Borohydride reduction of
N-(4-nitrobenzylidene)-4-iodoaniline has yielded the title compound, 1,2-bis[4-(4-iodophenylaminomethyl)phenyl]diazene 1-oxide, C
26H
22I
2N
4O. The molecules lie across centres of inversion in
P2
1/
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
(arene) hydrogen bonds.
Supporting information
CCDC reference: 211749
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.
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.
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).
4,4'-Bis-(4-iodophenylaminomethyl)-azoxybenzene
top
Crystal data top
C26H22I2N4O | F(000) = 640 |
Mr = 660.28 | Dx = 1.803 Mg m−3 |
Monoclinic, P21/c | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: -P 2ybc | Cell parameters from 4439 reflections |
a = 5.6959 (7) Å | θ = 2.7–33.0° |
b = 30.061 (3) Å | µ = 2.61 mm−1 |
c = 7.2017 (8) Å | T = 291 K |
β = 99.526 (2)° | Plate, colourless |
V = 1216.1 (2) Å3 | 0.40 × 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 tube | 3092 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.038 |
ϕ and ω scans | θmax = 33.0°, θmin = 2.7° |
Absorption correction: multi-scan SADABS (Bruker, 2000) | h = −8→8 |
Tmin = 0.403, Tmax = 0.946 | k = −39→46 |
12146 measured reflections | l = −11→10 |
Refinement top
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)] = 0.065 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.156 | H-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 parameters | Δρmax = 1.07 e Å−3 |
0 restraints | Δρmin = −1.19 e Å−3 |
Crystal data top
C26H22I2N4O | V = 1216.1 (2) Å3 |
Mr = 660.28 | Z = 2 |
Monoclinic, P21/c | Mo Kα radiation |
a = 5.6959 (7) Å | µ = 2.61 mm−1 |
b = 30.061 (3) Å | T = 291 K |
c = 7.2017 (8) Å | 0.40 × 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 = 0.946 | Rint = 0.038 |
12146 measured reflections | |
Refinement top
R[F2 > 2σ(F2)] = 0.065 | 0 restraints |
wR(F2) = 0.156 | H-atom parameters constrained |
S = 1.13 | Δρmax = 1.07 e Å−3 |
4439 reflections | Δρmin = −1.19 e Å−3 |
154 parameters | |
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top | x | y | z | Uiso*/Ueq | Occ. (<1) |
C11 | −0.0487 (8) | 0.42356 (17) | 0.0829 (6) | 0.0462 (10) | |
C12 | 0.1493 (10) | 0.4451 (2) | 0.0392 (7) | 0.0606 (14) | |
C13 | 0.3088 (10) | 0.4667 (2) | 0.1769 (8) | 0.0586 (13) | |
C14 | 0.2659 (9) | 0.46671 (16) | 0.3596 (7) | 0.0479 (11) | |
C15 | 0.0703 (9) | 0.44510 (18) | 0.4049 (7) | 0.0520 (12) | |
