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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.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S1600536809021151/hb2998sup1.cif
Contains datablocks global, I

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S1600536809021151/hb2998Isup2.hkl
Contains datablock I

CCDC reference: 741606

Key indicators

  • Single-crystal X-ray study
  • T = 89 K
  • Mean [sigma](C-C) = 0.002 Å
  • R factor = 0.013
  • wR factor = 0.033
  • Data-to-parameter ratio = 27.0

checkCIF/PLATON results

No syntax errors found



Alert level C ABSTM02_ALERT_3_C The ratio of expected to reported Tmax/Tmin(RR) is > 1.10 Tmin and Tmax reported: 0.410 0.818 Tmin and Tmax expected: 0.312 0.818 RR = 1.315 Please check that your absorption correction is appropriate. PLAT060_ALERT_4_C Ratio Tmax/Tmin (Exp-to-Rep) (too) Large ....... 1.32 PLAT480_ALERT_4_C Long H...A H-Bond Reported H42 .. I1 .. 3.12 Ang.
Alert level G PLAT164_ALERT_4_G Nr. of Refined C-H H-Atoms in Heavy-Atom Struct. 4 PLAT200_ALERT_1_G Check the Reported _diffrn_ambient_temperature . 293 K PLAT764_ALERT_4_G Overcomplete CIF Bond List Detected (Rep/Expd) . 1.20 Ratio
0 ALERT level A = In general: serious problem 0 ALERT level B = Potentially serious problem 3 ALERT level C = Check and explain 3 ALERT level G = General alerts; check 1 ALERT type 1 CIF construction/syntax error, inconsistent or missing data 0 ALERT type 2 Indicator that the structure model may be wrong or deficient 1 ALERT type 3 Indicator that the structure quality may be low 4 ALERT type 4 Improvement, methodology, query or suggestion 0 ALERT type 5 Informative message, check

Comment top

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.

Related literature top

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 top

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.

Refinement top

All H-atoms were located in a difference Fourier map and refined freely.

Computing details top

Data collection: APEX2 (Bruker 2006); cell refinement: APEX2 (Bruker 2006) and SAINT (Bruker 2006); data reduction: SAINT (Bruker 2006); 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 (Sheldrick, 2008), enCIFer (Allen et al., 2004), PLATON (Spek, 2009) and publCIF (Westrip, 2009).

Figures top
[Figure 1] Fig. 1. The structure of (I) with displacement ellipsoids for the non-hydrogen atoms drawn at the 50% probability level. Unlabelled atoms are generated by the symmetry operation (1–x, –y, 1–z).
[Figure 2] Fig. 2. Crystal packing for (I) viewed down the b axis with hydrogen bonds and short I···I contacts drawn as dashed lines.
1,4-bis(iodomethyl)benzene top
Crystal data top
C8H8I2F(000) = 324
Mr = 357.94Dx = 2.557 Mg m3
Monoclinic, P21/cMo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybcCell parameters from 5590 reflections
a = 9.0978 (3) Åθ = 2.3–33.0°
b = 4.5982 (2) ŵ = 6.69 mm1
c = 11.2793 (3) ÅT = 89 K
β = 99.808 (1)°Rectangular plate, pale yellow
V = 464.96 (3) Å30.21 × 0.15 × 0.03 mm
Z = 2
Data collection top
Bruker APEXII CCD area-detector
diffractometer
1674 independent reflections
Radiation source: fine-focus sealed tube1538 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.026
ω scansθmax = 33.4°, θmin = 3.7°
Absorption correction: multi-scan
(SADABS; Bruker, 2006)
h = 1313
Tmin = 0.410, Tmax = 0.818k = 57
8198 measured reflectionsl = 1616
Refinement top
Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.013Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.033All H-atom parameters refined
S = 1.06 w = 1/[σ2(Fo2) + (0.0145P)2 + 0.1407P]
where P = (Fo2 + 2Fc2)/3
1674 reflections(Δ/σ)max = 0.001
62 parametersΔρmax = 0.51 e Å3
0 restraintsΔρmin = 0.51 e Å3
Crystal data top
C8H8I2V = 464.96 (3) Å3
Mr = 357.94Z = 2
Monoclinic, P21/cMo Kα radiation
a = 9.0978 (3) ŵ = 6.69 mm1
b = 4.5982 (2) ÅT = 89 K
c = 11.2793 (3) Å0.21 × 0.15 × 0.03 mm
β = 99.808 (1)°
Data collection top
Bruker APEXII CCD area-detector
diffractometer
1674 independent reflections
Absorption correction: multi-scan
(SADABS; Bruker, 2006)
1538 reflections with I > 2σ(I)
Tmin = 0.410, Tmax = 0.818Rint = 0.026
8198 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0130 restraints
wR(F2) = 0.033All H-atom parameters refined
S = 1.06Δρmax = 0.51 e Å3
1674 reflectionsΔρmin = 0.51 e Å3
62 parameters
Special details top

Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes.

