2-Methoxy­benzaldehyde azine

The mol­ecule of the title compound, C₁₆H₁₆N₂O₂, is located on a centre of inversion (at the midpoint of the N-N bond), so that only one half of the mol­ecule is crystallographically independent, and it adopts a syn structure with respect to the meth­oxy group and the aldehyde H atom. The benzene ring and adjacent N atom are coplanar (r.m.s. deviation of 0.017 Å for the non-H atoms). The meth­oxy group deviates from the benzene plane by 0.167 (4) Å for the methyl C atom.

Key indicators

• Single-crystal X-ray study
• T = 293 K
• Mean [sigma](C-C) = 0.003 Å
• R factor = 0.046
• wR factor = 0.166
• Data-to-parameter ratio = 18.0

checkCIF/PLATON results

No syntax errors found



Alert level A
DIFF019_ALERT_1_A  _diffrn_standards_number is missing
            Number of standards used in measurement.
DIFF020_ALERT_1_A  _diffrn_standards_interval_count and
            _diffrn_standards_interval_time are missing. Number of measurements
            between standards or time (min) between standards.

Alert level C
PLAT241_ALERT_2_C Check High      Ueq as Compared to Neighbors for         C5

Alert level G
PLAT199_ALERT_1_G Check the Reported _cell_measurement_temperature        293 K
PLAT200_ALERT_1_G Check the Reported _diffrn_ambient_temperature .        293 K

   2 ALERT level A = In general: serious problem
   0 ALERT level B = Potentially serious problem
   1 ALERT level C = Check and explain
   2 ALERT level G = General alerts; check

   4 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   1 ALERT type 2 Indicator that the structure model may be wrong or deficient
   0 ALERT type 3 Indicator that the structure quality may be low
   0 ALERT type 4 Improvement, methodology, query or suggestion
   0 ALERT type 5 Informative message, check

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S1. Comment

Azines represent a well known class of organic compounds, obtained from the condensation of an aldehyde or ketone with hydrazine (Glaser et al., 1995; Amadei et al., 1998). As a extension of work on the structure characterization of azines, we report here the crystal structure of compound, 2,2'-di(N)-methoxybenzaldehyde azine (I).

The molecule geometry of (I) is illustrated is Fig. 1. A l l bond lengths are within in normal ranges (Allen et al., 1987). The molecule is plased on the centre of inversion (the middle N1—N1A bond) so that only half of the molecule of crystallographically independent. The methoxy group is syn to the H atom on C7, so the molecule adopts a syn configuration in solid state (Xu et al., 1994; Hsu & Nordman, 1993). The N1—C7 (1.269 (2) Å) and N1—N1A (1.403 (2) Å) distances indicate these correspond to double and single bonds, respectively. The torsion angle N1—C7—C1—C2 (-176.4 (1) °) indicates the molecule is practically planar. The maximum deviation from the mean phenyl plane is 0.017 Å for non–hydrogen atoms. The atom H7 and O1 atom of methoxy group form contact 2.401 Å and atom C8 of methoxy group displaced out of the phenyl plane on -0.167 (4) Å. The packing diagram of (I) is showed in Fig. 2.

Related literature

For related literature, see: Allen et al. (1987); Amadei et al. (1998); Glaser et al. (1995); Hsu et al. (1993); Xu et al. (1994).

S2. Experimental

The reagents are commercial products and used without further purification. 2-methoxybenzaldehyde (0.2 mmol, 28.4 mg) and the hydrazine (0.1 mmol, about 5.0 mg) were dissolved in ethanol (99%, 15 ml). The reaction mixture was stirring for 1 h to give a clear solution at room temperature. After allowing the solution to stand at room temperature in air for a week, large yellow crystals were isolated. The crystals were flitrated, washed three times with ethanol and dried in air, yield 82.4%.

S3. Refinement

The methyl H atoms were positioned geometrically and treated as riding (C—H = 0.96 Å and U_iso(H) = 1.5U_eq(C)); other H atoms were positioned geometrically and treated as riding (C—H = 0.93 Å and U_iso(H) = 1.2U_eq(C)).