C16 | −0.0883 (9) | 0.42386 (17) | 0.2660 (7) | 0.0481 (10) | |
C17 | −0.2247 (10) | 0.4015 (2) | −0.0689 (8) | 0.0627 (15) | |
N1 | −0.1072 (8) | 0.37175 (16) | −0.1815 (6) | 0.0623 (13) | |
N14 | 0.4229 (8) | 0.48628 (14) | 0.5175 (6) | 0.0530 (10) | |
O14 | 0.3713 (15) | 0.4722 (3) | 0.6943 (9) | 0.061 (2) | 0.50 |
I24 | −0.60670 (8) | 0.287175 (14) | −0.93967 (6) | 0.07211 (18) | |
C21 | −0.2268 (8) | 0.35259 (16) | −0.3447 (6) | 0.0442 (10) | |
C22 | −0.1097 (8) | 0.32065 (17) | −0.4363 (7) | 0.0510 (11) | |
C23 | −0.2133 (9) | 0.30266 (18) | −0.6060 (7) | 0.0518 (11) | |
C24 | −0.4425 (8) | 0.31586 (15) | −0.6852 (6) | 0.0439 (9) | |
C25 | −0.5615 (8) | 0.34664 (16) | −0.5969 (6) | 0.0434 (9) | |
C26 | −0.4571 (8) | 0.36469 (16) | −0.4253 (6) | 0.0469 (10) | |
H12 | 0.1766 | 0.4451 | −0.0846 | 0.073* | |
H13 | 0.4422 | 0.4809 | 0.1462 | 0.070* | |
H15 | 0.0442 | 0.4447 | 0.5290 | 0.062* | |
H16 | −0.2220 | 0.4098 | 0.2969 | 0.058* | |
H17A | −0.3400 | 0.3849 | −0.0114 | 0.075* | |
H17B | −0.3099 | 0.4241 | −0.1494 | 0.075* | |
H1 | 0.0411 | 0.3658 | −0.1460 | 0.075* | |
H22 | 0.0416 | 0.3113 | −0.3814 | 0.061* | |
H23 | −0.1313 | 0.2820 | −0.6669 | 0.062* | |
H25 | −0.7135 | 0.3556 | −0.6518 | 0.052* | |
H26 | −0.5414 | 0.3849 | −0.3642 | 0.056* | |
Atomic displacement parameters (Å2) top | U11 | U22 | U33 | U12 | U13 | U23 |
C11 | 0.038 (2) | 0.053 (2) | 0.044 (2) | −0.0007 (18) | −0.0053 (17) | −0.0103 (19) |
C12 | 0.059 (3) | 0.084 (4) | 0.037 (2) | −0.006 (3) | 0.001 (2) | −0.004 (2) |
C13 | 0.048 (3) | 0.072 (3) | 0.053 (3) | −0.016 (3) | 0.001 (2) | 0.002 (2) |
C14 | 0.051 (3) | 0.043 (2) | 0.043 (2) | 0.0041 (19) | −0.0110 (19) | −0.0107 (18) |
C15 | 0.059 (3) | 0.058 (3) | 0.036 (2) | 0.002 (2) | −0.0015 (19) | −0.0052 (19) |
C16 | 0.043 (2) | 0.054 (3) | 0.046 (2) | −0.005 (2) | 0.0029 (18) | −0.002 (2) |
C17 | 0.048 (3) | 0.078 (4) | 0.054 (3) | −0.001 (3) | −0.012 (2) | −0.024 (3) |
N1 | 0.047 (2) | 0.073 (3) | 0.057 (2) | 0.008 (2) | −0.0204 (19) | −0.023 (2) |
N14 | 0.053 (2) | 0.049 (2) | 0.050 (2) | −0.0014 (17) | −0.0100 (18) | −0.0104 (18) |
O14 | 0.075 (5) | 0.073 (5) | 0.032 (3) | −0.026 (4) | 0.004 (3) | −0.001 (3) |
I24 | 0.0829 (3) | 0.0701 (3) | 0.0539 (2) | 0.0037 (2) | −0.01645 (18) | −0.02211 (17) |
C21 | 0.038 (2) | 0.049 (2) | 0.042 (2) | −0.0009 (18) | −0.0067 (17) | −0.0052 (17) |
