Supporting information
Crystallographic Information File (CIF) https://doi.org/10.1107/S1600536803013977/om6149sup1.cif | |
Structure factor file (CIF format) https://doi.org/10.1107/S1600536803013977/om6149Isup2.hkl |
CCDC reference: 217614
The 2,4,5-trichloroiodobenzene crystals were obtained while attempting to synthesize 2,4,5-trichlorobiphenyl in the Suzuki reaction (Lehmler et al., 2001). Colorless needle-shaped crystals formed from solution in methanol.
The crystals are extensively disordered. The asymmetric unit contains nominally half a molecule, but it is disordered such that the Cl and I atoms are partially superimposed. Given the known chemical composition, a satisfactory model requires that the sum of the Cl atom occupancies should sum to 1.5 over the two halogen sites in the asymmetric unit, which was accomplished with the SUMP command in SHELXL97 (Sheldrick, 1997). This in turn allowed the I occupancy total over the two sites to be 0.5 while at the same time ensuring that the total occupancy of each site itself is unity. Bond distances for C—Cl and C—I are heavily correlated as a result of the disorder and it was not possible to independently refine both. The length of C—I bonds was optimized to be 1.15 times that of the corresponding C—Cl bonds. This treatment ensured that the C—Cl bonds were typical for this class of compound (e.g. Lehmler et al., 2001). The C—I bond length reported here should thus be regarded as a compromise to improve the least-squares fit and no particular claims are made for the accuracy of this C—I distance. The anisotropic displacement parameters (ADPs) of each individual pair of overlapping Cl/I were constrained to be equal while the ADPs between each pair were restrained to be similar.
Data collection: COLLECT (Nonius, 1998); cell refinement: SCALEPACK (Otwinowski & Minor, 1997); data reduction: DENZO-SMN (Otwinowski & Minor, 1997); program(s) used to solve structure: SHELXS97 (Sheldrick, 1990); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: XP in Siemens SHELXTL (Sheldrick, 1994); software used to prepare material for publication: SHELX97-2 (Sheldrick, 1997) and local procedures.
C6H2Cl3I | F(000) = 284 |
Mr = 307.33 | Dx = 2.471 Mg m−3 |
Monoclinic, P21/n | Mo Kα radiation, λ = 0.71073 Å |
a = 3.9191 (8) Å | Cell parameters from 993 reflections |
b = 10.894 (2) Å | θ = 1.0–27.5° |
c = 9.852 (2) Å | µ = 4.76 mm−1 |
β = 100.87 (3)° | T = 90 K |
V = 413.07 (15) Å3 | Block, colourless |
Z = 2 | 0.20 × 0.10 × 0.10 mm |
Nonius KappaCCD diffractometer | 936 independent reflections |
Radiation source: fine-focus sealed tube | 884 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.035 |
Detector resolution: 18 pixels mm-1 | θmax = 27.5°, θmin = 2.8° |
ω scans at fixed χ = 55° | h = −4→5 |
Absorption correction: multi-scan (SADABS; Sheldrick, 1997) | k = −13→14 |
Tmin = 0.570, Tmax = 0.621 | l = −12→12 |
6306 measured reflections |
Refinement on F2 | Secondary atom site location: difference Fourier map |
Least-squares matrix: full | Hydrogen site location: inferred from neighbouring sites |
R[F2 > 2σ(F2)] = 0.035 | H-atom parameters constrained |
wR(F2) = 0.078 | w = 1/[σ2(Fo2))2 + 1.7326P] where P = (Fo2 + 2Fc2)/3 |
S = 1.35 | (Δ/σ)max < 0.001 |
936 reflections | Δρmax = 0.64 e Å−3 |
56 parameters | Δρmin = −0.72 e Å−3 |
5 restraints | Extinction correction: SHELXL97, Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4 |
Primary atom site location: structure-invariant direct methods | Extinction coefficient: 0.011 (2) |
C6H2Cl3I | V = 413.07 (15) Å3 |
Mr = 307.33 | Z = 2 |
Monoclinic, P21/n | Mo Kα radiation |
a = 3.9191 (8) Å | µ = 4.76 mm−1 |
b = 10.894 (2) Å | T = 90 K |
c = 9.852 (2) Å | 0.20 × 0.10 × 0.10 mm |
β = 100.87 (3)° |
Nonius KappaCCD diffractometer | 936 independent reflections |
Absorption correction: multi-scan (SADABS; Sheldrick, 1997) | 884 reflections with I > 2σ(I) |
Tmin = 0.570, Tmax = 0.621 | Rint = 0.035 |
6306 measured reflections |
R[F2 > 2σ(F2)] = 0.035 | 5 restraints |
wR(F2) = 0.078 | H-atom parameters constrained |
