organic compounds
2,2′-Diiodoazobenzene
aDepartment of Chemistry and Chemical Biology, McMaster University, 1280 Main, Street West, Hamilton, Ontario, Canada L8S 4M1
*Correspondence e-mail: vargas@chemistry.mcmaster.ca
The molecular structure of the title compound, C12H8I2N2 [systematic name: (E)-bis(2-iodophenyl)diazene], exhibits an essentially planar trans geometry [maximum deviation = 0.022 (4) Å] with the iodine atoms ortho to the azo bridge. In the crystal, offset π-stacking leads to the formation of columns along the a axis [closest C⋯C distance = 3.383 (4) Å].
Related literature
For analogous 2,2′-dichloroazobenzenes, see: Komeyama et al. (1973); Crispini et al. (1998). For the structure of a related o-halogenated azobenzene, see: Wragg et al. (2011).
Experimental
Crystal data
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Data collection: SMART (Bruker, 2000); cell SMART (Bruker, 2000); data reduction: SAINT; program(s) used to solve structure: SHELXTL (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: Mercury (Macrae et al., 2006); software used to prepare material for publication: SHELXTL.
Supporting information
10.1107/S1600536812040718/tk5154sup1.cif
contains datablocks global, I. DOI:Structure factors: contains datablock I. DOI: 10.1107/S1600536812040718/tk5154Isup2.hkl
Supporting information file. DOI: 10.1107/S1600536812040718/tk5154Isup3.cml
Azobenzene (0.184 g, 1.01 mmol) and mercury trifluoroacetate (0.43 g, 1.01 mmol) were combined with freshly distilled trifluoroacetic acid (0.13 mL) under a nitrogen atmosphere. The mixture was heated with stirring for 4 h at 68 °C, after which a concentrated solution of sodium chloride (0.345 g, 5.90 mmol) and sodium acetate (2.085 g, 14.7 mmol) was added and the entire sample was placed in an ultrasonic bath for 20 min. After decanting the solvent, a mixture of iodine (0.279 g, 1.10 mmol) in methanol was added. With time, orange crystals of 2,2'-diiodoazobenzene grew from the solution and were collected by filtration. Yield = 0.047 g, 10%.
Carbon-bound H-atoms were placed in calculated positions (C–H 0.93 Å) and were included in the
in the riding model approximation with Uiso(H) set to 1.2Ueq(C).Data collection: SMART (Bruker, 2000); cell
SMART (Bruker, 2000); data reduction: SAINT (Bruker, 2000); program(s) used to solve structure: SHELXTL (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: Mercury (Macrae et al., 2006); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).C12H8I2N2 | F(000) = 800 |
Mr = 433.88 | Dx = 2.261 Mg m−3 |
Monoclinic, P21/c | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: -P 2ybc | Cell parameters from 4767 reflections |
a = 4.6306 (3) Å | θ = 2.6–24.6° |
b = 18.1105 (12) Å | µ = 4.91 mm−1 |
c = 15.3748 (10) Å | T = 296 K |
β = 98.532 (1)° | Rod, orange |
V = 1275.10 (14) Å3 | 0.63 × 0.09 × 0.04 mm |
Z = 4 |
Bruker SMART CCD area-detector diffractometer | 3186 independent reflections |
Radiation source: fine-focus sealed tube | 2536 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.027 |
ϕ and ω scans | θmax = 28.4°, θmin = 2.3° |
Absorption correction: analytical (SADABS; Sheldrick, 1996) | h = −4→6 |
Tmin = 0.322, Tmax = 0.873 | k = −24→22 |
16726 measured reflections | l = −20→18 |
Refinement on F2 | Primary atom site location: structure-invariant direct methods |
