. 2).