Supporting information
Crystallographic Information File (CIF) https://doi.org/10.1107/S1600536802002933/bt6113sup1.cif | |
Structure factor file (CIF format) https://doi.org/10.1107/S1600536802002933/bt6113Isup2.hkl |
CCDC reference: 182627
Key indicators
- Single-crystal X-ray study
- T = 178 K
- Mean (C-C) = 0.002 Å
- R factor = 0.045
- wR factor = 0.134
- Data-to-parameter ratio = 16.9
checkCIF results
No syntax errors found ADDSYM reports no extra symmetry
The title compound was prepared by the standard method (Hopf et al., 1981) by cycloaddition of but-3-yn-2-one (ethynyl methyl ketone) to 1,2,4,5-hexatetraene (biallenyl) in toluene at 348 K. Apart from the title compound, which is formed in 8% yield, other isomers are produced. These were separated by preparative middle pressure chromatography on silica gel with dichloromethane (Hillmer, 1991). Crystals were grown by evaporation from 2-propanol.
H atoms on sp2 C atoms were included using a riding model, starting from idealized positions. Methyl H atoms were located as rather weak but distinct maxima in difference syntheses, idealized and refined as rigid groups allowed to rotate but not tip.
Data collection: P3 (Nicolet, 1987); cell refinement: P3; data reduction: XDISK (Nicolet, 1987); program(s) used to solve structure: SHELXS97 (Sheldrick, 1990); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: XP (Siemens, 1994); software used to prepare material for publication: SHELXL97.
C20H20O2 | F(000) = 624 |
Mr = 292.36 | Dx = 1.305 Mg m−3 |
Monoclinic, C2/c | Mo Kα radiation, λ = 0.71073 Å |
a = 15.827 (6) Å | Cell parameters from 50 reflections |
b = 9.442 (2) Å | θ = 10–12° |
c = 11.423 (4) Å | µ = 0.08 mm−1 |
β = 119.34 (2)° | T = 178 K |
V = 1488.1 (8) Å3 | Prism, colourless |
Z = 4 | 0.7 × 0.45 × 0.4 mm |
Nicolet R3 diffractometer | Rint = 0.018 |
Radiation source: fine-focus sealed tube | θmax = 27.5°, θmin = 3.7° |
Graphite monochromator | h = −20→0 |
ω scans | k = −12→8 |
3126 measured reflections | l = −12→14 |
1710 independent reflections | 3 standard reflections every 147 reflections |
1411 reflections with I > 2σ(I) | intensity decay: none |
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)] = 0.045 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.134 | H-atom parameters constrained |
S = 1.03 | w = 1/[σ2(Fo2) + (0.0677P)2 + 1.4684P] where P = (Fo2 + 2Fc2)/3 |
1710 reflections | (Δ/σ)max < 0.001 |
101 parameters | Δρmax = 0.27 e Å−3 |
0 restraints | Δρmin = −0.27 e Å−3 |
C20H20O2 | V = 1488.1 (8) Å3 |
Mr = 292.36 | Z = 4 |
Monoclinic, C2/c | Mo Kα radiation |
a = 15.827 (6) Å | µ = 0.08 mm−1 |
b = 9.442 (2) Å | T = 178 K |
c = 11.423 (4) Å | 0.7 × 0.45 × 0.4 mm |
β = 119.34 (2)° |
Nicolet R3 diffractometer | Rint = 0.018 |
3126 measured reflections | 3 standard reflections every 147 reflections |
1710 independent reflections | intensity decay: none |
1411 reflections with I > 2σ(I) |
R[F2 > 2σ(F2)] = 0.045 | 0 restraints |