Least-squares matrix: full | Secondary atom site location: difference Fourier map |
R[F2 > 2σ(F2)] = 0.027 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.059 | H-atom parameters constrained |
S = 1.03 | w = 1/[σ2(Fo2) + (0.0243P)2 + 0.9205P] where P = (Fo2 + 2Fc2)/3 |
3186 reflections | (Δ/σ)max = 0.001 |
145 parameters | Δρmax = 0.56 e Å−3 |
0 restraints | Δρmin = −0.56 e Å−3 |
C12H8I2N2 | V = 1275.10 (14) Å3 |
Mr = 433.88 | Z = 4 |
Monoclinic, P21/c | Mo Kα radiation |
a = 4.6306 (3) Å | µ = 4.91 mm−1 |
b = 18.1105 (12) Å | T = 296 K |
c = 15.3748 (10) Å | 0.63 × 0.09 × 0.04 mm |
β = 98.532 (1)° |
Bruker SMART CCD area-detector diffractometer | 3186 independent reflections |
Absorption correction: analytical (SADABS; Sheldrick, 1996) | 2536 reflections with I > 2σ(I) |
Tmin = 0.322, Tmax = 0.873 | Rint = 0.027 |
16726 measured reflections |
R[F2 > 2σ(F2)] = 0.027 | 0 restraints |
wR(F2) = 0.059 | H-atom parameters constrained |
S = 1.03 | Δρmax = 0.56 e Å−3 |
3186 reflections | Δρmin = −0.56 e Å−3 |
145 parameters |
Experimental. Azobenzene (0.184 g, 1.01 mmol) and mercury trifluoroacetate (0.43 g, 1.01 mmol) were combined with freshly distilled trifluoroacetic acid (0.13 mL) under a nitrogen atmosphere. The mixture was heated with stirring during 4 h at 68°C, after which a concentrated solution of sodium chloride (0.345 g, 5.90 mmol) and sodium acetate (2.085 g, 14.7 mmol) was added and the entire sample was placed in an ultrasonic bath for 20 min. After decanting the solvent, a mixture of iodine (0.279 g, 1.10 mmol) in methanol was added. With time, crystals of 2,2'-diiodoazobenzene grew from the solution and were collected by filtration. Yield = 0.047 g, 10%. |
Geometry. All s.u.'s (except the s.u. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell s.u.'s are taken into account individually in the estimation of s.u.'s in distances, angles and torsion angles; correlations between s.u.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell s.u.'s is used for estimating s.u.'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 > 2σ(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 | ||
C1 | 1.0033 (6) | 0.62044 (15) | 0.74337 (19) | 0.0362 (6) | |
C2 | 1.1608 (6) | 0.67355 (16) | 0.7950 (2) | 0.0391 (6) | |
C3 | 1.3471 (7) | 0.72094 (17) | 0.7587 (2) | 0.0469 (7) | |
C4 | 1.3732 (7) | 0.71515 (18) | 0.6711 (2) | 0.0511 (8) | |
C5 | 1.2147 (7) | 0.66291 (18) | 0.6191 (2) | 0.0447 (7) | |
C6 | 1.0330 (7) | 0.61521 (17) | 0.6548 (2) | 0.0440 (7) | |
I1 | 1.12360 (6) | 0.685129 (15) | 0.927841 (16) | 0.06511 (10) | |
H1 | 1.4537 | 0.7564 | 0.7936 | 0.056* | |
H2 | 1.4983 | 0.7466 | 0.6468 | 0.061* | |
H3 | 1.2306 | 0.6599 | 0.5596 | 0.054* | |
H4 | 0.9297 | 0.5794 | 0.6196 | 0.053* | |
N1 | 0.8151 (5) | 0.57362 (13) | 0.78379 (16) | 0.0409 (6) | |
N2 | 0.6804 (5) | 0.52810 (14) | 0.73326 (16) | 0.0400 (5) | |
C7 | 0.4922 (6) | 0.48055 (16) | 0.77216 (18) | 0.0366 (6) | |
C8 | 0.3371 (6) | 0.42818 (16) | 0.71848 (19) | 0.0380 (6) | |
C9 | 0.1496 (6) | 0.37976 (17) | 0.7525 (2) | 0.0451 (7) | |
C10 | 0.1187 (7) | 0.38397 (18) | 0.8396 (2) | 0.0511 (8) | |
C11 | 0.2731 (7) | 0.43536 (19) | 0.8935 (2) | 0.0494 (8) | |
C12 | 0.4562 (7) | 0.48416 (18) | 0.8602 (2) | 0.0480 (8) | |