C22 | 0.037 (2) | 0.058 (3) | 0.054 (3) | 0.002 (2) | −0.0067 (18) | −0.008 (2) |
C23 | 0.049 (3) | 0.054 (3) | 0.051 (3) | 0.006 (2) | 0.003 (2) | −0.014 (2) |
C24 | 0.043 (2) | 0.044 (2) | 0.041 (2) | −0.0038 (18) | −0.0029 (17) | −0.0044 (17) |
C25 | 0.036 (2) | 0.051 (2) | 0.040 (2) | 0.0009 (18) | −0.0048 (16) | −0.0038 (17) |
C26 | 0.039 (2) | 0.053 (2) | 0.044 (2) | 0.0025 (19) | −0.0077 (17) | −0.0107 (19) |
Geometric parameters (Å, º) top
C11—C16 | 1.374 (7) | N1—C21 | 1.383 (5) |
C11—C12 | 1.381 (8) | N1—H1 | 0.86 |
C11—C17 | 1.510 (6) | N14—N14i | 1.261 (9) |
C12—C13 | 1.391 (7) | N14—O14 | 1.418 (8) |
C12—H12 | 0.93 | I24—C24 | 2.100 (4) |
C13—C14 | 1.377 (7) | C21—C26 | 1.392 (6) |
C13—H13 | 0.93 | C21—C22 | 1.395 (7) |
C14—C15 | 1.375 (8) | C22—C23 | 1.377 (6) |
C14—N14 | 1.450 (5) | C22—H22 | 0.93 |
C15—C16 | 1.388 (6) | C23—C24 | 1.393 (7) |
C15—H15 | 0.93 | C23—H23 | 0.93 |
C16—H16 | 0.93 | C24—C25 | 1.365 (7) |
C17—N1 | 1.444 (7) | C25—C26 | 1.390 (6) |
C17—H17A | 0.97 | C25—H25 | 0.93 |
C17—H17B | 0.97 | C26—H26 | 0.93 |
| | | |
C16—C11—C12 | 119.1 (4) | C21—N1—C17 | 121.8 (4) |
C16—C11—C17 | 120.2 (5) | C21—N1—H1 | 119.1 |
C12—C11—C17 | 120.7 (5) | C17—N1—H1 | 119.1 |
C11—C12—C13 | 121.2 (5) | N14i—N14—O14 | 129.0 (5) |
C11—C12—H12 | 119.4 | N14i—N14—C14 | 118.0 (5) |
C13—C12—H12 | 119.4 | O14—N14—C14 | 113.0 (5) |
C14—C13—C12 | 118.9 (5) | N1—C21—C26 | 122.9 (4) |
C14—C13—H13 | 120.6 | N1—C21—C22 | 118.8 (4) |
C12—C13—H13 | 120.6 | C26—C21—C22 | 118.3 (4) |
C15—C14—C13 | 120.4 (4) | C23—C22—C21 | 121.4 (4) |
C15—C14—N14 | 115.1 (4) | C23—C22—H22 | 119.3 |
C13—C14—N14 | 124.4 (5) | C21—C22—H22 | 119.3 |
C14—C15—C16 | 120.2 (5) | C22—C23—C24 | 119.1 (5) |
C14—C15—H15 | 119.9 | C22—C23—H23 | 120.4 |
C16—C15—H15 | 119.9 | C24—C23—H23 | 120.4 |
C11—C16—C15 | 120.2 (5) | C25—C24—C23 | 120.4 (4) |
C11—C16—H16 | 119.9 | C25—C24—I24 | 120.1 (3) |
C15—C16—H16 | 119.9 | C23—C24—I24 | 119.5 (4) |
N1—C17—C11 | 111.4 (4) | C24—C25—C26 | 120.4 (4) |
N1—C17—H17A | 109.3 | C24—C25—H25 | 119.8 |
C11—C17—H17A | 109.3 | C26—C25—H25 | 119.8 |
N1—C17—H17B | 109.3 | C25—C26—C21 | 120.3 (4) |
C11—C17—H17B | 109.3 | C25—C26—H26 | 119.9 |
H17A—C17—H17B | 108.0 | C21—C26—H26 | 119.9 |
| | | |
C16—C11—C12—C13 | 0.3 (9) | C17—N1—C21—C22 | −173.5 (6) |
C17—C11—C12—C13 | 178.0 (6) | C15—C14—N14—O14 | 11.6 (7) |
C11—C12—C13—C14 | −0.4 (9) | C13—C14—N14—O14 | −164.8 (6) |
C12—C13—C14—C15 | 0.9 (9) | C17—N1—C21—C26 | 8.5 (9) |
