Supporting information
Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270103012769/de1213sup1.cif | |
Structure factor file (CIF format) https://doi.org/10.1107/S0108270103012769/de1213Isup2.hkl |
CCDC reference: 219572
The structure was refined initially without considering disorder and converged with R = 0.033. The difference map suggested that molecule 1 might be disordered; there were peaks of 1.77 and 1.63 e Å−3 at the positions where I atoms bonded to C103 and C106 might be expected. The minor component of the disorder was constrained to have the same geometry as the major component with identical anisotropic displacement parameters for atoms in near coincidence. The refinement with disorder converged with R = 0.027 for 5.61 (6)% disorder. The minor component has been ignored in the discussion of the packing. The disorder leads to one unreasonably short I···I distance of 3.44 Å between I31 and I51(1 − x, 2 − y, 1 − z). This is presumably a consequence of inaccuracy in the position of the minor component plus the failure to find the small amount of disorder in molecule 3 that must be also be present.
Data collection: SMART (Siemens, 1995); cell refinement: SAINT (Siemens, 1995); data reduction: SAINT; program(s) used to solve structure: SHELXTL (Sheldrick, 1997); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL.
C10H12I2 | Z = 8 |
Mr = 386.00 | F(000) = 1424 |
Triclinic, P1 | Dx = 2.305 Mg m−3 |
Hall symbol: -P 1 | Melting point = 410–411 K |
a = 8.152 (2) Å | Mo Kα radiation, λ = 0.71073 Å |
b = 15.622 (4) Å | Cell parameters from 3385 reflections |
c = 18.080 (5) Å | θ = 2.6–27.2° |
α = 86.60 (1)° | µ = 5.61 mm−1 |
β = 86.93 (1)° | T = 174 K |
γ = 75.57 (1)° | Needle, colorless |
V = 2224.1 (10) Å3 | 0.50 × 0.10 × 0.05 mm |
Siemens SMART area-detector diffractometer | 10118 independent reflections |
Radiation source: fine-focus sealed tube | 7650 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.029 |
ω scans | θmax = 27.5°, θmin = 1.4° |
Absorption correction: multi-scan (SADABS; Sheldrick, 1996; Blessing, 1995) | h = −10→10 |
Tmin = 0.55, Tmax = 0.76 | k = −20→20 |
26644 measured reflections | l = −23→23 |
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)] = 0.027 | H-atom parameters constrained |
wR(F2) = 0.061 | w = 1/[σ2(Fo2) + (0.024P)2 + 1.06P] where P = (Fo2 + 2Fc2)/3 |
S = 1.00 | (Δ/σ)max = 0.004 |
10118 reflections | Δρmax = 0.93 e Å−3 |
471 parameters | Δρmin = −0.99 e Å−3 |
39 restraints | Extinction correction: SHELXTL, Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4 |
Primary atom site location: structure-invariant direct methods | Extinction coefficient: 0.00038 (4) |
C10H12I2 | γ = 75.57 (1)° |
Mr = 386.00 | V = 2224.1 (10) Å3 |
Triclinic, P1 | Z = 8 |
a = 8.152 (2) Å | Mo Kα radiation |
b = 15.622 (4) Å | µ = 5.61 mm−1 |
c = 18.080 (5) Å | T = 174 K |
α = 86.60 (1)° | 0.50 × 0.10 × 0.05 mm |
β = 86.93 (1)° |
Siemens SMART area-detector diffractometer | 10118 independent reflections |
Absorption correction: multi-scan (SADABS; Sheldrick, 1996; Blessing, 1995) | 7650 reflections with I > 2σ(I) |
Tmin = 0.55, Tmax = 0.76 | Rint = 0.029 |
26644 measured reflections |
R[F2 > 2σ(F2)] = 0.027 | 39 restraints |
wR(F2) = 0.061 | H-atom parameters constrained |
S = 1.00 | Δρmax = 0.93 e Å−3 |
10118 reflections | Δρmin = −0.99 e Å−3 |
471 parameters |
x | y | z | Uiso*/Ueq | Occ. (<1) | |
C101 | 0.6550 (5) | 0.8321 (2) | 0.8833 (2) | 0.0293 (8) | 0.9439 (6) |
C102 | 0.6339 (5) | 0.7786 (3) | 0.9466 (2) | 0.0304 (8) | 0.9439 (6) |
C103 | 0.6077 (5) | 0.6947 (3) | 0.9365 (2) | 0.0310 (9) | 0.9439 (6) |
C104 | 0.6042 (5) | 0.6689 (3) | 0.8644 (2) | 0.0303 (9) | 0.9439 (6) |
C105 | 0.6238 (5) | 0.7225 (3) | 0.8007 (2) | 0.0328 (9) | 0.9439 (6) |
C106 | 0.6492 (5) | 0.8061 (3) | 0.8108 (2) | 0.0313 (9) | 0.9439 (6) |
I11 | 0.69383 (4) | 0.95888 (2) | 0.89954 (2) | 0.04205 (9) | 0.9439 (6) |
C12 | 0.6417 (7) | 0.8094 (3) | 1.0240 (2) | 0.0422 (10) | 0.9439 (6) |
