Supporting information
Crystallographic Information File (CIF) https://doi.org/10.1107/S010827011000884X/gg3231sup1.cif | |
Structure factor file (CIF format) https://doi.org/10.1107/S010827011000884X/gg3231Isup2.hkl |
CCDC reference: 774909
To a stirred solution of N-cinnamyl-2-allyl-4-fluoroaniline (0.10 mol) in methanol (40 ml) was added sodium tungstate dihydrate, Na2WO4.2H2O (5 mol%), followed by 30% aqueous hydrogen peroxide solution (0.30 mol). The resulting mixture was then stirred at ambient temperature for 8 h, filtered and the solvent removed under reduced pressure. Toluene (50 ml) was added to the solid residue and the resulting solution was heated under reflux for 6 h. After cooling the solution to ambient temperature, the solvent was removed under reduced pressure and the crude product was purified by chromatography on silica using heptane–ethyl acetate as eluant (composition gradient 90:1 to 10:1 v/v). Crystallization from heptane gave colourless crystals of the title compound, (I), suitable for single-crystal X-ray diffraction (yield 52%, m.p. 423–424 K). MS (70 eV) m/z (%) 281 (M+, 67), 264 (33), 251 (21), 148 (41), 122 (100), 96 (33).
All H atoms were located in difference maps and then treated as riding atoms in geometrically idealized positions, with C—H = 0.95 (aromatic), 0.99 (CH2) or 1.00 Å (aliphatic CH) and with Uiso(H) = 1.2Ueq(C). The y coordinate for atom N1 was set to have precisely the same value as for the corresponding atom in compound (III), in order to ease comparison of the two sets of atomic coordinates. In the absence of significant resonant scattering, the Flack x parameter (Flack, 1983) was indeterminate (Flack & Bernardinelli, 2000), likewise the Hooft y parameter (Hooft et al., 2008). Accordingly, the Friedel-equivalent reflections were merged prior to the final refinement. The configuration at atom C4 in the reference molecule of (I) was set to be R, for consistency both with compounds (II) - (IV) (Acosta et al., 2008), and with several related compounds (Blanco et al., 2008; Gómez et al., 2008, 2009) crystallising as single enantiomorphs, where the configurations at C4 were deduced on the basis of the Flack x and the Hooft y parameters (Flack, 1983; Hooft et al., 2008) to be R in every case; on this basis the configuration for atom C2 in the reference molecule of (I) is S.
Data collection: COLLECT (Nonius, 1999); cell refinement: DIRAX/LSQ (Duisenberg et al., 2000); data reduction: EVALCCD (Duisenberg et al., 2003); program(s) used to solve structure: SIR2004 (Burla et al., 2005); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: PLATON (Spek, 2009); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008) and PLATON (Spek, 2009).