Computing details

Data collection: TEXRAY (Molecular Structure Corporation, 1999); cell refinement: TEXRAY; data reduction: TEXSAN (Molecular Structure Corporation, 1999); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEX (McArdle, 1995); software used to prepare material for publication: SHELXL97.

Figures

	Fig. 1. The structure (I) showing the atomic numbering scheme. Displacement ellipsoids are drawn at the 50% probability lavel. The H atoms are drawn as sphere with arbitrary radius.
	Fig. 2. Packing diagram of (I). The H atoms have been omitted for clarity.

2-Methoxybenzaldehyde azine

Crystal data

C16H16N2O2	F(000) = 284
Mr = 268.31	Dx = 1.225 Mg m^−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybc	Cell parameters from 5435 reflections
a = 7.755 (5) Å	θ = 3.2–27.5°
b = 14.757 (12) Å	µ = 0.08 mm^−1
c = 6.889 (5) Å	T = 293 K
β = 112.64 (3)°	Block, yellow
V = 727.6 (9) Å^3	0.26 × 0.21 × 0.18 mm
Z = 2

Data collection

Rigaku R-AXIS RAPID diffractometer	1203 reflections with I > 2σ(I)
Radiation source: rotating anode	Rint = 0.035
Graphite monochromator	θmax = 27.5°, θmin = 3.2°
oscillation scans	h = −10→9
6946 measured reflections	k = −19→19
1659 independent reflections	l = −8→8

Refinement

Refinement on F^2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F^2 > 2σ(F^2)] = 0.046	H-atom parameters constrained
wR(F^2) = 0.166	w = 1/[σ^2(Fo^2) + (0.1031P)^2 + 0.0369P] where P = (Fo^2 + 2Fc^2)/3
S = 1.01	(Δ/σ)max < 0.001
1659 reflections	Δρmax = 0.16 e Å^−3
92 parameters	Δρmin = −0.13 e Å^−3
0 restraints	Extinction correction: SHELXL97 (Sheldrick, 1997), Fc^*=kFc[1+0.001 x Fc^2λ^3/sin(2θ)]^-1/4
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.23 (3)

Special details

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 > 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 (Ų)

	x	y	z	Uiso*/Ueq
C1	0.1164 (2)	0.08853 (9)	0.1805 (2)	0.0613 (4)
C2	0.0362 (2)	0.13640 (9)	−0.0083 (2)	0.0678 (4)
C3	0.1480 (4)	0.16846 (13)	−0.1093 (3)	0.0966 (7)
H3A	0.0958	0.2016	−0.2332	0.116*
C4	0.3364 (4)	0.1510 (2)	−0.0251 (4)	0.1257 (10)
H4A	0.4111	0.1711	−0.0944	0.151*
C5	0.4147 (3)	0.1046 (2)	0.1579 (4)	0.1267 (9)
H5A	0.5427	0.0938	0.2141	0.152*
C6	0.3058 (2)	0.07374 (15)	0.2604 (3)	0.0903 (6)
H6A	0.3612	0.0422	0.3862	0.108*
C7	−0.00032 (18)	0.05390 (9)	0.28700 (19)	0.0577 (4)
H7A	−0.1292	0.0612	0.2234	0.069*
C8	−0.2450 (4)	0.18658 (18)	−0.2825 (3)	0.1183 (8)
H8A	−0.3763	0.1911	−0.3125	0.177*
H8B	−0.2260	0.1487	−0.3858	0.177*
H8C	−0.1954	0.2459	−0.2863	0.177*
N1	0.06864 (15)	0.01420 (8)	0.46363 (16)	0.0628 (4)
O1	−0.15225 (19)	0.14829 (8)	−0.07995 (17)	0.0871 (5)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
C1	0.0803 (9)	0.0508 (7)	0.0577 (7)	−0.0112 (5)	0.0321 (6)	−0.0054 (5)
C2	0.1069 (11)	0.0475 (7)	0.0580 (7)	−0.0068 (6)	0.0416 (7)	−0.0048 (5)
C3	0.1614 (19)	0.0734 (10)	0.0744 (10)	−0.0385 (11)	0.0670 (11)	−0.0075 (8)
C4	0.1358 (19)	0.161 (2)	0.1059 (16)	−0.0805 (17)	0.0745 (15)	−0.0260 (15)
C5	0.0896 (13)	0.185 (2)	0.1142 (17)	−0.0513 (14)	0.0486 (12)	−0.0095 (16)
C6	0.0744 (10)	0.1140 (14)	0.0814 (11)	−0.0237 (9)	0.0288 (8)	0.0008 (9)
C7	0.0667 (7)	0.0543 (7)	0.0536 (7)	0.0026 (5)	0.0248 (6)	0.0042 (5)
C8	0.1629 (19)	0.1248 (17)	0.0738 (11)	0.0578 (15)	0.0529 (11)	0.0415 (11)
N1	0.0672 (7)	0.0695 (7)	0.0532 (6)	−0.0008 (5)	0.0249 (5)	0.0069 (5)
O1	0.1201 (10)	0.0851 (8)	0.0633 (7)	0.0299 (6)	0.0433 (6)	0.0244 (5)