H12A | 0.6566 | 0.8699 | 1.0208 | 0.063* | 0.9439 (6) |
H12B | 0.7374 | 0.7700 | 1.0491 | 0.063* | 0.9439 (6) |
H12C | 0.5360 | 0.8083 | 1.0521 | 0.063* | 0.9439 (6) |
C13 | 0.5845 (10) | 0.6347 (4) | 1.0037 (4) | 0.0432 (11) | 0.9439 (6) |
H13A | 0.5681 | 0.5789 | 0.9871 | 0.065* | 0.9439 (6) |
H13B | 0.4849 | 0.6640 | 1.0338 | 0.065* | 0.9439 (6) |
H13C | 0.6853 | 0.6226 | 1.0335 | 0.065* | 0.9439 (6) |
I14 | 0.57274 (4) | 0.54028 (2) | 0.84903 (2) | 0.04691 (9) | 0.9439 (6) |
C15 | 0.6166 (8) | 0.6911 (3) | 0.7237 (2) | 0.0473 (11) | 0.9439 (6) |
H15A | 0.6099 | 0.7408 | 0.6873 | 0.071* | 0.9439 (6) |
H15B | 0.5163 | 0.6677 | 0.7210 | 0.071* | 0.9439 (6) |
H15C | 0.7188 | 0.6445 | 0.7129 | 0.071* | 0.9439 (6) |
C16 | 0.6731 (10) | 0.8681 (5) | 0.7456 (3) | 0.0474 (12) | 0.9439 (6) |
H16A | 0.6812 | 0.8372 | 0.6994 | 0.071* | 0.9439 (6) |
H16B | 0.7775 | 0.8872 | 0.7509 | 0.071* | 0.9439 (6) |
H16C | 0.5762 | 0.9199 | 0.7444 | 0.071* | 0.9439 (6) |
C201 | 0.8663 (5) | 0.2220 (2) | 0.05396 (19) | 0.0289 (8) | |
C202 | 0.8938 (5) | 0.3044 (2) | 0.0651 (2) | 0.0294 (8) | |
C203 | 0.8991 (5) | 0.3296 (2) | 0.1381 (2) | 0.0297 (8) | |
C204 | 0.8740 (5) | 0.2698 (2) | 0.1962 (2) | 0.0301 (8) | |
C205 | 0.8448 (5) | 0.1877 (2) | 0.1853 (2) | 0.0294 (8) | |
C206 | 0.8405 (5) | 0.1624 (2) | 0.1119 (2) | 0.0294 (8) | |
I21 | 0.86485 (4) | 0.18231 (2) | −0.05622 (2) | 0.04449 (8) | |
C22 | 0.9210 (6) | 0.3685 (3) | 0.0005 (2) | 0.0446 (11) | |
H22A | 0.9155 | 0.3417 | −0.0466 | 0.067* | |
H22B | 1.0324 | 0.3810 | 0.0036 | 0.067* | |
H22C | 0.8325 | 0.4238 | 0.0034 | 0.067* | |
C23 | 0.9301 (6) | 0.4183 (3) | 0.1520 (2) | 0.0422 (10) | |
H23A | 0.9588 | 0.4465 | 0.1048 | 0.063* | |
H23B | 1.0241 | 0.4102 | 0.1854 | 0.063* | |
H23C | 0.8276 | 0.4560 | 0.1747 | 0.063* | |
I24 | 0.88390 (4) | 0.30704 (2) | 0.30673 (2) | 0.04166 (8) | |
C25 | 0.8204 (6) | 0.1234 (3) | 0.2489 (2) | 0.0441 (11) | |
H25A | 0.8221 | 0.1507 | 0.2962 | 0.066* | |
H25B | 0.9121 | 0.0693 | 0.2466 | 0.066* | |
H25C | 0.7112 | 0.1087 | 0.2451 | 0.066* | |
C26 | 0.8080 (6) | 0.0746 (3) | 0.0968 (2) | 0.0424 (10) | |
H26A | 0.8228 | 0.0653 | 0.0435 | 0.064* | |
H26B | 0.6919 | 0.0740 | 0.1134 | 0.064* | |
H26C | 0.8882 | 0.0272 | 0.1236 | 0.064* | |
C301 | 0.3043 (5) | 0.8407 (2) | 0.3928 (2) | 0.0294 (8) | |
C302 | 0.3932 (5) | 0.7911 (2) | 0.45133 (19) | 0.0309 (8) | |
C303 | 0.4831 (5) | 0.7036 (2) | 0.43933 (19) | 0.0294 (8) | |
C304 | 0.4787 (5) | 0.6709 (2) | 0.3691 (2) | 0.0275 (8) | |
C305 | 0.3901 (5) | 0.7214 (2) | 0.31015 (19) | 0.0275 (8) | |
C306 | 0.2978 (5) | 0.8081 (2) | 0.3230 (2) | 0.0285 (8) | |
I31 | 0.17426 (4) | 0.97406 (2) | 0.41006 (2) | 0.04619 (8) | |
C32 | 0.3922 (6) | 0.8295 (3) | 0.5286 (2) | 0.0455 (11) | |
H32A | 0.3063 | 0.8858 | 0.5309 | 0.068* | |
H32B | 0.5040 | 0.8392 | 0.5366 | 0.068* | |
H32C | 0.3656 | 0.7876 | 0.5672 | 0.068* | |
C33 | 0.5801 (5) | 0.6462 (3) | 0.5007 (2) | 0.0418 (10) | |
H33A | 0.5715 | 0.6807 | 0.5449 | 0.063* | |
H33B | 0.6994 | 0.6256 | 0.4846 | 0.063* | |
H33C | 0.5321 | 0.5952 | 0.5124 | 0.063* | |
I34 | 0.60906 (3) | 0.53802 (2) | 0.35037 (2) | 0.03506 (7) | |
C35 | 0.3913 (5) | 0.6861 (2) | 0.2332 (2) | 0.0352 (9) | |
H35A | 0.4767 | 0.6297 | 0.2300 | 0.053* | |
H35B | 0.4186 | 0.7288 | 0.1957 | 0.053* | |
H35C | 0.2793 | 0.6770 | 0.2245 | 0.053* | |
C36 | 0.1955 (5) | 0.8624 (3) | 0.2618 (2) | 0.0386 (10) | |
H36A | 0.1179 | 0.9148 | 0.2823 | 0.058* | |
H36B | 0.1301 | 0.8267 | 0.2392 | 0.058* | |
H36C | 0.2721 | 0.8810 | 0.2240 | 0.058* | |
C401 | 0.0143 (4) | 0.3152 (2) | 0.58656 (19) | 0.0259 (8) | |
C402 | 0.0124 (4) | 0.3505 (2) | 0.65602 (19) | 0.0265 (8) | |
C403 | 0.1030 (5) | 0.2962 (2) | 0.71270 (19) | 0.0287 (8) | |
C404 | 0.1910 (5) | 0.2101 (2) | 0.69641 (19) | 0.0276 (8) | |
C405 | 0.1938 (5) | 0.1746 (2) | 0.62679 (19) | 0.0277 (8) | |
C406 | 0.1034 (5) | 0.2291 (2) | 0.5703 (2) | 0.0278 (8) | |
I41 | −0.12381 (3) | 0.39625 (2) | 0.50143 (2) | 0.03326 (7) | |
