2-[2-(5-Ethoxy-4-methoxy-2-nitro­phenyl)­vinyl]-1H-indole

In the title compound, C₁₉H₁₈N₂O₄, the indole moiety is planar and the dihedral angle between it and the substituted phenyl ring is 24.38 (5)°. In the solid state, inversion-related mol­ecules are linked to form N—H...O hydrogen-bonded dimers. The molecular packing is stabilized by C—H...π interactions.

Key indicators

• Single-crystal X-ray study
• T = 293 K
• Mean [sigma](C-C) = 0.003 Å
• R factor = 0.061
• wR factor = 0.189
• Data-to-parameter ratio = 18.0

checkCIF results

No syntax errors found

ADDSYM reports no extra symmetry

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S1. Comment

Substituted-indole compounds have gained much importance in the past years, since they are present in a number of natural products, many of which are found to possess antibacterial (Okabe & Adachi, 1998), antitumour (Schollmeyer et al., 1995), antidepressant (Grinev et al., 1984), antimicrobial (El-Sayed et al., 1986; Gadaginamath & Patil, 1999) and anti-inflammatory (Rodriguez et al., 1985) activities. The interaction of a phenylsulfonyl indole with calf-thymus DNA has been reported (Sivaraman et al., 1996). Indoles have been proved to dispaly high aldose reductose inhibitory activity (Rajeswaran et al., 1999). 2-Aroylindole derivatives are found to possess high cytotoxicity and are used as antimitotic agents (Mahboobi et al., 2001). The structure determination of the title compound, (I), was undertaken as part of our studies on indole derivatives.

The bond lengths and angles observed in the indole ring system show normal values. The Csp²—Csp² single bond distances, C2—C10 [1.444 (3) Å] and C11—C12 [1.466 (2) Å], and Csp²—Csp² double-bond distance C10═C11 [1.331 (3) Å] are comparable with the corresponding mean value of 1.455 (11) and 1.330 (14) Å, reported by Allen et al. (1987). These bond distances indicate conjugation along C3—C2—C9—C10—C11—C12. The C2—C10 bond is trans to C10—C11 [C2—C10—C11—C12 = −178.0 (2)°]. The dihedral angle between the indole plane and phenyl ring is 24.38 (5)°; the N1—C2—C10—C11 and C10—C11—C12—C13 torsion angles are 4.7 (3) and −30.5 (3)°, respectively.

The NO₂ group is twisted away from the attached phenyl ring with C12—C17—N21—O3 and C16—C17—N21—O4 torsion angles being −25.2 (3) and −24.3 (3)°, respectively. The rotation of the NO₂ group is restricted by a weak C11—H11···O3 interaction. The N—O distances in the nitro group agree with the mean value of 1.217 (11) Å (Allen et al., 1987). The coplanarity of the methoxy carbon with the phenyl ring [C20—O2—C15—C16 = 4.9 (3)°] results in H16···H20A (2.30 Å) and H16···H20C (2.34 Å) short contacts. These contacts cause the widening of O2—C15—C16 [125.3 (2)°] and narrowing of O2—C15—C14 [116.0 (2)°] angles from 120°. Similar features have been reported in structures containing methoxy substituents (Chandrakantha et al., 1990; Wakahara et al., 1972; Falkenberg & Carlstrom, 1971; Sakaki et al., 1975). The ethoxy group is also coplanar with the phenyl ring with C14—O1—C18—C19 = −179.1 (2) and C18—O1—C14—C13 = −2.8 (3)°; the resultant H13···H18A [2.31 Å] and H13···H18B [2.36 Å] short contacts cause the widening of C13—C14—O1 [125.5 (2)°] and narrowing of C15—C14—O1 [114.6 (2)°] angles, as reported in the literature (Chandrakantha et al., 1998; Sakaki et al., 1976).

One of the nitro group O atoms, O3, is involved in an intramolecular C11—H11···O3 interaction. The other O atom, O4, is involved in the formation of centro-symmetrically N1—H1···O4(-x, 1 − y, 1 − z) hydrogen-bonded dimers, in the solid state. Apart from these interactions, the molecular packing is also stabilized by C—H···π interactions (Table 2 and Fig. 2). In Table 2, CgA and CgB denote the centriods of the rings A and B, respectively.

