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Acta Crystallogr Sect E Struct Rep Online. 2009 October 1; 65(Pt 10): o2560.
Published online 2009 September 26. doi:  10.1107/S1600536809038082
PMCID: PMC2970277

2,4-Dimethoxy­benzaldehyde azine

Abstract

The title mol­ecule, C18H20N2O4, is located on a crystallographic centre of symmetry. The meth­oxy groups are coplanar with the benzene ring [interplanar angles of 14.4 (2) and 3.1 (3)°], indicating a conjugation effect.

Related literature

For the structures of related compounds, see: Narayana et al. (2007 [triangle]); Liu et al. (2007 [triangle]); Takakashi et al. (2006 [triangle]). For a statistical study of meth­oxy groups bound to phenyl rings, see: Hummel et al. (1988 [triangle]).

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Object name is e-65-o2560-scheme1.jpg

Experimental

Crystal data

  • C18H20N2O4
  • M r = 328.36
  • Monoclinic, An external file that holds a picture, illustration, etc.
Object name is e-65-o2560-efi1.jpg
  • a = 6.775 (2) Å
  • b = 9.014 (3) Å
  • c = 14.081 (3) Å
  • β = 100.42 (2)°
  • V = 845.7 (4) Å3
  • Z = 2
  • Mo Kα radiation
  • μ = 0.09 mm−1
  • T = 293 K
  • 0.45 × 0.30 × 0.12 mm

Data collection

  • Enraf–Nonius DIP1030 image-plate diffractometer
  • Absorption correction: none
  • 3535 measured reflections
  • 1293 independent reflections
  • 719 reflections with I > 2σ(I)
  • R int = 0.058
  • θmax = 24.1°

Refinement

  • R[F 2 > 2σ(F 2)] = 0.045
  • wR(F 2) = 0.121
  • S = 0.84
  • 1293 reflections
  • 110 parameters
  • H-atom parameters constrained
  • Δρmax = 0.12 e Å−3
  • Δρmin = −0.10 e Å−3

Data collection: XPRESS (MacScience, 2002 [triangle]; cell refinement: DENZO (Otwinowski & Minor, 1997 [triangle]); data reduction: DENZO and SCALEPACK (Otwinowski & Minor, 1997 [triangle]); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 [triangle]); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 [triangle]); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997 [triangle]); software used to prepare material for publication: WinGX (Farrugia, 1999 [triangle]).

Supplementary Material

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536809038082/rz2359sup1.cif

Structure factors: contains datablocks I. DOI: 10.1107/S1600536809038082/rz2359Isup2.hkl

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

Acknowledgments

MAAAAI is grateful to the Department of Chemistry, Rajshahi University of Engineering and Technology, for a research grant. MTHT thanks the Department of Chemistry, Rajshahi University, for the provision of laboratory facilities.

supplementary crystallographic information

Comment

The molecule of the title compound (Fig. 1) possesses a crystallographically imposed inversion centre at the midpoint of the N—N bond. Thus the conformation about the N1—N1i azine bridge (symmetry code: (i) -x - 1, -y + 1, -z + 1) is trans, with a torsion angle C1—N1—N1'—C1' of 180°. The molecule has coplanar non hydrogen atoms as found in other similar structures (Narayana et al., 2007; Takakashi et al., 2006). The coplanarity of methoxy groups with the benzene ring suggests the presence of a conjugation effect (Hummel et al., 1988). The bond distance N1—N1i of 1.414 (4) Å, is comparable to those measured in the structure of methoxybenzaldehyde azine and N,N'-bis(4-hydroxybenzylidene)-hydrazine, which are 1.418 and 1.415 Å, respectively (Narayana et al., 2007; Liu et al., 2007). The crystal packing does not show any π-π stacking interactions between aromatic rings.

Experimental

Hydrazine hydrate (99.99%) (0.13 g, 2.5 mmol) was added to a solution of 2,4-dimethoxybenzaldehyde (0.83 g, 5 mmol) in methanol (10 ml) with constant stirring for 5 min, at room temperature. A light yellow precipitate was formed, which was separated by filtration, washed with methanol and dried at 70°C for 1 h and then preserved in vacuo over anhydrous CaCl2 (0.43 g, 44.79%, m.p. 473 K). The compound was soluble in chloroform, benzene and toluene whereas insoluble in acetonitrile, methanol and ethanol. The compound (0.37 g) was dissolved in chloroform (60 ml) at boiling temperature and allowed to stand at room temperature (20–25°C). Bright large yellow crystals, suitable for X-ray single-crystal analysis, were obtained after 7 days. The crystals were collected, washed with absolute ethanol and dried in vacuo over anhydrous CaCl2.

