(E)-1,1′-Dibutyl-3,3′-biindolinyl­idene-2,2′-dione

Mao-Sen Yuan; Qi Fang

doi:10.1107/S160053681005066X

. 2010 Dec 8;67(Pt 1):o52. doi: 10.1107/S160053681005066X

(E)-1,1′-Dibutyl-3,3′-biindolinylidene-2,2′-dione

Mao-Sen Yuan ^a,^*, Qi Fang ^b

PMCID: PMC3050316 PMID: 21522762

Abstract

In the title molecule, C₂₄H₂₆N₂O₂, the two indol-2-one units, which are connected by a C=C double bond, are almost coplanar with an interplanar angle of 6.8 (1)°. On cooling from 293 to 120 K, the space group changes from P2₁/n to P2₁. Two intramolecular C—H⋯O hydrogen bonds occur.

Related literature

For uses of isoindigo derivatives as medicines, see: Sassatelli et al. (2004 ▶). For the room temperature (293 K) structure, see: Yuan et al. (2007 ▶).

Experimental

Crystal data

C₂₄H₂₆N₂O₂
M _r = 374.47
Monoclinic,
a = 8.9224 (3) Å
b = 11.9605 (5) Å
c = 9.6827 (4) Å
β = 110.782 (1)°
V = 966.07 (7) Å³
Z = 2
Mo Kα radiation
μ = 0.08 mm⁻¹
T = 120 K
0.20 × 0.11 × 0.09 mm

Data collection

Bruker SMART 6K CCD area-detector diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2006 ▶) T _min = 0.984, T _max = 0.993
13014 measured reflections
2926 independent reflections
2477 reflections with I > 2σ(I)
R _int = 0.041

Refinement

R[F ² > 2σ(F ²)] = 0.044
wR(F ²) = 0.121
S = 1.04
2926 reflections
257 parameters
1 restraint
H-atom parameters constrained
Δρ_max = 0.38 e Å⁻³
Δρ_min = −0.22 e Å⁻³

Data collection: SMART (Bruker, 2001 ▶); cell refinement: SAINT (Bruker, 2001 ▶); data reduction: SAINT; program(s) used to solve structure: SHELXTL (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL.

Supplementary Material

Crystal structure: contains datablocks I, global. DOI: 10.1107/S160053681005066X/jh2237sup1.cif

e-67-00o52-sup1.cif^{(19.8KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S160053681005066X/jh2237Isup2.hkl

e-67-00o52-Isup2.hkl^{(143.6KB, 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
C4—H4⋯O2	0.95	2.05	2.815 (3)	137
C24—H24⋯O1	0.95	2.04	2.805 (3)	136

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Acknowledgments

This work is supported by the National Natural Science Foundation of China (grant Nos. 50673054 and 20972089).

supplementary crystallographic information

Comment

Isoindigo can be obtained from various natural sources. Its derivatives are usually known as useful medicine (Sassatelli et al., 2004). Recently we have synthesized the title isoindigo derivative and determined its structure at room temperature (293 K) (Yuan et al., 2007). To reduce the disorder of the two butyl groups of the molecule at room temperature, we redetermined the structure at low temperature (120 K). Unexpectedly, we found some changes of the crystal at different temperatures. Here we mainly report the correlation between structures at high and low temperatures.

The band features of the molecule at 120 K are very similar to those at 293 k. For example, the C3—C2═C22—C23 fragment is quite conjugated and exhibits an E configuration, in which the bond lengths are 1.479 (3), 1.373 (3), and 1.477 (3) for C3—C2, C2═C22, and C22—C23, respectively. There are a pair of intramolecular hydrogen bonds C4—H4···O2 and C24—H24···O1 (see Fig. 1).

The cell parameters of the compound at 293 K and 120 K are very close. The cell volumn 1005.32 (4) Å³ at 293 K slightly shrinks to 966.07 (7) Å³ at 120 K. The temperature effect on the molecule is significant that the severely disordered terminal C atoms of the two butyl groups at 293 K become completely ordered at 120 k and all the atomic displacement parameters are greatly reduced.

At 293 K, the molecule is centrosymmetric and has a perfect planarity. At 120 K, however, the centrosymmetry is borken and a dihedral angle of 6.8 (1) ° between the two nine-membered indole planes are developed. Consequently, molecular chirality is produced, which brings the chirality to the crystal. Meanwhile, the space group of the crystal changed from P2₁/n to P2₁.

Experimental

1-Butyl-1H-indole-2,3-dione (1.5 g) and 1-butyl-1H -indole-2-one (1.5 g) were mixed with polyphosphoric acid (15 g), reacted at 333–338 K for 30 min. under N₂, and then to 433–442 K with stirring. After 3 h, the mixture was poured into ice water and stirred for 1 h. The solution was extracted in chloroform and dried over Na₂SO₄. After removing the solvent, the crude product was purified by column chromatography on silica gel, eluting with petrol ether, affording the title compound (1.4 g, 47.1%). The compound was dissolved in THF and purple plate title crystals formed on slow evaporation at room temperature.