A cis-stilbene derivative

The title compound, 4′-methoxy-α,2,3′,4-tetra­nitro­stilbene, C₁₅H₁₀N₄O₉, crystallizes in the centrosymmetric space group P2₁/c with one mol­ecule in the asymmetric unit. The phenyl rings are inclined to one another and form a dihedral angle of 57.4 (1)°. The size of this angle is a result of intermolecular C—H...O interactions involving the phenyl H atoms. The torsion angle between the phenyl rings, −7.5 (3)°, indicates a cis geometry between them. The methoxy group is almost coplanar with the phenyl ring, and the nitro groups are twisted with respect to the phenyl rings because of the short H...O contacts. The crystal packing is stabilized by C—H...O hydrogen bonds, and the intermolecular hydrogen bonds form a C(12) graph-set chain running along the [010] direction.

S1. Comment

Nitro compounds are well known for their uses as explosives, dye intermediates and battery cathodes (Sivasamy et al., 1988; Renuka et al., 2001)·These compounds are excellent precursors for aromatic amines and medicinally important compounds. Some synthetic nitro compounds are used in perfumery. m-Dinitrobenzene has been found to function as an organic cathode material in batteries. The new synthetic methodologies for polynitro compounds are of much importance in the chemical industry and defence research studies. α-Nitrostilbenes are excellent precursors for biologically active β-phenylethylamines and Michael acceptors (Robertson, 1960; Flintoft et al., 1999). A survey of the literature shows that only a few styrenes undergo direct nitration to give β-nitrostyrenes, while there are no reports of side-chain nitration of stilbenes. Against this background, and in order to obtain detailed information on the molecular conformation of nitrostilbenes in the solid state, X-ray studies of the title compound, (I), have been carried out and the results are presented here.

Fig. 1 shows a ZORTEP plot (Zsolnai, 1997) of (I) with the atom-numbering scheme. The phenyl rings are twisted out of the ethylenic bond plane as defined by the torsion angles C1—C6—C7═C8 and C7═C8—C9—C14. Therefore the phenyl rings are inclined to each other; the dihedral angle formed between their mean plane is 57.4 (1)° as a result of the C—H···O intermolecular interactions involving the phenyl H atoms. The bond length C7═C8 is typical of the reported ethylene C═C bond length [1.318 (5)–1.326 (3) Å (Finder et al., 1974; Bernstein,1975)] and of a non-conjugated double bond. The N═O distances of the nitro groups, except N3═O5, are comparable to the literature values C_ar—NO₂ = 1.217 (11) Å (Allen et al., 1987) and also agree with the average value of 1.216 (7) Å reported by Jeyakanthan (2000). Comparing the C7═C8 distance with the expected 1.317 (13) value for a localized double bond (Allen et al., 1987) it seems that there is a tendency to have some lengthening that is indicative of some π conjugation of the two phenyls through the central ethene bridge and agrees with the shortening of the two C6—C7 and C8—C9 bonds whose average distance, 1.471 (4), coincides with the value 1.470 (15) given by Allen et al. (1987) for a C_ar—C_sp²conjugate bond. Similar values have been observed for (Z)-5-(methoxymethyl)-3-[4-phenylethenyl)phenyl]-2-oxazolidinone (Durant et al., 1982).

Because of the high electron-withdrawing capacity of the two NO₂ groups, the dinitrophenyl ring causes high polarization of the olefinic double bond and enhanced electron density on the α carbon to the dinitrophenyl group. This mechanism is responsible for nitration on that carbon only. The valence angles between the olefinic double bond and the two phenyl rings, C7═C8—C9 = 127.8 (2) and C6—C7═C8 = 126.2 (2)°, are almost equal and are larger than 120°, which indicates steric repulsion between the two aromatic rings that are in a cis configuration. These values are comparable to the reported values of other cis stilbenes (Tinant et al., 1989, 1983). The methoxy group has an almost coplanar orientation with respect to atoms C2 and C4, as is evident from the torsion angles C2—C3—O9—C15 and C4—C3—O9—C15, respectively.

