organic compounds\(\def\hfill{\hskip 5em}\def\hfil{\hskip 3em}\def\eqno#1{\hfil {#1}}\)

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ISSN: 2056-9890

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

(Received 24 September 2012; accepted 26 September 2012; online 13 October 2012)

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[Komeyama, M., Yamamoto, S., Nishimura, N. & Hasegawa, S. (1973). Bull. Chem. Soc. Jpn, 46, 2606-2607.]); Crispini et al. (1998[Crispini, A., Ghedini, M. & Pucci, D. (1998). Acta Cryst. C54, 1869-1871.]). For the structure of a related o-halogenated azobenzene, see: Wragg et al. (2011[Wragg, D. S., Ahmed, M. A. K., Nilsen, O. & Fjellvåg, H. (2011). Acta Cryst. E67, o2326.]).

[Scheme 1]

Experimental

Crystal data
  • C12H8I2N2

  • Mr = 433.88

  • Monoclinic, P 21 /c

  • a = 4.6306 (3) Å

  • b = 18.1105 (12) Å

  • c = 15.3748 (10) Å

  • β = 98.532 (1)°

  • V = 1275.10 (14) Å3

  • Z = 4

  • Mo Kα radiation

  • μ = 4.91 mm−1

  • T = 296 K

  • 0.63 × 0.09 × 0.04 mm

Data collection
  • Bruker SMART CCD area-detector diffractometer

  • Absorption correction: analytical (SADABS; Sheldrick, 1996[Sheldrick, G. M. (1996). SADABS. University of Göttingen, Germany.]) Tmin = 0.322, Tmax = 0.873

  • 16726 measured reflections

  • 3186 independent reflections

  • 2536 reflections with I > 2σ(I)

  • Rint = 0.027

Refinement
  • R[F2 > 2σ(F2)] = 0.027

  • wR(F2) = 0.059

  • S = 1.03

  • 3186 reflections

  • 145 parameters

  • H-atom parameters constrained

  • Δρmax = 0.56 e Å−3

  • Δρmin = −0.56 e Å−3

Data collection: SMART (Bruker, 2000[Bruker (2000). SMART and SAINT. Bruker AXS Inc., Madison, Wisconsin, USA.]); cell refinement: SMART (Bruker, 2000[Bruker (2000). SMART and SAINT. Bruker AXS Inc., Madison, Wisconsin, USA.]); data reduction: SAINT; program(s) used to solve structure: SHELXTL (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]); molecular graphics: Mercury (Macrae et al., 2006[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.]); software used to prepare material for publication: SHELXTL.

Supporting information


Comment top

The molecules of 2,2'-diiodoazobenzene exhibit a trans geometry with the iodine atoms in positions ortho to the azo bridge and opposite the NN 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).

Related literature top

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 top

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%.

Refinement top

Carbon-bound H-atoms were placed in calculated positions (C–H 0.93 Å) and were included in the refinement in the riding model approximation with Uiso(H) set to 1.2Ueq(C).

Computing details top

Data collection: SMART (Bruker, 2000); cell refinement: 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).

Figures top
[Figure 1] Fig. 1. Perspective view of the crystal structure of 2,2'-diiodoazobenzene. Atoms are represented by their anisotropic displacement ellipsoids at 50% probability level. Hydrogen atoms are displayed as fixed-size spheres of 0.35 Å radius.
[Figure 2] Fig. 2. Intermolecular C1—C7* contacts (- - -) in the crystal of 2,2'-diiodoazobenzene. Hydrogen atoms are omitted for clarity.
[Figure 3] Fig. 3. Packing diagram of 2,2'-diiodoazobenzene viewed along the a axis. Hydrogen atoms are omitted for clarity.
[Figure 4] Fig. 4. Packing diagram of 2,2'-diiodoazobenzene viewed along the c axis. Hydrogen atoms are omitted for clarity.
(E)-bis(2-iodophenyl)diazene top
Crystal data top
C12H8I2N2F(000) = 800
Mr = 433.88Dx = 2.261 Mg m3
Monoclinic, P21/cMo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybcCell parameters from 4767 reflections
a = 4.6306 (3) Åθ = 2.6–24.6°
b = 18.1105 (12) ŵ = 4.91 mm1
c = 15.3748 (10) ÅT = 296 K
β = 98.532 (1)°Rod, orange
V = 1275.10 (14) Å30.63 × 0.09 × 0.04 mm
Z = 4
Data collection top
Bruker SMART CCD area-detector
diffractometer
3186 independent reflections
Radiation source: fine-focus sealed tube2536 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.027
ϕ and ω scansθmax = 28.4°, θmin = 2.3°
Absorption correction: analytical
(SADABS; Sheldrick, 1996)
h = 46
Tmin = 0.322, Tmax = 0.873k = 2422
16726 measured reflectionsl = 2018
Refinement top
Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.027Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.059H-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 parametersΔρmax = 0.56 e Å3
0 restraintsΔρmin = 0.56 e Å3
Crystal data top
C12H8I2N2V = 1275.10 (14) Å3
Mr = 433.88Z = 4
Monoclinic, P21/cMo Kα radiation
a = 4.6306 (3) ŵ = 4.91 mm1
b = 18.1105 (12) ÅT = 296 K
c = 15.3748 (10) Å0.63 × 0.09 × 0.04 mm
β = 98.532 (1)°
Data collection top
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 = 0.873Rint = 0.027
16726 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0270 restraints
wR(F2) = 0.059H-atom parameters constrained
S = 1.03Δρmax = 0.56 e Å3
3186 reflectionsΔρmin = 0.56 e Å3
145 parameters
Special details top

