6-Bromo-1-butylindoline-2,3-dione

Lei Ji; Qi Fang; Jian-dong Fan

doi:10.1107/S1600536808042098

. 2008 Dec 17;65(Pt 1):o136. doi: 10.1107/S1600536808042098

6-Bromo-1-butylindoline-2,3-dione

Lei Ji ^a, Qi Fang ^b,^*, Jian-dong Fan ^b

PMCID: PMC2968054 PMID: 21581596

Abstract

There are two independent molecules in the asymmetric unit of the title compound, C₁₂H₁₂BrNO₂. The C—C bond lengths of the two carbonyl C atoms of the five-membered rings are distinctly longer than a normal Csp ²—Csp ² single bond. One of the molecules makes parallel self-coupled (inversion) dimers by π–π interactions with phenyl–phenyl interplanar distances of 3.403 (2) Å. The other molecule also forms self-dimers at longer phenyl–phenyl plane distances [3.649 (2) Å]. In the crystal, a C—H⋯O interaction is seen.

Related literature

For synthesis and applications, see: Kopka et al. (2006 ▶); Pirrung et al. (2005 ▶); Zhou et al. (2006 ▶). For related crystal structures, see: Goldschmidt & Llewellyn (1950 ▶); Palenik et al. (1990 ▶).

Experimental

Crystal data

C₁₂H₁₂BrNO₂
M _r = 282.14
Monoclinic,
a = 13.3097 (2) Å
b = 11.8793 (2) Å
c = 16.2238 (2) Å
β = 112.340 (1)°
V = 2372.62 (6) Å³
Z = 8
Mo Kα radiation
μ = 3.45 mm⁻¹
T = 296 (2) K
0.37 × 0.13 × 0.11 mm

Data collection

Bruker APEXII CCD diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2005 ▶) T _min = 0.526, T _max = 0.744 (expected range = 0.487–0.689)
16713 measured reflections
5170 independent reflections
2424 reflections with I > 2σ(I)
R _int = 0.076

Refinement

R[F ² > 2σ(F ²)] = 0.039
wR(F ²) = 0.070
S = 0.93
5170 reflections
364 parameters
1 restraint
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.39 e Å⁻³
Δρ_min = −0.49 e Å⁻³

Data collection: APEX2 (Bruker, 2005 ▶); cell refinement: SAINT (Bruker, 2005 ▶); data reduction: SAINT; program(s) used to solve structure: SHELXL97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: SHELXTL (Sheldrick, 2008 ▶); software used to prepare material for publication: WinGX (Farrugia, 1999 ▶).

Supplementary Material

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536808042098/cs2100sup1.cif

e-65-0o136-sup1.cif^{(22KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536808042098/cs2100Isup2.hkl

e-65-0o136-Isup2.hkl^{(248.1KB, hkl)}

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

Table 1. Selected bond lengths (Å).

N1—C1	1.375 (3)
N1—C8	1.411 (4)
N1—C9	1.425 (4)
C1—C2	1.545 (4)
N2—C21	1.373 (3)
N2—C28	1.401 (3)
N2—C29	1.467 (4)
C21—C22	1.558 (4)

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Table 2. Hydrogen-bond geometry (Å, °).

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C7—H7⋯O3ⁱ	0.95 (3)	2.44 (3)	3.367 (5)	165 (2)

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Symmetry code: (i) Inline graphic .

Acknowledgments

This work are supported by the PhD Foundation of the Ministry of Education of China and by the National Natural Science Foundation of China (grant No. 50673054).

supplementary crystallographic information

Comment

Isatin, 2,3-indolinedione is traditionally obtained from oxidation of oxindole and indigo blue. Its derivates have long been used as precursors of medicines and reductive dyes (Zhou et al., 2006; Pirrung et al., 2005; Kopka et al., 2006). The first crystal structure report on isatin was by Goldschmidt and Llewellyn, 1950. Here we report the crystal structure of N-butyl-6-bromoisatin. There are two independent molecules in the asymmetric unit with very similar bond parameters. Except for the fused aromatic bond of C3≐C8 in one molecule and C23≐C28 bond in the other molecule, four other bonds in the five-membered heterocyclic rings can be classified as single C—C bonds and π-conjugated C≐N bonds. The C1—C2 (1.545 (4) Å) and C21—C22 (1.558 (4) Å) bond lengths are longer than expected for a C(sp²)-C(sp²) single bond. This may be the result of the repulsion of the lone pair electrons of the two oxygen atoms in cis-diones (Palenik et al., 1990). Nitrogen atoms and their three bonded carbons are perfectly co-planar, showing that the sp² N atoms allocate two p_z electrons for π-bonding. The bond lengths of the π-conjugated N≐C bonds (c.f. Table 1) are much shorter than a single C—N bond length. Molecules are packed in dimers (Figure 2). One kind of the independent molecules are linked through a symmetry center to form dimer stack A while two other molecules form another dimer stack B. Mean planes of A and B dimers have a dihedral angle of 85.8 (1)°. The phenyl-phenyl spacing (3.40 (1) Å) in A dimers is considerably shorter than the spacing (3.65 (1) Å) in teh B dimers, indicating relatively stronger intermolecular π-π interactions between these A molecules. The intermolecular interactions in dimer A are further strengthened by C–Br short contacts. The C1···Br1[-x+1, -y+1, -z] and C2···Br1[-x+1, -y+1, -z] in dimer A are 3.476 (3) Å and 3.538 (3) Å, respectively. By comparison, the corresponding C···Br contacts in dimer B are much longer with the shortest distance being 3.672 (4) Å for C22···Br2[-x+1, -y+1, -z]. It may be the result of these different C···Br contacts that the C1—C2 bond length in dimer A is marginally shorter than the C21—C22 bond in dimer B. Amongst intermolecular C—H···O hydrogen bonds the strongest is the C7—H7···O3 one between dimers A and B (see Table 2).

Experimental

6-Bromoisatin (10.5 g) was dissolved in 100 ml DMSO in a three-necked flask. Then KI (3.50 g), cetyltrimethyl ammonium bromide (1.00 g), and KOH (30.0 g) in 20.0 g water were added. Then 40.0 ml of n-bromobutane was added drop-wise into the above mixture with stirring. The mixture was stirred at 343 K for 2 days under nitrogen protection. The reaction mixture was washed by water, extracted with CHCl₃, then the chloroform layer was dried by Na₂SO₄. After vaporizing the solvent, the crude product was purified by column chromatography, resulting in 9.5 g (yield 71%) N-butyl-6-bromoisatin product. The compound was dissolved in chloroform again. On most of the solvent evaporating at room temperature orange lump title crystals were formed.