2-(4-{3-[1-(3-Bromo­prop­yl)-3,3-dimethyl-2,3-dihydro-1H-indol-2-yl­idene]prop-1-en­yl}-3-cyano-5,5-dimethyl-2,5-dihydro­furan-2-yl­idene)malononitrile

Graeme J Gainsford; M Delower H Bhuiyan; Andrew J Kay

doi:10.1107/S1600536809017747

. 2009 May 20;65(Pt 6):o1315. doi: 10.1107/S1600536809017747

2-(4-{3-[1-(3-Bromopropyl)-3,3-dimethyl-2,3-dihydro-1H-indol-2-ylidene]prop-1-enyl}-3-cyano-5,5-dimethyl-2,5-dihydrofuran-2-ylidene)malononitrile

Graeme J Gainsford ^a,^*, M Delower H Bhuiyan ^a, Andrew J Kay ^a

PMCID: PMC2969784 PMID: 21583172

Abstract

The backbone of the title molecule, C₂₆H₂₅BrN₄O, is approximately planar: the dihedral angle between the planes of the indoline ring system and the furan ring is 7.68 (14)°. In the crystal, layers lying parallel to (10 Inline graphic ) occur, with the molecules interacting via weak C—H⋯N(cyano) and C—H⋯Br bonds and short N(cyano)⋯Br contacts [3.345 (4) Å].

Related literature

For general background to zwitterionic dyes and their applications, see: Dalton (2002 ▶); Gainsford et al. (2007 ▶, 2008 ▶); Kay et al. (2004 ▶). For related structures, see: Li et al. (2005 ▶); Marder et al. (1993 ▶); Mushkalo & Sogulayaev (1986 ▶); Wang et al. (2007 ▶). For a description of the Cambridge Stuctural Database, see: Allen (2002 ▶).

Experimental

Crystal data

C₂₆H₂₅BrN₄O
M _r = 489.41
Monoclinic,
a = 10.2349 (4) Å
b = 9.4017 (4) Å
c = 24.4524 (10) Å
β = 96.175 (2)°
V = 2339.29 (17) Å³
Z = 4
Mo Kα radiation
μ = 1.78 mm⁻¹
T = 122 K
0.85 × 0.36 × 0.10 mm

Data collection

Bruker APEXII CCD diffractometer
Absorption correction: multi-scan (Blessing, 1995 ▶) T _min = 0.549, T _max = 0.746 (expected range = 0.616–0.837)
56895 measured reflections
6791 independent reflections
5482 reflections with I > 2σ(I)
R _int = 0.044

Refinement

R[F ² > 2σ(F ²)] = 0.059
wR(F ²) = 0.156
S = 1.19
6791 reflections
293 parameters
H-atom parameters constrained
Δρ_max = 3.08 e Å⁻³
Δρ_min = −0.60 e Å⁻³

Data collection: APEX2 (Bruker, 2005 ▶); cell refinement: SAINT (Bruker, 2005 ▶); data reduction: SAINT and SADABS (Bruker, 2005 ▶); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: ORTEP-3 (Farrugia, 1997 ▶), PLATON (Spek, 2009 ▶) and Mercury (Macrae et al., 2006 ▶); software used to prepare material for publication: SHELXL97 and PLATON.

Supplementary Material

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536809017747/hb2973sup1.cif

e-65-o1315-sup1.cif^{(23.2KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536809017747/hb2973Isup2.hkl

e-65-o1315-Isup2.hkl^{(325.6KB, hkl)}

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

Table 1. Hydrogen-bond geometry (Å, °).

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C9—H9B⋯N1ⁱ	0.98	2.59	3.449 (5)	147
C23—H23B⋯Br1ⁱⁱ	0.98	2.99	3.962 (4)	171
C26—H26B⋯Br1ⁱⁱⁱ	0.99	2.95	3.815 (4)	147

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Symmetry codes: (i) Inline graphic ; (ii) ; (iii) .

