Supporting information
Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270101012185/gg1075sup1.cif | |
Structure factor file (CIF format) https://doi.org/10.1107/S0108270101012185/gg1075Isup2.hkl |
CCDC reference: 174842
A sample of compound (I) was obtained from Aldrich. Crystals suitable for single-crystal X-ray diffraction were grown from a solution in ethanol. The same phase was obtained by recrystallization from CH2Cl2.
Compound (I) crystallized in the monoclinic system; space group P21/n was uniquely assigned from the systematic absences. H atoms were treated as riding atoms with C—H distances of 0.93 (aromatic) or 0.96 Å (methyl), and an N—H distance of 0.86 Å. The crystal quality was not high and, as expected, only ca 50% of the reflections were labelled `observed' at ambient temperature.
Data collection: KappaCCD Server Software (Nonius, 1997); cell refinement: DENZO-SMN (Otwinowski & Minor, 1997); data reduction: DENZO-SMN; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: PLATON (Spek, 2001); software used to prepare material for publication: SHELXL97 (Sheldrick, 1997) and PRPKAPPA (Ferguson, 1999).
C7H8N2O2 | F(000) = 640 |
Mr = 152.16 | Dx = 1.363 Mg m−3 |
Monoclinic, P21/n | Mo Kα radiation, λ = 0.71073 Å |
a = 8.2473 (7) Å | Cell parameters from 3128 reflections |
b = 7.5676 (7) Å | θ = 3.2–27.5° |
c = 23.7798 (16) Å | µ = 0.10 mm−1 |
β = 91.717 (5)° | T = 295 K |
V = 1483.5 (2) Å3 | Plate, orange |
Z = 8 | 0.36 × 0.18 × 0.08 mm |
Kappa-CCD diffractometer | 3128 independent reflections |
Radiation source: fine-focus sealed X-ray tube | 1517 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.105 |
ϕ scans, and ω scans with κ offsets | θmax = 27.5°, θmin = 3.2° |
Absorption correction: multi-scan (DENZO-SMN; Otwinowski & Minor, 1997) | h = −10→10 |
Tmin = 0.951, Tmax = 0.985 | k = −9→9 |
11137 measured reflections | l = −30→28 |
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)] = 0.061 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.204 | H-atom parameters constrained |
S = 1.01 | w = 1/[σ2(Fo2) + (0.1003P)2] where P = (Fo2 + 2Fc2)/3 |
3128 reflections | (Δ/σ)max = 0.002 |
201 parameters | Δρmax = 0.15 e Å−3 |
0 restraints | Δρmin = −0.13 e Å−3 |
C7H8N2O2 | V = 1483.5 (2) Å3 |
Mr = 152.16 | Z = 8 |
Monoclinic, P21/n | Mo Kα radiation |
a = 8.2473 (7) Å | µ = 0.10 mm−1 |
b = 7.5676 (7) Å | T = 295 K |
c = 23.7798 (16) Å | 0.36 × 0.18 × 0.08 mm |
β = 91.717 (5)° |
Kappa-CCD diffractometer | 3128 independent reflections |
Absorption correction: multi-scan (DENZO-SMN; Otwinowski & Minor, 1997) | 1517 reflections with I > 2σ(I) |
Tmin = 0.951, Tmax = 0.985 | Rint = 0.105 |
11137 measured reflections |
R[F2 > 2σ(F2)] = 0.061 | 0 restraints |
wR(F2) = 0.204 | H-atom parameters constrained |