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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
C11.0033 (6)0.62044 (15)0.74337 (19)0.0362 (6)
C21.1608 (6)0.67355 (16)0.7950 (2)0.0391 (6)
C31.3471 (7)0.72094 (17)0.7587 (2)0.0469 (7)
C41.3732 (7)0.71515 (18)0.6711 (2)0.0511 (8)
C51.2147 (7)0.66291 (18)0.6191 (2)0.0447 (7)
C61.0330 (7)0.61521 (17)0.6548 (2)0.0440 (7)
I11.12360 (6)0.685129 (15)0.927841 (16)0.06511 (10)
H11.45370.75640.79360.056*
H21.49830.74660.64680.061*
H31.23060.65990.55960.054*
H40.92970.57940.61960.053*
N10.8151 (5)0.57362 (13)0.78379 (16)0.0409 (6)
N20.6804 (5)0.52810 (14)0.73326 (16)0.0400 (5)
C70.4922 (6)0.48055 (16)0.77216 (18)0.0366 (6)
C80.3371 (6)0.42818 (16)0.71848 (19)0.0380 (6)
C90.1496 (6)0.37976 (17)0.7525 (2)0.0451 (7)
C100.1187 (7)0.38397 (18)0.8396 (2)0.0511 (8)
C110.2731 (7)0.43536 (19)0.8935 (2)0.0494 (8)
C120.4562 (7)0.48416 (18)0.8602 (2)0.0480 (8)
I20.37973 (5)0.421268 (15)0.585578 (15)0.06002 (9)
H50.04570.34470.71630.054*
H60.00760.35180.86240.061*
H70.25370.43710.95280.059*
H80.55610.51960.89670.058*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
C10.0328 (14)0.0323 (15)0.0429 (16)0.0017 (12)0.0041 (12)0.0035 (12)
C20.0373 (15)0.0366 (16)0.0435 (16)0.0024 (12)0.0062 (12)0.0016 (12)
C30.0422 (17)0.0358 (17)0.063 (2)0.0028 (13)0.0096 (15)0.0017 (14)
C40.0454 (18)0.0444 (19)0.067 (2)0.0018 (15)0.0191 (16)0.0139 (16)
C50.0493 (18)0.0481 (18)0.0387 (16)0.0036 (14)0.0138 (14)0.0088 (13)
C60.0478 (17)0.0414 (18)0.0429 (17)0.0018 (14)0.0063 (14)0.0012 (13)
I10.07890 (19)0.07058 (18)0.04761 (14)0.02011 (13)0.01516 (12)0.01476 (11)
N10.0414 (13)0.0395 (14)0.0417 (14)0.0054 (11)0.0055 (11)0.0003 (11)
N20.0386 (13)0.0388 (14)0.0420 (13)0.0048 (11)0.0040 (11)0.0009 (11)
C70.0339 (14)0.0373 (16)0.0384 (15)0.0009 (12)0.0045 (12)0.0029 (12)
C80.0377 (15)0.0369 (16)0.0393 (15)0.0032 (12)0.0051 (12)0.0028 (12)
C90.0412 (16)0.0395 (17)0.0541 (19)0.0053 (13)0.0050 (14)0.0001 (14)
C100.0509 (19)0.049 (2)0.056 (2)0.0044 (15)0.0161 (16)0.0109 (16)
C110.059 (2)0.055 (2)0.0338 (15)0.0093 (16)0.0077 (14)0.0050 (14)
C120.0529 (19)0.0504 (19)0.0393 (16)0.0092 (15)0.0030 (14)0.0020 (14)
I20.07077 (17)0.06949 (17)0.04103 (13)0.01261 (12)0.01232 (11)0.01094 (10)
Geometric parameters (Å, º) top
C1—C21.384 (4)N2—C71.419 (3)
C2—C31.391 (4)C7—C81.386 (4)
C3—C41.374 (5)C8—C91.390 (4)
C4—C51.378 (5)C9—C101.370 (4)
C5—C61.375 (4)C10—C111.374 (5)
C6—C11.393 (4)C11—C121.374 (4)
C2—I12.085 (3)C12—C71.390 (4)
C3—H10.9300C8—I22.086 (3)
C4—H20.9300C9—H50.9300
C5—H30.9300C10—H60.9300
C6—H40.9300C11—H70.9300
C1—N11.423 (3)C12—H80.9300
N1—N21.236 (3)
C1—C2—C3120.3 (3)N1—N2—C7115.1 (2)
C2—C3—C4119.7 (3)C7—C8—C9120.3 (3)
C3—C4—C5120.3 (3)C8—C9—C10119.6 (3)
C4—C5—C6120.3 (3)C9—C10—C11120.4 (3)
C5—C6—C1120.1 (3)C10—C11—C12120.4 (3)
C6—C1—C2119.2 (3)C11—C12—C7120.1 (3)
C1—C2—I1121.2 (2)C12—C7—N2123.5 (3)
C3—C2—I1118.5 (2)C8—C7—C12119.1 (3)
C2—C3—H1120.1C8—C7—N2117.4 (2)
C4—C3—H1120.1C7—C8—I2120.6 (2)
C3—C4—H2119.9C9—C8—I2119.1 (2)
C5—C4—H2119.9C8—C9—H5120.2
C4—C5—H3119.8C10—C9—H5120.2
C6—C5—H3119.8C9—C10—H6119.8
C5—C6—H4119.9C11—C10—H6119.8
C1—C6—H4119.9C10—C11—H7119.8
C6—C1—N1122.8 (3)C12—C11—H7119.8
C2—C1—N1117.9 (3)C11—C12—H8119.9
C1—N1—N2114.0 (2)C7—C12—H8119.9