C18H16FNO | F(000) = 296 |
Mr = 281.32 | Dx = 1.352 Mg m−3 |
Monoclinic, P21 | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: P2yb | Cell parameters from 1432 reflections |
a = 10.052 (4) Å | θ = 3.7–25.5° |
b = 5.299 (4) Å | µ = 0.09 mm−1 |
c = 12.976 (8) Å | T = 120 K |
β = 91.10 (4)° | Needle, colourless |
V = 691.1 (7) Å3 | 0.36 × 0.08 × 0.06 mm |
Z = 2 |
Bruker Nonius KappaCCD area-detector diffractometer | 1432 independent reflections |
Radiation source: Bruker Nonius FR591 rotating anode | 1112 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.081 |
Detector resolution: 9.091 pixels mm-1 | θmax = 25.5°, θmin = 3.7° |
ϕ and ω scans | h = −12→12 |
Absorption correction: multi-scan (SADABS; Sheldrick, 2003) | k = −6→6 |
Tmin = 0.956, Tmax = 0.995 | l = −15→15 |
9381 measured reflections |
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)] = 0.049 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.107 | H-atom parameters constrained |
S = 1.12 | w = 1/[σ2(Fo2) + (0.0469P)2 + 0.2187P] where P = (Fo2 + 2Fc2)/3 |
1432 reflections | (Δ/σ)max = 0.001 |
190 parameters | Δρmax = 0.23 e Å−3 |
1 restraint | Δρmin = −0.24 e Å−3 |
C18H16FNO | V = 691.1 (7) Å3 |
Mr = 281.32 | Z = 2 |
Monoclinic, P21 | Mo Kα radiation |
a = 10.052 (4) Å | µ = 0.09 mm−1 |
b = 5.299 (4) Å | T = 120 K |
c = 12.976 (8) Å | 0.36 × 0.08 × 0.06 mm |
β = 91.10 (4)° |
Bruker Nonius KappaCCD area-detector diffractometer | 1432 independent reflections |
Absorption correction: multi-scan (SADABS; Sheldrick, 2003) | 1112 reflections with I > 2σ(I) |
Tmin = 0.956, Tmax = 0.995 | Rint = 0.081 |
9381 measured reflections |
R[F2 > 2σ(F2)] = 0.049 | 1 restraint |
wR(F2) = 0.107 | H-atom parameters constrained |
S = 1.12 | Δρmax = 0.23 e Å−3 |
1432 reflections | Δρmin = −0.24 e Å−3 |
190 parameters |
x | y | z | Uiso*/Ueq | ||
F7 | 1.2068 (2) | 0.7113 (6) | 0.66422 (18) | 0.0375 (7) | |
O14 | 0.6429 (2) | 0.3291 (5) | 0.5663 (2) | 0.0237 (6) | |
N1 | 0.7007 (3) | 0.3167 (6) | 0.6689 (2) | 0.0211 (7) | |
C2 | 0.6123 (4) | 0.4842 (8) | 0.7281 (3) | 0.0222 (9) | |
H2 | 0.6646 | 0.5663 | 0.7853 | 0.027* | |
C3 | 0.5668 (4) | 0.6859 (8) | 0.6496 (3) | 0.0268 (10) | |
H3A | 0.4685 | 0.6951 | 0.6452 | 0.032* | |
H3B | 0.6023 | 0.8540 | 0.6689 | 0.032* | |
C4 | 0.6231 (4) | 0.5981 (8) | 0.5494 (3) | 0.0253 (10) | |
H4 | 0.5572 | 0.6263 | 0.4918 | 0.030* | |
C5 | 0.7551 (3) | 0.7126 (9) | 0.5234 (3) | 0.0231 (9) | |
H5A | 0.7789 | 0.6657 | 0.4522 | 0.028* | |
H5B | 0.7494 | 0.8988 | 0.5273 | 0.028* | |
