PMCCPMCCPMCC

Search tips
Search criteria 

Advanced

 
Logo of actaeInternational Union of Crystallographysearchopen accessarticle submissionjournal home pagethis article
 
Acta Crystallogr Sect E Struct Rep Online. 2008 September 1; 64(Pt 9): o1803–o1804.
Published online 2008 August 23. doi:  10.1107/S1600536808026652
PMCID: PMC2960703

N,N′-Bis(3-methoxy­benzyl­idene)ethane-1,2-diamine

Abstract

The mol­ecule of the title bidentate Schiff base ligand, C18H20N2O2, has twofold crystallographic rotation symmetry, giving one half-mol­ecule per asymmetric unit. It adopts a twisted E configuration with respect to the azomethine C=N bond. The imino group is coplanar with the aromatic ring. The dihedral angle between the two benzene rings is 69.52 (5)°. The meth­oxy group is coplanar with the benzene ring, as indicated by the C—O—C—C torsion angle of −179.56 (8)°. In the unit cell, mol­ecules are linked together by inter­molecular C—H(...)O hydrogen bonds, forming chains along the a axis; these chains are further stacked down the b axis by both inter­molecular C—H(...)O and C—H(...)π inter­actions.

Related literature

For related structures see: Fun et al. (2008a [triangle],b [triangle],c [triangle],d [triangle]); Calligaris & Randaccio, (1987 [triangle]). For information on Schiff base complexes and their applications, see: Kia et al. (2007a [triangle],b [triangle]); Pal et al. (2005 [triangle]); Hou et al. (2001 [triangle])

An external file that holds a picture, illustration, etc.
Object name is e-64-o1803-scheme1.jpg

Experimental

Crystal data

  • C18H20N2O2
  • M r = 296.36
  • Monoclinic, An external file that holds a picture, illustration, etc.
Object name is e-64-o1803-efi1.jpg
  • a = 22.7076 (3) Å
  • b = 6.0374 (1) Å
  • c = 11.6789 (2) Å
  • β = 100.235 (1)°
  • V = 1575.64 (4) Å3
  • Z = 4
  • Mo Kα radiation
  • μ = 0.08 mm−1
  • T = 100.0 (1) K
  • 0.49 × 0.33 × 0.22 mm

Data collection

  • Bruker SMART APEXII CCD area-detector diffractometer
  • Absorption correction: multi-scan (SADABS; Bruker, 2005 [triangle]) T min = 0.886, T max = 0.982
  • 11683 measured reflections
  • 2298 independent reflections
  • 1879 reflections with I > 2σ(I)
  • R int = 0.029

Refinement

  • R[F 2 > 2σ(F 2)] = 0.041
  • wR(F 2) = 0.108
  • S = 1.10
  • 2298 reflections
  • 113 parameters
  • H atoms treated by a mixture of independent and constrained refinement
  • Δρmax = 0.35 e Å−3
  • Δρmin = −0.21 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/S1600536808026652/fl2216sup1.cif

Structure factors: contains datablocks I. DOI: 10.1107/S1600536808026652/fl2216Isup2.hkl

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

Acknowledgments

HKF thanks the Malaysian Government and Universiti Sains Malaysia for the Science Fund grant No. 305/PFIZIK/613312. VM and ARV thank the University of Isfahan for financial support and Dr Reza Kia for the manuscript preparation.

supplementary crystallographic information

Comment

Schiff bases are one of most prevalent mixed-donor ligands found in the field of coordination chemistry. There has been growing interest in Schiff base ligands, mainly because of their wide applications in the fields of biochemistry, synthesis, and catalysis (Kia et al., 2007a,b; Pal et al., 2005; Hou et al., 2001). Many Schiff base complexes have been structurally characterized, but in comparison only a relatively small number of free Schiff bases have been described (Calligaris & Randaccio, 1987). As an extension of our work (Fun et al., 2008a, 2008b, 2008c, 2008d) on the structural characterization of Schiff base compounds, the title compound (I), (Fig. 1), is reported here.

(I) has twofold crystallographic rotation symmetry to give 1/2 molecule per asymmetric unit and it adopts a twisted E configuration with respect to the azomethine C=N bond. Bond lengths and angles are within normal ranges. The imino group is coplanar with the aromatic ring. The dihedral angle between two phenyl rings is 69.52 (5)°. The methoxy group is coplanar with the benzene ring as indicated by the C9–O1–C2–C1 torsion of -179.56 (8)°. In the unit cell, (Fig. 2), neighbouring molecules are linked together by intermolecular C—H···O hydrogen bonds to form chains along the a-axis and these chains are further stacked down the b-axis by both intermolecular C—H···O and C—H···π interactions (Table 1).

Experimental

The overall synthetic method has been described earlier (Fun et al., 2008a), except that ethylenediamine (1 mmol, 60 mg) and 3-methoxybenzaldehyde (2 mmol, 137 mg) were used as starting materials. Single crystals suitable for X-ray diffraction were obtained by evaporation of an ethanol solution at room temperature.

