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Borohydride reduction of N-(4-nitro­benzyl­idene)-4-iodo­aniline has yielded the title compound, 1,2-bis­[4-(4-iodo­phenyl­amino­methyl)­phenyl]­diazene 1-oxide, C26H22I2N4O. The mol­ecules lie across centres of inversion in P21/c, with the azoxy O atom disordered over two sites, each having an occupancy of 0.5. The mol­ecules are linked into sheets by a combination of C-H...O and C-H...[pi](arene) hydrogen bonds.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270103005511/sk1624sup1.cif
Contains datablocks global, I

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S0108270103005511/sk1624Isup2.hkl
Contains datablock I

CCDC reference: 211749

Comment top

The reduction of N-(nitrobenzylidene)-iodoanilines, (I), using sodium borohydride, generally yields the corresponding iodo-N-(nitrobenzyl)anilines (II), and six of the isomeric compounds (II) have so far been structurally characterized (Glidewell et al., 2002, 2003). However, analogous reduction of N-(4-nitrobenzylidene)-4-iodoaniline yielded not the expected 4-iodo-N-(4-nitrobenzyl)aniline but instead the title compound, (I), a further reduction of the nitrobenzylaniline presumed to have been the initial product of reduction.

Molecules of (I) lie across centres of inversion in space group P21/c, with the reference molecule selected to lie across the inversion centre at (1/2, 1/2, 1/2): the azoxy O atom is thus disordered over two sites, each with 0.5 occupancy. The molecular conformation can be defined in terms of four independent dihedral angles (Table 1). The inner ring C11–C16 is nearly coplanar with the central azoxy unit, as typically found in azoxybenzenes (Ejsmont, Domański et al., 2000; Ejsmont, Broda et al., 2002), and the terminal part of the molecule, comprising the –C11—C17—N1—C21– unit and the iodinated outer ring, is also nearly planar, but these two fragments are far from being coplanar overall, as shown by the C12—C11—C17—N1 torsional angle.

The molecules are linked by C—H···O and C—H···π(arene) hydrogen bonds (Table 2). Because of the partial occupancy of the O sites, we first discuss the effect of the C—H···π(arene) hydrogen bonds. Atom C16 at (x, y, z), which lies in the molecule centred at (1/2, 1/2,0.5), acts as hydrogen-bond donor to the outer ring, C21–C26, at (x, y, 1 + z), which lies in the molecule centred at (1/2, 1/2, 1.5), and propagation of this interaction by inversion and translation generates a molecular ladder running parallel to the [001] direction (Fig. 2). This ladder is reinforced by C—H···O hydrogen bonds. Atom C12 at (x, y, z), which is part of the molecule centred at (1/2, 1/2, 1/2), acts as hydrogen-bond donor to O14 at (x, y, −1 + z), which is part of the molecule centred at (1/2, 1/2, −0.5). Since each molecule contains only one O atom, each molecule can accept only one C—H···O hydrogen bond of this type, and a given pair of molecules, related by translation along the [001] direction, may in fact be linked by zero, one or two C—H···O hydrogen bonds, although on average there will be one such bond between each adjacent pair. The occurrence of exactly one C—H···O hydrogen bond between each pair of adjacent molecules would require perfect correlation of the O-atom site occupancies within a given ladder, although there need be no correlation between neighbouring ladders.

A similar, although more weakly bonded, ladder is generated along the [101] direction. Atom C25 at (x, y, z), in the molecule centred at (1/2, 1/2, 1/2), acts as hydrogen-bond donor to the inner ring at (−1 + x, y, −1 + z), which forms part of the molecule centred at (−0.5, 1/2, −0.5), while C17 at (x, y, z) acts as donor, via H17B, to O14, also at (−1 + x, y, −1 + z). Propagation of these interactions by inversion and translation generates the [101] ladder (Fig. 3), and the combination of ladders along [001] and [101] generates a sheet parallel to (010). Two such sheets run through each unit cell, in the domains 0.28 < y < 0.72 and −0.22 < y < 0.22, but there are no direction-specific interactions between adjacent sheets: in particular, there are no aromatic π···π stacking interactions, despite the number of aryl rings present. Note that the amino N plays no role in the supramolecular aggregation.

Experimental top

A sample of (I) was obtained by reduction of the corresponding N-(benzylidene)aniline using a fivefold molar excess of Na[BH4] in refluxing methanol for 1 h. After work-up, crystals of (I) suitable for single-crystal X-ray diffraction were grown by slow evaporation of a solution in ethanol.