Acknowledgments

We thank Drs J. Wikaira and C. Fitchett of the University of Canterbury, New Zealand, for their assistance with the data collection.

supplementary crystallographic information

Comment

The X-ray crystallographic and structural properties of zwitterionic dyes and their precursors have been a subject of some interest to us (Gainsford et al., 2007, 2008) due to their potential application in a number of photonic and optoelectronic devices (Dalton, 2002; Kay et al., 2004). The title compound was unintentionally synthesized en route to 2-{3-Cyano-4-[2-(10,10-dimethyl-6,7,8,10-tetrahydro-pyrido[1,2-a] indol-9-yl)-vinyl]-5,5-dimethyl-5H-furan-2-ylidene}-malononitrile. Compound REFCODES are from the C.S.D. (Version 5.30, with February 2009 updates; Allen, 2002)

The asymmetric unit contents are shown in Figure 1. The 5-membered ring plane of atoms O1,C4—C7 (hereafter "CDFP", [3-Cyano-5,5-Dimethyl-2,5-dihydrofuran-2-ylidene]propanedinitrile) can also be regarded as planar in this case (r.m.s. deviations 0.024 (3) Å). The dicyano group (N1,C1,C2,C3,N2) is planar (r.m.s.d. 0.008 (3) Å) but twisted by 6.6 (2)° with respect to the "CDFP" group; this is similar to the twist in related compound NOJKUT (Gainsford et al., 2008) of 5.69 (17)°. The fused indolylidene system (atoms N4, C14 to C21) is also essentially planar (r.m.s.d. 0.017 (3) Å) and makes a dihedral angle with the "CDFP" ring of 7.68 (14)°. This reflects a twist in the C11–C14 polyene chain beginning at C11: the plane through C11–C14 subtends 5.4 (3)° with the "CDFP" plane. There is considerable delocalization of charge along the polyene /"CDFP" chain with a bond length alternation (BLA) value (Marder et al., 1993) of 0.012Å compared with the free "CDFP" value of 0.108Å (Li et al., 2005) and 0.060Å in GIMQAV (Gainsford et al., 2007).

The almost planar molecules are arranged into nearly coplanar layers parallel to the (1,0,-2) plane with only C–H···N(cyano), C–H···Br and N(cyano)···Br contacts. The (methyl)C–H···N(cyano) contact (Table 1) is similar to that observed in several structures (Allen, 2002), where the methyl group is constrained by other interactions e.g. in JETGEV (Wang et al. 2007; N···H 2.57 Å, C–H···N 157°) the cyano nitrogen involved is bifurcated by a polyene C–H···N interation (H···N 2.72 Å, C–H···N 157°). Here the distance to the equivalent polyene H (H11) is 2.75 Å, with C–H···N 161°. In NOJKUT, a similar interaction is observed: H···N 2.45 Å, C–H···N 156°. The bromine atoms provide weak linking interactions: N2···Br1 3.345 (4)Å (Br1 at x - 1,1/2 - y,z - 1/2) and two C–H···Br interactions (Table 1). A final interaction is noted for completeness that would complete a weak interacting chain (N2···H23C(C23)H23B···Br1···N2) with H23C···N2 (N2 at 1 - x, y - 1/2,1/2 - z) and provide a weak interplanar link (see also Figure 2).

Experimental

A mixture of 1 g (2.77 mmol) of 1-(3-bromopropyl)-2,3,3-trimethyl-3H-indolium bromide (Mushkalo & Sogulayaev, 1986), 883 mg (2.21 mmol) of {4-(2-acetanilidoethenyl)-3-cyano-5,5-dimethyl-2(5H)-furanylidene} propanedinitrile (compound 11a; Kay et al., 2004) and triethylamine as a catalyst in 30 ml me thanol was refluxed for 3 h. After cooling to room temperature, the precipitate was filtered and washed with copious quantities of hot water, followed by small portions of cold methanol to afford the target molecule as a red-purple powder (720 mg, 67%). Platy crystals, of limited quality, were grown from a 2:1 dichloromethane/hexanes mixture. Mp: 264–266 °C; ¹H NMR (500 MHz, CDCl₃) δ 1.61 (6 H, s, 2 x CH₃), 1.72 (6 H, s, 2 x CH₃), 2.34 (2 H, qn, CH₂), 3.50 (2 H, t, J 5.7 Hz, CH₂), 4.06 (2 H, t, J 7.2 Hz, CH₂), 5.78 (1 H, d, J 12.9 Hz, CH), 5.85 (1 H, d, J 12.9 Hz, CH), 7.04 (1 H, d, J 7.8 Hz, ArH), 7.16–7.21 (1 H, m, ArH), 7.31–7.37 (2 H, m, ArH), 8.78 (1H, br s, ArH); ¹³C NMR (125 MHz, CDCl₃) δ 26.4, 27.7, 29.8, 29.9, 41.8, 48.9, 95.7, 99.9, 107.3, 109.3, 112.9, 113.8, 122.4, 124.6, 128.6, 140.4, 142.0, 147.3, 172.7, 177.4.