wR(F2) = 0.134 | H-atom parameters constrained |
S = 1.03 | Δρmax = 0.27 e Å−3 |
1710 reflections | Δρmin = −0.27 e Å−3 |
101 parameters |
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. Least-squares planes (x,y,z in crystal coordinates) and deviations from them (* indicates atom used to define plane) 6.0871 (0.0081) x + 0.0101 (0.0084) y - 11.3445 (0.0044) z = 1.7688 (0.0045) * -0.0041 (0.0006) C4 * 0.0041 (0.0006) C5 * -0.0041 (0.0006) C7 * 0.0041 (0.0006) C8 - 0.1819 (0.0019) C3 - 0.1738 (0.0019) C6 Rms deviation of fitted atoms = 0.0041 |
Refinement. Refinement of F2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F2, conventional R-factors R are based on F, with F set to zero for negative F2. The threshold expression of F2 > σ(F2) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F2 are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger. |
x | y | z | Uiso*/Ueq | ||
C2 | 0.48519 (12) | −0.03085 (16) | 0.17294 (15) | 0.0320 (4) | |
H2A | 0.5306 | −0.0922 | 0.1597 | 0.038* | |
H2B | 0.4193 | −0.0713 | 0.1201 | 0.038* | |
C3 | 0.48651 (10) | 0.11654 (15) | 0.12126 (13) | 0.0254 (3) | |
C4 | 0.57137 (10) | 0.19324 (15) | 0.15119 (13) | 0.0239 (3) | |
C5 | 0.56930 (9) | 0.34162 (15) | 0.14949 (13) | 0.0239 (3) | |
H5 | 0.6264 | 0.3926 | 0.1688 | 0.029* | |
C6 | 0.48496 (10) | 0.41606 (15) | 0.11998 (13) | 0.0246 (3) | |
C7 | 0.39885 (10) | 0.33973 (16) | 0.05875 (13) | 0.0275 (3) | |
H7 | 0.3387 | 0.3886 | 0.0167 | 0.033* | |
C8 | 0.39995 (10) | 0.19236 (16) | 0.05849 (13) | 0.0279 (3) | |
H8 | 0.3403 | 0.1423 | 0.0145 | 0.033* | |
C9 | 0.48858 (11) | 0.56335 (15) | 0.17402 (14) | 0.0288 (3) | |
H9A | 0.4255 | 0.6106 | 0.1178 | 0.035* | |
H9B | 0.5390 | 0.6189 | 0.1671 | 0.035* | |
C17 | 0.66673 (10) | 0.12126 (15) | 0.19799 (15) | 0.0294 (3) | |
C18 | 0.73574 (11) | 0.18517 (18) | 0.15758 (18) | 0.0382 (4) | |
H18A | 0.7760 | 0.2565 | 0.2239 | 0.046* | |
H18B | 0.6989 | 0.2299 | 0.0692 | 0.046* | |
H18C | 0.7773 | 0.1107 | 0.1534 | 0.046* | |
O | 0.68907 (9) | 0.01412 (13) | 0.26574 (14) | 0.0462 (4) |
U11 | U22 | U33 | U12 | U13 | U23 | |
C2 | 0.0436 (8) | 0.0235 (7) | 0.0339 (8) | −0.0042 (6) | 0.0230 (7) | −0.0040 (6) |
C3 | 0.0329 (7) | 0.0246 (7) | 0.0214 (6) | −0.0018 (5) | 0.0154 (5) | −0.0042 (5) |
C4 | 0.0279 (7) | 0.0258 (7) | 0.0204 (6) | 0.0021 (5) | 0.0137 (5) | −0.0002 (5) |
C5 | 0.0263 (6) | 0.0258 (7) | 0.0228 (6) | 0.0000 (5) | 0.0144 (5) | 0.0008 (5) |
C6 | 0.0300 (7) | 0.0250 (7) | 0.0221 (6) | 0.0032 (5) | 0.0153 (5) | 0.0048 (5) |
C7 | 0.0260 (7) | 0.0344 (8) | 0.0212 (6) | 0.0044 (6) | 0.0108 (5) | 0.0045 (5) |
C8 | 0.0276 (7) | 0.0338 (8) | 0.0211 (6) | −0.0052 (6) | 0.0111 (5) | −0.0036 (5) |
C9 | 0.0338 (7) | 0.0222 (7) | 0.0352 (8) | 0.0042 (5) | 0.0207 (6) | 0.0048 (5) |
C17 | 0.0316 (7) | 0.0262 (7) | 0.0314 (7) | 0.0026 (6) | 0.0163 (6) | −0.0041 (6) |
C18 | 0.0301 (8) | 0.0373 (9) | 0.0507 (10) | 0.0019 (6) | 0.0226 (7) | −0.0012 (7) |
O | 0.0469 (7) | 0.0346 (7) | 0.0616 (8) | 0.0158 (5) | 0.0300 (6) | 0.0152 (6) |