S2. Experimental

1-(Indol-2-yl)-2-(6-nitrovertatryl)ethene (0.68 g, 2 mmol) and sodium ethoxide (0.24 g, 5 mmol) were taken in dry THF (40 ml) and refluxed for 6 h. The solution was cooled and poured over crushed ice. The preciptated solid was filtered, washed with water (2 × 5 ml) and dried over CaCl₂. This was recrystallized from ethanol to afford the title compound.

S3. Refinement

The H atoms were geometrically positioned and were treated as riding on the parent atoms, with C—H distances in the range 0.93–0.97 Å and N—H distance of 0.86 Å. The rotating group refinement was used for the methyl groups.

Computing details

Data collection: SMART (Siemens, 1996); cell refinement: SAINT (Siemens, 1996); data reduction: SAINT; 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, 1990); software used to prepare material for publication: SHELXL97 and PARST (Nardelli, 1995).

Figures

	Fig. 1. The molecular structure of the title compound showing 35% probability displacement elliposids and the atom-numbering scheme.
	Fig. 2. The molecular packing of the title compound viewed down the b axis. For clarity, H atoms not involved in hydrogen bonding have been omitted.

2-[2-(4-Ethoxy-5-methoxy-2-nitrophenyl)vinyl]-1H-indole

Crystal data

C19H18N2O4	Z = 2
Mr = 338.35	F(000) = 356
Triclinic, P1	Dx = 1.306 Mg m^−3
Hall symbol: -P 1	Mo Kα radiation, λ = 0.71073 Å
a = 7.5949 (4) Å	Cell parameters from 3349 reflections
b = 10.0887 (6) Å	θ = 1.8–28.3°
c = 11.5777 (7) Å	µ = 0.09 mm^−1
α = 85.298 (1)°	T = 293 K
β = 76.924 (1)°	Plate, red
γ = 86.166 (1)°	0.44 × 0.28 × 0.16 mm
V = 860.14 (9) Å^3

Data collection

Siemens SMART CCD area-detector diffractometer	2759 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	Rint = 0.025
Graphite monochromator	θmax = 28.3°, θmin = 1.8°
ω scans	h = −8→10
5992 measured reflections	k = −13→13
4109 independent reflections	l = −15→12