Refinement top

Compound (I) is monoclinic and the space group P21/c was uniquely assigned from the systematic absences. H atoms were treated as riding atoms, with C—H distances of 0.93 Å (aromatic) and 0.97 Å (CH2) and N—H distances of 0.86 Å. Refinement of the site-occupancy factor for O14 gave a value of 0.52 (3); this factor was thereafter fixed at 0.50.

Computing details top

Data collection: SMART (Bruker, 1998); cell refinement: SAINT (Bruker, 2000); data reduction: SAINT (Bruker, 2000); program(s) used to solve structure: SHELXS86 (Sheldrick, 1990); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: PLATON (Spek, 2003); software used to prepare material for publication: SHELXL97 (Sheldrick, 1997) and PRPKAPPA (Ferguson, 1999).

Figures top
[Figure 1] Fig. 1. The molecular structure of (I), showing the atom-labelling scheme. Displacement ellipsoids are drawn at the 30% probability level. The atom O14 has occupancy 1/2, and the atoms marked with "a" are at the symmetry position (1 − x, 1 − y, 1 − z).
[Figure 2] Fig. 2. A stereoview of part of the crystal structure of (I), showing the formation of a molecular ladder along [001].
[Figure 3] Fig. 3. A stereoview of part of the crystal structure of (I), showing the formation of a molecular ladder along [101].
4,4'-Bis-(4-iodophenylaminomethyl)-azoxybenzene top
Crystal data top
C26H22I2N4OF(000) = 640
Mr = 660.28Dx = 1.803 Mg m3
Monoclinic, P21/cMo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybcCell parameters from 4439 reflections
a = 5.6959 (7) Åθ = 2.7–33.0°
b = 30.061 (3) ŵ = 2.61 mm1
c = 7.2017 (8) ÅT = 291 K
β = 99.526 (2)°Plate, colourless
V = 1216.1 (2) Å30.40 × 0.30 × 0.02 mm
Z = 2
Data collection top
Bruker SMART 1000 CCD area detector
diffractometer
4439 independent reflections
Radiation source: fine-focus sealed X-ray tube3092 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.038
ϕ and ω scansθmax = 33.0°, θmin = 2.7°
Absorption correction: multi-scan
SADABS (Bruker, 2000)
h = 88
Tmin = 0.403, Tmax = 0.946k = 3946
12146 measured reflectionsl = 1110
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)] = 0.065Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.156H-atom parameters constrained
S = 1.13 w = 1/[σ2(Fo2) + (0.0409P)2 + 3.3092P]
where P = (Fo2 + 2Fc2)/3
4439 reflections(Δ/σ)max = 0.001
154 parametersΔρmax = 1.07 e Å3
0 restraintsΔρmin = 1.19 e Å3
Crystal data top
C26H22I2N4OV = 1216.1 (2) Å3
Mr = 660.28Z = 2
Monoclinic, P21/cMo Kα radiation
a = 5.6959 (7) ŵ = 2.61 mm1
b = 30.061 (3) ÅT = 291 K
c = 7.2017 (8) Å0.40 × 0.30 × 0.02 mm
β = 99.526 (2)°
Data collection top
Bruker SMART 1000 CCD area detector
diffractometer
4439 independent reflections
Absorption correction: multi-scan
SADABS (Bruker, 2000)
3092 reflections with I > 2σ(I)
Tmin = 0.403, Tmax = 0.946Rint = 0.038
12146 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0650 restraints
wR(F2) = 0.156H-atom parameters constrained
S = 1.13Δρmax = 1.07 e Å3
4439 reflectionsΔρmin = 1.19 e Å3
154 parameters
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/UeqOcc. (<1)
C110.0487 (8)0.42356 (17)0.0829 (6)0.0462 (10)
C120.1493 (10)0.4451 (2)0.0392 (7)0.0606 (14)
C130.3088 (10)0.4667 (2)0.1769 (8)0.0586 (13)
C140.2659 (9)0.46671 (16)0.3596 (7)0.0479 (11)
C150.0703 (9)0.44510 (18)0.4049 (7)0.0520 (12)
C160.0883 (9)0.42386 (17)0.2660 (7)0.0481 (10)
C170.2247 (10)0.4015 (2)0.0689 (8)0.0627 (15)
N10.1072 (8)0.37175 (16)0.1815 (6)0.0623 (13)
N140.4229 (8)0.48628 (14)0.5175 (6)0.0530 (10)
O140.3713 (15)0.4722 (3)0.6943 (9)0.061 (2)0.50
I240.60670 (8)0.287175 (14)0.93967 (6)0.07211 (18)
C210.2268 (8)0.35259 (16)0.3447 (6)0.0442 (10)
C220.1097 (8)0.32065 (17)0.4363 (7)0.0510 (11)
C230.2133 (9)0.30266 (18)0.6060 (7)0.0518 (11)
C240.4425 (8)0.31586 (15)0.6852 (6)0.0439 (9)
C250.5615 (8)0.34664 (16)0.5969 (6)0.0434 (9)
