Supporting information
Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270100019405/sk1442sup1.cif | |
Structure factor file (CIF format) https://doi.org/10.1107/S0108270100019405/sk1442Isup2.hkl |
CCDC reference: 162581
A sample of compound (I) was obtained from Aldrich. Crystals suitable for single-crystal X-ray diffraction were grown from a solution in ethanol.
Compound (I) is monoclinic and the systematic absences permitted Cc and C2/c as possible space groups. The unit-cell dimensions were consistent with Z = 4, so space group Cc was chosen and confirmed by the successful structure solution and refinement. Before the final refinement, the space group setting was transformed from the standard setting Cc, in which β = 139.104 (2)°, to the non-standard setting Ia, in which β = 94.050 (2)°. H atoms were treated as riding with N—H = 0.86 Å and C—H = 0.93 (aromatic) or 0.96 Å (methyl). In the absence of any significant anomalous scatterers, Friedel equivalents were merged before refinement. Examination of the structure with PLATON (Spek, 2000) showed that there were no solvent-accessible voids in the crystal lattice.
Data collection: XPREP (Bruker, 1997); cell refinement: XPREP; data reduction: XPREP; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: PLATON (Spek, 2000); software used to prepare material for publication: SHELXL97 and WORDPERFECT macro PRPKAPPA (Ferguson, 1999).
C7H8N2O2 | F(000) = 320 |
Mr = 152.15 | Dx = 1.391 Mg m−3 |
Monoclinic, Ia | Mo Kα radiation, λ = 0.71073 Å |
a = 7.6113 (5) Å | Cell parameters from 1316 reflections |
b = 11.6304 (7) Å | θ = 3.0–32.5° |
c = 8.2286 (5) Å | µ = 0.10 mm−1 |
β = 94.050 (2)° | T = 150 K |
V = 726.60 (8) Å3 | Block, orange |
Z = 4 | 0.30 × 0.20 × 0.20 mm |
Bruker SMART 1000 CCD diffractometer | 1316 independent reflections |
Radiation source: fine-focus sealed X-ray tube | 1037 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.032 |
ϕ and ω scans with κ offsets | θmax = 32.5°, θmin = 3.0° |
Absorption correction: multi-scan (SADABS; Bruker, 1997) | h = −11→11 |
Tmin = 0.969, Tmax = 0.979 | k = −17→14 |
4272 measured reflections | l = −12→12 |
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)] = 0.043 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.113 | H-atom parameters constrained |
S = 1.00 | w = 1/[σ2(Fo2) + (0.0735P)2] where P = (Fo2 + 2Fc2)/3 |
1316 reflections | (Δ/σ)max < 0.001 |
101 parameters | Δρmax = 0.25 e Å−3 |
2 restraints | Δρmin = −0.26 e Å−3 |
C7H8N2O2 | V = 726.60 (8) Å3 |
Mr = 152.15 | Z = 4 |
Monoclinic, Ia | Mo Kα radiation |
a = 7.6113 (5) Å | µ = 0.10 mm−1 |
b = 11.6304 (7) Å | T = 150 K |