Refinement

Refinement on F^2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.061	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.189	H-atom parameters constrained
S = 1.02	w = 1/[σ^2(Fo^2) + (0.1036P)^2 + 0.0867P] where P = (Fo^2 + 2Fc^2)/3
4109 reflections	(Δ/σ)max < 0.001
228 parameters	Δρmax = 0.23 e Å^−3
0 restraints	Δρmin = −0.23 e Å^−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 > 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	0.38514 (19)	0.31020 (13)	−0.06658 (11)	0.0539 (4)
O2	0.4804 (2)	0.13263 (13)	0.08272 (12)	0.0586 (4)
O3	0.2156 (3)	0.51133 (18)	0.45182 (14)	0.0933 (6)
O4	0.2176 (3)	0.30062 (18)	0.47735 (13)	0.0910 (6)
N1	−0.0386 (3)	0.87630 (16)	0.32494 (15)	0.0588 (5)
H1	−0.0590	0.8144	0.3812	0.071*
C2	0.0604 (3)	0.85939 (19)	0.21157 (17)	0.0500 (4)
C3	0.0622 (3)	0.9808 (2)	0.1486 (2)	0.0598 (5)
H3	0.1203	0.9978	0.0694	0.072*
C4	−0.0393 (3)	1.07595 (19)	0.2241 (2)	0.0573 (5)
C5	−0.1001 (3)	1.00694 (19)	0.3348 (2)	0.0582 (5)
C6	−0.2040 (4)	1.0692 (3)	0.4316 (3)	0.0858 (8)
H6	−0.2440	1.0220	0.5042	0.103*
C7	−0.2458 (5)	1.2027 (3)	0.4164 (3)	0.0971 (10)
H7	−0.3153	1.2466	0.4801	0.117*
C8	−0.1879 (4)	1.2733 (3)	0.3098 (4)	0.0918 (9)
H8	−0.2180	1.3640	0.3029	0.110*
C9	−0.0867 (3)	1.2130 (2)	0.2135 (3)	0.0784 (8)
H9	−0.0494	1.2621	0.1415	0.094*
C10	0.1458 (3)	0.73275 (19)	0.17516 (17)	0.0513 (5)
H10	0.2180	0.7306	0.0988	0.062*
C11	0.1292 (3)	0.61877 (18)	0.24236 (17)	0.0502 (5)
H11	0.0539	0.6202	0.3178	0.060*
C12	0.2206 (2)	0.49116 (17)	0.20652 (15)	0.0449 (4)
C13	0.2612 (2)	0.46289 (18)	0.08610 (15)	0.0457 (4)
H13	0.2296	0.5267	0.0307	0.055*
C14	0.3461 (2)	0.34426 (18)	0.04690 (15)	0.0438 (4)
C15	0.3962 (2)	0.24551 (18)	0.12914 (15)	0.0447 (4)
C16	0.3539 (3)	0.26872 (18)	0.24771 (15)	0.0468 (4)
H16	0.3828	0.2041	0.3034	0.056*
C17	0.2679 (3)	0.38900 (18)	0.28445 (15)	0.0465 (4)
C18	0.3282 (3)	0.4009 (2)	−0.15483 (16)	0.0531 (5)
H18A	0.3841	0.4854	−0.1596	0.064*
H18B	0.1978	0.4167	−0.1351	0.064*
C19	0.3865 (3)	0.3368 (2)	−0.27094 (18)	0.0679 (6)
H19A	0.5155	0.3209	−0.2889	0.102*
H19B	0.3521	0.3948	−0.3329	0.102*
H19C	0.3292	0.2538	−0.2652	0.102*