C260.4571 (8)0.36469 (16)0.4253 (6)0.0469 (10)
H120.17660.44510.08460.073*
H130.44220.48090.14620.070*
H150.04420.44470.52900.062*
H160.22200.40980.29690.058*
H17A0.34000.38490.01140.075*
H17B0.30990.42410.14940.075*
H10.04110.36580.14600.075*
H220.04160.31130.38140.061*
H230.13130.28200.66690.062*
H250.71350.35560.65180.052*
H260.54140.38490.36420.056*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
C110.038 (2)0.053 (2)0.044 (2)0.0007 (18)0.0053 (17)0.0103 (19)
C120.059 (3)0.084 (4)0.037 (2)0.006 (3)0.001 (2)0.004 (2)
C130.048 (3)0.072 (3)0.053 (3)0.016 (3)0.001 (2)0.002 (2)
C140.051 (3)0.043 (2)0.043 (2)0.0041 (19)0.0110 (19)0.0107 (18)
C150.059 (3)0.058 (3)0.036 (2)0.002 (2)0.0015 (19)0.0052 (19)
C160.043 (2)0.054 (3)0.046 (2)0.005 (2)0.0029 (18)0.002 (2)
C170.048 (3)0.078 (4)0.054 (3)0.001 (3)0.012 (2)0.024 (3)
N10.047 (2)0.073 (3)0.057 (2)0.008 (2)0.0204 (19)0.023 (2)
N140.053 (2)0.049 (2)0.050 (2)0.0014 (17)0.0100 (18)0.0104 (18)
O140.075 (5)0.073 (5)0.032 (3)0.026 (4)0.004 (3)0.001 (3)
I240.0829 (3)0.0701 (3)0.0539 (2)0.0037 (2)0.01645 (18)0.02211 (17)
C210.038 (2)0.049 (2)0.042 (2)0.0009 (18)0.0067 (17)0.0052 (17)
C220.037 (2)0.058 (3)0.054 (3)0.002 (2)0.0067 (18)0.008 (2)
C230.049 (3)0.054 (3)0.051 (3)0.006 (2)0.003 (2)0.014 (2)
C240.043 (2)0.044 (2)0.041 (2)0.0038 (18)0.0029 (17)0.0044 (17)
C250.036 (2)0.051 (2)0.040 (2)0.0009 (18)0.0048 (16)0.0038 (17)
C260.039 (2)0.053 (2)0.044 (2)0.0025 (19)0.0077 (17)0.0107 (19)
Geometric parameters (Å, º) top
C11—C161.374 (7)N1—C211.383 (5)
C11—C121.381 (8)N1—H10.86
C11—C171.510 (6)N14—N14i1.261 (9)
C12—C131.391 (7)N14—O141.418 (8)
C12—H120.93I24—C242.100 (4)
C13—C141.377 (7)C21—C261.392 (6)
C13—H130.93C21—C221.395 (7)
C14—C151.375 (8)C22—C231.377 (6)
C14—N141.450 (5)C22—H220.93
C15—C161.388 (6)C23—C241.393 (7)
C15—H150.93C23—H230.93
C16—H160.93C24—C251.365 (7)
C17—N11.444 (7)C25—C261.390 (6)
C17—H17A0.97C25—H250.93
C17—H17B0.97C26—H260.93
C16—C11—C12119.1 (4)C21—N1—C17121.8 (4)
C16—C11—C17120.2 (5)C21—N1—H1119.1
C12—C11—C17120.7 (5)C17—N1—H1119.1
C11—C12—C13121.2 (5)N14i—N14—O14129.0 (5)
C11—C12—H12119.4N14i—N14—C14118.0 (5)
C13—C12—H12119.4O14—N14—C14113.0 (5)
C14—C13—C12118.9 (5)N1—C21—C26122.9 (4)
C14—C13—H13120.6N1—C21—C22118.8 (4)
C12—C13—H13120.6C26—C21—C22118.3 (4)
C15—C14—C13120.4 (4)C23—C22—C21121.4 (4)
C15—C14—N14115.1 (4)C23—C22—H22119.3
C13—C14—N14124.4 (5)C21—C22—H22119.3
C14—C15—C16120.2 (5)C22—C23—C24119.1 (5)
C14—C15—H15119.9C22—C23—H23120.4
C16—C15—H15119.9C24—C23—H23120.4
C11—C16—C15120.2 (5)C25—C24—C23120.4 (4)
C11—C16—H16119.9C25—C24—I24120.1 (3)
C15—C16—H16119.9C23—C24—I24119.5 (4)
N1—C17—C11111.4 (4)C24—C25—C26120.4 (4)
N1—C17—H17A109.3C24—C25—H25119.8
C11—C17—H17A109.3C26—C25—H25119.8
N1—C17—H17B109.3C25—C26—C21120.3 (4)
C11—C17—H17B109.3C25—C26—H26119.9
H17A—C17—H17B108.0C21—C26—H26119.9
C16—C11—C12—C130.3 (9)C17—N1—C21—C22173.5 (6)
C17—C11—C12—C13178.0 (6)C15—C14—N14—O1411.6 (7)
C11—C12—C13—C140.4 (9)C13—C14—N14—O14164.8 (6)
C12—C13—C14—C150.9 (9)C17—N1—C21—C268.5 (9)
C12—C13—C14—N14177.2 (5)N1—C21—C22—C23175.4 (5)
C13—C14—C15—C161.3 (8)C26—C21—C22—C232.7 (8)
N14—C14—C15—C16177.9 (5)C21—C22—C23—C241.7 (8)
C12—C11—C16—C150.7 (8)C22—C23—C24—C250.8 (8)
C17—C11—C16—C15178.4 (5)C22—C23—C24—I24178.1 (4)
C14—C15—C16—C111.2 (8)C23—C24—C25—C261.0 (8)
C16—C11—C17—N1130.7 (6)I24—C24—C25—C26177.9 (4)
C15—C14—N14—N14i166.2 (6)C24—C25—C26—C212.0 (8)
C13—C14—N14—N14i17.4 (9)N1—C21—C26—C25175.2 (5)
C12—C11—C17—N151.7 (8)C22—C21—C26—C252.8 (8)
C11—C17—N1—C21170.8 (5)
Symmetry code: (i) x+1, y+1, z+1.
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
C12—H12···O14ii0.932.243.078 (9)150
C17—H17B···O14iii0.972.453.380 (10)162
C16—H16···Cg2iv0.932.783.536 (5)139
C25—H25···Cg1iii0.932.973.631 (5)130
Symmetry codes: (ii) x, y, z1; (iii) x1, y, z1; (iv) x, y, z+1.