Refinement. Refinement of F2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F2, conventional R-factors R are based on F, with F set to zero for negative F2. The threshold expression of F2 > σ(F2) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F2 are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
C10.62504 (16)0.1521 (3)0.47504 (13)0.0138 (2)
C20.63784 (17)0.0405 (3)0.57245 (14)0.0154 (3)
C30.51429 (17)0.1903 (3)0.59710 (14)0.0154 (3)
C40.75717 (18)0.3189 (4)0.45106 (15)0.0190 (3)
I10.880515 (9)0.07951 (2)0.331669 (8)0.01438 (4)
H20.729 (3)0.073 (4)0.620 (2)0.021 (6)*
H410.841 (3)0.354 (5)0.524 (2)0.031 (6)*
H30.523 (2)0.330 (5)0.6678 (19)0.022 (5)*
H420.733 (3)0.509 (5)0.405 (2)0.021 (5)*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
C10.0142 (6)0.0109 (6)0.0180 (6)0.0017 (5)0.0078 (5)0.0032 (5)
C20.0133 (6)0.0159 (7)0.0174 (7)0.0007 (5)0.0038 (5)0.0010 (5)
C30.0175 (6)0.0126 (6)0.0175 (6)0.0006 (5)0.0070 (5)0.0012 (5)
C40.0191 (7)0.0150 (7)0.0258 (8)0.0039 (5)0.0124 (6)0.0051 (6)
I10.01367 (5)0.01628 (6)0.01473 (5)0.00037 (3)0.00680 (3)0.00092 (3)
Geometric parameters (Å, º) top
C1—C3i1.396 (2)C3—C1i1.396 (2)
C1—C21.401 (2)C3—H31.01 (2)
C1—C41.489 (2)C4—I12.1907 (15)
C2—C31.386 (2)C4—H411.04 (2)
C2—H20.92 (2)C4—H421.02 (2)
C3i—C1—C2118.88 (13)C1i—C3—H3118.7 (12)
C3i—C1—C4120.68 (14)C1—C4—I1111.52 (10)
C2—C1—C4120.42 (14)C1—C4—H41116.4 (13)
C3—C2—C1120.64 (14)I1—C4—H41100.5 (13)
C3—C2—H2119.1 (14)C1—C4—H42114.9 (13)
C1—C2—H2120.3 (14)I1—C4—H42101.8 (13)
C2—C3—C1i120.48 (14)H41—C4—H42109.8 (19)
C2—C3—H3120.9 (12)
C3i—C1—C2—C30.1 (2)C3i—C1—C4—I191.95 (15)
C4—C1—C2—C3178.24 (14)C2—C1—C4—I189.71 (15)
C1—C2—C3—C1i0.1 (2)
Symmetry code: (i) x+1, y, z+1.
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
C4—H42···I1ii1.02 (2)3.12 (2)3.9774 (16)141.8 (16)
Symmetry code: (ii) x, y+1, z.

Experimental details

Crystal data
Chemical formulaC8H8I2
Mr357.94
Crystal system, space groupMonoclinic, P21/c
Temperature (K)89
a, b, c (Å)9.0978 (3), 4.5982 (2), 11.2793 (3)
β (°) 99.808 (1)
V3)464.96 (3)
Z2
Radiation typeMo Kα
µ (mm1)6.69
Crystal size (mm)0.21 × 0.15 × 0.03
Data collection
DiffractometerBruker APEXII CCD area-detector
diffractometer
Absorption correctionMulti-scan
(SADABS; Bruker, 2006)
Tmin, Tmax0.410, 0.818
No. of measured, independent and
observed [I > 2σ(I)] reflections
8198, 1674, 1538
Rint0.026
(sin θ/λ)max1)0.775
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.013, 0.033, 1.06
No. of reflections1674
No. of parameters62
H-atom treatmentAll H-atom parameters refined
Δρmax, Δρmin (e Å3)0.51, 0.51

Computer programs: , APEX2 (Bruker 2006) and SAINT (Bruker 2006), SAINT (Bruker 2006), SIR92 (Altomare et al., 1993), SHELXL97 (Sheldrick, 2008) and TITAN (Hunter & Simpson, 1999), ORTEP-3 (Farrugia, 1997) and Mercury (Macrae et al., 2006), SHELXL97 (Sheldrick, 2008), enCIFer (Allen et al., 2004), PLATON (Spek, 2009) and publCIF (Westrip, 2009).

Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
C4—H42···I1i1.02 (2)3.12 (2)3.9774 (16)141.8 (16)
Symmetry code: (i) x, y+1, z.
 

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