C42 | −0.0838 (5) | 0.4445 (2) | 0.6709 (2) | 0.0367 (9) | |
H42A | −0.1495 | 0.4705 | 0.6277 | 0.055* | |
H42B | −0.0034 | 0.4796 | 0.6802 | 0.055* | |
H42C | −0.1608 | 0.4442 | 0.7144 | 0.055* | |
C43 | 0.1041 (6) | 0.3327 (3) | 0.7888 (2) | 0.0400 (10) | |
H43A | 0.1470 | 0.2839 | 0.8248 | 0.060* | |
H43B | −0.0114 | 0.3639 | 0.8041 | 0.060* | |
H43C | 0.1775 | 0.3739 | 0.7865 | 0.060* | |
I44 | 0.32471 (3) | 0.12637 (2) | 0.78180 (2) | 0.03778 (7) | |
C45 | 0.2896 (5) | 0.0811 (2) | 0.6125 (2) | 0.0402 (10) | |
H45A | 0.2803 | 0.0692 | 0.5605 | 0.060* | |
H45B | 0.2419 | 0.0399 | 0.6447 | 0.060* | |
H45C | 0.4092 | 0.0733 | 0.6231 | 0.060* | |
C46 | 0.1029 (6) | 0.1955 (3) | 0.4936 (2) | 0.0429 (10) | |
H46A | 0.0742 | 0.2459 | 0.4576 | 0.064* | |
H46B | 0.0188 | 0.1604 | 0.4929 | 0.064* | |
H46C | 0.2155 | 0.1586 | 0.4806 | 0.064* | |
C501 | 0.6449 (14) | 0.7999 (5) | 0.8079 (4) | 0.0313 (9) | 0.0561 (6) |
C502 | 0.650 (4) | 0.8290 (9) | 0.8795 (4) | 0.0293 (8) | 0.0561 (6) |
C503 | 0.629 (4) | 0.7719 (9) | 0.9403 (4) | 0.0304 (8) | 0.0561 (6) |
C504 | 0.605 (2) | 0.6896 (6) | 0.9264 (4) | 0.0310 (9) | 0.0561 (6) |
C505 | 0.599 (4) | 0.6599 (10) | 0.8546 (4) | 0.0303 (9) | 0.0561 (6) |
C506 | 0.620 (4) | 0.7168 (10) | 0.7942 (4) | 0.0328 (9) | 0.0561 (6) |
I51 | 0.6768 (12) | 0.8869 (5) | 0.7167 (3) | 0.0474 (12) | 0.0561 (6) |
C52 | 0.678 (8) | 0.9195 (16) | 0.8916 (5) | 0.04205 (9) | 0.0561 (6) |
H52A | 0.6895 | 0.9503 | 0.8435 | 0.063* | 0.0561 (6) |
H52B | 0.7813 | 0.9128 | 0.9190 | 0.063* | 0.0561 (6) |
H52C | 0.5808 | 0.9540 | 0.9202 | 0.063* | 0.0561 (6) |
C53 | 0.634 (8) | 0.8011 (17) | 1.0189 (4) | 0.0422 (10) | 0.0561 (6) |
H53A | 0.6177 | 0.7540 | 1.0545 | 0.063* | 0.0561 (6) |
H53B | 0.5443 | 0.8548 | 1.0267 | 0.063* | 0.0561 (6) |
H53C | 0.7447 | 0.8132 | 1.0260 | 0.063* | 0.0561 (6) |
I54 | 0.5729 (12) | 0.6032 (4) | 1.0183 (4) | 0.0432 (11) | 0.0561 (6) |
C55 | 0.571 (8) | 0.5696 (17) | 0.8431 (5) | 0.04691 (9) | 0.0561 (6) |
H55A | 0.5697 | 0.5612 | 0.7899 | 0.070* | 0.0561 (6) |
H55B | 0.4626 | 0.5651 | 0.8669 | 0.070* | 0.0561 (6) |
H55C | 0.6631 | 0.5239 | 0.8650 | 0.070* | 0.0561 (6) |
C56 | 0.616 (8) | 0.6906 (17) | 0.7151 (5) | 0.0473 (11) | 0.0561 (6) |
H56A | 0.5956 | 0.6313 | 0.7152 | 0.071* | 0.0561 (6) |
H56B | 0.7245 | 0.6906 | 0.6892 | 0.071* | 0.0561 (6) |
H56C | 0.5244 | 0.7331 | 0.6896 | 0.071* | 0.0561 (6) |
U11 | U22 | U33 | U12 | U13 | U23 | |
C101 | 0.0232 (19) | 0.0239 (19) | 0.041 (2) | −0.0047 (15) | −0.0040 (16) | −0.0027 (16) |
C102 | 0.028 (2) | 0.029 (2) | 0.032 (2) | −0.0033 (16) | −0.0030 (16) | −0.0019 (16) |
C103 | 0.026 (2) | 0.027 (2) | 0.037 (2) | −0.0033 (16) | 0.0006 (17) | 0.0021 (17) |
C104 | 0.023 (2) | 0.0249 (19) | 0.042 (2) | −0.0029 (16) | −0.0008 (17) | −0.0055 (17) |
C105 | 0.027 (2) | 0.038 (2) | 0.032 (2) | −0.0037 (17) | −0.0030 (17) | −0.0063 (17) |
C106 | 0.025 (2) | 0.031 (2) | 0.036 (2) | −0.0030 (16) | −0.0019 (16) | 0.0032 (17) |
I11 | 0.03916 (17) | 0.02601 (15) | 0.0618 (2) | −0.00878 (13) | −0.00703 (14) | −0.00114 (13) |
C12 | 0.050 (3) | 0.042 (2) | 0.037 (2) | −0.014 (2) | −0.010 (2) | −0.0064 (19) |
C13 | 0.055 (2) | 0.033 (4) | 0.043 (3) | −0.016 (3) | 0.006 (2) | 0.006 (2) |
I14 | 0.04444 (18) | 0.03200 (17) | 0.0674 (2) | −0.01301 (15) | −0.00082 (15) | −0.01358 (14) |
C15 | 0.050 (3) | 0.053 (3) | 0.039 (2) | −0.011 (2) | −0.008 (2) | −0.008 (2) |
C16 | 0.054 (2) | 0.049 (3) | 0.035 (4) | −0.007 (2) | 0.002 (3) | 0.005 (3) |
C201 | 0.029 (2) | 0.032 (2) | 0.0249 (18) | −0.0036 (16) | −0.0005 (15) | −0.0059 (15) |
C202 | 0.0253 (19) | 0.029 (2) | 0.032 (2) | ,-0.0041 (16) | 0.0016 (16) | 0.0004 (16) |
C203 | 0.025 (2) | 0.0255 (19) | 0.036 (2) | −0.0012 (16) | −0.0043 (16) | −0.0028 (16) |
C204 | 0.028 (2) | 0.032 (2) | 0.0284 (19) | −0.0025 (16) | −0.0035 (16) | −0.0047 (16) |
C205 | 0.027 (2) | 0.0256 (19) | 0.033 (2) | −0.0020 (16) | −0.0011 (16) | 0.0036 (16) |