S = 1.01 | Δρmax = 0.15 e Å−3 |
3128 reflections | Δρmin = −0.13 e Å−3 |
201 parameters |
Experimental. The program DENZO-SMN (Otwinowski & Minor, 1997) uses a scaling algorithm [Fox, G·C. & Holmes, K·C. (1966). Acta Cryst. 20, 886–891] which effectively corrects for absorption effects. High redundancy data were used in the scaling program hence the 'multi-scan' code word was used. No transmission coefficients are available from the program (only scale factors for each frame). The scale factors in the experimental table are calculated from the 'size' command in the SHELXL97 input file. |
x | y | z | Uiso*/Ueq | ||
C11 | 0.7363 (3) | 0.1807 (4) | 0.02890 (10) | 0.0718 (7) | |
N11 | 0.8565 (4) | 0.2392 (5) | −0.00532 (13) | 0.1207 (12) | |
C12 | 0.5764 (3) | 0.2283 (4) | 0.01893 (9) | 0.0683 (7) | |
C13 | 0.4595 (3) | 0.1742 (3) | 0.05494 (10) | 0.0663 (6) | |
N13 | 0.2933 (3) | 0.2317 (4) | 0.04011 (11) | 0.0855 (7) | |
O11 | 0.1829 (4) | 0.1746 (7) | 0.06640 (19) | 0.1696 (16) | |
O12 | 0.2714 (3) | 0.3355 (4) | 0.00279 (10) | 0.1187 (9) | |
C14 | 0.4913 (3) | 0.0696 (3) | 0.10266 (10) | 0.0695 (7) | |
C17 | 0.3714 (5) | 0.0100 (5) | 0.14474 (14) | 0.0988 (10) | |
C15 | 0.6533 (4) | 0.0225 (4) | 0.11058 (10) | 0.0717 (7) | |
C16 | 0.7720 (3) | 0.0732 (4) | 0.07528 (10) | 0.0713 (7) | |
C21 | 0.6440 (3) | 0.0732 (3) | 0.35279 (9) | 0.0629 (6) | |
N21 | 0.5306 (3) | 0.0434 (4) | 0.39292 (9) | 0.0874 (7) | |
C22 | 0.8069 (3) | 0.0431 (3) | 0.36392 (9) | 0.0601 (6) | |
C23 | 0.9181 (3) | 0.0699 (3) | 0.32240 (9) | 0.0586 (6) | |
N23 | 1.0872 (3) | 0.0316 (3) | 0.33856 (10) | 0.0749 (6) | |
O21 | 1.1323 (3) | 0.0552 (3) | 0.38727 (9) | 0.0985 (8) | |
O22 | 1.1771 (3) | −0.0229 (5) | 0.30290 (11) | 0.1264 (10) | |
C24 | 0.8766 (3) | 0.1309 (3) | 0.26819 (9) | 0.0618 (6) | |
C27 | 0.9930 (4) | 0.1617 (4) | 0.22176 (11) | 0.0860 (8) | |
C25 | 0.7130 (3) | 0.1659 (4) | 0.25962 (9) | 0.0695 (7) | |
C26 | 0.5993 (3) | 0.1387 (4) | 0.29952 (10) | 0.0712 (7) | |
H11A | 0.8327 | 0.3066 | −0.0335 | 0.145* | |
H11B | 0.9556 | 0.2084 | 0.0014 | 0.145* | |
H12 | 0.5480 | 0.2972 | −0.0122 | 0.082* | |
H17A | 0.4275 | −0.0486 | 0.1754 | 0.148* | |
H17B | 0.2955 | −0.0703 | 0.1271 | 0.148* | |
H17C | 0.3143 | 0.1106 | 0.1587 | 0.148* | |
H15 | 0.6822 | −0.0471 | 0.1415 | 0.086* | |
H16 | 0.8781 | 0.0357 | 0.0822 | 0.086* | |
H21A | 0.5607 | 0.0053 | 0.4257 | 0.105* | |
H21B | 0.4296 | 0.0628 | 0.3853 | 0.105* | |
H22 | 0.8419 | 0.0048 | 0.3994 | 0.072* | |
H27A | 1.0824 | 0.2320 | 0.2357 | 0.129* | |
H27B | 0.9384 | 0.2226 | 0.1913 | 0.129* | |
H27C | 1.0327 | 0.0503 | 0.2087 | 0.129* | |
H25 | 0.6784 | 0.2104 | 0.2248 | 0.083* | |
H26 | 0.4909 | 0.1640 | 0.2911 | 0.085* |
U11 | U22 | U33 | U12 | U13 | U23 | |