C5A | 0.8606 (3) | 0.6182 (8) | 0.5982 (3) | 0.0193 (8) | |
C6 | 0.9886 (3) | 0.7139 (8) | 0.5984 (3) | 0.0232 (9) | |
H6 | 1.0114 | 0.8480 | 0.5535 | 0.028* | |
C7 | 1.0816 (4) | 0.6123 (9) | 0.6644 (3) | 0.0260 (10) | |
C8 | 1.0558 (4) | 0.4192 (8) | 0.7296 (3) | 0.0270 (10) | |
H8 | 1.1233 | 0.3537 | 0.7743 | 0.032* | |
C9 | 0.9288 (3) | 0.3207 (8) | 0.7292 (3) | 0.0216 (8) | |
H9 | 0.9079 | 0.1836 | 0.7732 | 0.026* | |
C9A | 0.8323 (3) | 0.4219 (7) | 0.6646 (3) | 0.0181 (8) | |
C21 | 0.4991 (3) | 0.3389 (9) | 0.7722 (3) | 0.0227 (9) | |
H21 | 0.4501 | 0.2273 | 0.7285 | 0.027* | |
C22 | 0.4647 (3) | 0.3599 (8) | 0.8694 (3) | 0.0240 (9) | |
H22 | 0.5189 | 0.4650 | 0.9121 | 0.029* | |
C221 | 0.3520 (3) | 0.2382 (8) | 0.9179 (3) | 0.0216 (9) | |
C222 | 0.2934 (4) | 0.0213 (8) | 0.8775 (3) | 0.0238 (9) | |
H222 | 0.3295 | −0.0563 | 0.8183 | 0.029* | |
C223 | 0.1830 (4) | −0.0822 (8) | 0.9229 (3) | 0.0276 (10) | |
H223 | 0.1426 | −0.2283 | 0.8936 | 0.033* | |
C224 | 0.1309 (4) | 0.0237 (8) | 1.0098 (3) | 0.0267 (10) | |
H224 | 0.0550 | −0.0488 | 1.0406 | 0.032* | |
C225 | 0.1897 (4) | 0.2361 (9) | 1.0521 (3) | 0.0286 (10) | |
H225 | 0.1547 | 0.3099 | 1.1126 | 0.034* | |
C226 | 0.2990 (4) | 0.3403 (9) | 1.0064 (3) | 0.0249 (9) | |
H226 | 0.3393 | 0.4858 | 1.0363 | 0.030* |
U11 | U22 | U33 | U12 | U13 | U23 | |
F7 | 0.0189 (11) | 0.0520 (17) | 0.0416 (15) | −0.0089 (12) | 0.0004 (10) | −0.0065 (14) |
O14 | 0.0240 (13) | 0.0202 (14) | 0.0266 (14) | −0.0003 (13) | −0.0050 (11) | −0.0033 (14) |
N1 | 0.0198 (15) | 0.0204 (17) | 0.0229 (16) | −0.0008 (16) | −0.0036 (12) | 0.0002 (16) |
C2 | 0.0201 (19) | 0.019 (2) | 0.027 (2) | 0.0005 (18) | 0.0007 (15) | −0.0031 (18) |
C3 | 0.0209 (19) | 0.020 (2) | 0.039 (3) | 0.0024 (19) | 0.0045 (16) | 0.002 (2) |
C4 | 0.022 (2) | 0.022 (2) | 0.031 (2) | 0.0016 (18) | −0.0059 (17) | 0.003 (2) |
C5 | 0.0249 (19) | 0.023 (2) | 0.021 (2) | 0.0027 (19) | −0.0016 (15) | 0.006 (2) |
C5A | 0.0200 (19) | 0.0184 (19) | 0.020 (2) | 0.0035 (16) | 0.0020 (14) | −0.0056 (17) |
C6 | 0.025 (2) | 0.022 (2) | 0.023 (2) | −0.0028 (19) | 0.0057 (15) | −0.0024 (19) |
C7 | 0.0155 (19) | 0.037 (2) | 0.026 (2) | −0.0017 (19) | 0.0031 (16) | −0.010 (2) |
C8 | 0.024 (2) | 0.034 (3) | 0.023 (2) | 0.0089 (19) | −0.0042 (16) | −0.005 (2) |
C9 | 0.0225 (19) | 0.0200 (19) | 0.022 (2) | 0.0038 (19) | 0.0004 (15) | 0.001 (2) |
C9A | 0.0199 (18) | 0.018 (2) | 0.0167 (19) | −0.0035 (16) | 0.0026 (14) | −0.0036 (17) |
C21 | 0.0167 (17) | 0.025 (2) | 0.027 (2) | −0.0023 (19) | −0.0001 (14) | −0.001 (2) |
C22 | 0.0201 (18) | 0.025 (2) | 0.027 (2) | −0.0004 (19) | −0.0028 (15) | 0.000 (2) |