I2 | 0.37973 (5) | 0.421268 (15) | 0.585578 (15) | 0.06002 (9) | |
H5 | 0.0457 | 0.3447 | 0.7163 | 0.054* | |
H6 | −0.0076 | 0.3518 | 0.8624 | 0.061* | |
H7 | 0.2537 | 0.4371 | 0.9528 | 0.059* | |
H8 | 0.5561 | 0.5196 | 0.8967 | 0.058* |
U11 | U22 | U33 | U12 | U13 | U23 | |
C1 | 0.0328 (14) | 0.0323 (15) | 0.0429 (16) | 0.0017 (12) | 0.0041 (12) | 0.0035 (12) |
C2 | 0.0373 (15) | 0.0366 (16) | 0.0435 (16) | 0.0024 (12) | 0.0062 (12) | −0.0016 (12) |
C3 | 0.0422 (17) | 0.0358 (17) | 0.063 (2) | −0.0028 (13) | 0.0096 (15) | 0.0017 (14) |
C4 | 0.0454 (18) | 0.0444 (19) | 0.067 (2) | 0.0018 (15) | 0.0191 (16) | 0.0139 (16) |
C5 | 0.0493 (18) | 0.0481 (18) | 0.0387 (16) | 0.0036 (14) | 0.0138 (14) | 0.0088 (13) |
C6 | 0.0478 (17) | 0.0414 (18) | 0.0429 (17) | −0.0018 (14) | 0.0063 (14) | −0.0012 (13) |
I1 | 0.07890 (19) | 0.07058 (18) | 0.04761 (14) | −0.02011 (13) | 0.01516 (12) | −0.01476 (11) |
N1 | 0.0414 (13) | 0.0395 (14) | 0.0417 (14) | −0.0054 (11) | 0.0055 (11) | 0.0003 (11) |
N2 | 0.0386 (13) | 0.0388 (14) | 0.0420 (13) | −0.0048 (11) | 0.0040 (11) | 0.0009 (11) |
C7 | 0.0339 (14) | 0.0373 (16) | 0.0384 (15) | 0.0009 (12) | 0.0045 (12) | 0.0029 (12) |
C8 | 0.0377 (15) | 0.0369 (16) | 0.0393 (15) | 0.0032 (12) | 0.0051 (12) | 0.0028 (12) |
C9 | 0.0412 (16) | 0.0395 (17) | 0.0541 (19) | −0.0053 (13) | 0.0050 (14) | −0.0001 (14) |
C10 | 0.0509 (19) | 0.049 (2) | 0.056 (2) | −0.0044 (15) | 0.0161 (16) | 0.0109 (16) |
C11 | 0.059 (2) | 0.055 (2) | 0.0338 (15) | −0.0093 (16) | 0.0077 (14) | 0.0050 (14) |
C12 | 0.0529 (19) | 0.0504 (19) | 0.0393 (16) | −0.0092 (15) | 0.0030 (14) | −0.0020 (14) |
I2 | 0.07077 (17) | 0.06949 (17) | 0.04103 (13) | −0.01261 (12) | 0.01232 (11) | −0.01094 (10) |
C1—C2 | 1.384 (4) | N2—C7 | 1.419 (3) |
C2—C3 | 1.391 (4) | C7—C8 | 1.386 (4) |
C3—C4 | 1.374 (5) | C8—C9 | 1.390 (4) |
C4—C5 | 1.378 (5) | C9—C10 | 1.370 (4) |
C5—C6 | 1.375 (4) | C10—C11 | 1.374 (5) |
C6—C1 | 1.393 (4) | C11—C12 | 1.374 (4) |
C2—I1 | 2.085 (3) | C12—C7 | 1.390 (4) |
C3—H1 | 0.9300 | C8—I2 | 2.086 (3) |
C4—H2 | 0.9300 | C9—H5 | 0.9300 |
C5—H3 | 0.9300 | C10—H6 | 0.9300 |
C6—H4 | 0.9300 | C11—H7 | 0.9300 |
C1—N1 | 1.423 (3) | C12—H8 | 0.9300 |
N1—N2 | 1.236 (3) | ||
C1—C2—C3 | 120.3 (3) | N1—N2—C7 | 115.1 (2) |
C2—C3—C4 | 119.7 (3) | C7—C8—C9 | 120.3 (3) |
C3—C4—C5 | 120.3 (3) | C8—C9—C10 | 119.6 (3) |
C4—C5—C6 | 120.3 (3) | C9—C10—C11 | 120.4 (3) |
C5—C6—C1 | 120.1 (3) | C10—C11—C12 | 120.4 (3) |
C6—C1—C2 | 119.2 (3) | C11—C12—C7 | 120.1 (3) |
C1—C2—I1 | 121.2 (2) | C12—C7—N2 | 123.5 (3) |
C3—C2—I1 | 118.5 (2) | C8—C7—C12 | 119.1 (3) |
C2—C3—H1 | 120.1 | C8—C7—N2 | 117.4 (2) |
C4—C3—H1 | 120.1 | C7—C8—I2 | 120.6 (2) |
C3—C4—H2 | 119.9 | C9—C8—I2 | 119.1 (2) |
C5—C4—H2 | 119.9 | C8—C9—H5 | 120.2 |
C4—C5—H3 | 119.8 | C10—C9—H5 | 120.2 |
C6—C5—H3 | 119.8 | C9—C10—H6 | 119.8 |
C5—C6—H4 | 119.9 | C11—C10—H6 | 119.8 |
C1—C6—H4 | 119.9 | C10—C11—H7 | 119.8 |
C6—C1—N1 | 122.8 (3) | C12—C11—H7 | 119.8 |
C2—C1—N1 | 117.9 (3) | C11—C12—H8 | 119.9 |
C1—N1—N2 | 114.0 (2) | C7—C12—H8 | 119.9 |
Experimental details
Crystal data | |
Chemical formula | C12H8I2N2 |
Mr | 433.88 |
Crystal system, space group | Monoclinic, P21/c |
Temperature (K) | 296 |
a, b, c (Å) | 4.6306 (3), 18.1105 (12), 15.3748 (10) |
β (°) | 98.532 (1) |
V (Å3) | 1275.10 (14) |
Z | 4 |
Radiation type | Mo Kα |