C11 | 0.0582 (16) | 0.0864 (18) | 0.0708 (14) | −0.0048 (13) | 0.0011 (10) | −0.0005 (11) |
N11 | 0.0735 (19) | 0.176 (3) | 0.1136 (19) | −0.0034 (19) | 0.0154 (14) | 0.0478 (19) |
C12 | 0.0623 (16) | 0.0749 (16) | 0.0671 (13) | −0.0019 (12) | −0.0089 (10) | 0.0024 (10) |
C13 | 0.0550 (14) | 0.0624 (14) | 0.0810 (14) | 0.0011 (11) | −0.0075 (10) | −0.0090 (10) |
N13 | 0.0580 (15) | 0.0864 (17) | 0.1112 (17) | 0.0025 (12) | −0.0121 (12) | −0.0093 (13) |
O11 | 0.0513 (16) | 0.192 (4) | 0.266 (4) | 0.0012 (18) | 0.0152 (19) | 0.091 (3) |
O12 | 0.0852 (17) | 0.153 (2) | 0.1165 (17) | 0.0308 (16) | −0.0253 (12) | 0.0201 (15) |
C14 | 0.0701 (17) | 0.0589 (14) | 0.0796 (15) | −0.0008 (12) | 0.0062 (11) | −0.0056 (10) |
C17 | 0.098 (3) | 0.092 (2) | 0.109 (2) | −0.0017 (19) | 0.0340 (17) | 0.0098 (16) |
C15 | 0.0768 (19) | 0.0673 (15) | 0.0708 (14) | 0.0067 (12) | −0.0015 (11) | 0.0048 (10) |
C16 | 0.0565 (15) | 0.0779 (16) | 0.0792 (15) | 0.0090 (12) | −0.0045 (11) | −0.0002 (11) |
C21 | 0.0527 (14) | 0.0694 (15) | 0.0666 (13) | −0.0009 (11) | 0.0012 (9) | −0.0056 (10) |
N21 | 0.0549 (14) | 0.126 (2) | 0.0811 (14) | −0.0001 (13) | 0.0065 (10) | −0.0016 (11) |
C22 | 0.0506 (13) | 0.0678 (14) | 0.0617 (12) | −0.0002 (10) | −0.0033 (9) | 0.0028 (9) |
C23 | 0.0471 (12) | 0.0585 (12) | 0.0701 (13) | 0.0000 (10) | −0.0013 (9) | 0.0010 (9) |
N23 | 0.0513 (13) | 0.0806 (15) | 0.0929 (15) | 0.0007 (10) | 0.0032 (11) | 0.0125 (10) |
O21 | 0.0611 (13) | 0.132 (2) | 0.1012 (14) | −0.0076 (12) | −0.0230 (10) | 0.0174 (11) |
O22 | 0.0718 (17) | 0.182 (3) | 0.1263 (18) | 0.0433 (17) | 0.0202 (13) | 0.0067 (16) |
C24 | 0.0659 (16) | 0.0559 (13) | 0.0636 (12) | −0.0003 (11) | 0.0038 (9) | 0.0010 (9) |
C27 | 0.093 (2) | 0.0890 (19) | 0.0770 (16) | −0.0054 (16) | 0.0202 (13) | 0.0101 (12) |
C25 | 0.0707 (17) | 0.0734 (15) | 0.0637 (13) | 0.0039 (12) | −0.0100 (11) | 0.0060 (10) |
C26 | 0.0545 (15) | 0.0789 (17) | 0.0793 (15) | 0.0086 (12) | −0.0123 (11) | −0.0037 (11) |
C11—C12 | 1.381 (4) | C21—C22 | 1.380 (4) |
C12—C13 | 1.371 (4) | C22—C23 | 1.383 (4) |
C13—C14 | 1.402 (4) | C23—C24 | 1.402 (3) |
C14—C15 | 1.390 (4) | C24—C25 | 1.384 (4) |
C15—C16 | 1.364 (4) | C25—C26 | 1.370 (4) |
C16—C11 | 1.395 (4) | C26—C21 | 1.399 (3) |
C11—N11 | 1.374 (4) | C21—N21 | 1.374 (4) |
C13—N13 | 1.471 (4) | C23—N23 | 1.465 (3) |
N13—O11 | 1.201 (4) | N23—O21 | 1.219 (3) |
N13—O12 | 1.195 (4) | N23—O22 | 1.215 (3) |
C14—C17 | 1.497 (4) | C24—C27 | 1.503 (4) |
N11—H11A | 0.8600 | N21—H21A | 0.8600 |
N11—H11B | 0.8600 | N21—H21B | 0.8600 |
C12—H12 | 0.9300 | C22—H22 | 0.9300 |
C15—H15 | 0.9300 | C25—H25 | 0.9300 |
C16—H16 | 0.9300 | C26—H26 | 0.9300 |
C17—H17A | 0.9600 | C27—H27A | 0.9600 |
C17—H17B | 0.9600 | C27—H27B | 0.9600 |
C17—H17C | 0.9600 | C27—H27C | 0.9600 |
N11—C11—C12 | 121.1 (3) | N21—C21—C22 | 121.2 (2) |