C206 | 0.027 (2) | 0.0235 (19) | 0.037 (2) | −0.0041 (16) | −0.0018 (16) | −0.0017 (16) |
I21 | 0.05500 (19) | 0.04967 (17) | 0.03035 (14) | −0.01407 (14) | −0.00356 (12) | −0.00773 (12) |
C22 | 0.055 (3) | 0.037 (2) | 0.042 (2) | −0.014 (2) | 0.003 (2) | −0.0006 (19) |
C23 | 0.046 (3) | 0.034 (2) | 0.047 (3) | −0.008 (2) | −0.003 (2) | −0.0083 (19) |
I24 | 0.04568 (17) | 0.04407 (16) | 0.03250 (14) | −0.00307 (13) | −0.00678 (12) | −0.00965 (12) |
C25 | 0.059 (3) | 0.038 (2) | 0.034 (2) | −0.013 (2) | 0.002 (2) | 0.0068 (18) |
C26 | 0.058 (3) | 0.030 (2) | 0.044 (2) | −0.020 (2) | −0.007 (2) | 0.0012 (18) |
C301 | 0.032 (2) | 0.0224 (18) | 0.032 (2) | −0.0051 (16) | 0.0038 (16) | 0.0019 (15) |
C302 | 0.035 (2) | 0.033 (2) | 0.028 (2) | −0.0142 (17) | 0.0026 (16) | −0.0033 (16) |
C303 | 0.030 (2) | 0.034 (2) | 0.0261 (19) | −0.0139 (17) | −0.0031 (15) | 0.0061 (16) |
C304 | 0.0263 (19) | 0.0224 (18) | 0.034 (2) | −0.0077 (15) | 0.0009 (16) | 0.0033 (15) |
C305 | 0.027 (2) | 0.0291 (19) | 0.0282 (19) | −0.0111 (16) | −0.0023 (15) | 0.0003 (15) |
C306 | 0.027 (2) | 0.0285 (19) | 0.031 (2) | −0.0095 (16) | 0.0003 (16) | 0.0014 (15) |
I31 | 0.05187 (18) | 0.03191 (15) | 0.04865 (17) | 0.00185 (13) | 0.00270 (14) | −0.00891 (12) |
C32 | 0.052 (3) | 0.046 (3) | 0.037 (2) | −0.010 (2) | −0.007 (2) | 0.0056 (19) |
C33 | 0.046 (3) | 0.039 (2) | 0.039 (2) | −0.008 (2) | −0.011 (2) | 0.0006 (19) |
I34 | 0.03664 (15) | 0.02573 (13) | 0.04096 (15) | −0.00419 (11) | −0.00423 (11) | 0.00065 (11) |
C35 | 0.042 (2) | 0.026 (2) | 0.038 (2) | −0.0076 (18) | −0.0113 (18) | 0.0010 (17) |
C36 | 0.039 (2) | 0.036 (2) | 0.037 (2) | −0.0021 (19) | −0.0051 (18) | −0.0009 (18) |
C401 | 0.0278 (19) | 0.0259 (18) | 0.0253 (18) | −0.0100 (15) | −0.0051 (15) | 0.0068 (15) |
C402 | 0.0254 (19) | 0.0240 (18) | 0.0313 (19) | −0.0086 (15) | 0.0009 (15) | −0.0019 (15) |
C403 | 0.032 (2) | 0.034 (2) | 0.0244 (18) | −0.0160 (17) | 0.0006 (15) | −0.0021 (15) |
C404 | 0.027 (2) | 0.0289 (19) | 0.0282 (19) | −0.0100 (16) | −0.0057 (15) | 0.0051 (15) |
C405 | 0.033 (2) | 0.0228 (18) | 0.0287 (19) | −0.0114 (16) | −0.0006 (16) | 0.0011 (15) |
C406 | 0.030 (2) | 0.0249 (19) | 0.0299 (19) | −0.0103 (16) | −0.0011 (16) | −0.0014 (15) |
I41 | 0.03578 (15) | 0.03000 (13) | 0.03390 (14) | −0.00815 (11) | −0.00821 (11) | 0.00552 (10) |
C42 | 0.040 (2) | 0.032 (2) | 0.036 (2) | −0.0039 (18) | −0.0032 (18) | −0.0060 (17) |
C43 | 0.050 (3) | 0.036 (2) | 0.034 (2) | −0.011 (2) | −0.0051 (19) | 0.0009 (18) |
I44 | 0.04448 (16) | 0.03661 (14) | 0.03343 (14) | −0.01281 (12) | −0.01109 (12) | 0.00945 (11) |
C45 | 0.046 (3) | 0.031 (2) | 0.041 (2) | −0.0036 (19) | −0.0071 (19) | 0.0020 (18) |
C46 | 0.054 (3) | 0.036 (2) | 0.035 (2) | −0.001 (2) | −0.012 (2) | −0.0047 (18) |
C501 | 0.025 (2) | 0.031 (2) | 0.036 (2) | −0.0030 (16) | −0.0019 (16) | 0.0032 (17) |
C502 | 0.0232 (19) | 0.0239 (19) | 0.041 (2) | −0.0047 (15) | −0.0040 (16) | −0.0027 (16) |
C503 | 0.028 (2) | 0.029 (2) | 0.032 (2) | −0.0033 (16) | −0.0030 (16) | −0.0019 (16) |
C504 | 0.026 (2) | 0.027 (2) | 0.037 (2) | −0.0033 (16) | 0.0006 (17) | 0.0021 (17) |
C505 | 0.023 (2) | 0.0249 (19) | 0.042 (2) | −0.0029 (16) | −0.0008 (17) | −0.0055 (17) |
C506 | 0.027 (2) | 0.038 (2) | 0.032 (2) | −0.0037 (17) | −0.0030 (17) | −0.0063 (17) |
I51 | 0.054 (2) | 0.049 (3) | 0.035 (4) | −0.007 (2) | 0.002 (3) | 0.005 (3) |
C52 | 0.03916 (17) | 0.02601 (15) | 0.0618 (2) | −0.00878 (13) | −0.00703 (14) | −0.00114 (13) |
C53 | 0.050 (3) | 0.042 (2) | 0.037 (2) | −0.014 (2) | −0.010 (2) | −0.0064 (19) |
I54 | 0.055 (2) | 0.033 (4) | 0.043 (3) | −0.016 (3) | 0.006 (2) | 0.006 (2) |
C55 | 0.04444 (18) | 0.03200 (17) | 0.0674 (2) | −0.01301 (15) | −0.00082 (15) | −0.01358 (14) |
C56 | 0.050 (3) | 0.053 (3) | 0.039 (2) | −0.011 (2) | −0.008 (2) | −0.008 (2) |
C101—C106 | 1.402 (5) | C32—H32A | 0.9800 |
C101—C102 | 1.405 (5) | C32—H32B | 0.9800 |
C101—I11 | 2.121 (4) | C32—H32C | 0.9800 |
C102—C103 | 1.403 (5) | C33—H33A | 0.9800 |
C102—C12 | 1.515 (5) | C33—H33B | 0.9800 |