C221 | 0.0223 (19) | 0.023 (2) | 0.019 (2) | 0.0012 (18) | −0.0041 (15) | 0.0016 (18) |
C222 | 0.022 (2) | 0.025 (2) | 0.024 (2) | −0.0013 (19) | 0.0004 (16) | −0.0035 (19) |
C223 | 0.028 (2) | 0.025 (2) | 0.029 (2) | −0.0042 (19) | −0.0020 (17) | 0.0013 (19) |
C224 | 0.025 (2) | 0.029 (2) | 0.026 (2) | 0.0010 (19) | 0.0017 (16) | 0.0054 (19) |
C225 | 0.027 (2) | 0.030 (2) | 0.029 (2) | 0.008 (2) | 0.0042 (16) | −0.002 (2) |
C226 | 0.025 (2) | 0.022 (2) | 0.028 (2) | 0.003 (2) | −0.0054 (15) | 0.002 (2) |
F7—C7 | 1.363 (4) | C7—C8 | 1.356 (6) |
O14—N1 | 1.443 (4) | C8—C9 | 1.379 (5) |
O14—C4 | 1.455 (5) | C8—H8 | 0.9500 |
N1—C9A | 1.437 (4) | C9—C9A | 1.379 (5) |
N1—C2 | 1.481 (5) | C9—H9 | 0.9500 |
C2—C21 | 1.497 (5) | C21—C22 | 1.319 (5) |
C2—C3 | 1.540 (6) | C21—H21 | 0.9500 |
C2—H2 | 1.0000 | C22—C221 | 1.457 (5) |
C3—C4 | 1.502 (6) | C22—H22 | 0.9500 |
C3—H3A | 0.9900 | C221—C226 | 1.386 (5) |
C3—H3B | 0.9900 | C221—C222 | 1.390 (6) |
C4—C5 | 1.504 (5) | C222—C223 | 1.379 (5) |
C4—H4 | 1.0000 | C222—H222 | 0.9500 |
C5—C5A | 1.509 (5) | C223—C224 | 1.373 (6) |
C5—H5A | 0.9900 | C223—H223 | 0.9500 |
C5—H5B | 0.9900 | C224—C225 | 1.380 (6) |
C5A—C9A | 1.383 (5) | C224—H224 | 0.9500 |
C5A—C6 | 1.383 (5) | C225—C226 | 1.374 (6) |
C6—C7 | 1.366 (5) | C225—H225 | 0.9500 |
C6—H6 | 0.9500 | C226—H226 | 0.9500 |
N1—O14—C4 | 103.6 (3) | C8—C7—C6 | 123.5 (4) |
C9A—N1—O14 | 107.5 (3) | F7—C7—C6 | 117.9 (4) |
C9A—N1—C2 | 110.5 (3) | C7—C8—C9 | 118.1 (4) |
O14—N1—C2 | 102.5 (3) | C7—C8—H8 | 121.0 |
N1—C2—C21 | 111.0 (3) | C9—C8—H8 | 121.0 |
N1—C2—C3 | 104.2 (3) | C9A—C9—C8 | 119.7 (4) |
C21—C2—C3 | 113.0 (3) | C9A—C9—H9 | 120.1 |
N1—C2—H2 | 109.5 | C8—C9—H9 | 120.1 |
C21—C2—H2 | 109.5 | C9—C9A—C5A | 121.4 (3) |
C3—C2—H2 | 109.5 | C9—C9A—N1 | 117.6 (3) |
C4—C3—C2 | 104.2 (3) | C5A—C9A—N1 | 121.1 (3) |
C4—C3—H3A | 110.9 | C22—C21—C2 | 122.5 (4) |
C2—C3—H3A | 110.9 | C22—C21—H21 | 118.8 |
C4—C3—H3B | 110.9 | C2—C21—H21 | 118.8 |
C2—C3—H3B | 110.9 | C21—C22—C221 | 126.5 (4) |
H3A—C3—H3B | 108.9 | C21—C22—H22 | 116.7 |
O14—C4—C3 | 103.0 (3) | C221—C22—H22 | 116.7 |
O14—C4—C5 | 108.1 (3) | C226—C221—C222 | 117.9 (4) |
C3—C4—C5 | 114.7 (4) | C226—C221—C22 | 120.0 (4) |
O14—C4—H4 | 110.2 | C222—C221—C22 | 122.1 (4) |
C3—C4—H4 | 110.2 | C223—C222—C221 | 120.4 (4) |
C5—C4—H4 | 110.2 | C223—C222—H222 | 119.8 |
C4—C5—C5A | 109.5 (3) | C221—C222—H222 | 119.8 |
C4—C5—H5B | 109.8 | C224—C223—C222 | 120.7 (4) |
C5A—C5—H5B | 109.8 | C224—C223—H223 | 119.6 |
C4—C5—H5A | 109.8 | C222—C223—H223 | 119.6 |
C5A—C5—H5A | 109.8 | C223—C224—C225 | 119.6 (4) |
H5A—C5—H5B | 108.2 | C223—C224—H224 | 120.2 |
C9A—C5A—C6 | 118.5 (3) | C225—C224—H224 | 120.2 |
