2,4-Dimethoxy­benzaldehyde azine

Islam, M.A.A.A.A.; Tarafder, M.T.H.; Alam, M.A.; Guidolin, N.; Zangrando, E.

doi:10.1107/S1600536809038082

organic compounds

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ISSN: 2056-9890

Volume 65| Part 10| October 2009| Page o2560

doi:10.1107/S1600536809038082

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2,4-Dimethoxybenzaldehyde azine

M. A. A. A. A. Islam,^a M. T. H. Tarafder,^b ^* M. A. Alam,^a N. Guidolin ^c and E. Zangrando ^c

^aDepartment of Chemistry, Rajshahi University of Engineering and Technology, Rajshahi 6204, Bangladesh, ^bDepartment of Chemistry, Rajshahi University, Rajshahi 6205, Bangladesh, and ^cDipartimento di Scienze Chimiche, Via Licio Giorgieri 1, 34127 Trieste, Italy
^*Correspondence e-mail: ttofazzal@yahoo.com

(Received 9 September 2009; accepted 21 September 2009; online 26 September 2009)

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 ); Liu et al. (2007 ); Takakashi et al. (2006 ). For a statistical study of methoxy groups bound to phenyl rings, see: Hummel et al. (1988 ).

Experimental

Crystal data

C₁₈H₂₀N₂O₄
M_r = 328.36
Monoclinic, P 2₁ /c
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
θ_max = 24.1°

Refinement

R[F² > 2σ(F²)] = 0.045
wR(F²) = 0.121
S = 0.84
1293 reflections
110 parameters
H-atom parameters constrained
Δρ_max = 0.12 e Å⁻³
Δρ_min = −0.10 e Å⁻³

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

Supporting information

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

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

checkCIF report

Comment top

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.

Related literature top

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

Experimental top

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.

Computing details top

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

Figures top

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.

2,4-Dimethoxybenzaldehyde azine top

Crystal data top

C₁₈H₂₀N₂O₄	F(000) = 348
M_r = 328.36	D_x = 1.289 Mg m⁻³
Monoclinic, P2₁/c	Melting point: 475 K
Hall symbol: -P 2ybc	Mo Kα radiation, λ = 0.71073 Å
a = 6.775 (2) Å	Cell parameters from 482 reflections
b = 9.014 (3) Å	θ = 3.6–20.7°
c = 14.081 (3) Å	µ = 0.09 mm⁻¹
β = 100.42 (2)°	T = 293 K
V = 845.7 (4) Å³	Plate, yellow
Z = 2	0.45 × 0.30 × 0.12 mm

Data collection top

Enraf–Nonius DIP1030 image-plate diffractometer	719 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	R_int = 0.058
Graphite monochromator	θ_max = 24.1°, θ_min = 2.9°
ϕ–scans with narrow frames	h = −7→7
3535 measured reflections	k = −10→10
1293 independent reflections	l = −16→16

Refinement top

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)] = 0.045	H-atom parameters constrained
wR(F²) = 0.121	w = 1/[σ²(F_o²) + (0.0678P)²] where P = (F_o² + 2F_c²)/3
S = 0.84	(Δ/σ)_max < 0.001
1293 reflections	Δρ_max = 0.12 e Å⁻³
110 parameters	Δρ_min = −0.10 e Å⁻³
0 restraints	Extinction correction: SHELXL97 (Sheldrick, 2008), Fc^*=kFc[1+0.001xFc²λ³/sin(2θ)]^-1/4
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.070 (13)

Crystal data top

C₁₈H₂₀N₂O₄	V = 845.7 (4) Å³
M_r = 328.36	Z = 2
Monoclinic, P2₁/c	Mo Kα radiation
a = 6.775 (2) Å	µ = 0.09 mm⁻¹
b = 9.014 (3) Å	T = 293 K
c = 14.081 (3) Å	0.45 × 0.30 × 0.12 mm
β = 100.42 (2)°

Data collection top

Enraf–Nonius DIP1030 image-plate diffractometer	719 reflections with I > 2σ(I)
3535 measured reflections	R_int = 0.058
1293 independent reflections	θ_max = 24.1°