C103—C104 | 1.390 (5) | C33—H33C | 0.9800 |
C103—C13 | 1.524 (6) | C35—H35A | 0.9800 |
C104—C105 | 1.410 (5) | C35—H35B | 0.9800 |
C104—I14 | 2.124 (4) | C35—H35C | 0.9800 |
C105—C106 | 1.396 (6) | C36—H36A | 0.9800 |
C105—C15 | 1.512 (6) | C36—H36B | 0.9800 |
C106—C16 | 1.516 (6) | C36—H36C | 0.9800 |
C12—H12A | 0.9800 | C401—C402 | 1.399 (5) |
C12—H12B | 0.9800 | C401—C406 | 1.401 (5) |
C12—H12C | 0.9800 | C401—I41 | 2.118 (3) |
C13—H13A | 0.9800 | C402—C403 | 1.408 (5) |
C13—H13B | 0.9800 | C402—C42 | 1.514 (5) |
C13—H13C | 0.9800 | C403—C404 | 1.397 (5) |
C15—H15A | 0.9800 | C403—C43 | 1.522 (5) |
C15—H15B | 0.9800 | C404—C405 | 1.403 (5) |
C15—H15C | 0.9800 | C404—I44 | 2.124 (3) |
C16—H16A | 0.9800 | C405—C406 | 1.406 (5) |
C16—H16B | 0.9800 | C405—C45 | 1.504 (5) |
C16—H16C | 0.9800 | C406—C46 | 1.511 (5) |
C201—C202 | 1.388 (5) | C42—H42A | 0.9800 |
C201—C206 | 1.404 (5) | C42—H42B | 0.9800 |
C201—I21 | 2.123 (3) | C42—H42C | 0.9800 |
C202—C203 | 1.404 (5) | C43—H43A | 0.9800 |
C202—C22 | 1.536 (5) | C43—H43B | 0.9800 |
C203—C204 | 1.406 (5) | C43—H43C | 0.9800 |
C203—C23 | 1.506 (5) | C45—H45A | 0.9800 |
C204—C205 | 1.389 (5) | C45—H45B | 0.9800 |
C204—I24 | 2.124 (4) | C45—H45C | 0.9800 |
C205—C206 | 1.411 (5) | C46—H46A | 0.9800 |
C205—C25 | 1.520 (5) | C46—H46B | 0.9800 |
C206—C26 | 1.503 (5) | C46—H46C | 0.9800 |
C22—H22A | 0.9800 | C501—C506 | 1.402 (6) |
C22—H22B | 0.9800 | C501—C502 | 1.405 (5) |
C22—H22C | 0.9800 | C501—I51 | 2.121 (4) |
C23—H23A | 0.9800 | C502—C503 | 1.403 (6) |
C23—H23B | 0.9800 | C502—C52 | 1.515 (5) |
C23—H23C | 0.9800 | C503—C504 | 1.390 (5) |
C25—H25A | 0.9800 | C503—C53 | 1.524 (6) |
C25—H25B | 0.9800 | C504—C505 | 1.410 (6) |
C25—H25C | 0.9800 | C504—I54 | 2.124 (4) |
C26—H26A | 0.9800 | C505—C506 | 1.396 (6) |
C26—H26B | 0.9800 | C505—C55 | 1.512 (6) |
C26—H26C | 0.9800 | C506—C56 | 1.516 (6) |
C301—C302 | 1.396 (5) | C52—H52A | 0.9800 |
C301—C306 | 1.397 (5) | C52—H52B | 0.9800 |
C301—I31 | 2.122 (3) | C52—H52C | 0.9800 |
C302—C303 | 1.404 (5) | C53—H53A | 0.9800 |
C302—C32 | 1.551 (5) | C53—H53B | 0.9800 |
C303—C304 | 1.402 (5) | C53—H53C | 0.9800 |
C303—C33 | 1.511 (5) | C55—H55A | 0.9800 |
C304—C305 | 1.407 (5) | C55—H55B | 0.9800 |
C304—I34 | 2.121 (3) | C55—H55C | 0.9800 |
C305—C306 | 1.402 (5) | C56—H56A | 0.9800 |
C305—C35 | 1.526 (5) | C56—H56B | 0.9800 |
C306—C36 | 1.509 (5) | C56—H56C | 0.9800 |
C106—C101—C102 | 123.2 (4) | C302—C32—H32C | 109.5 |
C106—C101—I11 | 119.1 (3) | H32A—C32—H32C | 109.5 |
C102—C101—I11 | 117.8 (3) | H32B—C32—H32C | 109.5 |
C103—C102—C101 | 118.2 (4) | C303—C33—H33A | 109.5 |
C103—C102—C12 | 120.5 (4) | C303—C33—H33B | 109.5 |
C101—C102—C12 | 121.4 (4) | H33A—C33—H33B | 109.5 |
C104—C103—C102 | 118.3 (4) | C303—C33—H33C | 109.5 |
C104—C103—C13 | 121.9 (4) | H33A—C33—H33C | 109.5 |
C102—C103—C13 | 119.8 (4) | H33B—C33—H33C | 109.5 |
C103—C104—C105 | 123.8 (4) | C305—C35—H35A | 109.5 |
C103—C104—I14 | 118.3 (3) | C305—C35—H35B | 109.5 |
C105—C104—I14 | 117.9 (3) | H35A—C35—H35B | 109.5 |
C106—C105—C104 | 117.9 (4) | C305—C35—H35C | 109.5 |
C106—C105—C15 | 120.8 (4) | H35A—C35—H35C | 109.5 |
C104—C105—C15 | 121.3 (4) | H35B—C35—H35C | 109.5 |
C105—C106—C101 | 118.6 (4) | C306—C36—H36A | 109.5 |
C105—C106—C16 | 121.7 (4) | C306—C36—H36B | 109.5 |
C101—C106—C16 | 119.7 (4) | H36A—C36—H36B | 109.5 |
C102—C12—H12A | 109.5 | C306—C36—H36C | 109.5 |
C102—C12—H12B | 109.5 | H36A—C36—H36C | 109.5 |
H12A—C12—H12B | 109.5 | H36B—C36—H36C | 109.5 |
C102—C12—H12C | 109.5 | C402—C401—C406 | 123.4 (3) |
H12A—C12—H12C | 109.5 | C402—C401—I41 | 118.3 (2) |
H12B—C12—H12C | 109.5 | C406—C401—I41 | 118.2 (3) |
C103—C13—H13A | 109.5 | C401—C402—C403 | 118.2 (3) |
C103—C13—H13B | 109.5 | C401—C402—C42 | 121.7 (3) |
H13A—C13—H13B | 109.5 | C403—C402—C42 | 120.1 (3) |
C103—C13—H13C | 109.5 | C404—C403—C402 | 118.3 (3) |
H13A—C13—H13C | 109.5 | C404—C403—C43 | 122.2 (3) |
H13B—C13—H13C | 109.5 | C402—C403—C43 | 119.5 (3) |
