1,4-Bis(iodo­meth­yl)benzene

C John McAdam; Lyall R Hanton; Stephen C Moratti; Jim Simpson

doi:10.1107/S1600536809021151

. 2009 Jun 13;65(Pt 7):o1573–o1574. doi: 10.1107/S1600536809021151

1,4-Bis(iodomethyl)benzene

C John McAdam ^a, Lyall R Hanton ^a, Stephen C Moratti ^a, Jim Simpson ^a,^*

PMCID: PMC2969495 PMID: 21582852

Abstract

The centrosymmetric title compound, C₈H₈I₂, was prepared by metathesis from the dibromo analogue. In the crystal structure, weak C—H⋯I interactions link the molecules into stacks down the b axis. The structure is further stabilized by short I⋯I contacts [3.8433 (2) Å], forming undulating sheets in the (101) plane.

Related literature

For the synthesis, see: Moore & Stupp (1986 ▶); Kida et al. (2005 ▶). For related structures, see: Basaran et al. (1992 ▶); Fun et al. (2009 ▶); Jones & Kus (2007 ▶); Zhang et al. (2007 ▶). For applications of dihalo-p-xylenes in living radical polymerization processes, see: Samakande et al., (2007 ▶); Asandei et al. (2008 ▶). For other polymer applications, see: Leir & Stark (1989 ▶); Hochberg & Schulz (1993 ▶). For additional applications of dihalo-p-xylenes, see: Le Baccon et al. (2001 ▶); Sobransingh & Kaifer (2006 ▶); Song et al. (2008 ▶); Au et al. (2009 ▶). For details of halogen⋯halogen interactions, see: Pedireddi et al. (1994 ▶) and for reference structural data, see: Allen et al. (1987 ▶).

Experimental

Crystal data

C₈H₈I₂
M _r = 357.94
Monoclinic,
a = 9.0978 (3) Å
b = 4.5982 (2) Å
c = 11.2793 (3) Å
β = 99.808 (1)°
V = 464.96 (3) Å³
Z = 2
Mo Kα radiation
μ = 6.69 mm⁻¹
T = 89 K
0.21 × 0.15 × 0.03 mm

Data collection

Bruker APEXII CCD area-detector diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2006 ▶) T _min = 0.410, T _max = 0.818
8198 measured reflections
1674 independent reflections
1538 reflections with I > 2σ(I)
R _int = 0.026

Refinement

R[F ² > 2σ(F ²)] = 0.013
wR(F ²) = 0.033
S = 1.06
1674 reflections
62 parameters
All H-atom parameters refined
Δρ_max = 0.51 e Å⁻³
Δρ_min = −0.51 e Å⁻³

Data collection: APEX2 (Bruker 2006 ▶); cell refinement: APEX2 and SAINT (Bruker 2006 ▶); data reduction: SAINT; program(s) used to solve structure: SIR92 (Altomare et al., 1993 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶) and TITAN (Hunter & Simpson, 1999 ▶); molecular graphics: ORTEP-3 (Farrugia, 1997 ▶) and Mercury (Macrae et al., 2006 ▶); software used to prepare material for publication: SHELXL97, enCIFer (Allen et al., 2004 ▶), PLATON (Spek, 2009 ▶) and publCIF (Westrip, 2009 ▶).

Supplementary Material

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536809021151/hb2998sup1.cif

e-65-o1573-sup1.cif^{(12.5KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536809021151/hb2998Isup2.hkl

e-65-o1573-Isup2.hkl^{(82.5KB, 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—H42⋯I1ⁱ	1.02 (2)	3.12 (2)	3.9774 (16)	141.8 (16)

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Symmetry code: (i) Inline graphic .

Acknowledgments

We thank the New Economy Research Fund (grant No. UOO-X0808) for support of this work and the University of Otago for the purchase of the diffractometer.

supplementary crystallographic information

Comment

Dihalo-p-xylenes are extensively used in polymer science (Leir & Stark, 1989; Hochberg & Schulz, 1993; Samakande et al., 2007) and as a versatile synthon for –CH₂—C₆H₄—CH₂– connective units in other areas of chemistry (Le Baccon et al., 2001; Song et al., 2008; Au et al., 2009). The bulk of this work utilizes the commercially available α,α'-dibromo-p-xylene, but the diiodo- derivative offers additional reactivity (Moore & Stupp, 1986; Sobransingh & Kaifer, 2006; Asandei et al., 2008). Our interest in the title compound, (I), Fig. 1, is as one of the components in xylene bridged electroactive gels. In these, the chemical links are quaternary amines formed by reaction of the alkylhalogen termini with amine residues in the other gel component.

The molecule lies about an inversion centre located at the centroid of the benzene ring. The C1···C4 atoms lie in a plane (r.m.s. deviation 0.01 Å) and the C—C and C—I distances in the molecule are unremarkable (Allen et al., 1987). This structure is the fourth in a series of XCH₂C₆H₄CH₂X molecules; X = F, II (Fun et al., 2009); Cl, III (Basaran et al., (1992); Br, IV (Jones & Kus, 2007; Zhang et al., 2007). All four molecules are closely isostructural with only the C—halogen bond distance distinguishing them. Indeed the CH₂C₆H₄CH₂ fragment of the title compound overlays with corresponding portions of the related molecules with r.m.s. deviations, 0.032 Å for II, 0.013 Å for III and 0.007 Å for IV respectively (Macrae et al., 2006).

In the crystal structure, weak C—H···I interactions and short I···I contacts, 3.8433 (2) Å, form undulating sheets in the 101 plane, Fig. 2. Each I atom interacts with two adjacent iodine atoms (symmetry operations 2 - x, -1/2 + y, 1/2 - z and 2 - x, 1/2 + y, 1/2 - z). The I···I contacts observed here fit with the type II designation of halogen···halogen interactions proposed previously (Pedireddi et al. 1994). The packing arrangement for I is closely similar to that observed for IV, (Jones & Kus, 2007; Zhang et al., 2007). I, III and IV all crystallize in the space group P21/c with unit cells that differ only in a small but significant increase in volume as the size of the halogen increases.

Experimental

The title compound was prepared by a combination of the methods of Moore & Stupp (1986) and Kida et al. (2005). Thus α,α'-dibromo-p-xylene (1.32 g, 5 mmol) was refluxed for 7 h with sodium iodide (2.25 g, 15 mmol) in acetone (25 ml). The solution was allowed to cool overnight, and the resulting yellow plates of (I) that developed were rinsed gently with water to remove sodium bromide and air dried. Confirmation of the metathesized (iodo) product was by microanalysis, mass spectroscopy and diagnostic tests. ¹H and ¹³C NMR spectra are distinct from those of the dibromo precursor.