The crystal structure of the title compound, C
14H
12N
4O
3, shows that the stereochemistry about the N=N double bond of the N=N—N(H) moiety is
trans. The whole molecule is almost planar (r.m.s. deviation = 0.0654 Å), the interplanar angle between the phenyl rings being 0.7 (1)° and the largest interplanar angle being that between the phenyl ring and the nitro group of the 4-nitrophenyl substituent [11.5 (2)°]. Intermolecular N—H
O interactions between molecules related by translation give rise to chains along the [110] and [1
0] directions, and these chains are held together by N
O π–π interactions. An unequal distribution of the double-bond character among the N atoms suggests a delocalization of π electrons over the diazoamine group and the adjacent aryl substituents.
Supporting information
CCDC reference: 241221
4-Nitroaniline (2.76 g, 20.0 mmol) was dissolved in a 50% aqueous solution of HCl (40 ml) and cooled to 270–273 K. A sodium nitrite solution (1.37 g, 20.0 mmol) in water (20 ml) was added slowly with continuous stirring. A solution of 4-acetylaniline (2.70 g, 20.0 mmol) in glacial acetic acid (40 ml) was added slowly to the reaction mixture. Stirring was continued for 2 h (at a temperature below 268 K). The resulting mixture was neutralized with a 10% aqueous solution of NaHCO3. The orange crude product was isolated by filtration and dried over P2O5 under vacuum. The product was recrystallized from a tetrahydrofuran/n-hexane mixture (1:1). Orange column-shaped crystals of (I), suitable for X-ray analysis, were obtained by slow evaporation of the solvent mixture (yield 5.12 g, 90%; m.p. 433–434 K).
H atoms of the phenyl rings and of the methyl group were positioned geometrically (C—H = 0.93 Å for Csp2 and 0.96 Å for Csp3 atoms) and treated as riding on their respective C atoms, with Uiso(H) values set at 1.2Ueq(Csp2) and 1.5Ueq(Csp3). The positional parameters of atom H3 were obtained from a difference map and refined with an isotropic displacement parameter. The methyl group was refined as a rigid group, with the rotation around the C2—C3 bond as a free variable. The nitro O atoms and the acetyl O atom have elongated displacement ellipsoids (Fig. 1). Split peaks for these atoms were not observed and consequently a disorder model was not used in the refinement.
Data collection: CAD-4 EXPRESS (Enraf Nonius, 1994); cell refinement: CAD-4 EXPRESS (Enraf Nonius, 1994); data reduction: XCAD4 (Harms & Wocadlo, 1995); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997), DIAMOND (Brandenburg, 1996); software used to prepare material for publication: WinGX (Farrugia, 1999).
Crystal data top
C14H12N4O3 | F(000) = 1184 |
Mr = 284.28 | Dx = 1.388 Mg m−3 |
Monoclinic, C2/c | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: -C 2yc | Cell parameters from 25 reflections |
a = 14.357 (6) Å | θ = 10.2–24.0° |