Experimental details

Crystal data
Chemical formulaC12H8I2N2
Mr433.88
Crystal system, space groupMonoclinic, P21/c
Temperature (K)296
a, b, c (Å)4.6306 (3), 18.1105 (12), 15.3748 (10)
β (°) 98.532 (1)
V3)1275.10 (14)
Z4
Radiation typeMo Kα
µ (mm1)4.91
Crystal size (mm)0.63 × 0.09 × 0.04
Data collection
DiffractometerBruker SMART CCD area-detector
diffractometer
Absorption correctionAnalytical
(SADABS; Sheldrick, 1996)
Tmin, Tmax0.322, 0.873
No. of measured, independent and
observed [I > 2σ(I)] reflections
16726, 3186, 2536
Rint0.027
(sin θ/λ)max1)0.668
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.027, 0.059, 1.03
No. of reflections3186
No. of parameters145
H-atom treatmentH-atom parameters constrained
Δρmax, Δρmin (e Å3)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

First citationBruker (2000). SMART and SAINT. Bruker AXS Inc., Madison, Wisconsin, USA.
First citationCrispini, A., Ghedini, M. & Pucci, D. (1998). Acta Cryst. C54, 1869–1871.  Web of Science CSD CrossRef CAS IUCr Journals
First citationKomeyama, M., Yamamoto, S., Nishimura, N. & Hasegawa, S. (1973). Bull. Chem. Soc. Jpn, 46, 2606–2607.  CrossRef CAS Web of Science
First citationMacrae, 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
First citationSheldrick, G. M. (1996). SADABS. University of Göttingen, Germany.
First citationSheldrick, G. M. (2008). Acta Cryst. A64, 112–122.  Web of Science CrossRef CAS IUCr Journals
First citationWragg, D. S., Ahmed, M. A. K., Nilsen, O. & Fjellvåg, H. (2011). Acta Cryst. E67, o2326.  Web of Science CSD CrossRef IUCr Journals

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