Refinement

All H atoms were located geometrically and treated as riding atoms, with C—H = 0.93–0.96 Å, and with Uiso(H) = 1.2Ueq(C) or 1.5Ueq(C) for methyl H atoms.

Figures

Fig. 1.
ORTEP drawing (ellipsoids at the 40% probability level) of the title compound with atom labelling scheme. Primed atom at -x - 1, -y + 1, -z + 1.

Crystal data

C18H20N2O4F(000) = 348
Mr = 328.36Dx = 1.289 Mg m3
Monoclinic, P21/cMelting point: 475 K
Hall symbol: -P 2ybcMo Kα radiation, λ = 0.71073 Å
a = 6.775 (2) ÅCell parameters from 482 reflections
b = 9.014 (3) Åθ = 3.6–20.7°
c = 14.081 (3) ŵ = 0.09 mm1
β = 100.42 (2)°T = 293 K
V = 845.7 (4) Å3Plate, yellow
Z = 20.45 × 0.30 × 0.12 mm

Data collection

Enraf–Nonius DIP1030 image-plate diffractometer719 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tubeRint = 0.058
graphiteθmax = 24.1°, θmin = 2.9°
[var phi]–scans with narrow framesh = −7→7
3535 measured reflectionsk = −10→10
1293 independent reflectionsl = −16→16

Refinement

Refinement on F2Secondary atom site location: difference Fourier map
Least-squares matrix: fullHydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.045H-atom parameters constrained
wR(F2) = 0.121w = 1/[σ2(Fo2) + (0.0678P)2] where P = (Fo2 + 2Fc2)/3
S = 0.84(Δ/σ)max < 0.001
1293 reflectionsΔρmax = 0.12 e Å3
110 parametersΔρmin = −0.10 e Å3
0 restraintsExtinction correction: SHELXL97 (Sheldrick, 2008), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
Primary atom site location: structure-invariant direct methodsExtinction coefficient: 0.070 (13)

Special details

Geometry. All s.u.'s (except the s.u. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell s.u.'s are taken into account individually in the estimation of s.u.'s in distances, angles and torsion angles; correlations between s.u.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell s.u.'s is used for estimating s.u.'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 > 2σ(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
N1−0.4202 (3)0.4904 (2)0.53948 (13)0.0857 (6)
O10.0297 (2)0.77203 (18)0.52320 (12)0.0960 (6)
O20.4398 (2)0.55904 (18)0.80720 (11)0.0952 (6)
C1−0.2709 (4)0.5738 (3)0.53259 (16)0.0833 (7)
H1−0.28000.63760.48000.100*
C2−0.0880 (3)0.5722 (2)0.60384 (15)0.0745 (6)
C30.0667 (3)0.6732 (2)0.59790 (16)0.0768 (6)
C40.2433 (3)0.6732 (2)0.66487 (16)0.0785 (7)
H40.34310.74250.66060.094*
C50.2699 (3)0.5695 (3)0.73791 (16)0.0787 (6)
C60.1196 (4)0.4673 (3)0.74624 (17)0.0850 (7)
H60.13720.39840.79620.102*
C7−0.0547 (3)0.4704 (3)0.67925 (18)0.0830 (7)
H7−0.15460.40170.68450.100*
C80.1918 (4)0.8551 (3)0.49880 (19)0.1041 (9)
H8A0.14290.91850.44490.156*
H8B0.29050.78850.48200.156*
H8C0.25140.91440.55310.156*
C90.5936 (3)0.6675 (3)0.80431 (19)0.1042 (9)
H9A0.70460.64880.85570.156*
H9B0.54100.76480.81180.156*
H9C0.63810.66140.74350.156*

Atomic displacement parameters (Å2)

U11U22U33U12U13U23
N10.0716 (13)0.0972 (13)0.0854 (14)0.0055 (12)0.0066 (9)−0.0007 (11)
O10.0858 (11)0.1004 (12)0.0995 (12)−0.0022 (9)0.0106 (9)0.0169 (10)
O20.0820 (11)0.1060 (13)0.0915 (12)−0.0027 (9)−0.0012 (9)0.0038 (9)
C10.0778 (16)0.0904 (16)0.0803 (15)0.0037 (13)0.0101 (13)0.0021 (12)
C20.0693 (14)0.0799 (14)0.0732 (14)0.0017 (12)0.0099 (12)−0.0017 (12)
C30.0782 (15)0.0787 (15)0.0728 (14)0.0082 (13)0.0118 (13)0.0026 (12)
C40.0734 (15)0.0799 (15)0.0818 (15)−0.0017 (12)0.0132 (13)−0.0029 (13)
C50.0722 (15)0.0864 (15)0.0755 (15)0.0053 (13)0.0084 (13)−0.0065 (13)
C60.0806 (16)0.0919 (16)0.0815 (16)0.0009 (13)0.0114 (14)0.0056 (13)
C70.0772 (16)0.0870 (16)0.0841 (16)−0.0032 (12)0.0126 (13)−0.0010 (13)
C80.1061 (19)0.0956 (17)0.113 (2)−0.0067 (16)0.0255 (16)0.0164 (15)
C90.0775 (16)0.115 (2)0.114 (2)−0.0073 (15)0.0006 (15)−0.0033 (16)

