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

Fun, H.-K.; Mirkhani, V.; Vartooni, A.R.

doi:10.1107/S1600536808026652

organic compounds

CRYSTALLOGRAPHIC
COMMUNICATIONS

ISSN: 2056-9890

Volume 64| Part 9| September 2008| Pages o1803-o1804

doi:10.1107/S1600536808026652

Open

access

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

Hoong-Kun Fun,^a ^* Valiollah Mirkhani ^b ‡ and Akbar Rostami Vartooni ^b

^aX-ray Crystallography Unit, School of Physics, Universiti Sains Malaysia, 11800 USM, Penang, Malaysia, and ^bChemistry Department, University of Isfahan, Isfahan 81746-73441, Iran
^*Correspondence e-mail: hkfun@usm.my

(Received 7 August 2008; accepted 18 August 2008; online 23 August 2008)

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

Experimental

Crystal data

C₁₈H₂₀N₂O₂
M_r = 296.36
Monoclinic, C 2/c
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 ) 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[F² > 2σ(F²)] = 0.041
wR(F²) = 0.108
S = 1.10
2298 reflections
113 parameters
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.35 e Å⁻³
Δρ_min = −0.21 e Å⁻³

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C9—H9A⋯O1ⁱ	0.96	2.50	3.3809 (13)	153
C8—H8B⋯Cg1ⁱⁱ	0.984 (13)	2.822 (13)	3.6221 (12)	138.9 (9)
C9—H9C⋯Cg1ⁱⁱⁱ	0.96	2.75	3.5636 (12)	143
Symmetry codes: (i) $[-x+{\script{1\over 2}}, y-{\script{1\over 2}}, -z+{\script{1\over 2}}]$ ; (ii) x, y+1, z; (iii) $[-x+{\script{1\over 2}}, -y+{\script{1\over 2}}, -z]$ . Cg1 is the centroid of the C1–C6 benzene ring.

Data collection: APEX2 (Bruker, 2005); cell refinement: APEX2; data reduction: SAINT (Bruker, 2005); program(s) used to solve structure: SHELXTL (Sheldrick, 2008 ); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL and PLATON (Spek, 2003 ).

Supporting information

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536808026652/fl2216sup1.cif

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

checkCIF report

Comment top

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).

Related literature top

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

Experimental top

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.

Computing details top

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).

Figures top

	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.

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

Crystal data top

C₁₈H₂₀N₂O₂	F(000) = 632
M_r = 296.36	D_x = 1.249 Mg m⁻³
Monoclinic, C2/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -C 2yc	Cell parameters from 3509 reflections
a = 22.7076 (3) Å	θ = 3.6–33.9°
b = 6.0374 (1) Å	µ = 0.08 mm⁻¹
c = 11.6789 (2) Å	T = 100 K
β = 100.235 (1)°	Block, colourless
V = 1575.64 (4) Å³	0.49 × 0.33 × 0.22 mm
Z = 4

Data collection top

Bruker SMART APEXII CCD area-detector diffractometer	2298 independent reflections
Radiation source: fine-focus sealed tube	1879 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.029
ϕ and ω scans	θ_max = 30.0°, θ_min = 3.5°
Absorption correction: multi-scan (SADABS; Bruker, 2005)	h = −31→31
T_min = 0.886, T_max = 0.982	k = −8→8
11683 measured reflections	l = −14→16

Refinement top

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)] = 0.041	Hydrogen site location: inferred from neighbouring sites
wR(F²) = 0.108	H atoms treated by a mixture of independent and constrained refinement
S = 1.11	w = 1/[σ²(F_o²) + (0.0467P)² + 0.7792P] where P = (F_o² + 2F_c²)/3
2298 reflections	(Δ/σ)_max < 0.001
113 parameters	Δρ_max = 0.35 e Å⁻³
0 restraints	Δρ_min = −0.21 e Å⁻³

Crystal data top

C₁₈H₂₀N₂O₂	V = 1575.64 (4) Å³
M_r = 296.36	Z = 4
Monoclinic, C2/c	Mo Kα radiation
a = 22.7076 (3) Å	µ = 0.08 mm⁻¹
b = 6.0374 (1) Å	T = 100 K
c = 11.6789 (2) Å	0.49 × 0.33 × 0.22 mm
β = 100.235 (1)°

Data collection top

Bruker SMART APEXII CCD area-detector diffractometer	2298 independent reflections
Absorption correction: multi-scan (SADABS; Bruker, 2005)	1879 reflections with I > 2σ(I)
T_min = 0.886, T_max = 0.982	R_int = 0.029
11683 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.041	0 restraints
wR(F²) = 0.108	H atoms treated by a mixture of independent and constrained refinement
S = 1.11	Δρ_max = 0.35 e Å⁻³
2298 reflections	Δρ_min = −0.21 e Å⁻³
113 parameters