b = 7.1964 (13) Å | µ = 0.10 mm−1 |
c = 26.779 (5) Å | T = 293 K |
β = 100.35 (4)° | Prism, orange |
V = 2721.7 (13) Å3 | 0.40 × 0.40 × 0.25 mm |
Z = 8 | |
Data collection top
Enraf-Nonius CAD-4 diffractometer | Rint = 0.015 |
Radiation source: fine-focus sealed tube | θmax = 28.0°, θmin = 3.0° |
Graphite monochromator | h = −18→18 |
ω scans | k = 0→9 |
3468 measured reflections | l = −1→35 |
3266 independent reflections | 3 standard reflections every 60 min |
1809 reflections with I > 2σ(I) | intensity decay: <1% |
Refinement top
Refinement on F2 | 0 restraints |
Least-squares matrix: full | H atoms treated by a mixture of independent and constrained refinement |
R[F2 > 2σ(F2)] = 0.052 | |
wR(F2) = 0.142 | (Δ/σ)max < 0.001 |
S = 1.01 | Δρmax = 0.14 e Å−3 |
3266 reflections | Δρmin = −0.14 e Å−3 |
195 parameters | |
Crystal data top
C14H12N4O3 | V = 2721.7 (13) Å3 |
Mr = 284.28 | Z = 8 |
Monoclinic, C2/c | Mo Kα radiation |
a = 14.357 (6) Å | µ = 0.10 mm−1 |
b = 7.1964 (13) Å | T = 293 K |
c = 26.779 (5) Å | 0.40 × 0.40 × 0.25 mm |
β = 100.35 (4)° | |
Data collection top
Enraf-Nonius CAD-4 diffractometer | Rint = 0.015 |
3468 measured reflections | 3 standard reflections every 60 min |
3266 independent reflections | intensity decay: <1% |
1809 reflections with I > 2σ(I) | |
Refinement top
R[F2 > 2σ(F2)] = 0.052 | 0 restraints |
wR(F2) = 0.142 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.01 | Δρmax = 0.14 e Å−3 |
3266 reflections | Δρmin = −0.14 e Å−3 |
195 parameters | |
Special details top
Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes. |
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top | x | y | z | Uiso*/Ueq | |
O1 | 0.01964 (11) | 0.6804 (2) | 0.39769 (6) | 0.0771 (5) | |
O11 | 0.76728 (14) | 0.2796 (3) | 0.75888 (7) | 0.1064 (7) | |
O12 | 0.63806 (14) | 0.3986 (3) | 0.77367 (6) | 0.0976 (7) | |
N1 | 0.68538 (16) | 0.3291 (3) | 0.74482 (8) | 0.0761 (6) | |
N11 | 0.52677 (12) | 0.2366 (3) | 0.53903 (6) | 0.0566 (5) | |
N12 | 0.44704 (11) | 0.3132 (2) | 0.52462 (6) | 0.0532 (4) | |
N13 | 0.41564 (12) | 0.2878 (3) | 0.47558 (7) | 0.0567 (5) | |
C2 | 0.07135 (14) | 0.5958 (3) | 0.37417 (8) | 0.0530 (5) | |
C3 | 0.04492 (16) | 0.5816 (4) | 0.31830 (8) | 0.0720 (7) | |
H3A | −0.0176 | 0.6309 | 0.3076 | 0.108* | |
H3B | 0.0459 | 0.4535 | 0.3084 | 0.108* | |
H3C | 0.0891 | 0.6508 | 0.3027 | 0.108* | |
C11 | 0.56121 (14) | 0.2645 (3) | 0.59145 (7) | 0.0515 (5) | |
C12 | 0.51637 (15) | 0.3705 (3) | 0.62349 (8) | 0.0607 (6) | |
H12 | 0.4589 | 0.4281 | 0.611 | 0.073* | |
C13 | 0.55709 (16) | 0.3898 (3) | 0.67364 (8) | 0.0643 (6) | |
H13 | 0.5273 | 0.4598 | 0.6954 | 0.077* | |
C14 | 0.64239 (15) | 0.3047 (3) | 0.69143 (8) | 0.0586 (6) | |
C15 | 0.68790 (16) | 0.1988 (3) | 0.66067 (8) | 0.0626 (6) | |
H15 | 0.7453 | 0.1416 | 0.6735 | 0.075* | |
C16 | 0.64685 (14) | 0.1788 (3) | 0.61037 (8) | 0.0578 (6) | |