Refinement

H atoms bound to C7 and C8 were located from the difference Fourier map and freely refined. The rest of the hydrogen atoms were positioned geometrically with C—H = 0.93–0.96 Å and refined in riding mode with Uiso(H) = 1.2 or 1.5 Ueq(C). A rotating-group model was used for the methyl group.

Figures

Fig. 1.
The molecular structure of (I) with atom labels and 50% probability ellipsoids for non-H atoms [symmetry code for A: -x + 1, Y, 0.5 - Z].
Fig. 2.
The crystal packing of (I), viewed down the b axis, showing chains along the a axis and stacking of these chains along the b axis. Intermolecular interactions are shown as dashed lines.

Crystal data

C18H20N2O2F000 = 632
Mr = 296.36Dx = 1.249 Mg m3
Monoclinic, C2/cMo Kα radiation λ = 0.71073 Å
Hall symbol: -C 2ycCell parameters from 3509 reflections
a = 22.7076 (3) Åθ = 3.6–33.9º
b = 6.03740 (10) ŵ = 0.08 mm1
c = 11.6789 (2) ÅT = 100.0 (1) K
β = 100.2350 (10)ºBlock, colourless
V = 1575.64 (4) Å30.49 × 0.33 × 0.22 mm
Z = 4

Data collection

Bruker SMART APEXII CCD area-detector diffractometer2298 independent reflections
Radiation source: fine-focus sealed tube1879 reflections with I > 2σ(I)
Monochromator: graphiteRint = 0.029
T = 100.0(1) Kθmax = 30.0º
[var phi] and ω scansθmin = 3.5º
Absorption correction: multi-scan(SADABS; Bruker, 2005)h = −31→31
Tmin = 0.886, Tmax = 0.982k = −8→8
11683 measured reflectionsl = −14→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)] = 0.041H atoms treated by a mixture of independent and constrained refinement
wR(F2) = 0.108  w = 1/[σ2(Fo2) + (0.0467P)2 + 0.7792P] where P = (Fo2 + 2Fc2)/3
S = 1.11(Δ/σ)max < 0.001
2298 reflectionsΔρmax = 0.35 e Å3
113 parametersΔρmin = −0.21 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
O10.29856 (3)0.12810 (12)0.16829 (6)0.02029 (18)
N10.44163 (4)0.77578 (14)0.17093 (8)0.0197 (2)
C10.36408 (4)0.39310 (16)0.11788 (8)0.0166 (2)
H1A0.36290.46250.18850.020*
C20.33032 (4)0.20304 (16)0.08715 (8)0.0167 (2)
C30.33099 (4)0.10022 (17)−0.01966 (9)0.0196 (2)
H3A0.3080−0.0257−0.04070.024*
C40.36637 (4)0.18805 (18)−0.09415 (9)0.0216 (2)
H4A0.36710.1197−0.16530.026*
C50.40051 (4)0.37574 (18)−0.06388 (9)0.0203 (2)
H5A0.42400.4328−0.11450.024*
C60.39970 (4)0.47980 (17)0.04289 (8)0.0172 (2)
C70.43794 (4)0.67504 (17)0.07480 (9)0.0184 (2)
C80.48159 (5)0.96685 (17)0.18898 (10)0.0215 (2)
C90.26352 (5)−0.06749 (17)0.14119 (10)0.0225 (2)
H9A0.2443−0.10470.20550.034*
H9B0.2890−0.18740.12670.034*
H9C0.2337−0.04190.07310.034*
H7A0.4614 (6)0.722 (2)0.0143 (11)0.027 (3)*
H8B0.4562 (6)1.100 (2)0.1792 (11)0.025 (3)*
H8A0.5085 (6)0.971 (2)0.1293 (12)0.026 (3)*

Atomic displacement parameters (Å2)

U11U22U33U12U13U23
O10.0226 (4)0.0197 (4)0.0195 (4)−0.0036 (3)0.0063 (3)−0.0004 (3)
N10.0174 (4)0.0181 (4)0.0228 (4)−0.0004 (3)0.0018 (3)0.0020 (3)
C10.0170 (4)0.0178 (4)0.0144 (4)0.0026 (3)0.0015 (3)−0.0002 (3)
C20.0152 (4)0.0179 (4)0.0167 (5)0.0027 (3)0.0020 (3)0.0019 (3)
C30.0190 (5)0.0191 (5)0.0196 (5)0.0007 (4)0.0006 (4)−0.0027 (4)
C40.0202 (5)0.0281 (5)0.0157 (5)0.0031 (4)0.0014 (4)−0.0039 (4)
C50.0177 (5)0.0271 (5)0.0161 (5)0.0012 (4)0.0031 (4)0.0016 (4)
C60.0153 (4)0.0192 (5)0.0163 (4)0.0022 (3)0.0003 (3)0.0022 (4)
C70.0164 (4)0.0197 (5)0.0189 (5)0.0008 (4)0.0026 (4)0.0056 (4)
C80.0186 (5)0.0162 (5)0.0291 (6)−0.0010 (4)0.0027 (4)0.0027 (4)
C90.0226 (5)0.0189 (5)0.0255 (5)−0.0033 (4)0.0025 (4)0.0019 (4)

Geometric parameters (Å, °)