Refinement top

R[F² > 2σ(F²)] = 0.045	0 restraints
wR(F²) = 0.121	H-atom parameters constrained
S = 0.84	Δρ_max = 0.12 e Å⁻³
1293 reflections	Δρ_min = −0.10 e Å⁻³
110 parameters

Special details top

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) top

	x	y	z	U_iso*/U_eq
N1	−0.4202 (3)	0.4904 (2)	0.53948 (13)	0.0857 (6)
O1	0.0297 (2)	0.77203 (18)	0.52320 (12)	0.0960 (6)
O2	0.4398 (2)	0.55904 (18)	0.80720 (11)	0.0952 (6)
C1	−0.2709 (4)	0.5738 (3)	0.53259 (16)	0.0833 (7)
H1	−0.2800	0.6376	0.4800	0.100*
C2	−0.0880 (3)	0.5722 (2)	0.60384 (15)	0.0745 (6)
C3	0.0667 (3)	0.6732 (2)	0.59790 (16)	0.0768 (6)
C4	0.2433 (3)	0.6732 (2)	0.66487 (16)	0.0785 (7)
H4	0.3431	0.7425	0.6606	0.094*
C5	0.2699 (3)	0.5695 (3)	0.73791 (16)	0.0787 (6)
C6	0.1196 (4)	0.4673 (3)	0.74624 (17)	0.0850 (7)
H6	0.1372	0.3984	0.7962	0.102*
C7	−0.0547 (3)	0.4704 (3)	0.67925 (18)	0.0830 (7)
H7	−0.1546	0.4017	0.6845	0.100*
C8	0.1918 (4)	0.8551 (3)	0.49880 (19)	0.1041 (9)
H8A	0.1429	0.9185	0.4449	0.156*
H8B	0.2905	0.7885	0.4820	0.156*
H8C	0.2514	0.9144	0.5531	0.156*
C9	0.5936 (3)	0.6675 (3)	0.80431 (19)	0.1042 (9)
H9A	0.7046	0.6488	0.8557	0.156*
H9B	0.5410	0.7648	0.8118	0.156*
H9C	0.6381	0.6614	0.7435	0.156*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
N1	0.0716 (13)	0.0972 (13)	0.0854 (14)	0.0055 (12)	0.0066 (9)	−0.0007 (11)
O1	0.0858 (11)	0.1004 (12)	0.0995 (12)	−0.0022 (9)	0.0106 (9)	0.0169 (10)
O2	0.0820 (11)	0.1060 (13)	0.0915 (12)	−0.0027 (9)	−0.0012 (9)	0.0038 (9)
C1	0.0778 (16)	0.0904 (16)	0.0803 (15)	0.0037 (13)	0.0101 (13)	0.0021 (12)
C2	0.0693 (14)	0.0799 (14)	0.0732 (14)	0.0017 (12)	0.0099 (12)	−0.0017 (12)
C3	0.0782 (15)	0.0787 (15)	0.0728 (14)	0.0082 (13)	0.0118 (13)	0.0026 (12)
C4	0.0734 (15)	0.0799 (15)	0.0818 (15)	−0.0017 (12)	0.0132 (13)	−0.0029 (13)
C5	0.0722 (15)	0.0864 (15)	0.0755 (15)	0.0053 (13)	0.0084 (13)	−0.0065 (13)
C6	0.0806 (16)	0.0919 (16)	0.0815 (16)	0.0009 (13)	0.0114 (14)	0.0056 (13)
C7	0.0772 (16)	0.0870 (16)	0.0841 (16)	−0.0032 (12)	0.0126 (13)	−0.0010 (13)
C8	0.1061 (19)	0.0956 (17)	0.113 (2)	−0.0067 (16)	0.0255 (16)	0.0164 (15)
C9	0.0775 (16)	0.115 (2)	0.114 (2)	−0.0073 (15)	0.0006 (15)	−0.0033 (16)