Experimental details

Crystal data
Chemical formulaC26H22I2N4O
Mr660.28
Crystal system, space groupMonoclinic, P21/c
Temperature (K)291
a, b, c (Å)5.6959 (7), 30.061 (3), 7.2017 (8)
β (°) 99.526 (2)
V3)1216.1 (2)
Z2
Radiation typeMo Kα
µ (mm1)2.61
Crystal size (mm)0.40 × 0.30 × 0.02
Data collection
DiffractometerBruker SMART 1000 CCD area detector
diffractometer
Absorption correctionMulti-scan
SADABS (Bruker, 2000)
Tmin, Tmax0.403, 0.946
No. of measured, independent and
observed [I > 2σ(I)] reflections
12146, 4439, 3092
Rint0.038
(sin θ/λ)max1)0.767
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.065, 0.156, 1.13
No. of reflections4439
No. of parameters154
H-atom treatmentH-atom parameters constrained
Δρmax, Δρmin (e Å3)1.07, 1.19

Computer programs: SMART (Bruker, 1998), SAINT (Bruker, 2000), SHELXS86 (Sheldrick, 1990), PLATON (Spek, 2003), SHELXL97 (Sheldrick, 1997) and PRPKAPPA (Ferguson, 1999).

Selected torsion angles (º) top
C13—C14—N14—N14i17.4 (9)C11—C17—N1—C21170.8 (5)
C12—C11—C17—N151.7 (8)C17—N1—C21—C22173.5 (6)
Symmetry code: (i) x+1, y+1, z+1.
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
C12—H12···O14ii0.932.243.078 (9)150
C17—H17B···O14iii0.972.453.380 (10)162
C16—H16···Cg2iv0.932.783.536 (5)139
C25—H25···Cg1iii0.932.973.631 (5)130
Symmetry codes: (ii) x, y, z1; (iii) x1, y, z1; (iv) x, y, z+1.
 

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