Nitro group O4═N2═O3 has an almost coplanar orientation with respect to the side chain C6—C7═C8—C9, as is evident from the torsion angles O3═N2—C8—C7 and O4═N2—C8—C7, respectively. The dihedral angle between C9,···,C14 and O5═N3═O6 is 19.9 (1)° and between C1,···,C6 and O1═N1═O2 is 48.1 (1)°. These nitro groups are twisted out of the plane passing through the phenyl rings to which they are attached, whereas the nitro group O7═N4═O8 is nearly coplanar with C9,···,C14 as the dihedral angle is 9.5 (1)°. The twistings of the nitro groups are evidenced by the following short H···O contacts: H1···O2 2.60, H7···O4 2.32, H13···O6 2.41, H13···O8 2.44, H11—O7 2.44 Å. Atoms C7 and C8 deviate from the planes of the respective phenyl rings by 0.094 (2) and 0.025 (2) Å, respectively. The inter torsion angle between the phenyl rings C6—C7═C8—C9 = −7.5 (3)° also indicates a cis geometry between them.

In addition to the van der Waals interactions the crystal packing is stabilized by C—H···O interactions (Table 2). The C4—H4···O8 hydrogen bond forms a graph-set chain C(12) (Bernstein et al., 1995) in a zigzag manner represented by C4—H4···O8═N4—C12—C13—C14—C9—C8═C7—C6—C5 running along the [010] direction (Fig 2).

S2. Experimental

To 5mM (1.80 g) of 4'-methoxy-2,4-dinitrostilbene, 5.5 ml of fuming nitric acid was added slowly with stirring. The reaction mixture was kept at 363 K for five minutes. After cooling to 298–303 K, the reaction mixture was poured over crushed ice, the crude product was filtered off, washed with water, desiccated over anhydrous CaCl₂ and recrystallized from acetone (Saravanan & Srinivasan, 2002).

S3. Refinement

All the H atoms were geometrically fixed and allowed to ride on their parent atoms, with C—H = 0.93–0.96 Å and U_iso = 1.5U_eq(C) for methyl H atoms and 1.2U_eq(C) for other H atoms.

Computing details

Data collection: CAD-4 Software (Enraf–Nonius, 1989); cell refinement: CAD-4 Software; data reduction: TEXSAN (Molecular Structure Corporation, 1985); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ZORTEP (Zsolnai, 1997) and PLATON (Spek, 2003); software used to prepare material for publication: SHELX97 and PARST (Nardelli, 1995).

Figures

	Fig. 1. : Molecular structure showing 30% probability displacement ellipsoids with the atom-numbering scheme. H atoms are shown as small spheres of arbitrary radii.
	Fig. 2. : The crystal structure of (I) with the hydrogen-bonding scheme shown as dashed lines.

4'-methoxy-α,2,3'4-tetranitrostilbene

Crystal data

C15H10N4O9	F(000) = 800
Mr = 390.27	Dx = 1.521 Mg m^−3
Monoclinic, P21/c	Cu Kα radiation, λ = 1.54178 Å
a = 7.096 (4) Å	Cell parameters from 25 reflections
b = 8.550 (3) Å	θ = 5.4–67.9°
c = 28.101 (5) Å	µ = 1.12 mm^−1
β = 90.87 (3)°	T = 293 K
V = 1704.7 (12) Å^3	Block, colorless
Z = 4	0.6 × 0.40 × 0.35 mm

Data collection

Enraf-Nonius CAD-4 diffractometer	Rint = 0.034
Radiation source: fine-focus sealed tube	θmax = 67.9°, θmin = 5.4°
Graphite monochromator	h = 0→8
Non–profiled w/2θ scans	k = −10→10
6505 measured reflections	l = −33→33
3105 independent reflections	3 standard reflections every 100 reflections
2787 reflections with I > 2σ(I)	intensity decay: none

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)] = 0.051	H-atom parameters constrained
wR(F^2) = 0.153	w = 1/[σ^2(Fo^2) + (0.0939P)^2 + 0.330P] where P = (Fo^2 + 2Fc^2)/3
S = 1.05	(Δ/σ)max = 0.001
3105 reflections	Δρmax = 0.40 e Å^−3
255 parameters	Δρmin = −0.21 e Å^−3
0 restraints	Extinction correction: SHELXL, Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.035 (2)

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 > 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 (Ų)