C20	0.5163 (3)	0.0253 (2)	0.1640 (2)	0.0606 (5)
H20A	0.5972	0.0530	0.2092	0.091*
H20B	0.5709	−0.0495	0.1205	0.091*
H20C	0.4050	0.0005	0.2168	0.091*
N21	0.2303 (3)	0.40219 (18)	0.41256 (14)	0.0589 (4)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O1	0.0717 (9)	0.0553 (8)	0.0345 (6)	0.0050 (6)	−0.0125 (6)	−0.0055 (6)
O2	0.0791 (10)	0.0499 (8)	0.0452 (7)	0.0086 (7)	−0.0133 (7)	−0.0057 (6)
O3	0.165 (2)	0.0682 (11)	0.0490 (9)	0.0046 (11)	−0.0266 (10)	−0.0191 (8)
O4	0.1530 (19)	0.0694 (11)	0.0397 (8)	0.0003 (11)	−0.0052 (9)	0.0102 (7)
N1	0.0857 (13)	0.0405 (9)	0.0478 (9)	0.0030 (8)	−0.0132 (8)	0.0016 (7)
C2	0.0521 (10)	0.0472 (10)	0.0514 (10)	−0.0064 (8)	−0.0133 (8)	0.0009 (8)
C3	0.0539 (12)	0.0592 (12)	0.0627 (12)	−0.0106 (9)	−0.0102 (10)	0.0159 (10)
C4	0.0523 (11)	0.0448 (10)	0.0792 (14)	−0.0094 (8)	−0.0262 (10)	0.0094 (10)
C5	0.0734 (13)	0.0412 (10)	0.0648 (13)	0.0021 (9)	−0.0265 (11)	−0.0047 (9)
C6	0.125 (2)	0.0616 (15)	0.0705 (15)	0.0189 (14)	−0.0228 (15)	−0.0159 (12)
C7	0.122 (3)	0.0619 (16)	0.113 (2)	0.0234 (16)	−0.037 (2)	−0.0308 (17)
C8	0.0894 (19)	0.0463 (13)	0.148 (3)	0.0085 (13)	−0.045 (2)	−0.0123 (17)
C9	0.0685 (15)	0.0494 (13)	0.119 (2)	−0.0117 (11)	−0.0319 (15)	0.0228 (13)
C10	0.0520 (11)	0.0516 (11)	0.0482 (10)	−0.0040 (8)	−0.0071 (8)	−0.0019 (8)
C11	0.0559 (11)	0.0492 (11)	0.0440 (9)	−0.0024 (8)	−0.0069 (8)	−0.0058 (8)
C12	0.0488 (10)	0.0453 (9)	0.0394 (9)	−0.0071 (7)	−0.0062 (7)	−0.0028 (7)
C13	0.0524 (10)	0.0441 (10)	0.0396 (9)	−0.0038 (7)	−0.0097 (8)	0.0015 (7)
C14	0.0476 (10)	0.0481 (9)	0.0355 (8)	−0.0064 (7)	−0.0078 (7)	−0.0028 (7)
C15	0.0497 (10)	0.0426 (9)	0.0415 (9)	−0.0023 (7)	−0.0094 (8)	−0.0038 (7)
C16	0.0587 (11)	0.0441 (10)	0.0374 (9)	−0.0049 (8)	−0.0116 (8)	0.0026 (7)
C17	0.0560 (11)	0.0489 (10)	0.0335 (8)	−0.0083 (8)	−0.0067 (7)	−0.0015 (7)
C18	0.0600 (12)	0.0604 (12)	0.0407 (9)	−0.0018 (9)	−0.0157 (8)	−0.0017 (8)
C19	0.0858 (16)	0.0793 (15)	0.0419 (10)	−0.0006 (12)	−0.0209 (10)	−0.0076 (10)
C20	0.0749 (14)	0.0509 (11)	0.0589 (12)	0.0060 (10)	−0.0239 (10)	−0.0031 (9)
N21	0.0798 (12)	0.0587 (10)	0.0363 (8)	−0.0023 (8)	−0.0093 (8)	−0.0036 (7)