c = 8.2286 (5) Å | 0.30 × 0.20 × 0.20 mm |
β = 94.050 (2)° |
Bruker SMART 1000 CCD diffractometer | 1316 independent reflections |
Absorption correction: multi-scan (SADABS; Bruker, 1997) | 1037 reflections with I > 2σ(I) |
Tmin = 0.969, Tmax = 0.979 | Rint = 0.032 |
4272 measured reflections |
R[F2 > 2σ(F2)] = 0.043 | 2 restraints |
wR(F2) = 0.113 | H-atom parameters constrained |
S = 1.00 | Δρmax = 0.25 e Å−3 |
1316 reflections | Δρmin = −0.26 e Å−3 |
101 parameters |
x | y | z | Uiso*/Ueq | ||
C1 | 0.9082 (2) | 0.07296 (16) | 0.7383 (2) | 0.0344 (4) | |
C2 | 0.8859 (2) | −0.04640 (14) | 0.71078 (18) | 0.0337 (4) | |
C3 | 0.8083 (3) | −0.08360 (15) | 0.5633 (2) | 0.0360 (4) | |
C4 | 0.7538 (2) | −0.00392 (17) | 0.44279 (18) | 0.0352 (4) | |
C5 | 0.7736 (3) | 0.11337 (16) | 0.4687 (2) | 0.0405 (4) | |
C6 | 0.8508 (3) | 0.15102 (16) | 0.6156 (2) | 0.0399 (4) | |
N1 | 0.9814 (3) | 0.11329 (15) | 0.8825 (2) | 0.0478 (4) | |
C7 | 0.9475 (3) | −0.13003 (19) | 0.8422 (3) | 0.0465 (5) | |
N2 | 0.6745 (2) | −0.04422 (15) | 0.29017 (18) | 0.0463 (4) | |
O1 | 0.6538 (3) | −0.14825 (15) | 0.2675 (2) | 0.0621 (5) | |
O2 | 0.6279 (4) | 0.02700 (18) | 0.1852 (2) | 0.0811 (7) | |
H3 | 0.7922 | −0.1618 | 0.5440 | 0.043* | |
H5 | 0.7354 | 0.1657 | 0.3883 | 0.049* | |
H6 | 0.8652 | 0.2295 | 0.6338 | 0.048* | |
H1A | 0.9923 | 0.1861 | 0.8981 | 0.057* | |
H1B | 1.0168 | 0.0660 | 0.9582 | 0.057* | |
H7A | 0.9344 | −0.2071 | 0.8015 | 0.070* | |
H7B | 0.8782 | −0.1206 | 0.9344 | 0.070* | |
H7C | 1.0692 | −0.1157 | 0.8747 | 0.070* |
U11 | U22 | U33 | U12 | U13 | U23 | |
C1 | 0.0390 (9) | 0.0353 (8) | 0.0284 (7) | −0.0033 (7) | −0.0018 (6) | −0.0021 (6) |
C2 | 0.0384 (10) | 0.0309 (8) | 0.0310 (8) | −0.0026 (6) | −0.0023 (6) | 0.0024 (5) |
C3 | 0.0448 (9) | 0.0310 (7) | 0.0312 (7) | −0.0022 (7) | −0.0055 (6) | −0.0015 (6) |
C4 | 0.0433 (9) | 0.0355 (8) | 0.0255 (6) | −0.0017 (6) | −0.0063 (6) | −0.0026 (5) |
C5 | 0.0518 (11) | 0.0358 (9) | 0.0327 (8) | 0.0002 (7) | −0.0051 (7) | 0.0050 (6) |
C6 | 0.0557 (11) | 0.0299 (8) | 0.0330 (8) | −0.0019 (7) | −0.0046 (7) | −0.0013 (6) |
N1 | 0.0676 (12) | 0.0397 (9) | 0.0341 (8) | −0.0040 (8) | −0.0107 (7) | −0.0052 (6) |
C7 | 0.0579 (12) | 0.0408 (9) | 0.0387 (9) | −0.0025 (8) | −0.0119 (8) | 0.0097 (7) |
N2 | 0.0584 (11) | 0.0479 (10) | 0.0304 (8) | −0.0021 (8) | −0.0121 (7) | −0.0046 (6) |
O1 | 0.0877 (12) | 0.0457 (8) | 0.0497 (8) | −0.0066 (8) | −0.0182 (8) | −0.0136 (7) |
O2 | 0.132 (2) | 0.0645 (12) | 0.0408 (9) | −0.0039 (12) | −0.0375 (10) | 0.0062 (8) |
C1—C2 | 1.415 (2) | C4—N2 | 1.433 (2) |
C2—C3 | 1.381 (2) | N2—O1 | 1.233 (2) |