N11—C11—C16 | 121.1 (3) | N21—C21—C26 | 121.4 (2) |
C12—C11—C16 | 117.8 (2) | C22—C21—C26 | 117.4 (2) |
C11—N11—H11A | 120.0 | C21—N21—H21A | 120.0 |
C11—N11—H11B | 120.0 | C21—N21—H21B | 120.0 |
H11A—N11—H11B | 120.0 | H21A—N21—H21B | 120.0 |
C13—C12—C11 | 120.0 (2) | C21—C22—C23 | 120.1 (2) |
C13—C12—H12 | 120.0 | C21—C22—H22 | 119.9 |
C11—C12—H12 | 120.0 | C23—C22—H22 | 119.9 |
C12—C13—C14 | 123.8 (2) | C22—C23—C24 | 123.8 (2) |
C12—C13—N13 | 115.4 (2) | C22—C23—N23 | 115.50 (19) |
C14—C13—N13 | 120.8 (2) | C24—C23—N23 | 120.7 (2) |
O12—N13—O11 | 121.6 (3) | O21—N23—O22 | 122.5 (3) |
O12—N13—C13 | 119.5 (3) | O22—N23—C23 | 118.7 (2) |
O11—N13—C13 | 119.0 (3) | O21—N23—C23 | 118.8 (2) |
C15—C14—C13 | 114.2 (2) | C25—C24—C23 | 114.1 (2) |
C15—C14—C17 | 118.9 (2) | C25—C24—C27 | 120.2 (2) |
C13—C14—C17 | 126.8 (3) | C23—C24—C27 | 125.6 (2) |
C14—C17—H17A | 109.5 | C24—C27—H27A | 109.5 |
C14—C17—H17B | 109.5 | C24—C27—H27B | 109.5 |
H17A—C17—H17B | 109.5 | H27A—C27—H27B | 109.5 |
C14—C17—H17C | 109.5 | C24—C27—H27C | 109.5 |
H17A—C17—H17C | 109.5 | H27A—C27—H27C | 109.5 |
H17B—C17—H17C | 109.5 | H27B—C27—H27C | 109.5 |
C16—C15—C14 | 123.3 (2) | C26—C25—C24 | 123.6 (2) |
C16—C15—H15 | 118.3 | C26—C25—H25 | 118.2 |
C14—C15—H15 | 118.3 | C24—C25—H25 | 118.2 |
C15—C16—C11 | 120.8 (3) | C25—C26—C21 | 120.9 (2) |
C15—C16—H16 | 119.6 | C25—C26—H26 | 119.6 |
C11—C16—H16 | 119.6 | C21—C26—H26 | 119.6 |
C12—C13—N13—O11 | 172.5 (4) | C22—C23—N23—O21 | −31.5 (3) |
C12—C13—N13—O12 | −8.4 (4) | C22—C23—N23—O22 | 148.3 (3) |
D—H···A | D—H | H···A | D···A | D—H···A |
N11—H11B···O11i | 0.86 | 2.41 | 3.181 (5) | 150 |
N21—H21B···O21ii | 0.86 | 2.45 | 3.285 (4) | 163 |
Symmetry codes: (i) x+1, y, z; (ii) x−1, y, z. |
Experimental details
Crystal data | |
Chemical formula | C7H8N2O2 |
Mr | 152.16 |
Crystal system, space group | Monoclinic, P21/n |
Temperature (K) | 295 |
a, b, c (Å) | 8.2473 (7), 7.5676 (7), 23.7798 (16) |
β (°) | 91.717 (5) |
V (Å3) | 1483.5 (2) |
Z | 8 |
Radiation type | Mo Kα |
µ (mm−1) | 0.10 |
Crystal size (mm) | 0.36 × 0.18 × 0.08 |
Data collection | |
Diffractometer | Kappa-CCD diffractometer |
Absorption correction | Multi-scan (DENZO-SMN; Otwinowski & Minor, 1997) |
Tmin, Tmax | 0.951, 0.985 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 11137, 3128, 1517 |
Rint | 0.105 |
(sin θ/λ)max (Å−1) | 0.650 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.061, 0.204, 1.01 |
No. of reflections | 3128 |
No. of parameters | 201 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 0.15, −0.13 |
Computer programs: KappaCCD Server Software (Nonius, 1997), DENZO-SMN (Otwinowski & Minor, 1997), DENZO-SMN, SHELXS97 (Sheldrick, 1997), PLATON (Spek, 2001), SHELXL97 (Sheldrick, 1997) and PRPKAPPA (Ferguson, 1999).