C105—C15—H15A | 109.5 | C403—C404—C405 | 123.7 (3) |
C105—C15—H15B | 109.5 | C403—C404—I44 | 118.8 (3) |
H15A—C15—H15B | 109.5 | C405—C404—I44 | 117.5 (3) |
C105—C15—H15C | 109.5 | C404—C405—C406 | 117.9 (3) |
H15A—C15—H15C | 109.5 | C404—C405—C45 | 121.5 (3) |
H15B—C15—H15C | 109.5 | C406—C405—C45 | 120.7 (3) |
C106—C16—H16A | 109.5 | C401—C406—C405 | 118.5 (3) |
C106—C16—H16B | 109.5 | C401—C406—C46 | 120.8 (3) |
H16A—C16—H16B | 109.5 | C405—C406—C46 | 120.7 (3) |
C106—C16—H16C | 109.5 | C402—C42—H42A | 109.5 |
H16A—C16—H16C | 109.5 | C402—C42—H42B | 109.5 |
H16B—C16—H16C | 109.5 | H42A—C42—H42B | 109.5 |
C202—C201—C206 | 123.5 (3) | C402—C42—H42C | 109.5 |
C202—C201—I21 | 119.0 (3) | H42A—C42—H42C | 109.5 |
C206—C201—I21 | 117.5 (3) | H42B—C42—H42C | 109.5 |
C201—C202—C203 | 118.9 (3) | C403—C43—H43A | 109.5 |
C201—C202—C22 | 122.3 (3) | C403—C43—H43B | 109.5 |
C203—C202—C22 | 118.8 (3) | H43A—C43—H43B | 109.5 |
C202—C203—C204 | 117.7 (3) | C403—C43—H43C | 109.5 |
C202—C203—C23 | 120.1 (3) | H43A—C43—H43C | 109.5 |
C204—C203—C23 | 122.2 (3) | H43B—C43—H43C | 109.5 |
C205—C204—C203 | 123.6 (3) | C405—C45—H45A | 109.5 |
C205—C204—I24 | 118.5 (3) | C405—C45—H45B | 109.5 |
C203—C204—I24 | 117.9 (3) | H45A—C45—H45B | 109.5 |
C204—C205—C206 | 118.5 (3) | C405—C45—H45C | 109.5 |
C204—C205—C25 | 122.8 (3) | H45A—C45—H45C | 109.5 |
C206—C205—C25 | 118.7 (3) | H45B—C45—H45C | 109.5 |
C201—C206—C205 | 117.8 (3) | C406—C46—H46A | 109.5 |
C201—C206—C26 | 121.4 (3) | C406—C46—H46B | 109.5 |
C205—C206—C26 | 120.8 (3) | H46A—C46—H46B | 109.5 |
C202—C22—H22A | 109.5 | C406—C46—H46C | 109.5 |
C202—C22—H22B | 109.5 | H46A—C46—H46C | 109.5 |
H22A—C22—H22B | 109.5 | H46B—C46—H46C | 109.5 |
C202—C22—H22C | 109.5 | C506—C501—C502 | 123.2 (4) |
H22A—C22—H22C | 109.5 | C506—C501—I51 | 119.1 (3) |
H22B—C22—H22C | 109.5 | C502—C501—I51 | 117.8 (3) |
C203—C23—H23A | 109.5 | C503—C502—C501 | 118.2 (4) |
C203—C23—H23B | 109.5 | C503—C502—C52 | 120.5 (4) |
H23A—C23—H23B | 109.5 | C501—C502—C52 | 121.4 (4) |
C203—C23—H23C | 109.5 | C504—C503—C502 | 118.3 (4) |
H23A—C23—H23C | 109.5 | C504—C503—C53 | 121.9 (4) |
H23B—C23—H23C | 109.5 | C502—C503—C53 | 119.8 (4) |
C205—C25—H25A | 109.5 | C503—C504—C505 | 123.8 (4) |
C205—C25—H25B | 109.5 | C503—C504—I54 | 118.3 (3) |
H25A—C25—H25B | 109.5 | C505—C504—I54 | 117.9 (3) |
C205—C25—H25C | 109.5 | C506—C505—C504 | 117.9 (4) |
H25A—C25—H25C | 109.5 | C506—C505—C55 | 120.8 (4) |
H25B—C25—H25C | 109.5 | C504—C505—C55 | 121.3 (4) |
C206—C26—H26A | 109.5 | C505—C506—C501 | 118.6 (4) |
C206—C26—H26B | 109.5 | C505—C506—C56 | 121.7 (4) |
H26A—C26—H26B | 109.5 | C501—C506—C56 | 119.7 (4) |
C206—C26—H26C | 109.5 | C502—C52—H52A | 109.5 |
H26A—C26—H26C | 109.5 | C502—C52—H52B | 109.5 |
H26B—C26—H26C | 109.5 | H52A—C52—H52B | 109.5 |
C302—C301—C306 | 123.9 (3) | C502—C52—H52C | 109.5 |
C302—C301—I31 | 118.3 (3) | H52A—C52—H52C | 109.5 |
C306—C301—I31 | 117.8 (3) | H52B—C52—H52C | 109.5 |
C301—C302—C303 | 118.3 (3) | C503—C53—H53A | 109.5 |
C301—C302—C32 | 121.9 (3) | C503—C53—H53B | 109.5 |
C303—C302—C32 | 119.8 (3) | H53A—C53—H53B | 109.5 |
C304—C303—C302 | 118.1 (3) | C503—C53—H53C | 109.5 |
C304—C303—C33 | 121.1 (3) | H53A—C53—H53C | 109.5 |
C302—C303—C33 | 120.8 (3) | H53B—C53—H53C | 109.5 |
C303—C304—C305 | 123.4 (3) | C505—C55—H55A | 109.5 |
C303—C304—I34 | 118.7 (3) | C505—C55—H55B | 109.5 |
C305—C304—I34 | 117.9 (3) | H55A—C55—H55B | 109.5 |
C306—C305—C304 | 118.2 (3) | C505—C55—H55C | 109.5 |
C306—C305—C35 | 119.0 (3) | H55A—C55—H55C | 109.5 |
C304—C305—C35 | 122.8 (3) | H55B—C55—H55C | 109.5 |
C301—C306—C305 | 118.2 (3) | C506—C56—H56A | 109.5 |
C301—C306—C36 | 122.6 (3) | C506—C56—H56B | 109.5 |
C305—C306—C36 | 119.2 (3) | H56A—C56—H56B | 109.5 |
C302—C32—H32A | 109.5 | C506—C56—H56C | 109.5 |
C302—C32—H32B | 109.5 | H56A—C56—H56C | 109.5 |
H32A—C32—H32B | 109.5 | H56B—C56—H56C | 109.5 |
Experimental details
Crystal data | |
Chemical formula | C10H12I2 |
Mr | 386.00 |