	x	y	z	Uiso*/Ueq
O1	0.1874 (2)	0.1860 (2)	0.52822 (6)	0.0855 (5)
O2	0.4469 (3)	0.2238 (2)	0.56743 (5)	0.0942 (6)
O3	1.1528 (3)	−0.0702 (3)	0.34689 (7)	0.1049 (7)
O4	1.2314 (2)	0.0131 (3)	0.41697 (7)	0.1040 (6)
O5	1.1444 (3)	0.2907 (3)	0.32908 (8)	0.1183 (8)
O6	1.1386 (3)	0.2623 (3)	0.25500 (8)	0.1344 (9)
O7	0.3657 (4)	−0.0256 (3)	0.21271 (7)	0.1239 (9)
O8	0.5474 (4)	0.1373 (2)	0.17860 (5)	0.1054 (7)
O9	0.1993 (2)	0.43552 (17)	0.46735 (5)	0.0709 (4)
N1	0.3538 (3)	0.22431 (18)	0.53070 (5)	0.0622 (4)
N2	1.1235 (2)	0.0062 (2)	0.38283 (7)	0.0730 (5)
N3	1.0710 (3)	0.2431 (2)	0.29384 (7)	0.0737 (5)
N4	0.5007 (4)	0.0607 (2)	0.21280 (6)	0.0830 (6)
C1	0.6226 (2)	0.19939 (19)	0.47871 (5)	0.0501 (4)
H1	0.6785	0.1353	0.5016	0.060*
C2	0.4501 (2)	0.26703 (19)	0.48702 (5)	0.0507 (4)
C3	0.3652 (2)	0.37135 (19)	0.45504 (6)	0.0524 (4)
C4	0.4622 (3)	0.4054 (2)	0.41373 (6)	0.0550 (4)
H4	0.4127	0.4779	0.3923	0.066*
C5	0.6306 (2)	0.3332 (2)	0.40424 (6)	0.0526 (4)
H5	0.6909	0.3557	0.3759	0.063*
C6	0.7133 (2)	0.22707 (19)	0.43592 (5)	0.0485 (4)
C7	0.8888 (2)	0.1438 (2)	0.42611 (6)	0.0538 (4)
H7	0.9696	0.1252	0.4519	0.065*
C8	0.9433 (2)	0.0922 (2)	0.38397 (6)	0.0533 (4)
C9	0.8334 (2)	0.09022 (18)	0.33887 (6)	0.0496 (4)
C10	0.6604 (2)	0.0123 (2)	0.33830 (6)	0.0544 (4)
H10	0.6183	−0.0345	0.3661	0.065*
C11	0.5508 (3)	0.0032 (2)	0.29757 (6)	0.0595 (5)
H11	0.4355	−0.0484	0.2977	0.071*
C12	0.6152 (3)	0.0721 (2)	0.25666 (6)	0.0600 (5)
C13	0.7851 (3)	0.1492 (2)	0.25508 (6)	0.0621 (5)
H13	0.8268	0.1941	0.2270	0.075*
C14	0.8908 (3)	0.15779 (19)	0.29608 (6)	0.0546 (4)
C15	0.1127 (3)	0.5435 (3)	0.43490 (9)	0.0773 (6)
H15A	0.1939	0.6321	0.4308	0.116*
H15B	−0.0055	0.5777	0.4474	0.116*
H15C	0.0916	0.4931	0.4047	0.116*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O1	0.0840 (10)	0.0847 (10)	0.0890 (11)	0.0046 (8)	0.0348 (8)	0.0213 (8)
O2	0.1245 (14)	0.1098 (13)	0.0486 (8)	0.0069 (11)	0.0149 (8)	0.0170 (8)