C9A—C5A—C5 | 120.0 (3) | C226—C225—C224 | 119.7 (4) |
C6—C5A—C5 | 121.5 (4) | C226—C225—H225 | 120.1 |
C7—C6—C5A | 118.8 (4) | C224—C225—H225 | 120.1 |
C7—C6—H6 | 120.6 | C225—C226—C221 | 121.6 (4) |
C5A—C6—H6 | 120.6 | C225—C226—H226 | 119.2 |
C8—C7—F7 | 118.6 (4) | C221—C226—H226 | 119.2 |
C4—O14—N1—C9A | −68.9 (3) | C8—C9—C9A—C5A | 1.3 (6) |
C4—O14—N1—C2 | 47.5 (3) | C8—C9—C9A—N1 | −178.5 (4) |
C9A—N1—C2—C21 | −155.6 (3) | C6—C5A—C9A—C9 | −0.6 (5) |
O14—N1—C2—C21 | 90.1 (3) | C5—C5A—C9A—C9 | 175.8 (4) |
C9A—N1—C2—C3 | 82.5 (3) | C6—C5A—C9A—N1 | 179.1 (4) |
O14—N1—C2—C3 | −31.8 (3) | C5—C5A—C9A—N1 | −4.5 (5) |
N1—C2—C3—C4 | 5.6 (4) | O14—N1—C9A—C9 | −146.5 (3) |
C21—C2—C3—C4 | −115.0 (4) | C2—N1—C9A—C9 | 102.4 (4) |
N1—O14—C4—C3 | −43.6 (3) | O14—N1—C9A—C5A | 33.7 (4) |
N1—O14—C4—C5 | 78.2 (4) | C2—N1—C9A—C5A | −77.4 (4) |
C2—C3—C4—O14 | 22.4 (4) | N1—C2—C21—C22 | 131.8 (4) |
C2—C3—C4—C5 | −94.8 (4) | C3—C2—C21—C22 | −111.5 (4) |
O14—C4—C5—C5A | −46.4 (4) | C2—C21—C22—C221 | 176.3 (4) |
C3—C4—C5—C5A | 67.9 (5) | C21—C22—C221—C226 | −157.0 (4) |
C4—C5—C5A—C9A | 10.5 (5) | C21—C22—C221—C222 | 22.3 (6) |
C4—C5—C5A—C6 | −173.2 (4) | C226—C221—C222—C223 | 2.3 (5) |
C9A—C5A—C6—C7 | −0.4 (5) | C22—C221—C222—C223 | −177.1 (4) |
C5—C5A—C6—C7 | −176.7 (4) | C221—C222—C223—C224 | −1.4 (6) |
C5A—C6—C7—C8 | 0.7 (6) | C222—C223—C224—C225 | 0.1 (6) |
C5A—C6—C7—F7 | −179.3 (4) | C223—C224—C225—C226 | 0.4 (6) |
F7—C7—C8—C9 | 180.0 (4) | C224—C225—C226—C221 | 0.4 (6) |
C6—C7—C8—C9 | 0.0 (6) | C222—C221—C226—C225 | −1.8 (5) |
C7—C8—C9—C9A | −1.0 (6) | C22—C221—C226—C225 | 177.6 (4) |
D—H···A | D—H | H···A | D···A | D—H···A |
C4—H4···O14i | 1.00 | 2.39 | 3.278 (5) | 148 |
C5—H5B···O14ii | 0.99 | 2.57 | 3.504 (6) | 157 |
C6—H6···Cg1iii | 0.95 | 2.98 | 3.815 (5) | 147 |
C8—H8···Cg2iv | 0.95 | 2.97 | 3.860 (5) | 158 |
C22—H22···Cg2v | 0.95 | 3.00 | 3.896 (5) | 158 |
Symmetry codes: (i) −x+1, y+1/2, −z+1; (ii) x, y+1, z; (iii) −x+2, y+1/2, −z+1; (iv) x+1, y, z; (v) −x+1, y+1/2, −z+2. |
Experimental details
Crystal data | |
Chemical formula | C18H16FNO |
Mr | 281.32 |
Crystal system, space group | Monoclinic, P21 |
Temperature (K) | 120 |
a, b, c (Å) | 10.052 (4), 5.299 (4), 12.976 (8) |
β (°) | 91.10 (4) |
V (Å3) | 691.1 (7) |
Z | 2 |
Radiation type | Mo Kα |
µ (mm−1) | 0.09 |
Crystal size (mm) | 0.36 × 0.08 × 0.06 |
Data collection | |
Diffractometer | Bruker Nonius KappaCCD area-detector diffractometer |
Absorption correction | Multi-scan (SADABS; Sheldrick, 2003) |
Tmin, Tmax | 0.956, 0.995 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 9381, 1432, 1112 |
Rint | 0.081 |