µ (mm−1) | 4.91 |
Crystal size (mm) | 0.63 × 0.09 × 0.04 |
Data collection | |
Diffractometer | Bruker SMART CCD area-detector diffractometer |
Absorption correction | Analytical (SADABS; Sheldrick, 1996) |
Tmin, Tmax | 0.322, 0.873 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 16726, 3186, 2536 |
Rint | 0.027 |
(sin θ/λ)max (Å−1) | 0.668 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.027, 0.059, 1.03 |
No. of reflections | 3186 |
No. of parameters | 145 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 0.56, −0.56 |
Computer programs: SMART (Bruker, 2000), SAINT (Bruker, 2000), SHELXTL (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), Mercury (Macrae et al., 2006).
Acknowledgements
The authors are grateful for financial support from the Natural Sciences and Engineering Research Council of Canada (NSERC).
References
Bruker (2000). SMART and SAINT. Bruker AXS Inc., Madison, Wisconsin, USA. Google Scholar
Crispini, A., Ghedini, M. & Pucci, D. (1998). Acta Cryst. C54, 1869–1871. Web of Science CSD CrossRef CAS IUCr Journals Google Scholar
Komeyama, M., Yamamoto, S., Nishimura, N. & Hasegawa, S. (1973). Bull. Chem. Soc. Jpn, 46, 2606–2607. CrossRef CAS Web of Science Google Scholar
Macrae, C. F., Edgington, P. R., McCabe, P., Pidcock, E., Shields, G. P., Taylor, R., Towler, M. & van de Streek, J. (2006). J. Appl. Cryst. 39, 453–457. Web of Science CrossRef CAS IUCr Journals Google Scholar
Sheldrick, G. M. (1996). SADABS. University of Göttingen, Germany. Google Scholar
Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. Web of Science CrossRef CAS IUCr Journals Google Scholar
Wragg, D. S., Ahmed, M. A. K., Nilsen, O. & Fjellvåg, H. (2011). Acta Cryst. E67, o2326. Web of Science CSD CrossRef IUCr Journals Google Scholar
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The molecules of 2,2'-diiodoazobenzene exhibit a trans geometry with the iodine atoms in positions ortho to the azo bridge and opposite the N═N double bond (Fig. 1). The molecules are nearly planar, with the maximum deviation from the average plane being 0.022 (4) Å for atom I1. The aromatic rings of 2,2'-diiodoazobenzene are nearly co-planar with each other (interplanar angle = 0.08 (3)°) and with the azo bridge (N1—N2—C7—C12 = 0.5 (4)°; N2—N1—C1—C6 = -0.1 (4)°). These features are also observed in the structure of 2-iodoazobenzene (Wragg et al., 2011). In contrast, the structures of dichloro analogues display parallel aromatic rings that are rotated from the plane of the azo bridge with N—N—C—C angles = 14.30 (6)° and -14.30 (6)° (Komeyama et al., 1973), and 14.4 (3)° and -14.4 (1)° (Crispini et al., 1998); the corresponding interplanar distances are 0.173 (1) and 0.351 (3) Å, respectively. Such structural differences are likely linked to the presence of intermolecular contacts in the structures of the iodo derivatives and their absence in the dichloro compounds. An offset π-stacking pattern (Fig. 2) allows significant overlap of adjacent molecules. The shortest intermolecular contact in 2,2'-diiodoazobenzene is between C1 and C7* (3.383 (4) Å, cf. sum of van der Waals radii = 3.40 Å; symmetry operation: 1+x, y, z). The stacking leads a columnar arrangement along a (Fig. 3). A herringbone pattern is observed perpendicular to the c axis (Fig. 4).