H16 | 0.6767 | 0.1075 | 0.589 | 0.069* | |
C21 | 0.32960 (13) | 0.3626 (3) | 0.45181 (7) | 0.0468 (5) | |
C22 | 0.30022 (14) | 0.3275 (3) | 0.40068 (7) | 0.0510 (5) | |
H22 | 0.3369 | 0.254 | 0.3832 | 0.061* | |
C23 | 0.21645 (13) | 0.4016 (3) | 0.37578 (7) | 0.0506 (5) | |
H23 | 0.1972 | 0.378 | 0.3413 | 0.061* | |
C24 | 0.15986 (12) | 0.5111 (3) | 0.40088 (7) | 0.0463 (5) | |
C25 | 0.18991 (14) | 0.5430 (3) | 0.45256 (7) | 0.0518 (5) | |
H25 | 0.1524 | 0.614 | 0.4702 | 0.062* | |
C26 | 0.27378 (13) | 0.4716 (3) | 0.47791 (7) | 0.0526 (5) | |
H26 | 0.2933 | 0.4957 | 0.5123 | 0.063* | |
H3 | 0.4492 (16) | 0.231 (3) | 0.4581 (8) | 0.064 (7)* | |
Atomic displacement parameters (Å2) top | U11 | U22 | U33 | U12 | U13 | U23 |
O1 | 0.0617 (10) | 0.0969 (13) | 0.0741 (11) | 0.0288 (9) | 0.0160 (8) | 0.0031 (9) |
O11 | 0.0804 (13) | 0.154 (2) | 0.0741 (12) | 0.0106 (14) | −0.0147 (10) | 0.0004 (13) |
O12 | 0.0881 (13) | 0.1498 (19) | 0.0564 (10) | −0.0121 (13) | 0.0170 (10) | −0.0025 (11) |
N1 | 0.0706 (14) | 0.0978 (17) | 0.0571 (12) | −0.0151 (12) | 0.0042 (11) | 0.0136 (12) |
N11 | 0.0468 (10) | 0.0631 (11) | 0.0567 (10) | 0.0047 (9) | 0.0012 (8) | 0.0034 (9) |
N12 | 0.0477 (10) | 0.0593 (11) | 0.0518 (10) | −0.0020 (8) | 0.0070 (8) | 0.0054 (8) |
N13 | 0.0461 (10) | 0.0718 (13) | 0.0516 (11) | 0.0092 (9) | 0.0071 (8) | −0.0003 (9) |
C2 | 0.0424 (11) | 0.0556 (13) | 0.0613 (13) | 0.0007 (10) | 0.0102 (10) | 0.0024 (10) |
C3 | 0.0576 (14) | 0.0901 (18) | 0.0636 (14) | 0.0080 (13) | −0.0015 (11) | 0.0056 (13) |
C11 | 0.0476 (11) | 0.0535 (12) | 0.0526 (11) | −0.0052 (10) | 0.0066 (9) | 0.0063 (10) |
C12 | 0.0500 (12) | 0.0704 (15) | 0.0608 (14) | 0.0056 (11) | 0.0075 (10) | 0.0061 (11) |
C13 | 0.0630 (14) | 0.0727 (16) | 0.0585 (13) | −0.0013 (12) | 0.0144 (11) | 0.0033 (12) |
C14 | 0.0553 (13) | 0.0689 (15) | 0.0496 (12) | −0.0117 (11) | 0.0042 (10) | 0.0110 (11) |
C15 | 0.0500 (12) | 0.0703 (15) | 0.0641 (14) | 0.0007 (11) | 0.0013 (10) | 0.0142 (12) |
C16 | 0.0496 (12) | 0.0609 (14) | 0.0613 (13) | 0.0022 (11) | 0.0056 (10) | 0.0049 (11) |
C21 | 0.0412 (10) | 0.0496 (12) | 0.0500 (11) | −0.0010 (9) | 0.0087 (8) | 0.0030 (9) |
C22 | 0.0467 (11) | 0.0556 (12) | 0.0516 (11) | 0.0043 (10) | 0.0109 (9) | −0.0058 (10) |
C23 | 0.0455 (11) | 0.0593 (13) | 0.0460 (11) | −0.0018 (10) | 0.0054 (9) | −0.0056 (10) |
C24 | 0.0393 (10) | 0.0499 (12) | 0.0505 (11) | −0.0012 (9) | 0.0103 (8) | 0.0004 (9) |
C25 | 0.0470 (11) | 0.0601 (13) | 0.0508 (11) | 0.0040 (10) | 0.0152 (9) | −0.0027 (10) |
C26 | 0.0491 (12) | 0.0641 (14) | 0.0444 (11) | 0.0010 (10) | 0.0076 (9) | −0.0023 (10) |
Geometric parameters (Å, º) top
O1—C2 | 1.219 (2) | C12—H12 | 0.93 |
O11—N1 | 1.222 (3) | C13—C14 | 1.375 (3) |
O11—N1i | 3.317 (3) | C13—H13 | 0.93 |
O12—N1 | 1.223 (3) | C14—C15 | 1.371 (3) |
N1—C14 | 1.462 (3) | C15—C16 | 1.377 (3) |
