1,2-Diiodo-4,5-dimethyl-benzene.

The structure of the title compound, C(8)H(8)I(2), conforms closely to the mm2 symmetry expected for the free mol-ecule and is the first reported structure of a diiodo-dimethyl-benzene. Repulsion by neighboring I atoms and the neighboring methyl groups opposite to them results in a slight elongation of the mol-ecule along the approximate twofold rotation axis that bis-ects the ring between the two I atoms. In the extended structure, the mol-ecules form inversion-related pairs which are organized in approximately hexa-gonal close-packed layers and the layers then stacked so that mol-ecules in neighboring layers abut head-to-tail in a manner that optimizes dipole-dipole inter-actions.

Related literature

For the synthesis see: Suzuki (1988 ▶). For the structure of 1,2-diiodo-4,5-dimethoxy­benzene, see: Cukiernik et al. (2008 ▶). For methods of iodinating substituted benzenes, see: Hathaway et al. (2007 ▶). For related work on diacetyl­enes, see: Hathaway (1988 ▶); Hathaway & Scates (1997 ▶).

Experimental

Crystal data

C8H8I2

M = 357.94

Monoclinic,

a = 9.4458 (1) Å

b = 8.1334 (1) Å

c = 13.4562 (2) Å

β = 110.109 (1)°

V = 970.77 (2) Å3

Z = 4

Mo Kα radiation

μ = 6.41 mm−1

T = 298 K

0.3 × 0.2 × 0.18 mm

Data collection

Nonius KappaCCD diffractometer

Absorption correction: multi-scan (SORTAV; Blessing, 1995 ▶) T min = 0.184, T max = 0.316

32763 measured reflections

4243 independent reflections

2520 reflections with I > 2σ(I)

R int = 0.057

Refinement

R[F 2 > 2σ(F 2)] = 0.035

wR(F 2) = 0.090

S = 1.10

4243 reflections

94 parameters

H-atom parameters constrained

Δρmax = 0.90 e Å−3

Δρmin = −0.75 e Å−3

Data collection: COLLECT (Hooft, 1998 ▶); cell refinement: SCALEPACK (Otwinowski & Minor, 1997 ▶); data reduction: SCALEPACK and DENZO (Otwinowski & Minor, 1997 ▶); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: ORTEP-3 (Farrugia, 1997 ▶); software used to prepare material for publication: WinGX (Farrugia, 1999 ▶).

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536809016018/is2407sup1.cif

Structure factors: contains datablocks I. DOI: 10.1107/S1600536809016018/is2407Isup2.hkl

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

C8H8I2	F(000) = 648
Mr = 357.94	Dx = 2.449 Mg m−3
Monoclinic, P21/n	Melting point = 365–363 K
Hall symbol: -P 2yn	Mo Kα radiation, λ = 0.71073 Å
a = 9.4458 (1) Å	Cell parameters from 4493 reflections
b = 8.1334 (1) Å	θ = 2.9–35.0°
c = 13.4562 (2) Å	µ = 6.41 mm−1
β = 110.109 (1)°	T = 298 K
V = 970.77 (2) Å3	Prism, colorless
Z = 4	0.3 × 0.2 × 0.18 mm

Nonius KappaCCD diffractometer	2520 reflections with I > 2σ(I)
φ and ω scans	Rint = 0.057
Absorption correction: multi-scan (SORTAV; Blessing, 1995)	θmax = 35.1°, θmin = 3.0°
Tmin = 0.184, Tmax = 0.316	h = −15→15
32763 measured reflections	k = −13→13
4243 independent reflections	l = −21→21

Refinement on F2	H-atom parameters constrained
Least-squares matrix: full	w = 1/[σ2(Fo2) + (0.0253P)2 + 1.2156P] where P = (Fo2 + 2Fc2)/3
R[F2 > 2σ(F2)] = 0.035	(Δ/σ)max = 0.002
wR(F2) = 0.090	Δρmax = 0.90 e Å−3
S = 1.10	Δρmin = −0.75 e Å−3
4243 reflections	Extinction correction: SHELXL97 (Sheldrick, 2008), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
94 parameters	Extinction coefficient: 0.0069 (6)
0 restraints

Experimental. 13 C-NMR (CDCl3, 75.5 MHz): δ 140.0, 138.6, 104.0, 19.1. IR (thin film on a KBr disk) cm-1: 2976, 2938, 1720, 1438, 1370, 1329, 1264, 1153, 1018, 864.