C3—C4 | 1.398 (2) | N2—O2 | 1.231 (2) |
C3—H3 | 0.9300 | C2—C7 | 1.505 (2) |
C4—C5 | 1.387 (3) | N1—H1A | 0.8600 |
C5—C6 | 1.377 (3) | N1—H1B | 0.8600 |
C5—H5 | 0.9300 | C7—H7A | 0.9600 |
C6—C1 | 1.405 (2) | C7—H7B | 0.9600 |
C6—H6 | 0.9300 | C7—H7C | 0.9600 |
C1—N1 | 1.358 (2) | ||
N1—C1—C6 | 119.51 (16) | C5—C6—C1 | 121.14 (17) |
N1—C1—C2 | 121.04 (15) | C5—C6—H6 | 119.4 |
C6—C1—C2 | 119.44 (15) | C1—C6—H6 | 119.4 |
C3—C2—C1 | 119.13 (14) | C1—N1—H1A | 120.0 |
C3—C2—C7 | 121.43 (15) | C1—N1—H1B | 120.0 |
C1—C2—C7 | 119.44 (14) | H1A—N1—H1B | 120.0 |
C2—C3—C4 | 120.16 (16) | C2—C7—H7A | 109.5 |
C2—C3—H3 | 119.9 | C2—C7—H7B | 109.5 |
C4—C3—H3 | 119.9 | H7A—C7—H7B | 109.5 |
C5—C4—C3 | 121.28 (15) | C2—C7—H7C | 109.5 |
C5—C4—N2 | 119.38 (16) | H7A—C7—H7C | 109.5 |
C3—C4—N2 | 119.34 (17) | H7B—C7—H7C | 109.5 |
C6—C5—C4 | 118.84 (16) | O2—N2—O1 | 121.80 (16) |
C6—C5—H5 | 120.6 | O2—N2—C4 | 118.53 (16) |
C4—C5—H5 | 120.6 | O1—N2—C4 | 119.67 (16) |
N1—C1—C2—C3 | 178.99 (18) | C2—C3—C4—C5 | −0.9 (3) |
N1—C1—C2—C7 | −1.2 (3) | C3—C4—N2—O1 | 0.7 (3) |
C6—C1—C2—C3 | 0.1 (2) | C3—C4—N2—O2 | −179.8 (2) |
C6—C1—C2—C7 | 179.93 (17) | C5—C4—N2—O1 | −178.79 (19) |
N1—C1—C6—C5 | −179.0 (2) | C5—C4—N2—O2 | 0.8 (3) |
C2—C1—C6—C5 | −0.1 (3) | N2—C4—C5—C6 | −179.66 (18) |
C1—C2—C3—C4 | 0.4 (3) | C3—C4—C5—C6 | 0.9 (3) |
C7—C2—C3—C4 | −179.40 (18) | C4—C5—C6—C1 | −0.4 (3) |
C2—C3—C4—N2 | 179.62 (16) |
D—H···A | D—H | H···A | D···A | D—H···A |
N1—H1A···O1i | 0.86 | 2.56 | 3.239 (3) | 136 |
N1—H1B···O2ii | 0.86 | 2.27 | 3.117 (3) | 169 |
Symmetry codes: (i) x+1/2, y+1/2, z+1/2; (ii) x+1/2, −y, z+1. |
Experimental details
Crystal data | |
Chemical formula | C7H8N2O2 |
Mr | 152.15 |
Crystal system, space group | Monoclinic, Ia |
Temperature (K) | 150 |
a, b, c (Å) | 7.6113 (5), 11.6304 (7), 8.2286 (5) |
β (°) | 94.050 (2) |
V (Å3) | 726.60 (8) |
Z | 4 |
Radiation type | Mo Kα |
µ (mm−1) | 0.10 |
Crystal size (mm) | 0.30 × 0.20 × 0.20 |
Data collection | |
Diffractometer | Bruker SMART 1000 CCD diffractometer |
Absorption correction | Multi-scan (SADABS; Bruker, 1997) |
Tmin, Tmax | 0.969, 0.979 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 4272, 1316, 1037 |
Rint | 0.032 |
(sin θ/λ)max (Å−1) | 0.757 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.043, 0.113, 1.00 |
No. of reflections | 1316 |
No. of parameters | 101 |
No. of restraints | 2 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 0.25, −0.26 |
Computer programs: XPREP (Bruker, 1997), XPREP, SHELXS97 (Sheldrick, 1997), SHELXL97 (Sheldrick, 1997), PLATON (Spek, 2000), SHELXL97 and WORDPERFECT macro PRPKAPPA (Ferguson, 1999).