O3	0.0861 (11)	0.1192 (15)	0.1100 (13)	0.0423 (10)	0.0247 (10)	−0.0232 (11)
O4	0.0688 (9)	0.1294 (16)	0.1133 (14)	0.0377 (10)	−0.0148 (10)	0.0005 (12)
O5	0.1076 (14)	0.155 (2)	0.0931 (13)	−0.0649 (14)	0.0158 (11)	−0.0068 (13)
O6	0.1398 (19)	0.162 (2)	0.1027 (14)	−0.0639 (16)	0.0551 (14)	0.0205 (14)
O7	0.170 (2)	0.1087 (15)	0.0912 (13)	−0.0568 (15)	−0.0463 (13)	0.0033 (11)
O8	0.187 (2)	0.0796 (11)	0.0495 (8)	−0.0126 (12)	−0.0097 (10)	0.0004 (7)
O9	0.0733 (8)	0.0713 (9)	0.0689 (8)	0.0283 (7)	0.0235 (6)	0.0139 (6)
N1	0.0851 (11)	0.0508 (8)	0.0514 (9)	0.0146 (7)	0.0211 (8)	0.0070 (6)
N2	0.0569 (9)	0.0753 (11)	0.0870 (12)	0.0183 (8)	0.0136 (9)	0.0052 (9)
N3	0.0797 (11)	0.0624 (10)	0.0798 (12)	−0.0113 (8)	0.0280 (9)	0.0101 (9)
N4	0.1380 (18)	0.0552 (9)	0.0553 (10)	−0.0070 (11)	−0.0105 (10)	−0.0090 (8)
C1	0.0642 (10)	0.0477 (8)	0.0384 (8)	0.0075 (7)	0.0009 (6)	0.0016 (6)
C2	0.0651 (10)	0.0451 (8)	0.0423 (8)	0.0056 (7)	0.0113 (7)	0.0009 (6)
C3	0.0615 (9)	0.0469 (8)	0.0490 (9)	0.0116 (7)	0.0091 (7)	0.0001 (7)
C4	0.0676 (10)	0.0526 (9)	0.0448 (8)	0.0144 (8)	0.0031 (7)	0.0075 (7)
C5	0.0617 (9)	0.0552 (9)	0.0413 (8)	0.0068 (7)	0.0100 (7)	0.0049 (7)
C6	0.0527 (8)	0.0502 (9)	0.0427 (8)	0.0053 (7)	0.0029 (6)	0.0000 (6)
C7	0.0520 (9)	0.0584 (10)	0.0510 (9)	0.0060 (7)	0.0011 (7)	0.0075 (7)
C8	0.0461 (8)	0.0539 (9)	0.0602 (9)	0.0079 (7)	0.0093 (7)	0.0066 (7)
C9	0.0526 (8)	0.0464 (8)	0.0504 (9)	0.0055 (6)	0.0170 (7)	0.0005 (6)
C10	0.0584 (9)	0.0569 (10)	0.0483 (8)	−0.0025 (7)	0.0165 (7)	0.0037 (7)
C11	0.0657 (10)	0.0550 (10)	0.0580 (10)	−0.0045 (8)	0.0082 (8)	−0.0033 (8)
C12	0.0889 (13)	0.0451 (8)	0.0459 (9)	0.0020 (8)	0.0038 (8)	−0.0068 (7)
C13	0.0943 (14)	0.0436 (9)	0.0492 (9)	0.0002 (9)	0.0227 (9)	0.0013 (7)
C14	0.0656 (10)	0.0436 (8)	0.0551 (9)	−0.0004 (7)	0.0215 (8)	0.0018 (7)
C15	0.0729 (12)	0.0743 (13)	0.0850 (14)	0.0304 (10)	0.0115 (10)	0.0122 (11)