Geometric parameters (Å, º)

C1—C6	1.373 (2)	C5—H5A	0.9300
C1—C2	1.398 (2)	C6—H6A	0.9300
C1—C7	1.4590 (19)	C7—N1	1.2684 (17)
C2—O1	1.362 (2)	C7—H7A	0.9300
C2—C3	1.388 (2)	C8—O1	1.418 (2)
C3—C4	1.373 (4)	C8—H8A	0.9600
C3—H3A	0.9300	C8—H8B	0.9600
C4—C5	1.355 (4)	C8—H8C	0.9600
C4—H4A	0.9300	N1—N1^i	1.404 (2)
C5—C6	1.370 (3)
C6—C1—C2	118.49 (14)	C5—C6—C1	121.1 (2)
C6—C1—C7	121.18 (14)	C5—C6—H6A	119.4
C2—C1—C7	120.32 (14)	C1—C6—H6A	119.4
O1—C2—C3	124.40 (16)	N1—C7—C1	122.00 (13)
O1—C2—C1	115.69 (13)	N1—C7—H7A	119.0
C3—C2—C1	119.92 (17)	C1—C7—H7A	119.0
C4—C3—C2	119.54 (19)	O1—C8—H8A	109.5
C4—C3—H3A	120.2	O1—C8—H8B	109.5
C2—C3—H3A	120.2	H8A—C8—H8B	109.5
C5—C4—C3	120.68 (18)	O1—C8—H8C	109.5
C5—C4—H4A	119.7	H8A—C8—H8C	109.5
C3—C4—H4A	119.7	H8B—C8—H8C	109.5
C4—C5—C6	120.2 (2)	C7—N1—N1^i	112.50 (13)
C4—C5—H5A	119.9	C2—O1—C8	118.37 (15)
C6—C5—H5A	119.9
C6—C1—C2—O1	179.56 (13)	C4—C5—C6—C1	0.2 (4)
C7—C1—C2—O1	0.69 (18)	C2—C1—C6—C5	−0.3 (3)
C6—C1—C2—C3	−0.6 (2)	C7—C1—C6—C5	178.59 (19)
C7—C1—C2—C3	−179.48 (13)	C6—C1—C7—N1	4.8 (2)
O1—C2—C3—C4	−178.68 (17)	C2—C1—C7—N1	−176.39 (12)
C1—C2—C3—C4	1.5 (3)	C1—C7—N1—N1^i	−179.52 (12)
C2—C3—C4—C5	−1.5 (3)	C3—C2—O1—C8	7.6 (2)
C3—C4—C5—C6	0.7 (4)	C1—C2—O1—C8	−172.55 (16)

Symmetry code: (i) −x, −y, −z+1.