N1—O11ii | 3.317 (3) | C15—H15 | 0.93 |
N11—N12 | 1.267 (2) | C16—H16 | 0.93 |
N11—C11 | 1.416 (3) | C21—C22 | 1.382 (3) |
N12—N13 | 1.322 (2) | C21—C26 | 1.395 (3) |
N13—C21 | 1.392 (3) | C22—C23 | 1.374 (3) |
C2—C24 | 1.474 (3) | C22—H22 | 0.93 |
C2—C3 | 1.479 (3) | C23—C24 | 1.389 (3) |
C3—H3A | 0.96 | C23—H23 | 0.93 |
C3—H3B | 0.96 | C24—C25 | 1.393 (3) |
C3—H3C | 0.96 | C25—C26 | 1.371 (3) |
C11—C16 | 1.387 (3) | C25—H25 | 0.93 |
C11—C12 | 1.389 (3) | C26—H26 | 0.93 |
C12—C13 | 1.372 (3) | | |
| | | |
N1—O11—N1i | 117.85 (18) | C14—C13—H13 | 120.3 |
O11—N1—O12 | 122.5 (2) | C15—C14—C13 | 122.0 (2) |
O11—N1—C14 | 118.7 (2) | C15—C14—N1 | 119.4 (2) |
O12—N1—C14 | 118.8 (2) | C13—C14—N1 | 118.6 (2) |
O11—N1—O11ii | 95.94 (16) | C14—C15—C16 | 118.6 (2) |
O12—N1—O11ii | 76.10 (16) | C14—C15—H15 | 120.7 |
C14—N1—O11ii | 98.11 (13) | C16—C15—H15 | 120.7 |
N12—N11—C11 | 112.07 (17) | C15—C16—C11 | 120.4 (2) |
N11—N12—N13 | 111.74 (17) | C15—C16—H16 | 119.8 |
N12—N13—C21 | 121.09 (19) | C11—C16—H16 | 119.8 |
N12—N13—O1iii | 128.89 (13) | C22—C21—N13 | 118.03 (18) |
C21—N13—O1iii | 107.79 (13) | C22—C21—C26 | 119.91 (18) |
O1—C2—C24 | 120.52 (19) | N13—C21—C26 | 122.06 (18) |
O1—C2—C3 | 119.17 (19) | C23—C22—C21 | 119.64 (19) |
C24—C2—C3 | 120.30 (19) | C23—C22—H22 | 120.2 |
C2—C3—H3A | 109.5 | C21—C22—H22 | 120.2 |
C2—C3—H3B | 109.5 | C22—C23—C24 | 121.50 (18) |
H3A—C3—H3B | 109.5 | C22—C23—H23 | 119.2 |
C2—C3—H3C | 109.5 | C24—C23—H23 | 119.2 |
H3A—C3—H3C | 109.5 | C23—C24—C25 | 118.09 (18) |
H3B—C3—H3C | 109.5 | C23—C24—C2 | 121.87 (18) |
C16—C11—C12 | 119.8 (2) | C25—C24—C2 | 120.03 (18) |
C16—C11—N11 | 115.30 (19) | C26—C25—C24 | 121.18 (18) |
C12—C11—N11 | 124.89 (19) | C26—C25—H25 | 119.4 |
C13—C12—C11 | 119.8 (2) | C24—C25—H25 | 119.4 |
C13—C12—H12 | 120.1 | C25—C26—C21 | 119.66 (18) |
C11—C12—H12 | 120.1 | C25—C26—H26 | 120.2 |
C12—C13—C14 | 119.3 (2) | C21—C26—H26 | 120.2 |
C12—C13—H13 | 120.3 | | |
Symmetry codes: (i) −x+3/2, y−1/2, −z+3/2; (ii) −x+3/2, y+1/2, −z+3/2; (iii) x+1/2, y−1/2, z. |
Experimental details
Crystal data |
Chemical formula | C14H12N4O3 |
Mr | 284.28 |
Crystal system, space group | Monoclinic, C2/c |
Temperature (K) | 293 |
a, b, c (Å) | 14.357 (6), 7.1964 (13), 26.779 (5) |
β (°) | 100.35 (4) |
V (Å3) | 2721.7 (13) |
Z | 8 |
Radiation type | Mo Kα |
µ (mm−1) | 0.10 |
Crystal size (mm) | 0.40 × 0.40 × 0.25 |
|
Data collection |
Diffractometer | Enraf-Nonius CAD-4 diffractometer |
Absorption correction | – |
No. of measured, independent and observed [I > 2σ(I)] reflections | 3468, 3266, 1809 |
Rint | 0.015 |
(sin θ/λ)max (Å−1) | 0.660 |
|
Refinement |
R[F2 > 2σ(F2)], wR(F2), S | 0.052, 0.142, 1.01 |
No. of reflections | 3266 |
No. of parameters | 195 |
H-atom treatment | H atoms treated by a mixture of independent and constrained refinement |
Δρmax, Δρmin (e Å−3) | 0.14, −0.14 |