(sin θ/λ)max (Å−1) | 0.606 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.049, 0.107, 1.12 |
No. of reflections | 1432 |
No. of parameters | 190 |
No. of restraints | 1 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 0.23, −0.24 |
Computer programs: COLLECT (Nonius, 1999), DIRAX/LSQ (Duisenberg et al., 2000), EVALCCD (Duisenberg et al., 2003), SIR2004 (Burla et al., 2005), SHELXL97 (Sheldrick, 2008) and PLATON (Spek, 2009).
D—H···A | D—H | H···A | D···A | D—H···A |
C4—H4···O14i | 1.00 | 2.39 | 3.278 (5) | 148 |
C5—H5B···O14ii | 0.99 | 2.57 | 3.504 (6) | 157 |
C6—H6···Cg1iii | 0.95 | 2.98 | 3.815 (5) | 147 |
C8—H8···Cg2iv | 0.95 | 2.97 | 3.860 (5) | 158 |
C22—H22···Cg2v | 0.95 | 3.00 | 3.896 (5) | 158 |
Symmetry codes: (i) −x+1, y+1/2, −z+1; (ii) x, y+1, z; (iii) −x+2, y+1/2, −z+1; (iv) x+1, y, z; (v) −x+1, y+1/2, −z+2. |
We report here the structure of the title compound, (I) (Fig. 1), and we compare its intermolecular hydrogen bonding with that in the (2R,4R) diastereoisomer, (II), and then we compare the diastereoisomeric pair, (I) and (II), with their 7-chloro analogues, (III) and (IV) (Acosta et al., 2008). Both members of the diastereoisomeric pair of compounds (I) and (II) crystallize as a single enantiomer in space group P21. The absolute configurations could not be established and so for both compounds the configuration at C4 was arbitrarily set to be R for the crystals selected for data collection. By contrast, the 7-chloro analogues, compounds (III) and (IV), both crystallize as racemic twins in space groups P21 and P212121, respectively (Acosta et al., 2008). In view of the crystallization behaviour of (III) and (IV) and of the absence from the synthetic procedure of any reagent capable of imparting enantioselective bias, it seems probable that all of these compounds, including (I), are in fact initially formed as racemic mixtures. On the other hand, if this is so, it is not at all easy to see why the 7-fluoro compounds (I) and (II) both crystallize as conglomerates, while their 7-chloro analogues (III) and (IV) both crystallize as racemic twins.
In the crystal structure of (I), there are two C—H···O hydrogen bonds (Table 1). The shorter of these, involving atom C4 as the donor, links molecules related by the 21 screw axis along (1/2, y, 1/2) into a C(3) chain (Bernstein et al., 1995) running parallel to the [010] direction. This chain formation is augmented by the second, longer, hydrogen bond, which links molecules related by translation along [010] into a C(4) chain, while the combination of the two hydrogen bonds generates a chain of edge-fused R23(8) rings (Fig. 2).