Crystal system, space group | Triclinic, P1 |
Temperature (K) | 174 |
a, b, c (Å) | 8.152 (2), 15.622 (4), 18.080 (5) |
α, β, γ (°) | 86.60 (1), 86.93 (1), 75.57 (1) |
V (Å3) | 2224.1 (10) |
Z | 8 |
Radiation type | Mo Kα |
µ (mm−1) | 5.61 |
Crystal size (mm) | 0.50 × 0.10 × 0.05 |
Data collection | |
Diffractometer | Siemens SMART area-detector diffractometer |
Absorption correction | Multi-scan (SADABS; Sheldrick, 1996; Blessing, 1995) |
Tmin, Tmax | 0.55, 0.76 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 26644, 10118, 7650 |
Rint | 0.029 |
(sin θ/λ)max (Å−1) | 0.649 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.027, 0.061, 1.00 |
No. of reflections | 10118 |
No. of parameters | 471 |
No. of restraints | 39 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 0.93, −0.99 |
Computer programs: SMART (Siemens, 1995), SAINT (Siemens, 1995), SAINT, SHELXTL (Sheldrick, 1997), SHELXTL.
Molecule | X—I···I | I···I | I···I—X | Reference |
I2 | 171 | 3.63 | 104 | d |
p-I2C6H4b | 160 | 4.13 | 97 | e |
p-I2C6H4c | 164 | 4.11 | 98 | e |
p-I2C6F4 | 161 | 4.06 | 99 | f |
C6I6 | 175 | 3.77 | 115 | g |
C6I6 | 177 | 3.78 | 124 | g |
C6I6 | 175 | 4.03 | 122 | g |
C6(CH3)3I3 | 173 | 3.89 | 120 | h |
C6(CH3)3I3 | 173 | 3.93 | 120 | h |
C6(CH3)3I3 | 165 | 3.97 | 119 | h |
C6(CH3)3I3 | 173 | 3.85 | 120 | i |
C6(CH3)3I3 | 174 | 3.90 | 119 | i |
C6(CH3)3I3 | 166 | 3.93 | 120 | i |
Notes: (a) for purposes of comparison, the angles have been rounded to the nearest degree and the distances to the nearest 0.01 Å; the s.u. values have been omitted; (b) polymorph 1; (c) polymorph ?; (d) Wycoff (1963); (e) Boese & Miebach (1996); (f) Chaplot et al. (1981); (g) Steer et al. (1970); (h) Boudjada et al. (2001); (i) Bosch & Barnes (2002). |
Y | Z | C—Y···Z | Y···Z | Y···Z—C |
I41i | I34 | 177 | 3.82 | 120 |
I34 | I24 | 174 | 3.85 | 115 |
I24 | I41i | 175 | 3.85 | 120 |
I44 | I11ii | 163 | 4.07 | 104 |
C12iii | I44 | 177 | 3.75 | 126 |
I11iv | I21 | 169 | 4.20 | 121 |
I21 | C36v | 172 | 3.90 | 133 |
I14 | C35vi | 162 | 3.85 | 137 |
C13iii | I14 | 165 | 4.09 | 130 |
I31 | C46vii | 155 | 3.76 | 137 |
C16viii | I31 | 169 | 3.99 | 109 |
C15 | C33 | 171 | 4.17 | 132 |
C42i | C15 | 174 | 4.15 | 119 |
C43 | C22ix | 152 | 4.05 | 133 |
C23vi | C43 | 166 | 4.03 | 131 |
C45 | C32ii | 158 | 4.17 | 136 |
C25x | C45 | 167 | 4.19 | 118 |
I31 | I31xi | 118 | 4.18 | 118 |
C26x | I44 | 137 | 4.06 | 129 |
C36viii | I11 | 132 | 4.14 | 127 |
I21 | C35v | 130 | 4.08 | 126 |
I24 | C46i | 137 | 4.01 | 133 |
I41 | C33xii | 131 | 4.05 | 131 |
Notes: (a) for purposes of comparison, the angles have been rounded to the nearest degree and the distances to the nearest 0.01 Å; the s.u. values have been omitted. Each entry has been ordered so that the larger angle is given first. Symmetry codes: (i) 1 + x, y, z; (ii) x, y − 1, z; (iii) 1 − x, 1 − y, 2 − z; (iv) x, y − 1, z − 1; (v) 1 − x, 1 − y, −z; (vi) 1 − x, 1 − y, 1 − z; (vii) x, 1 + y, z; (viii) 1 − x, 2 − y, 1 − z; (ix) x − 1, y, 1 + z; (x) 1 − x, −y, 1 − z; (xi) −x, 2 − y, 1 − z; (xii) x − 1, y, z. |
Following the determination of the structure of the complex p-C6(CH3)4I2/p-C6F4(CN)2 (Britton & Gleason, 2002), we have determined the crystal structure of diiododurene, (I). There are four molecules in the asymmetric unit. In the notation of Zorky and co-workers (Zorky et al., 1967; Belsky et al., 1995; Zorky, 1996), the description of the unit cell would be P1, Z = 8(14). This is remarkable in that none of the four independent molecules lies on a center of symmetry. Kitaigorodsky (1961, 1973) went so far as to state that a molecular center of symmetry always coincides with a crystallographic center of symmetry, even though he described pyrene as an exception to this rule. Recently, the program CSDSymmetry (Yao et al., 2002) has been used to re-examine this question and finds that out of 18 008 molecules with approximate molecular symmetry 1, only 15 156 lie on the crystallographic inversion center.