C11—C12 | 1.381 (4) | C21—C22 | 1.380 (4) |
C12—C13 | 1.371 (4) | C22—C23 | 1.383 (4) |
C13—C14 | 1.402 (4) | C23—C24 | 1.402 (3) |
C14—C15 | 1.390 (4) | C24—C25 | 1.384 (4) |
C15—C16 | 1.364 (4) | C25—C26 | 1.370 (4) |
C16—C11 | 1.395 (4) | C26—C21 | 1.399 (3) |
C11—N11 | 1.374 (4) | C21—N21 | 1.374 (4) |
C13—N13 | 1.471 (4) | C23—N23 | 1.465 (3) |
N13—O11 | 1.201 (4) | N23—O21 | 1.219 (3) |
N13—O12 | 1.195 (4) | N23—O22 | 1.215 (3) |
C14—C17 | 1.497 (4) | C24—C27 | 1.503 (4) |
C12—C13—N13—O11 | 172.5 (4) | C22—C23—N23—O21 | −31.5 (3) |
C12—C13—N13—O12 | −8.4 (4) | C22—C23—N23—O22 | 148.3 (3) |
D—H···A | D—H | H···A | D···A | D—H···A |
N11—H11B···O11i | 0.86 | 2.41 | 3.181 (5) | 150 |
N21—H21B···O21ii | 0.86 | 2.45 | 3.285 (4) | 163 |
Symmetry codes: (i) x+1, y, z; (ii) x−1, y, z. |
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When crystallized from ethanol, 4-methyl-3-nitro-aniline, (I), is triclinic P1 at 150 (2) K with Z' = 4 (Cannon et al., 2001). Of the four independent molecules, two form individual chains built from N—H···O hydrogen bonds, while the other two types combine to form molecular ladders. At ambient temperatures, however, this material is monoclinic P21/n with Z' = 2. The unit-cell dimensions and the atomic coordinates indicate that the low-temperature triclinic and the ambient-temperature monoclinic polymorphs are related by a simple displacive phase-transformation.
The molecular dimensions of the two independent molecules in the monoclinic polymorph (Fig. 1) are very similar (Table 1) and the C—C bond lengths show a significant deviation of the aryl rings from regular hexagons; this feature was observed also in the triclinic polymorph. The two molecules do, however, differ markedly in the twist of the nitro groups out of the plane of the adjacent rings (Table 1); this difference alone precludes the possibility of any further symmetry.
Each molecule acts as a single donor and as a single acceptor in N—H···O hydrogen bonds (Table 2); thus, half of the N—H bonds and half of the O atoms do not participate in the hydrogen bonding, so that the sole motif of supramolecular aggregation is the formation of C(7) chains (Bernstein et al., 1995). Molecules of type 1 and 2, containing atoms N11 and N21, respectively, each act as hydrogen-bond donors to another molecule of the same type, so generating by translation two distinct chains, both running parallel to the [100] direction and each containing just one type of molecule (Fig. 2). Four chains of each type run through each unit cell, but there are no hydrogen bonds of either N—H···O type or C—H···O type between adjacent chains, nor are there any aromatic π–π-stacking interactions.
The unit-cell dimensions of the triclinic and monoclinic polymorphs of (I) are very similar and the triclinic unit cell can be derived from the present monoclinic cell by means of the transformation (010, 100, 001). Subject to this transformation and an origin shift, the atomic coordinates of the two forms indicate that triclinic molecules of types 1 and 2 (Cannon et al., 2001) map into the monoclinic type 2 molecules at (x, y, z) and (1/2 - x, 1/2 + y, 1/2 - z), respectively, while triclinic molecules 3 and 4 map into the monoclinic type 1 molecules at (-x, -y, -z) and (-1/2 + x, 1/2 - y, 1/2 + z), respectively. It is noteworthy that the conformations of the various molecules, as judged by the C—C—N—O torsion angles (Table 1) and particularly by the dihedral angles between the aryl rings and the C—NO2 groups, faithfully follow this mapping. Thus, in the triclinic polymorph, molecules 1 and 2 have nitro-group twists of 31.91 (8) and 28.99 (8)°, respectively, comparable with the 32.5 (2)° twist in monoclinic type 2 molecules, while triclinic type 3 and 4 molecules have nitro-group twists of 7.91 (8) and 3.92 (8)°, respectively, compared with a twist of 7.5 (2)° in monoclinic type 1 molecules. These observations all point to a simple displacive phase transformation between the triclinic and monoclinic polymorphs.