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.Mean plane calculation for molecule: m1 = -0.09103(0.00034) m2 = 0.84014(0.00006) m3 = -0.53468(0.00010) D = 1.69893(0.00184) Atom d s d/s (d/s)**2 I1 * -0.0006 0.0003 - 1.888 3.565 I2 * 0.0008 0.0003 2.741 7.511 C1 * -0.0032 0.0034 - 0.919 0.844 C2 * -0.0310 0.0033 - 9.414 88.619 C3 * -0.0569 0.0035 - 16.075 258.411 C4 * -0.0270 0.0036 - 7.562 57.183 C5 * 0.0431 0.0036 11.962 143.098 C6 * 0.0336 0.0037 9.187 84.400 C41 * -0.0843 0.0048 - 17.682 312.643 C51 * 0.1187 0.0049 24.074 579.539 ============ Sum((d/s)**2) for starred atoms 1535.813 Chi-squared at 95% for 7 degrees of freedom: 14.10 The group of atoms deviates significantly from planarity

	x	y	z	Uiso*/Ueq
I1	0.60697 (3)	0.54314 (4)	0.23538 (2)	0.06585 (12)
I2	0.74073 (3)	0.78802 (4)	0.48114 (2)	0.06329 (11)
C1	0.4696 (4)	0.6067 (4)	0.3230 (3)	0.0443 (7)
C2	0.5208 (4)	0.6956 (4)	0.4163 (3)	0.0432 (7)
C3	0.4222 (4)	0.7288 (4)	0.4696 (3)	0.0472 (7)
H3	0.4573	0.7864	0.5331	0.057*
C4	0.2729 (4)	0.6790 (4)	0.4315 (3)	0.0465 (7)
C5	0.2204 (4)	0.5941 (4)	0.3360 (3)	0.0478 (7)
C6	0.3202 (4)	0.5567 (5)	0.2835 (3)	0.0484 (8)
H6	0.2861	0.497	0.2208	0.058*
C41	0.1722 (5)	0.7162 (6)	0.4942 (4)	0.0655 (11)
H41A	0.0932	0.7893	0.4546	0.098*
H41B	0.2302	0.7671	0.56	0.098*
H41C	0.1289	0.6158	0.5082	0.098*
C51	0.0575 (5)	0.5410 (6)	0.2889 (4)	0.0686 (11)
H51A	0.0313	0.476	0.3395	0.103*
H51B	0.0438	0.477	0.2263	0.103*
H51C	−0.0061	0.6364	0.2708	0.103*

	U11	U22	U33	U12	U13	U23
I1	0.06034 (17)	0.0866 (2)	0.05987 (17)	0.00565 (14)	0.03258 (13)	−0.00308 (14)
I2	0.04658 (14)	0.06653 (19)	0.06980 (19)	−0.01353 (11)	0.01107 (11)	−0.00086 (13)
C1	0.0471 (16)	0.0459 (17)	0.0444 (16)	−0.0011 (14)	0.0215 (13)	0.0011 (13)
C2	0.0424 (15)	0.0438 (17)	0.0406 (15)	−0.0035 (13)	0.0106 (12)	0.0038 (13)
C3	0.0541 (18)	0.0462 (18)	0.0394 (15)	−0.0009 (15)	0.0137 (13)	−0.0036 (14)
C4	0.0478 (17)	0.0467 (18)	0.0489 (17)	0.0030 (14)	0.0217 (14)	0.0042 (14)
C5	0.0437 (16)	0.0456 (18)	0.0529 (18)	−0.0012 (14)	0.0152 (14)	0.0045 (14)
C6	0.0485 (18)	0.0529 (19)	0.0411 (16)	−0.0062 (15)	0.0119 (13)	−0.0046 (14)
C41	0.068 (3)	0.075 (3)	0.067 (2)	0.005 (2)	0.041 (2)	0.000 (2)
C51	0.046 (2)	0.073 (3)	0.083 (3)	−0.007 (2)	0.0168 (19)	−0.006 (2)

I1—C1	2.097 (3)	C41—H41B	0.96
I2—C2	2.097 (3)	C41—H41C	0.96
C1—C2	1.384 (5)	C4—C5	1.391 (5)
C1—C6	1.386 (5)	C5—C51	1.512 (5)
C2—C3	1.384 (5)	C51—H51A	0.96
C3—C4	1.385 (5)	C51—H51B	0.96
C3—H3	0.93	C51—H51C	0.96
C4—C41	1.504 (5)	C5—C6	1.392 (5)
C41—H41A	0.96	C6—H6	0.93
I1···I2i	4.1737 (3)	I1···I2ii	4.2126 (4)
C2—C1—C6	119.6 (3)	H41A—C41—H41C	109.5
C2—C1—I1	123.2 (2)	H41B—C41—H41C	109.5
C6—C1—I1	117.2 (2)	C5—C4—C41	121.7 (4)
C1—C2—C3	119.0 (3)	C4—C5—C6	119.2 (3)
C1—C2—I2	123.5 (2)	C4—C5—C51	121.2 (4)
C3—C2—I2	117.5 (2)	C5—C51—H51A	109.5
C2—C3—C4	122.1 (3)	C5—C51—H51B	109.5
C2—C3—H3	118.9	H51A—C51—H51B	109.5
C4—C3—H3	118.9	C5—C51—H51C	109.5
C3—C4—C5	118.8 (3)	H51A—C51—H51C	109.5
C3—C4—C41	119.5 (3)	H51B—C51—H51C	109.5
C4—C41—H41A	109.5	C6—C5—C51	119.6 (4)
C4—C41—H41B	109.5	C1—C6—C5	121.3 (3)
H41A—C41—H41B	109.5	C1—C6—H6	119.4
C4—C41—H41C	109.5	C5—C6—H6	119.4