Special details top

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) top

	x	y	z	U_iso*/U_eq
O1	0.29856 (3)	0.12810 (12)	0.16829 (6)	0.02029 (18)
N1	0.44163 (4)	0.77578 (14)	0.17093 (8)	0.0197 (2)
C1	0.36408 (4)	0.39310 (16)	0.11788 (8)	0.0166 (2)
H1A	0.3629	0.4625	0.1885	0.020*
C2	0.33032 (4)	0.20304 (16)	0.08715 (8)	0.0167 (2)
C3	0.33099 (4)	0.10022 (17)	−0.01966 (9)	0.0196 (2)
H3A	0.3080	−0.0257	−0.0407	0.024*
C4	0.36637 (4)	0.18805 (18)	−0.09415 (9)	0.0216 (2)
H4A	0.3671	0.1197	−0.1653	0.026*
C5	0.40051 (4)	0.37574 (18)	−0.06388 (9)	0.0203 (2)
H5A	0.4240	0.4328	−0.1145	0.024*
C6	0.39970 (4)	0.47980 (17)	0.04289 (8)	0.0172 (2)
C7	0.43794 (4)	0.67504 (17)	0.07480 (9)	0.0184 (2)
C8	0.48159 (5)	0.96685 (17)	0.18898 (10)	0.0215 (2)
C9	0.26352 (5)	−0.06749 (17)	0.14119 (10)	0.0225 (2)
H9A	0.2443	−0.1047	0.2055	0.034*
H9B	0.2890	−0.1874	0.1267	0.034*
H9C	0.2337	−0.0419	0.0731	0.034*
H7A	0.4614 (6)	0.722 (2)	0.0143 (11)	0.027 (3)*
H8B	0.4562 (6)	1.100 (2)	0.1792 (11)	0.025 (3)*
H8A	0.5085 (6)	0.971 (2)	0.1293 (12)	0.026 (3)*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
O1	0.0226 (4)	0.0197 (4)	0.0195 (4)	−0.0036 (3)	0.0063 (3)	−0.0004 (3)
N1	0.0174 (4)	0.0181 (4)	0.0228 (4)	−0.0004 (3)	0.0018 (3)	0.0020 (3)
C1	0.0170 (4)	0.0178 (4)	0.0144 (4)	0.0026 (3)	0.0015 (3)	−0.0002 (3)
C2	0.0152 (4)	0.0179 (4)	0.0167 (5)	0.0027 (3)	0.0020 (3)	0.0019 (3)
C3	0.0190 (5)	0.0191 (5)	0.0196 (5)	0.0007 (4)	0.0006 (4)	−0.0027 (4)
C4	0.0202 (5)	0.0281 (5)	0.0157 (5)	0.0031 (4)	0.0014 (4)	−0.0039 (4)
C5	0.0177 (5)	0.0271 (5)	0.0161 (5)	0.0012 (4)	0.0031 (4)	0.0016 (4)
C6	0.0153 (4)	0.0192 (5)	0.0163 (4)	0.0022 (3)	0.0003 (3)	0.0022 (4)
C7	0.0164 (4)	0.0197 (5)	0.0189 (5)	0.0008 (4)	0.0026 (4)	0.0056 (4)
C8	0.0186 (5)	0.0162 (5)	0.0291 (6)	−0.0010 (4)	0.0027 (4)	0.0027 (4)
C9	0.0226 (5)	0.0189 (5)	0.0255 (5)	−0.0033 (4)	0.0025 (4)	0.0019 (4)

Geometric parameters (Å, º) top

O1—C2	1.3659 (12)	C4—H4A	0.9300
O1—C9	1.4277 (12)	C5—C6	1.3993 (14)
N1—C7	1.2665 (14)	C5—H5A	0.9300
N1—C8	1.4597 (13)	C6—C7	1.4723 (14)
C1—C2	1.3912 (14)	C7—H7A	0.999 (13)
C1—C6	1.3954 (13)	C8—C8ⁱ	1.519 (2)
C1—H1A	0.9300	C8—H8B	0.984 (13)
C2—C3	1.3958 (14)	C8—H8A	1.005 (13)
C3—C4	1.3899 (14)	C9—H9A	0.9600
C3—H3A	0.9300	C9—H9B	0.9600
C4—C5	1.3830 (15)	C9—H9C	0.9600

C2—O1—C9	117.53 (8)	C1—C6—C7	121.54 (9)
C7—N1—C8	116.68 (9)	C5—C6—C7	118.98 (9)
C2—C1—C6	120.12 (9)	N1—C7—C6	123.50 (9)
C2—C1—H1A	119.9	N1—C7—H7A	122.1 (8)
C6—C1—H1A	119.9	C6—C7—H7A	114.4 (8)
O1—C2—C1	115.39 (8)	N1—C8—C8ⁱ	111.10 (7)
O1—C2—C3	124.31 (9)	N1—C8—H8B	106.9 (8)
C1—C2—C3	120.29 (9)	C8ⁱ—C8—H8B	108.8 (8)
C4—C3—C2	119.28 (9)	N1—C8—H8A	111.0 (8)
C4—C3—H3A	120.4	C8ⁱ—C8—H8A	110.5 (7)
C2—C3—H3A	120.4	H8B—C8—H8A	108.3 (11)
C5—C4—C3	120.84 (9)	O1—C9—H9A	109.5
C5—C4—H4A	119.6	O1—C9—H9B	109.5
C3—C4—H4A	119.6	H9A—C9—H9B	109.5
C4—C5—C6	120.01 (9)	O1—C9—H9C	109.5
C4—C5—H5A	120.0	H9A—C9—H9C	109.5
C6—C5—H5A	120.0	H9B—C9—H9C	109.5
C1—C6—C5	119.46 (9)