Selected geometric parameters (Å, º) topO1—C2 | 1.219 (2) | N11—N12 | 1.267 (2) |
O11—N1 | 1.222 (3) | N12—N13 | 1.322 (2) |
O12—N1 | 1.223 (3) | | |
| | | |
N12—N11—C11 | 112.07 (17) | O1—C2—C24 | 120.52 (19) |
N11—N12—N13 | 111.74 (17) | C24—C2—C3 | 120.30 (19) |
N12—N13—C21 | 121.09 (19) | | |
Numerous examples of free 1,3-disubstituted triazenes, RN=N—N(H)R (R = aryl or alkyl), characterized by X-ray diffraction studies have confirmed a trans stereochemistry about the N=N double bond (Moore & Robinson, 1986). On the other hand, free 1,3-diaryltriazenes show that the N=N—N(H) moiety is able to support intermolecular interactions by hydrogen bonding with polarizable atoms of the terminal aryl rings, giving rise to infinite chains that are commonly associated by weak interactions. This work forms part of a study of intermolecular hydrogen-bonding interactions in the solid state of asymmetric disubstituted 1,3-diaryltriazenes having π acid groups on the terminal aryl rings.
The molecular structure of (I) is shown in Fig. 1 and selected geometric parameters are given in Table 1. A typical feature of free diaryltriazenes is the delocalization of the π electrons on the triazene group, extending to the terminal aryl substituents. This observation is supported by the deviations from normal N—N and Car—N bond lengths. The N11=N12 bond [1.267 (2) Å] is longer than the characteristic value for a double bond (1.236 Å), whereas the N12—N13 bond [1.322 (2) Å] is shorter than the characteristic value for a single bond (1.404 Å; Allen et al., 1987; Teatum et al., 1960). Both the C21—N13 [1.392 (3) Å] and the C11—N11 bonds [1.416 (3) Å] are shorter than expected for N—Caryl single bonds (secondary amines, NHR2, R = Csp2; 1.452 Å; Orpen et al., 1989). These values are in good agreement with those found in the related compounds 1,3-bis(3-nitrophenyl)- triazene [N=N = 1.261 (2) Å and N—N = 1.326 (2) Å; Zhang et al., 1999] and 1,3-bis(4-acetylphenyl)triazene [N=N = 1.267 (4) Å and N—N = 1.329 (3) Å; Walton et al., 1991].
The crystal structure contains molecules related by translation, which form chains along the [110] and [1–10] directions via N—H···O hydrogen bonds [N13···O1i = 2.881 (3) Å and N13—H3···O1i = 159 (2)°; symmetry code: (i) 1/2 + x, −1/2 + y, z]. These chains are held together by N···O π–π interactions [N1···O11ii = 3.317 (3) Å and O11···N1iii = 3.317 (3) Å; symmetry codes: (ii) 3/2 − x, 1/2 + y, 3/2 − z; (iii) 3/2 − x, −1/2 + y, 3/2 − z; Fig. 2]. On the other hand, these weak intermolecular N···O π–π contacts hinder the coplanarity of the O11/N1/O12 nitro group with the C11–C16 phenyl ring [the interplanar angle is 11.5 (2)°]. The phenyl rings are planar within experimental error (r.m.s. 0.0032 Å) and make an interplanar angle of 0.7 (1)°, indicating that the whole molecule is almost planar.