C12—C13—C14—N14 | 177.2 (5) | N1—C21—C22—C23 | −175.4 (5) |
C13—C14—C15—C16 | −1.3 (8) | C26—C21—C22—C23 | 2.7 (8) |
N14—C14—C15—C16 | −177.9 (5) | C21—C22—C23—C24 | −1.7 (8) |
C12—C11—C16—C15 | −0.7 (8) | C22—C23—C24—C25 | 0.8 (8) |
C17—C11—C16—C15 | −178.4 (5) | C22—C23—C24—I24 | −178.1 (4) |
C14—C15—C16—C11 | 1.2 (8) | C23—C24—C25—C26 | −1.0 (8) |
C16—C11—C17—N1 | −130.7 (6) | I24—C24—C25—C26 | 177.9 (4) |
C15—C14—N14—N14i | −166.2 (6) | C24—C25—C26—C21 | 2.0 (8) |
C13—C14—N14—N14i | 17.4 (9) | N1—C21—C26—C25 | 175.2 (5) |
C12—C11—C17—N1 | 51.7 (8) | C22—C21—C26—C25 | −2.8 (8) |
C11—C17—N1—C21 | −170.8 (5) | | |
Symmetry code: (i) −x+1, −y+1, −z+1. |
Hydrogen-bond geometry (Å, º) top
D—H···A | D—H | H···A | D···A | D—H···A |
C12—H12···O14ii | 0.93 | 2.24 | 3.078 (9) | 150 |
C17—H17B···O14iii | 0.97 | 2.45 | 3.380 (10) | 162 |
C16—H16···Cg2iv | 0.93 | 2.78 | 3.536 (5) | 139 |
C25—H25···Cg1iii | 0.93 | 2.97 | 3.631 (5) | 130 |
Symmetry codes: (ii) x, y, z−1; (iii) x−1, y, z−1; (iv) x, y, z+1. |
Experimental details
Crystal data |
Chemical formula | C26H22I2N4O |
Mr | 660.28 |
Crystal system, space group | Monoclinic, P21/c |
Temperature (K) | 291 |
a, b, c (Å) | 5.6959 (7), 30.061 (3), 7.2017 (8) |
β (°) | 99.526 (2) |
V (Å3) | 1216.1 (2) |
Z | 2 |
Radiation type | Mo Kα |
µ (mm−1) | 2.61 |
Crystal size (mm) | 0.40 × 0.30 × 0.02 |
|
Data collection |
Diffractometer | Bruker SMART 1000 CCD area detector diffractometer |
Absorption correction | Multi-scan SADABS (Bruker, 2000) |
Tmin, Tmax | 0.403, 0.946 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 12146, 4439, 3092 |
Rint | 0.038 |
(sin θ/λ)max (Å−1) | 0.767 |
|
Refinement |
R[F2 > 2σ(F2)], wR(F2), S | 0.065, 0.156, 1.13 |
No. of reflections | 4439 |
No. of parameters | 154 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 1.07, −1.19 |
Selected torsion angles (º) topC13—C14—N14—N14i | 17.4 (9) | C11—C17—N1—C21 | −170.8 (5) |
C12—C11—C17—N1 | 51.7 (8) | C17—N1—C21—C22 | −173.5 (6) |
Symmetry code: (i) −x+1, −y+1, −z+1. |
Hydrogen-bond geometry (Å, º) top
D—H···A | D—H | H···A | D···A | D—H···A |
C12—H12···O14ii | 0.93 | 2.24 | 3.078 (9) | 150 |
C17—H17B···O14iii | 0.97 | 2.45 | 3.380 (10) | 162 |
C16—H16···Cg2iv | 0.93 | 2.78 | 3.536 (5) | 139 |
C25—H25···Cg1iii | 0.93 | 2.97 | 3.631 (5) | 130 |
Symmetry codes: (ii) x, y, z−1; (iii) x−1, y, z−1; (iv) x, y, z+1. |
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.