C9—O1—C2—C1	−179.56 (8)	C2—C1—C6—C5	0.84 (14)
C9—O1—C2—C3	−0.45 (14)	C2—C1—C6—C7	−177.36 (8)
C6—C1—C2—O1	177.98 (8)	C4—C5—C6—C1	−0.24 (15)
C6—C1—C2—C3	−1.17 (14)	C4—C5—C6—C7	178.01 (9)
O1—C2—C3—C4	−178.19 (9)	C8—N1—C7—C6	−179.92 (9)
C1—C2—C3—C4	0.88 (15)	C1—C6—C7—N1	0.51 (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 code: (i) −x+1, y, −z+1/2.

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
C9—H9A···O1ⁱⁱ	0.96	2.50	3.3809 (13)	153
C8—H8B···Cg1ⁱⁱⁱ	0.984 (13)	2.822 (13)	3.6221 (12)	138.9 (9)
C9—H9C···Cg1^iv	0.96	2.75	3.5636 (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.

Experimental details

Crystal data
Chemical formula	C₁₈H₂₀N₂O₂
M_r	296.36
Crystal system, space group	Monoclinic, C2/c
Temperature (K)	100
a, b, c (Å)	22.7076 (3), 6.0374 (1), 11.6789 (2)
β (°)	100.235 (1)
V (Å³)	1575.64 (4)
Z	4
Radiation type	Mo Kα
µ (mm⁻¹)	0.08
Crystal size (mm)	0.49 × 0.33 × 0.22

Data collection
Diffractometer	Bruker SMART APEXII CCD area-detector diffractometer
Absorption correction	Multi-scan (SADABS; Bruker, 2005)
T_min, T_max	0.886, 0.982
No. of measured, independent and observed [I > 2σ(I)] reflections	11683, 2298, 1879
R_int	0.029
(sin θ/λ)_max (Å⁻¹)	0.703

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.041, 0.108, 1.11
No. of reflections	2298
No. of parameters	113
H-atom treatment	H atoms treated by a mixture of independent and constrained refinement
Δρ_max, Δρ_min (e Å⁻³)	0.35, −0.21

Computer programs: APEX2 (Bruker, 2005), SAINT (Bruker, 2005), SHELXTL (Sheldrick, 2008) and PLATON (Spek, 2003).

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
C9—H9A···O1ⁱ	0.9600	2.5000	3.3809 (13)	153.00
C8—H8B···Cg1ⁱⁱ	0.984 (13)	2.822 (13)	3.6221 (12)	138.9 (9)
C9—H9C···Cg1ⁱⁱⁱ	0.9600	2.7500	3.5636 (12)	143.00

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

Footnotes

‡Additional correspondence author: e-mail: mirkhani@sci.ui.ac.ir.

Acknowledgements

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.

References

Bruker (2005). APEX2, SAINT and SADABS. Bruker AXS Inc., Madison, Wisconsin, USA. Google Scholar
Calligaris, M. & Randaccio, L. (1987). Comprehensive Coordination Chemistry, Vol. 2, edited by G. Wilkinson, pp. 715–738. London: Pergamon. Google Scholar
Fun, H.-K., Kargar, H. & Kia, R. (2008b). Acta Cryst. E64, o1308. Web of Science CSD CrossRef IUCr Journals Google Scholar
Fun, H.-K., Kia, R. & Kargar, H. (2008a). Acta Cryst. E64, o1335. Web of Science CSD CrossRef IUCr Journals Google Scholar
Fun, H.-K., Mirkhani, V., Kia, R. & Vartooni, A. R. (2008c). Acta Cryst. E64, o1374–o1375. Web of Science CrossRef IUCr Journals Google Scholar
Fun, H.-K., Mirkhani, V., Kia, R. & Vartooni, A. R. (2008d). Acta Cryst. E64, o1471. Web of Science CSD CrossRef IUCr Journals Google Scholar
Hou, B., Friedman, N., Ruhman, S., Sheves, M. & Ottolenghi, M. (2001). J. Phys. Chem. B, 105, 7042–7048. Web of Science CrossRef CAS Google Scholar
Kia, R., Mirkhani, V., Harkema, S. & van Hummel, G. J. (2007b). Inorg. Chim. Acta, 360, 3369–3375. Web of Science CSD CrossRef CAS Google Scholar
Kia, R., Mirkhani, V., Kalman, A. & Deak, A. (2007a). Polyhedron, 26, 1117–1716. Google Scholar
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. Web of Science CSD CrossRef PubMed CAS Google Scholar
Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. Web of Science CrossRef CAS IUCr Journals Google Scholar
Spek, A. L. (2003). J. Appl. Cryst. 36, 7–13. Web of Science CrossRef CAS IUCr Journals Google Scholar