In addition to the C—H···O hydrogen bonds there are also three C—H···π(arene) hydrogen bonds. All of these are fairly long, but they combine with the C—H···O hydrogen bonds to generate a three-dimensional hydrogen-bonded framework of considerable complexity. The formation of the framework can, however, be readily analysed in terms of two further one-dimensional sub-structures in addition to that formed by the two C—H···O hydrogen bonds. In the second and most complex sub-structure, atoms H4 and H6 in the molecule at (x, y, z) act as hydrogen-bond donors to, respectively, atom O14 in the molecule at (1 - x, 1/2 + y, 1 - z) and the fused aryl ring in the molecule at (2 - x, 1/2 + y, 1 - z). In addition, atom C8 at (x, y, z) acts as donor to the pendent aryl ring C221–C226 in the molecule at (1 + x, y, z). The combination of these three hydrogen bonds then generates a chain of edge-fused rings running parallel to the [100] direction and containing two distinct types of hydrogen-bonded ring (Fig. 3). For the final sub-structure, atoms H4 and H22 in the molecule at (x, y, z) act as hydrogen-bond donors to, respectively, atom O14 in the molecule at (1 - x, 1/2 + y, 1 - z) and the pendent aryl ring in the molecule at (1 - x, 1/2 + y, 2 - z), so forming a chain running parallel to the [001] direction and built from alternating C—H···O and C—H···π(arene) hydrogen bonds and in which alternate molecules act as double donors of hydrogen bonds and as double acceptors (Fig. 4). The combination of this simple chain along [001] with the chains of rings along [100] and [010] suffices to generate a continuous three-dimensional structure.
The complexity of the hydrogen bonding in (I) is in sharp contrast with the simplicity observed in the structure of its diastereoisomer, (II), where just a single C—H···O hydrogen bond links molecules related by translation into simple C(4) chains (Acosta et al., 2008). However, in contrast with the structure of (I), C—H···π(arene) interactions are absent from the structure of (II). Moreover, the chains in (II) run parallel to the [100] direction in space group P21, whereas in (I), also in space group P21, the C(4) motif is generated by translation along the [010] direction.
The hydrogen-bonded structures of the diastereoisomeric pair (III) and (IV) are also sharply different (Acosta et al., 2008). In (III), a combination of C—H···O and C—H···N hydrogen bonds links the molecules into a chain of R23(9) rings, just as in (I), but C—H···π(arene) hydrogen bonds are absent from the structure of (III). In (IV), which unlike (I)–(III) crystallizes in space group P212121, the molecules are linked into complex chains by a combination of a two-centre C—H···N hydrogen bond and a three-centre C—H···(O,N) hydrogen bond, but again C—H···π(arene) hydrogen bonds are absent from this structure.
Compounds (I) and (III) have similar unit-cell dimensions, except for the unit-cell vector a, where the value in (III) exceeds that in (I) by ca 0.53 Å, or some 5.2%. In contrast, the b and c values in (I) and (II) each differ by less than 1%, and the β angles also differ by less than 1°. Thus, the difference of ca 5.3% in the unit-cell volumes is almost entirely accounted for by the difference in the a repeat vectors. Thus, compounds (I) and (II) [(III)?] are approximately isomorphous but they are not isostructural, firstly because (III) crystallizes as a racemic twin while (I) does not, and secondly because there are no C—H···π(arene) hydrogen bonds in the structure of (III). In addition to the different values of the a repeat vector, a detailed comparison of the atomic coordinates for (I) and (III) shows some significant differences, particularly for the C and H atoms involved in the C—H···π(arene) hydrogen bonds in (I).
The bond distances and angles in (I) present no usual values. The ring-puckering angles (Cremer & Pople, 1975) indicate that both of the heterocyclic rings adopt conformations intermediate between the envelope and half-chair forms.