O1—C21.3659 (12)C4—H4A0.9300
O1—C91.4277 (12)C5—C61.3993 (14)
N1—C71.2665 (14)C5—H5A0.9300
N1—C81.4597 (13)C6—C71.4723 (14)
C1—C21.3912 (14)C7—H7A0.999 (13)
C1—C61.3954 (13)C8—C8i1.519 (2)
C1—H1A0.9300C8—H8B0.984 (13)
C2—C31.3958 (14)C8—H8A1.005 (13)
C3—C41.3899 (14)C9—H9A0.9600
C3—H3A0.9300C9—H9B0.9600
C4—C51.3830 (15)C9—H9C0.9600
C2—O1—C9117.53 (8)C1—C6—C7121.54 (9)
C7—N1—C8116.68 (9)C5—C6—C7118.98 (9)
C2—C1—C6120.12 (9)N1—C7—C6123.50 (9)
C2—C1—H1A119.9N1—C7—H7A122.1 (8)
C6—C1—H1A119.9C6—C7—H7A114.4 (8)
O1—C2—C1115.39 (8)N1—C8—C8i111.10 (7)
O1—C2—C3124.31 (9)N1—C8—H8B106.9 (8)
C1—C2—C3120.29 (9)C8i—C8—H8B108.8 (8)
C4—C3—C2119.28 (9)N1—C8—H8A111.0 (8)
C4—C3—H3A120.4C8i—C8—H8A110.5 (7)
C2—C3—H3A120.4H8B—C8—H8A108.3 (11)
C5—C4—C3120.84 (9)O1—C9—H9A109.5
C5—C4—H4A119.6O1—C9—H9B109.5
C3—C4—H4A119.6H9A—C9—H9B109.5
C4—C5—C6120.01 (9)O1—C9—H9C109.5
C4—C5—H5A120.0H9A—C9—H9C109.5
C6—C5—H5A120.0H9B—C9—H9C109.5
C1—C6—C5119.46 (9)
C9—O1—C2—C1−179.56 (8)C2—C1—C6—C50.84 (14)
C9—O1—C2—C3−0.45 (14)C2—C1—C6—C7−177.36 (8)
C6—C1—C2—O1177.98 (8)C4—C5—C6—C1−0.24 (15)
C6—C1—C2—C3−1.17 (14)C4—C5—C6—C7178.01 (9)
O1—C2—C3—C4−178.19 (9)C8—N1—C7—C6−179.92 (9)
C1—C2—C3—C40.88 (15)C1—C6—C7—N10.51 (15)
C2—C3—C4—C5−0.27 (15)C5—C6—C7—N1−177.70 (10)
C3—C4—C5—C6−0.04 (15)C7—N1—C8—C8i−136.92 (11)

Symmetry codes: (i) −x+1, y, −z+1/2.

Hydrogen-bond geometry (Å, °)

D—H···AD—HH···AD···AD—H···A
C9—H9A···O1ii0.962.503.3809 (13)153
C8—H8B···Cg1iii0.984 (13)2.822 (13)3.6221 (12)138.9 (9)
C9—H9C···Cg1iv0.962.753.5636 (12)143

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

Footnotes

Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: FL2216).

References

  • Bruker (2005). APEX2, SAINT and SADABS Bruker AXS Inc., Madison, Wisconsin, USA.
  • Calligaris, M. & Randaccio, L. (1987). Comprehensive Coordination Chemistry, Vol. 2, edited by G. Wilkinson, pp. 715–738. London: Pergamon.
  • Fun, H.-K., Kargar, H. & Kia, R. (2008b). Acta Cryst. E64, o1308. [PMC free article] [PubMed]
  • Fun, H.-K., Kia, R. & Kargar, H. (2008a). Acta Cryst. E64, o1335. [PMC free article] [PubMed]
  • Fun, H.-K., Mirkhani, V., Kia, R. & Vartooni, A. R. (2008c). Acta Cryst. E64, o1374–o1375. [PMC free article] [PubMed]
  • Fun, H.-K., Mirkhani, V., Kia, R. & Vartooni, A. R. (2008d). Acta Cryst. E64, o1471. [PMC free article] [PubMed]
  • Hou, B., Friedman, N., Ruhman, S., Sheves, M. & Ottolenghi, M. (2001). J. Phys. Chem. B, 105, 7042–7048.
  • Kia, R., Mirkhani, V., Harkema, S. & van Hummel, G. J. (2007b). Inorg. Chim. Acta, 360, 3369–3375.
  • Kia, R., Mirkhani, V., Kalman, A. & Deak, A. (2007a). Polyhedron, 26, 1117–1716.
  • Pal, S., Barik, A. K., Gupta, S., Hazra, A., Kar, S. K., Peng, S.-M., Lee, G.-H., Butcher, R. J., El Fallah, M. S. & Ribas, J. (2005). Inorg. Chem.44, 3880–3889. [PubMed]
  • Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. [PubMed]
  • Spek, A. L. (2003). J. Appl. Cryst.36, 7–13.

Articles from Acta Crystallographica Section E: Structure Reports Online are provided here courtesy of International Union of Crystallography