Geometric parameters (Å, º)

O1—N1	1.226 (3)	C4—H4	0.9300
O2—N1	1.217 (2)	C5—C6	1.395 (2)
O3—N2	1.223 (3)	C5—H5	0.9300
O4—N2	1.220 (3)	C6—C7	1.464 (2)
O5—N3	1.184 (3)	C7—C8	1.327 (2)
O6—N3	1.210 (2)	C7—H7	0.9300
O7—N4	1.210 (3)	C8—C9	1.478 (3)
O8—N4	1.213 (3)	C9—C10	1.397 (2)
O9—C3	1.348 (2)	C9—C14	1.400 (2)
O9—C15	1.430 (2)	C10—C11	1.376 (3)
N1—C2	1.460 (2)	C10—H10	0.9300
N2—C8	1.476 (2)	C11—C12	1.376 (3)
N3—C14	1.474 (3)	C11—H11	0.9300
N4—C12	1.469 (3)	C12—C13	1.375 (3)
C1—C2	1.377 (2)	C13—C14	1.367 (3)
C1—C6	1.393 (2)	C13—H13	0.9300
C1—H1	0.9300	C15—H15A	0.9600
C2—C3	1.396 (2)	C15—H15B	0.9600
C3—C4	1.390 (2)	C15—H15C	0.9600
C4—C5	1.374 (2)
C3—O9—C15	117.88 (14)	C8—C7—C6	126.2 (2)
O2—N1—O1	123.87 (17)	C8—C7—H7	116.9
O2—N1—C2	117.28 (18)	C6—C7—H7	116.9
O1—N1—C2	118.80 (17)	C7—C8—N2	116.70 (16)
O4—N2—O3	124.22 (18)	C7—C8—C9	127.8 (2)
O4—N2—C8	119.51 (18)	N2—C8—C9	114.93 (15)
O3—N2—C8	116.27 (18)	C10—C9—C14	117.00 (16)
O5—N3—O6	122.1 (2)	C10—C9—C8	117.87 (14)
O5—N3—C14	120.36 (17)	C14—C9—C8	125.12 (16)
O6—N3—C14	117.5 (2)	C11—C10—C9	121.47 (15)
O7—N4—O8	123.6 (2)	C11—C10—H10	119.3
O7—N4—C12	118.05 (18)	C9—C10—H10	119.3
O8—N4—C12	118.3 (2)	C12—C11—C10	118.69 (17)
C2—C1—C6	119.92 (15)	C12—C11—H11	120.7
C2—C1—H1	120.0	C10—C11—H11	120.7
C6—C1—H1	120.0	C11—C12—C13	122.31 (18)
C1—C2—C3	122.36 (15)	C11—C12—N4	119.09 (19)
C1—C2—N1	117.79 (15)	C13—C12—N4	118.59 (17)
C3—C2—N1	119.84 (15)	C14—C13—C12	117.92 (15)
O9—C3—C4	125.07 (15)	C14—C13—H13	121.0
O9—C3—C2	117.70 (15)	C12—C13—H13	121.0
C4—C3—C2	117.18 (15)	C13—C14—C9	122.60 (17)
C5—C4—C3	120.76 (15)	C13—C14—N3	117.10 (15)
C5—C4—H4	119.6	C9—C14—N3	120.31 (17)
C3—C4—H4	119.6	O9—C15—H15A	109.5
C4—C5—C6	121.81 (15)	O9—C15—H15B	109.5
C4—C5—H5	119.1	H15A—C15—H15B	109.5
C6—C5—H5	119.1	O9—C15—H15C	109.5
C1—C6—C5	117.77 (15)	H15A—C15—H15C	109.5
C1—C6—C7	119.04 (14)	H15B—C15—H15C	109.5
C5—C6—C7	123.2 (1)
C6—C1—C2—C3	−3.8 (3)	O3—N2—C8—C9	−7.4 (3)
C6—C1—C2—N1	175.10 (16)	C7—C8—C9—C10	−56.5 (2)
O2—N1—C2—C1	46.2 (2)	N2—C8—C9—C10	114.06 (18)
O1—N1—C2—C1	−131.25 (18)	C7—C8—C9—C14	124.9 (2)
O2—N1—C2—C3	−134.81 (19)	N2—C8—C9—C14	−64.5 (2)
O1—N1—C2—C3	47.7 (2)	C14—C9—C10—C11	−0.4 (2)
C15—O9—C3—C4	2.0 (3)	C8—C9—C10—C11	−179.11 (15)
C15—O9—C3—C2	179.5 (2)	C9—C10—C11—C12	0.4 (3)
C1—C2—C3—O9	−177.61 (16)	C10—C11—C12—C13	0.2 (3)
N1—C2—C3—O9	3.5 (3)	C10—C11—C12—N4	178.95 (16)
C1—C2—C3—C4	0.0 (3)	O7—N4—C12—C11	−9.3 (3)
N1—C2—C3—C4	−178.91 (16)	O8—N4—C12—C11	171.3 (2)
O9—C3—C4—C5	−179.76 (17)	O7—N4—C12—C13	169.6 (2)
C2—C3—C4—C5	2.8 (3)	O8—N4—C12—C13	−9.9 (3)
C3—C4—C5—C6	−1.9 (3)	C11—C12—C13—C14	−0.7 (3)
C2—C1—C6—C5	4.7 (2)	N4—C12—C13—C14	−179.47 (16)
C2—C1—C6—C7	−174.90 (15)	C12—C13—C14—C9	0.7 (3)
C4—C5—C6—C1	−2.0 (3)	C12—C13—C14—N3	−179.02 (16)
C4—C5—C6—C7	177.63 (17)	C10—C9—C14—C13	−0.2 (2)
C1—C6—C7—C8	144.2 (2)	C8—C9—C14—C13	178.46 (15)
C5—C6—C7—C8	−35.4 (3)	C10—C9—C14—N3	179.53 (15)
C6—C7—C8—N2	−177.96 (16)	C8—C9—C14—N3	−1.9 (2)
C6—C7—C8—C9	−7.5 (3)	O5—N3—C14—C13	160.0 (2)
O4—N2—C8—C7	−14.9 (3)	O6—N3—C14—C13	−19.8 (3)
O3—N2—C8—C7	164.2 (2)	O5—N3—C14—C9	−19.7 (3)
O4—N2—C8—C9	173.47 (19)	O6—N3—C14—C9	160.5 (2)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
C4—H4···O8^i	0.93	2.43	3.266 (2)	149
C15—H15B···O1^ii	0.96	2.50	3.321 (3)	144
C10—H10···O2^iii	0.93	2.52	3.426 (3)	164
C11—H11···O3^iv	0.93	2.46	3.226 (3)	140

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