5-Bromo-2-iodo-1,3-dimethyl­benzene

Rui Liu; Yu-Hao Li; Wei Luo; Shan Liu; Hong-Jun Zhu

doi:10.1107/S1600536807064537

. 2007 Dec 6;64(Pt 1):o219. doi: 10.1107/S1600536807064537

5-Bromo-2-iodo-1,3-dimethylbenzene

Rui Liu ^a, Yu-Hao Li ^a, Wei Luo ^a, Shan Liu ^a, Hong-Jun Zhu ^a,^*

PMCID: PMC2915280 PMID: 21200785

Abstract

The asymmetric unit of the title compound, C₈H₈BrI, contains three independent molecules. In each molecule, the Br, I and C atoms of the methyl groups lie in the benzene ring plane. Intramolecular C—H⋯I hydrogen bonds result in the formation of three planar five-membered rings, which are nearly coplanar with the adjacent rings.

Related literature

For general background, see: Hu et al. (2001 ▶). For bond-length data, see: Allen et al. (1987 ▶).

Experimental

Crystal data

C₈H₈BrI
M _r = 310.94
Triclinic,
a = 10.282 (2) Å
b = 11.314 (2) Å
c = 12.951 (3) Å
α = 69.27 (3)°
β = 89.11 (3)°
γ = 83.70 (3)°
V = 1400.1 (6) Å³
Z = 6
Mo Kα radiation
μ = 7.64 mm⁻¹
T = 294 (2) K
0.10 × 0.10 × 0.10 mm

Data collection

Enraf–Nonius CAD-4 diffractometer
Absorption correction: ψ scan (North et al., 1968 ▶) T _min = 0.466, T _max = 0.466
5802 measured reflections
5481 independent reflections
2809 reflections with I > 2σ(I)
R _int = 0.042
3 standard reflections frequency: 120 min intensity decay: none

Refinement

R[F ² > 2σ(F ²)] = 0.059
wR(F ²) = 0.133
S = 1.06
5481 reflections
271 parameters
H-atom parameters constrained
Δρ_max = 0.76 e Å⁻³
Δρ_min = −0.72 e Å⁻³

Data collection: CAD-4 Software (Enraf–Nonius, 1985 ▶); cell refinement: CAD-4 Software; data reduction: XCAD4 (Harms & Wocadlo, 1995 ▶); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997 ▶); molecular graphics: PLATON (Spek, 2003 ▶); software used to prepare material for publication: SHELXTL (Bruker, 2000 ▶).

Supplementary Material

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536807064537/hk2404sup1.cif

e-64-0o219-sup1.cif^{(21.3KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536807064537/hk2404Isup2.hkl

e-64-0o219-Isup2.hkl^{(268.3KB, 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
C1—H1A⋯I1	0.96	2.70	3.316 (11)	122
C10—H10A⋯I2	0.96	2.70	3.303 (10)	122
C18—H18A⋯I3	0.96	2.63	3.252 (10)	123

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Acknowledgments

The authors thank the Center of Testing and Analysis, Nanjing University, for support.

supplementary crystallographic information

Comment

The title compound, (I), contains two different halogen groups, which can react with different groups to prepare various function organic compounds by the different reaction activity of Br and I. It is a kind of aromatic organic intermediate that can be used for many fields such as aromatic conductive polymer, organometallic chemistry (Hu et al., 2001). We herein report its crystal structure.

The asymmetric unit of (I) contains three independent molecules (Fig. 1), in which the bond lengths and angles (Table 1) are within normal ranges (Allen et al., 1987). The Br, I and C atoms of the methyl groups lie in the benzene ring planes. The intramolecular C—H···I hydrogen bonds (Table 2) result in the formations of three planar five-membered rings; B (I1/H1A/C1/C4/C5), D (I2/H10A/C10—C12) and F (I3/H18A/C18—C20). Rings A (C3—C8), C (C11—C16) and E (C19—C24) are, of course, planar and the dihedral angles between them are A/B = 1.29 (3)°, C/D = 1.73 (3)° and E/F = 1.77 (2)°. So, the adjacent rings are also nearly co-planar.

As can be seen from the packing diagram, (Fig. 2), the molecules are stacked along the b axis. The π-π interactions of benzene rings with a face-to-face stacking distance of 3.636 Å are also found.

Experimental

For the preparation of the title compound, a mixture of 4-bromo-2,6-dimethyl- aniline (4.0 g, 20 mmol), concentrated sulfuric acid (40 mmol, 2.24 ml) and water (100 ml) was stirred in an ice bath. When the mixture was below 278 K, the solution of sodium nitrite (1.75 g, 25 mmol) and water (100 ml) was added dropwise. Then, the mixture was added to a solution of KI (3.3 g, 20 mmol) and water (50 ml) with stirring. The solid residue was extracted with boiling hexane (40 ml) and hexane was distilled off. The product was recrystallized from ethanol. The crystals were obtained by dissolving (I) in ethanol (20 ml) and evaporating ethanol slowly at room temperature for about 10 d.