Geometric parameters (Å, º)

O1—C14	1.348 (2)	C10—C11	1.331 (3)
O1—C18	1.436 (2)	C10—H10	0.93
O2—C15	1.357 (2)	C11—C12	1.466 (2)
O2—C20	1.429 (2)	C11—H11	0.93
O3—N21	1.214 (2)	C12—C17	1.397 (3)
O4—N21	1.215 (2)	C12—C13	1.407 (2)
N1—C5	1.374 (2)	C13—C14	1.381 (3)
N1—C2	1.375 (3)	C13—H13	0.93
N1—H1	0.86	C14—C15	1.415 (2)
C2—C3	1.372 (3)	C15—C16	1.373 (2)
C2—C10	1.444 (3)	C16—C17	1.390 (3)
C3—C4	1.420 (3)	C16—H16	0.93
C3—H3	0.93	C17—N21	1.461 (2)
C4—C5	1.403 (3)	C18—C19	1.502 (3)
C4—C9	1.408 (3)	C18—H18A	0.97
C5—C6	1.387 (3)	C18—H18B	0.97
C6—C7	1.369 (4)	C19—H19A	0.96
C6—H6	0.93	C19—H19B	0.96
C7—C8	1.369 (4)	C19—H19C	0.96
C7—H7	0.93	C20—H20A	0.96
C8—C9	1.365 (4)	C20—H20B	0.96
C8—H8	0.93	C20—H20C	0.96
C9—H9	0.93
C14—O1—C18	118.32 (14)	C13—C12—C11	119.93 (17)
C15—O2—C20	117.57 (15)	C14—C13—C12	122.66 (17)
C5—N1—C2	109.78 (17)	C14—C13—H13	118.7
C5—N1—H1	125.1	C12—C13—H13	118.7
C2—N1—H1	125.1	O1—C14—C13	125.5 (2)
C3—C2—N1	107.60 (17)	O1—C14—C15	114.6 (2)
C3—C2—C10	129.88 (19)	C13—C14—C15	119.95 (15)
N1—C2—C10	122.49 (17)	O2—C15—C16	125.3 (2)
C2—C3—C4	108.72 (19)	O2—C15—C14	116.0 (2)
C2—C3—H3	125.6	C16—C15—C14	118.75 (16)
C4—C3—H3	125.6	C15—C16—C17	119.92 (17)
C5—C4—C9	117.7 (2)	C15—C16—H16	120.0
C5—C4—C3	106.05 (17)	C17—C16—H16	120.0
C9—C4—C3	136.2 (2)	C16—C17—C12	123.52 (16)
N1—C5—C6	130.0 (2)	C16—C17—N21	114.91 (16)
N1—C5—C4	107.84 (18)	C12—C17—N21	121.57 (16)
C6—C5—C4	122.2 (2)	O1—C18—C19	106.67 (16)
C7—C6—C5	117.7 (3)	O1—C18—H18A	110.4
C7—C6—H6	121.2	C19—C18—H18A	110.4
C5—C6—H6	121.2	O1—C18—H18B	110.4
C6—C7—C8	121.7 (3)	C19—C18—H18B	110.4
C6—C7—H7	119.2	H18A—C18—H18B	108.6
C8—C7—H7	119.2	C18—C19—H19A	109.5
C9—C8—C7	121.3 (2)	C18—C19—H19B	109.5
C9—C8—H8	119.4	H19A—C19—H19B	109.5
C7—C8—H8	119.4	C18—C19—H19C	109.5
C8—C9—C4	119.5 (3)	H19A—C19—H19C	109.5
C8—C9—H9	120.3	H19B—C19—H19C	109.5
C4—C9—H9	120.3	O2—C20—H20A	109.5
C11—C10—C2	125.09 (18)	O2—C20—H20B	109.5
C11—C10—H10	117.5	H20A—C20—H20B	109.5
C2—C10—H10	117.5	O2—C20—H20C	109.5
C10—C11—C12	124.98 (18)	H20A—C20—H20C	109.5
C10—C11—H11	117.5	H20B—C20—H20C	109.5
C12—C11—H11	117.5	O3—N21—O4	121.71 (17)
C17—C12—C13	115.15 (16)	O3—N21—C17	120.58 (17)
C17—C12—C11	124.88 (16)	O4—N21—C17	117.70 (17)
C5—N1—C2—C3	0.1 (2)	C11—C12—C13—C14	−179.61 (17)
C5—N1—C2—C10	178.67 (17)	C18—O1—C14—C13	−2.8 (3)
N1—C2—C3—C4	−0.4 (2)	C18—O1—C14—C15	175.91 (16)
C10—C2—C3—C4	−178.82 (19)	C12—C13—C14—O1	178.52 (17)
C2—C3—C4—C5	0.5 (2)	C12—C13—C14—C15	−0.2 (3)
C2—C3—C4—C9	179.8 (2)	C20—O2—C15—C16	4.9 (3)
C2—N1—C5—C6	−179.9 (2)	C20—O2—C15—C14	−173.73 (17)
C2—N1—C5—C4	0.2 (2)	O1—C14—C15—O2	1.8 (2)
C9—C4—C5—N1	−179.91 (18)	C13—C14—C15—O2	−179.40 (16)
C3—C4—C5—N1	−0.5 (2)	O1—C14—C15—C16	−176.92 (16)
C9—C4—C5—C6	0.2 (3)	C13—C14—C15—C16	1.9 (3)
C3—C4—C5—C6	179.7 (2)	O2—C15—C16—C17	179.71 (17)
N1—C5—C6—C7	179.8 (3)	C14—C15—C16—C17	−1.7 (3)
C4—C5—C6—C7	−0.4 (4)	C15—C16—C17—C12	−0.2 (3)
C5—C6—C7—C8	0.0 (5)	C15—C16—C17—N21	−179.89 (17)
C6—C7—C8—C9	0.5 (5)	C13—C12—C17—C16	1.9 (3)
C7—C8—C9—C4	−0.7 (4)	C11—C12—C17—C16	179.70 (17)
C5—C4—C9—C8	0.3 (3)	C13—C12—C17—N21	−178.47 (16)
C3—C4—C9—C8	−178.9 (2)	C11—C12—C17—N21	−0.6 (3)
C3—C2—C10—C11	−177.0 (2)	C14—O1—C18—C19	−179.10 (16)
N1—C2—C10—C11	4.7 (3)	C16—C17—N21—O3	154.4 (2)
C2—C10—C11—C12	−177.99 (17)	C12—C17—N21—O3	−25.2 (3)
C10—C11—C12—C17	151.7 (2)	C16—C17—N21—O4	−24.3 (3)
C10—C11—C12—C13	−30.5 (3)	C12—C17—N21—O4	156.0 (2)
C17—C12—C13—C14	−1.7 (3)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
C11—H11···O3	0.93	2.35	2.771 (3)	107
N1—H1···O4^i	0.86	2.11	2.919 (2)	156
C18—H18A···CgB^ii	0.97	2.84	3.714 (2)	150
C20—H20A···CgA^iii	0.96	2.81	3.770 (3)	175

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