C1—C2 | 1.415 (2) | C1—N1 | 1.358 (2) |
C2—C3 | 1.381 (2) | C4—N2 | 1.433 (2) |
C3—C4 | 1.398 (2) | N2—O1 | 1.233 (2) |
C4—C5 | 1.387 (3) | N2—O2 | 1.231 (2) |
C5—C6 | 1.377 (3) | C2—C7 | 1.505 (2) |
C6—C1 | 1.405 (2) |
D—H···A | D—H | H···A | D···A | D—H···A |
N1—H1A···O1i | 0.86 | 2.56 | 3.239 (3) | 136 |
N1—H1B···O2ii | 0.86 | 2.27 | 3.117 (3) | 169 |
Symmetry codes: (i) x+1/2, y+1/2, z+1/2; (ii) x+1/2, −y, z+1. |
The introduction of C-methyl groups into 2- or 3-nitroanilines gives rise to patterns of supramolecular aggregation very different from those observed in the unsubstituted analogues (Cannon et al., 2001). In this paper, we report the structure of 2-methyl-4-nitroaniline, (I), where again the supramolecular structure is markedly different from that found in 4-nitroaniline itself [Cambridge Structural Database (CSD) refcode (Allen & Kennard, 1993) NANILI02 (Tonogaki et al., 1993)]. Compound (I) is listed in the CSD (BAJCIY; Lipscomb et al., 1981), but there are no atomic coordinates recorded either in the CSD or in the original report, nor does this report discuss the supramolecular aggregation. It seems clear, however, from both the cell dimensions and the space group that the structure reported here is for the same polymorph of (I) as BAJCIY.
The molecules of (I) (Fig. 1) lie in general positions and each acts as double donor and as a double acceptor of N—H···O hydrogen bonds. The three-dimensional structure is readily analysed in terms of two independent C(8) chain motifs (Bernstein et al., 1995). The amino N1 atom at (x, y, z) acts as a hydrogen-bond donor, via H1B, to O2 in the molecule at (1/2 + x, -y, 1 + z), while N1 at (1/2 + x, -y, 1 + z) in turn acts as donor to O2 at (1 + x, y, 2 + z); this hydrogen bond thus produces a zigzag chain running parallel to the [102] direction and generated by the glide plane at y = 0. A t the same time, N1 at (x, y, z) also acts as donor, this time via H1A, to O1 in the molecule at (1/2 + x, 1/2 + y, 1/2 + z), so producing by translation a chain running parallel to the [111] direction; the glide plane at y = 0 generates an entirely similar chain parallel to [1\-11]. The combination of the [102] and [111] chains generates continuous sheets parallel to (\-211) and built from a single type of R88(54) ring (Fig. 2); similarly, the combination of the [102] and [1\-11] chains generates continuous sheets parallel to (21\-1). Every intersection between the stacked sheets generates a [102] chain, and the molecules are thus linked into a continuous three-dimensional framework.
The structure of (I) thus differs from that of 4-nitroaniline itself (Tonogaki et al., 1993) in two ways. In 4-nitroaniline, the molecules are linked by N—H···O hydrogen bonds into two-dimensional sheets, which are weakly linked by aromatic π–π stacking interactions; in compound (I), the hydrogen-bonded structure is three dimensional and there are no π–π-stacking interactions. The structure of (I) also differs from those of the isomeric compounds 4-methyl-2-nitroaniline, (II), and 4-methyl-3-nitroaniline, (III), in both of which the supramolecular structure is one-dimensional; the supramolecular structure of (II) consists of chains, while that of (III) contains both simple chains and molecular ladders (Cannon et al., 2001). Thus, very simple nitroanilines can have supramolecular structures in one, two or three dimensions.
The C—NH2 bond in (I (Table 1) is marginally longer than the analogous bonds in (II) and in 3,4-dimethyl-2-nitroaniline, (IV), in each of which Z' = 2 (Cannon et al., 2001) [range 1.341 (5)–1.347 (4) Å, mean 1.345 (5) Å], but significantly shorter than those in (III) where Z' = 4 [range 1.370 (2)–1.380 (2) Å, mean 1.376 (2) Å]. Likewise, the C—NO2 bond in (I) is slightly longer than those in (II) and (IV) [range 1.413 (4)–1.437 (5) Å, mean 1.426 (3) Å], but much shorter than those in (III) [range 1.465 (2)–1.469 (2) Å, mean 1.467 (2) Å]. Despite this, the C—C bond lengths in the aromatic ring of (I) indicate only a modest contribution from the quinonoid form (Ia).