Geometric parameters (Å, °)

N1—C11.278 (3)C4—H40.9300
N1—N1i1.414 (4)C5—C61.393 (3)
O1—C31.366 (2)C6—C71.372 (3)
O1—C81.422 (3)C6—H60.9300
O2—C51.371 (3)C7—H70.9300
O2—C91.435 (3)C8—H8A0.9600
C1—C21.446 (3)C8—H8B0.9600
C1—H10.9300C8—H8C0.9600
C2—C71.391 (3)C9—H9A0.9600
C2—C31.402 (3)C9—H9B0.9600
C3—C41.383 (3)C9—H9C0.9600
C4—C51.378 (3)
C1—N1—N1i111.8 (2)C7—C6—C5118.7 (2)
C3—O1—C8119.13 (18)C7—C6—H6120.7
C5—O2—C9116.98 (19)C5—C6—H6120.7
N1—C1—C2122.2 (2)C6—C7—C2122.6 (2)
N1—C1—H1118.9C6—C7—H7118.7
C2—C1—H1118.9C2—C7—H7118.7
C7—C2—C3117.0 (2)O1—C8—H8A109.5
C7—C2—C1122.4 (2)O1—C8—H8B109.5
C3—C2—C1120.5 (2)H8A—C8—H8B109.5
O1—C3—C4122.7 (2)O1—C8—H8C109.5
O1—C3—C2115.7 (2)H8A—C8—H8C109.5
C4—C3—C2121.5 (2)H8B—C8—H8C109.5
C5—C4—C3119.3 (2)O2—C9—H9A109.5
C5—C4—H4120.4O2—C9—H9B109.5
C3—C4—H4120.4H9A—C9—H9B109.5
O2—C5—C4123.9 (2)O2—C9—H9C109.5
O2—C5—C6115.3 (2)H9A—C9—H9C109.5
C4—C5—C6120.8 (2)H9B—C9—H9C109.5
N1i—N1—C1—C2−178.8 (2)C2—C3—C4—C51.5 (3)
N1—C1—C2—C76.4 (3)C9—O2—C5—C42.6 (3)
N1—C1—C2—C3−175.1 (2)C9—O2—C5—C6−176.66 (18)
C8—O1—C3—C415.1 (3)C3—C4—C5—O2179.32 (18)
C8—O1—C3—C2−166.0 (2)C3—C4—C5—C6−1.5 (3)
C7—C2—C3—O1−179.90 (18)O2—C5—C6—C7−179.73 (19)
C1—C2—C3—O11.5 (3)C4—C5—C6—C71.0 (3)
C7—C2—C3—C4−1.0 (3)C5—C6—C7—C2−0.5 (3)
C1—C2—C3—C4−179.62 (19)C3—C2—C7—C60.5 (3)
O1—C3—C4—C5−179.68 (18)C1—C2—C7—C6179.1 (2)

Symmetry codes: (i) −x−1, −y+1, −z+1.

Footnotes

Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: RZ2359).

References

  • Farrugia, L. J. (1997). J. Appl. Cryst.30, 565.
  • Farrugia, L. J. (1999). J. Appl. Cryst.32, 837–838.
  • Hummel, W., Huml, K. & Burgi, H.-B. (1988). Helv. Chim. Acta, 71, 1291–1302.
  • Liu, G., Xie, L., Wang, Y. & Wang, J.-D. (2007). Acta Cryst. E63, o2611.
  • MacScience (2002). XPRESS MacScience Co. Ltd, Yokohama, Japan.
  • Narayana, B., Yathirajan, H. S., Sarojini, B. K. & Bolte, M. (2007). Private communication (deposition number 653075). CCDC, Union Road, Cambridge, England.
  • Otwinowski, Z. & Minor, W. (1997). Methods in Enzymology, Vol. 276, Macromolecular Crystallography, Part A, edited by C. W. Carter Jr & R. M. Sweet, pp. 307–326. New York: Academic Press.
  • Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. [PubMed]
  • Takakashi, H., Kubo, K., Takechi, H., Matsumoto, T. & Ideta, K. (2006). J. Oleo Sci.55, 483–486.

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