Geometric parameters (Å, º) top

N1—C1	1.278 (3)	C4—H4	0.9300
N1—N1ⁱ	1.414 (4)	C5—C6	1.393 (3)
O1—C3	1.366 (2)	C6—C7	1.372 (3)
O1—C8	1.422 (3)	C6—H6	0.9300
O2—C5	1.371 (3)	C7—H7	0.9300
O2—C9	1.435 (3)	C8—H8A	0.9600
C1—C2	1.446 (3)	C8—H8B	0.9600
C1—H1	0.9300	C8—H8C	0.9600
C2—C7	1.391 (3)	C9—H9A	0.9600
C2—C3	1.402 (3)	C9—H9B	0.9600
C3—C4	1.383 (3)	C9—H9C	0.9600
C4—C5	1.378 (3)

C1—N1—N1ⁱ	111.8 (2)	C7—C6—C5	118.7 (2)
C3—O1—C8	119.13 (18)	C7—C6—H6	120.7
C5—O2—C9	116.98 (19)	C5—C6—H6	120.7
N1—C1—C2	122.2 (2)	C6—C7—C2	122.6 (2)
N1—C1—H1	118.9	C6—C7—H7	118.7
C2—C1—H1	118.9	C2—C7—H7	118.7
C7—C2—C3	117.0 (2)	O1—C8—H8A	109.5
C7—C2—C1	122.4 (2)	O1—C8—H8B	109.5
C3—C2—C1	120.5 (2)	H8A—C8—H8B	109.5
O1—C3—C4	122.7 (2)	O1—C8—H8C	109.5
O1—C3—C2	115.7 (2)	H8A—C8—H8C	109.5
C4—C3—C2	121.5 (2)	H8B—C8—H8C	109.5
C5—C4—C3	119.3 (2)	O2—C9—H9A	109.5
C5—C4—H4	120.4	O2—C9—H9B	109.5
C3—C4—H4	120.4	H9A—C9—H9B	109.5
O2—C5—C4	123.9 (2)	O2—C9—H9C	109.5
O2—C5—C6	115.3 (2)	H9A—C9—H9C	109.5
C4—C5—C6	120.8 (2)	H9B—C9—H9C	109.5

N1ⁱ—N1—C1—C2	−178.8 (2)	C2—C3—C4—C5	1.5 (3)
N1—C1—C2—C7	6.4 (3)	C9—O2—C5—C4	2.6 (3)
N1—C1—C2—C3	−175.1 (2)	C9—O2—C5—C6	−176.66 (18)
C8—O1—C3—C4	15.1 (3)	C3—C4—C5—O2	179.32 (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—O1	1.5 (3)	C4—C5—C6—C7	1.0 (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—C6	0.5 (3)
O1—C3—C4—C5	−179.68 (18)	C1—C2—C7—C6	179.1 (2)

Symmetry code: (i) −x−1, −y+1, −z+1.

Experimental details

Crystal data
Chemical formula	C₁₈H₂₀N₂O₄
M_r	328.36
Crystal system, space group	Monoclinic, P2₁/c
Temperature (K)	293
a, b, c (Å)	6.775 (2), 9.014 (3), 14.081 (3)
β (°)	100.42 (2)
V (Å³)	845.7 (4)
Z	2
Radiation type	Mo Kα
µ (mm⁻¹)	0.09
Crystal size (mm)	0.45 × 0.30 × 0.12

Data collection
Diffractometer	Enraf–Nonius DIP1030 image-plate diffractometer
Absorption correction	–
No. of measured, independent and observed [I > 2σ(I)] reflections	3535, 1293, 719
R_int	0.058
θ_max (°)	24.1
(sin θ/λ)_max (Å⁻¹)	0.575

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.045, 0.121, 0.84
No. of reflections	1293
No. of parameters	110
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.12, −0.10

Computer programs: XPRESS (MacScience, 2002, DENZO (Otwinowski & Minor, 1997), DENZO and SCALEPACK (Otwinowski & Minor, 1997), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), ORTEP-3 for Windows (Farrugia, 1997), WinGX (Farrugia, 1999).

Acknowledgements

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.

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