S = 1.35 | Δρmax = 0.64 e Å−3 |
936 reflections | Δρmin = −0.72 e Å−3 |
56 parameters |
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. |
x | y | z | Uiso*/Ueq | Occ. (<1) | |
Cl1 | 0.151 (2) | 0.4432 (7) | 0.2017 (8) | 0.0208 (4) | 0.6201 (14) |
I1 | 0.1386 (9) | 0.4246 (2) | 0.1821 (3) | 0.0208 (4) | 0.3799 (14) |
Cl2 | −0.063 (3) | 0.2275 (4) | 0.4017 (10) | 0.0314 (7) | 0.8799 (14) |
I2 | −0.060 (6) | 0.2056 (10) | 0.403 (2) | 0.0314 (7) | 0.1201 (14) |
C1 | 0.0622 (11) | 0.4691 (4) | 0.3699 (4) | 0.0249 (9) | |
C2 | −0.0299 (11) | 0.3787 (4) | 0.4563 (5) | 0.0258 (9) | |
C3 | −0.0924 (11) | 0.4098 (4) | 0.5855 (5) | 0.0263 (9) | |
H3 | −0.1562 | 0.3480 | 0.6441 | 0.032* |
U11 | U22 | U33 | U12 | U13 | U23 | |
Cl1 | 0.0303 (4) | 0.0179 (10) | 0.0161 (9) | 0.0004 (6) | 0.0089 (6) | −0.0089 (5) |
I1 | 0.0303 (4) | 0.0179 (10) | 0.0161 (9) | 0.0004 (6) | 0.0089 (6) | −0.0089 (5) |
Cl2 | 0.0475 (6) | 0.0129 (19) | 0.0321 (6) | −0.0048 (19) | 0.0033 (4) | 0.0012 (17) |
I2 | 0.0475 (6) | 0.0129 (19) | 0.0321 (6) | −0.0048 (19) | 0.0033 (4) | 0.0012 (17) |
C1 | 0.0204 (19) | 0.031 (2) | 0.021 (2) | 0.0020 (17) | −0.0018 (15) | 0.0022 (17) |
C2 | 0.022 (2) | 0.026 (2) | 0.026 (2) | −0.0012 (16) | −0.0048 (16) | 0.0023 (17) |
C3 | 0.021 (2) | 0.030 (2) | 0.026 (2) | −0.0012 (17) | −0.0018 (16) | 0.0066 (17) |
Cl1—C1 | 1.778 (8) | C1—C2 | 1.393 (6) |
I1—C1 | 1.989 (5) | C2—C3 | 1.383 (6) |
Cl2—C2 | 1.729 (7) | C3—C1i | 1.389 (6) |
I2—C2 | 1.955 (12) | C3—H3 | 0.9500 |
C1—C3i | 1.389 (6) | ||
C3i—C1—C2 | 119.7 (4) | C1—C2—Cl2 | 119.7 (5) |
C3i—C1—Cl1 | 115.2 (4) | C3—C2—I2 | 118.0 (7) |
C2—C1—Cl1 | 125.1 (4) | C1—C2—I2 | 121.9 (7) |
C3i—C1—I1 | 120.5 (3) | C2—C3—C1i | 120.3 (4) |
C2—C1—I1 | 119.8 (3) | C2—C3—H3 | 119.8 |
C3—C2—C1 | 120.0 (4) | C1i—C3—H3 | 119.8 |
C3—C2—Cl2 | 120.3 (5) | ||
C3i—C1—C2—C3 | 0.3 (7) | C3i—C1—C2—I2 | −177.7 (8) |
Cl1—C1—C2—C3 | 179.9 (5) | Cl1—C1—C2—I2 | 2.0 (10) |
I1—C1—C2—C3 | −178.3 (3) | I1—C1—C2—I2 | 3.8 (9) |
C3i—C1—C2—Cl2 | −179.3 (5) | C1—C2—C3—C1i | −0.3 (7) |
Cl1—C1—C2—Cl2 | 0.4 (7) | Cl2—C2—C3—C1i | 179.3 (5) |
I1—C1—C2—Cl2 | 2.2 (6) | I2—C2—C3—C1i | 177.8 (8) |
Symmetry code: (i) −x, −y+1, −z+1. |
Experimental details
Crystal data | |
Chemical formula | C6H2Cl3I |
Mr | 307.33 |
Crystal system, space group | Monoclinic, P21/n |
Temperature (K) | 90 |
a, b, c (Å) | 3.9191 (8), 10.894 (2), 9.852 (2) |
β (°) | 100.87 (3) |
V (Å3) | 413.07 (15) |
Z | 2 |
Radiation type | Mo Kα |
µ (mm−1) | 4.76 |
Crystal size (mm) | 0.20 × 0.10 × 0.10 |
Data collection | |
Diffractometer | Nonius KappaCCD diffractometer |
Absorption correction | Multi-scan (SADABS; Sheldrick, 1997) |
Tmin, Tmax | 0.570, 0.621 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 6306, 936, 884 |
Rint | 0.035 |
(sin θ/λ)max (Å−1) | 0.650 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.035, 0.078, 1.35 |
No. of reflections | 936 |
No. of parameters | 56 |
No. of restraints | 5 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 0.64, −0.72 |
Computer programs: COLLECT (Nonius, 1998), SCALEPACK (Otwinowski & Minor, 1997), DENZO-SMN (Otwinowski & Minor, 1997), SHELXS97 (Sheldrick, 1990), SHELXL97 (Sheldrick, 1997), XP in Siemens SHELXTL (Sheldrick, 1994), SHELX97-2 (Sheldrick, 1997) and local procedures.
PCBs are an important group of widespread environmental contaminants, known to cause a variety of toxic effects (Robertson & Hansen, 2001). During our attempts to synthesize pure PCB congeners, we obtained crystals of the title compound, (I), whose structure is reported herein.
2,4,5-trichloro-1-iodobenzene is one compound in a series of chlorinated derivatives of iodo- or bromobenzenes, which are `building blocks' to obtain polychlorinated biphenyls (PCBs). The 2,4,5-trichlorophenyl moiety is commonly found in PCB congeners in combination with a second phenyl moiety, and its three-dimensional structure is correlated with the toxicity of PCBs (Lehmler & Robertson, 2001). The availability of crystal structure data will therefore aid us in our understanding of toxicity of PCB congeners with a 2,4,5-substitution pattern.