Three of the four independent molecules of (I) are free of measurable disorder, but the fourth shows a disorder with the minor component having an occupancy of 5.61 (6)%. Fig. 1 shows the labelling and the anisotropic displacement ellipsoids for the disordered pair; the numbering and ellispsoids for the remaining molecules are similar. To check the disorder, a second set of data was collected on a new crystal. The disorder from this refinement was 5.52 (7)%.
The bond lengths and angles are normal and agree within experimental error among the four molecules. The Crystal Data section of the Experimental reports the refinement with all four molecules independent of each other. To obtain the best possible estimates for the bond lengths and angles in an isolated molecule, the data were refined with all chemically equivalent bond lengths and angles constrained to be the same. The constraints only increased R from 0.027 to 0.028. The results are: C1—I = 2.124 (2) Å, C1—C2 = 1.398 (1) Å, C2—C3 = 1.406 (2) Å, C2—CH3 = 1.516 (2) Å, C2—C1—C2' = 123.72 (13)° and C1—C2—C2' = 118.14 (8)°. The angles can be compared with those found in two separate determinations of triiodomesitylene (Boudjada et al., 2001), viz. 123.8 (3) and 116.2 (3)° (Bosch & Barnes, 2002), and 123.5 (6) and 116.5 (6)°. The results in both molecules agree with the trends described by Domenicano (1992).
Fig. 2 shows a view approximately along the a axis. The molecules pack in two kinds of stacks, with molecules 1 and 2 alternating in one, and molecules 3 and 4 alternating in the other. The stacks are aligned in an hexagonal array of parallel stacks with each stack surrounded by two of the same kind and four of the other kind. In stack-12, molecule 1 is tilted 23.1 (2)° away from the normal to the stack direction (a axis), while molecule 2 is tilted 24.1 (2)°. The perpendicular distances between the planes are both 3.75 (2) Å. In stack-34, the tilts are molecule 3 = 25.2 (2)° and molecule 4 = 24.9 (2)°. The distances between the planes are alternately 3.69 (2) and 3.66 (2) Å.
In addition to the stacks involving π interactions, there are approximately planar ribbons of molecules at angles to the stacks. Fig. 3 shows two views of these ribbons. There are two types of ribbons, one involving molecules 1 and 2, the other molecules 3 and 4. In ribbon-12, the molecular order is −1–1-2–2-1–1-, while in ribbon-34, the order is −3–4-3–4-.
Before discussing the intermolecular σ contacts, we will look at some earlier I···I and CMe···CMe contacts. It is well known (Bent, 1968) that the shortest X—I1···I2—Y intermolecular interactions involving small molecules usually occur with a nearly linear X—I1···I2 angle and a nearly tetrahedral I1···I2—Y angle. This is interpreted that I1 is a Lewis acid (electron acceptor) and I2 is a Lewis base (electron donor). Incentrosymetric diiodides, this leads to linear chains of molecules. In triiodides with approximate threefold symmetry, such interactions can lead to cyclic I···I···I groups. Table 1 gives the distances and angles for some of these interactions. The linear interactions have distances slightly larger than 4.0 Å, while the I···I···I cylic arrangements have distances slightly less than 4.0 Å. This suggests that the I···I interactions in the cylic arrangement are stronger than those in the linear arrangement. Both the occurrence of this cyclic arrangement and the shortening of the distances were described by Anthony et al. (1998) for Cl and Br atoms in 2,4,6-tris(4-halophenoxy)-1,3,5-triazine.
It is also well known that similar cyclic C···C···C contacts occur in hexamethylbenzene (Lonsdale-Yardley, 1929). In the most recent determination of the structure (Le Maguères et al., 2001), the three C···C distances are 3.85, 3.94, and 3.95 Å.
Based on the distances quoted above, we report in Table 2 all of the I···I, I···CMe, and CMe···CMe distances that are shorter than 4.20 Å and that lie approximately in the plane of one or both of the molecules. The distances shorter than 4.20 Å that arise from the π contacts are not included. The arrangement is such that every entry has the C—Y···Z angle larger than the Y···Z—C angle, i.e. that Y is the Lewis acid and Z the Lewis base.
There are five I···I contacts where the angles are consistent with a Lewis acid–base interaction and one where they are not. The first three I···I contacts in the list form a cyclic I···I···I group, with distances comparable to those in the I···I···I groups in hexaiodobenzene and triiodomesitylene. An arrangement of this sort would not be possible if there were only one-half or one molecule in the asymmetric unit; this may be the reason for the complexity of the structure.
There are three I···CMe and three CMe···I contacts where the angles are consistant with a Lewis acid–base interaction, and three I···CMe and two CMe···I contacts where they are not. If the angles do tell us something meaningful about the interactions, then the methyl and iodo groups appear to be roughly interchangeable with respect to these Lewis acid–base interactions.
There are six CMe···CMe contacts where the angles are similar to those in the short I···I interactions. All have distances slightly larger than those in hexamethylbenzene, but none is involved in a cyclic arrangement. It is, however, difficult to regard these as Lewis acid–base interactions.
Although there are four crystallographically different molecules in the unit cell and the details of the packing as shown above are complex, there is also a certain simplicity about the packing. The coordinates of the molecular centers are, approximately: molecule 1 (5/8, 3/4, 7/8), molecule 2 (7/8, 1/4, 1/8), molecule 3 (3/8, 3/4, 3/8), and molecule 4 (1/8, 1/4, 5/8). If the molecules were spherical, which would require the a axis to be about twice as large, then the packing of the spheres would be roughly hexagonal close-packed with b the hexagonal axis.