1,2,4,5-Tetra­iodo­benzene

The title compound, C₆H₂I₄, has crystallographically exact C_i and approximate D_2h molecular symmetry. Two half-mol­ecules comprise the asymmetric unit. The mol­ecules are stacked along the c axis and neigbouring stacks are connected via weak I...I inter­molecular inter­actions.

Key indicators

• Single-crystal X-ray study
• T = 223 K
• Mean [sigma](C-C) = 0.008 Å
• R factor = 0.045
• wR factor = 0.110
• Data-to-parameter ratio = 32.7

checkCIF/PLATON results

No syntax errors found



Alert level C
PLAT125_ALERT_4_C No _symmetry_space_group_name_Hall Given .......          ?
PLAT764_ALERT_4_C 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
   2 ALERT level C = Check and explain
   0 ALERT level G = General alerts; check

   0 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
   0 ALERT type 3 Indicator that the structure quality may be low
   2 ALERT type 4 Improvement, methodology, query or suggestion
   0 ALERT type 5 Informative message, check

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Computing details

Data collection: SMART (Bruker, 1997); cell refinement: SMART; data reduction: SHELXTL (Sheldrick, 1997b) and SAINT (Bruker, 1997); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997a); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997a); molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL.

1,2,4,5-tetraiodobenzene

Crystal data

C6H2I4	F(000) = 1000
Mr = 581.68	Dx = 3.739 Mg m^−3
Monoclinic, P2/c	Mo Kα radiation, λ = 0.71073 Å
a = 17.8144 (8) Å	Cell parameters from 8192 reflections
b = 7.4999 (8) Å	θ = 2.1–25.0°
c = 7.9125 (8) Å	µ = 12.00 mm^−1
β = 102.203 (2)°	T = 223 K
V = 1033.27 (15) Å^3	Plate, cut, colourless
Z = 4	0.40 × 0.10 × 0.08 mm

Data collection

Bruker SMART CCD area detector diffractometer	3006 independent reflections
Radiation source: fine-focus sealed tube	2485 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.078
φ and ω scans	θmax = 30.0°, θmin = 2.3°
Absorption correction: multi-scan (SADABS; Sheldrick, 2001)	h = −18→25
Tmin = 0.129, Tmax = 0.381	k = −8→10
8332 measured reflections	l = −11→11

Refinement

Refinement on F^2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F^2 > 2σ(F^2)] = 0.045	H-atom parameters constrained
wR(F^2) = 0.110	w = 1/[σ^2(Fo^2) + (0.0526P)^2] where P = (Fo^2 + 2Fc^2)/3
S = 1.04	(Δ/σ)max < 0.001
3006 reflections	Δρmax = 1.47 e Å^−3
92 parameters	Δρmin = −1.84 e Å^−3
0 restraints	Extinction correction: SHELXL97, Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.0040 (3)

Special details

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 (Ų)

	x	y	z	Uiso*/Ueq
I1	0.12124 (3)	0.15513 (7)	0.68451 (7)	0.03190 (10)
I2	0.18047 (3)	0.62698 (7)	0.73215 (7)	0.03116 (10)
I4	0.38087 (3)	0.65031 (6)	0.56686 (7)	0.03375 (10)
I6	0.67999 (3)	0.88392 (7)	0.42765 (6)	0.02877 (10)
C1	0.0505 (4)	0.3659 (5)	0.5740 (5)	0.0230 (8)
C2	0.0724 (4)	0.5458 (5)	0.5946 (5)	0.0222 (8)
C3	0.0216 (4)	0.6777 (5)	0.5214 (5)	0.0235 (8)
H3	0.0361	0.7981	0.5365	0.028*
C4	0.4505 (4)	0.8634 (5)	0.5255 (5)	0.0223 (8)
C5	0.5232 (4)	0.8238 (5)	0.4957 (5)	0.0237 (8)
H5	0.5390	0.7044	0.4927	0.028*
C6	0.5719 (4)	0.9594 (5)	0.4707 (5)	0.0218 (8)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
I1	0.0279 (3)	0.0260 (3)	0.0419 (3)	0.00650 (9)	0.0077 (2)	0.00415 (18)
I2	0.0202 (3)	0.0346 (3)	0.0365 (3)	−0.00720 (9)	0.00099 (9)	−0.00335 (18)
I4	0.0320 (3)	0.0242 (3)	0.0484 (3)	−0.0067 (2)	0.0160 (2)	−0.00051 (19)
I6	0.0200 (3)	0.0334 (3)	0.0345 (3)	0.00754 (9)	0.00949 (8)	0.00348 (18)
C1	0.022 (3)	0.018 (3)	0.031 (3)	0.002 (3)	0.011 (3)	−0.002 (2)
C2	0.018 (3)	0.029 (3)	0.020 (3)	−0.007 (3)	0.004 (2)	−0.003 (2)
C3	0.020 (3)	0.020 (3)	0.034 (4)	−0.001 (3)	0.012 (3)	−0.003 (3)
C4	0.016 (3)	0.024 (3)	0.028 (3)	−0.002 (3)	0.008 (3)	0.002 (2)
C5	0.025 (4)	0.018 (3)	0.028 (3)	0.003 (3)	0.003 (3)	0.002 (2)
C6	0.019 (3)	0.024 (3)	0.023 (3)	0.005 (3)	0.007 (2)	0.001 (2)

Geometric parameters (Å, º)

I1—C1	2.094 (7)	C3—C1^i	1.384 (7)
I2—C2	2.092 (6)	C3—H3	0.9400
I4—C4	2.091 (7)	C4—C6^ii	1.390 (7)
I6—C6	2.102 (7)	C4—C5	1.397 (7)
C1—C3^i	1.384 (7)	C5—C6	1.378 (7)
C1—C2	1.404 (7)	C5—H5	0.9400
C2—C3	1.383 (7)	C6—C4^ii	1.390 (7)
C3^i—C1—C2	119.6 (6)	C6^ii—C4—C5	119.2 (6)
C3^i—C1—I1	117.1 (5)	C6^ii—C4—I4	123.0 (5)
C2—C1—I1	123.3 (5)	C5—C4—I4	117.8 (5)
C3—C2—C1	119.8 (6)	C6—C5—C4	120.1 (6)
C3—C2—I2	117.3 (5)	C6—C5—H5	119.9
C1—C2—I2	122.9 (5)	C4—C5—H5	120.0
C2—C3—C1^i	120.6 (6)	C5—C6—C4^ii	120.7 (6)
C2—C3—H3	119.7	C5—C6—I6	116.8 (5)
C1^i—C3—H3	119.7	C4^ii—C6—I6	122.5 (5)

Symmetry codes: (i) −x, −y+1, −z+1; (ii) −x+1, −y+2, −z+1.