C2—C3 | 1.516 (2) | C7—C8 | 1.392 (2) |
C2—C2i | 1.584 (3) | C7—H7 | 0.9500 |
C2—H2A | 0.9900 | C8—H8 | 0.9500 |
C2—H2B | 0.9900 | C9—C9i | 1.590 (3) |
C3—C8 | 1.393 (2) | C9—H9A | 0.9900 |
C3—C4 | 1.4126 (19) | C9—H9B | 0.9900 |
C4—C5 | 1.401 (2) | C17—O | 1.2162 (19) |
C4—C17 | 1.4949 (19) | C17—C18 | 1.505 (2) |
C5—C6 | 1.3959 (19) | C18—H18A | 0.9800 |
C5—H5 | 0.9500 | C18—H18B | 0.9800 |
C6—C7 | 1.390 (2) | C18—H18C | 0.9800 |
C6—C9 | 1.511 (2) | ||
C3—C2—C2i | 112.31 (7) | C8—C7—H7 | 119.7 |
C3—C2—H2A | 109.1 | C7—C8—C3 | 121.53 (13) |
C2i—C2—H2A | 109.1 | C7—C8—H8 | 119.2 |
C3—C2—H2B | 109.1 | C3—C8—H8 | 119.2 |
C2i—C2—H2B | 109.1 | C6—C9—C9i | 112.88 (7) |
H2A—C2—H2B | 107.9 | C6—C9—H9A | 109.0 |
C8—C3—C4 | 116.08 (13) | C9i—C9—H9A | 109.0 |
C8—C3—C2 | 118.33 (13) | C6—C9—H9B | 109.0 |
C4—C3—C2 | 124.71 (13) | C9i—C9—H9B | 109.0 |
C5—C4—C3 | 119.75 (12) | H9A—C9—H9B | 107.8 |
C5—C4—C17 | 118.17 (12) | O—C17—C4 | 122.24 (14) |
C3—C4—C17 | 121.81 (13) | O—C17—C18 | 120.02 (14) |
C6—C5—C4 | 121.32 (12) | C4—C17—C18 | 117.73 (13) |
C6—C5—H5 | 119.3 | C17—C18—H18A | 109.5 |
C4—C5—H5 | 119.3 | C17—C18—H18B | 109.5 |
C7—C6—C5 | 116.50 (13) | H18A—C18—H18B | 109.5 |
C7—C6—C9 | 120.95 (12) | C17—C18—H18C | 109.5 |
C5—C6—C9 | 121.63 (12) | H18A—C18—H18C | 109.5 |
C6—C7—C8 | 120.62 (13) | H18B—C18—H18C | 109.5 |
C6—C7—H7 | 119.7 | ||
C2i—C2—C3—C8 | −95.12 (19) | C6—C7—C8—C3 | 1.3 (2) |
C2i—C2—C3—C4 | 73.7 (2) | C4—C3—C8—C7 | −17.11 (19) |
C8—C3—C4—C5 | 16.01 (18) | C2—C3—C8—C7 | 152.65 (13) |
C2—C3—C4—C5 | −153.02 (13) | C7—C6—C9—C9i | 89.40 (18) |
C8—C3—C4—C17 | −170.06 (12) | C5—C6—C9—C9i | −79.23 (19) |
C2—C3—C4—C17 | 20.91 (19) | C5—C4—C17—O | 141.82 (15) |
C3—C4—C5—C6 | 0.63 (19) | C3—C4—C17—O | −32.2 (2) |
C17—C4—C5—C6 | −173.52 (12) | C5—C4—C17—C18 | −38.66 (18) |
C4—C5—C6—C7 | −16.51 (18) | C3—C4—C17—C18 | 147.32 (14) |
C4—C5—C6—C9 | 152.61 (12) | C3—C2—C2i—C3i | 14.1 (3) |
C5—C6—C7—C8 | 15.59 (18) | C6—C9—C9i—C6i | −5.6 (2) |
C9—C6—C7—C8 | −153.60 (13) |
Symmetry code: (i) −x+1, y, −z+1/2. |
D—H···A | D—H | H···A | D···A | D—H···A |
C18—H18A···Oii | 0.98 | 2.48 | 3.288 (2) | 139 |
Symmetry code: (ii) −x+3/2, y+1/2, −z+1/2. |
Experimental details
Crystal data | |
Chemical formula | C20H20O2 |
Mr | 292.36 |
Crystal system, space group | Monoclinic, C2/c |
Temperature (K) | 178 |
a, b, c (Å) | 15.827 (6), 9.442 (2), 11.423 (4) |
β (°) | 119.34 (2) |
V (Å3) | 1488.1 (8) |
Z | 4 |
Radiation type | Mo Kα |
µ (mm−1) | 0.08 |
Crystal size (mm) | 0.7 × 0.45 × 0.4 |
Data collection | |
Diffractometer | Nicolet R3 diffractometer |
Absorption correction | – |
No. of measured, independent and observed [I > 2σ(I)] reflections | 3126, 1710, 1411 |
Rint | 0.018 |
(sin θ/λ)max (Å−1) | 0.649 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.045, 0.134, 1.03 |
No. of reflections | 1710 |
No. of parameters | 101 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 0.27, −0.27 |
Computer programs: P3 (Nicolet, 1987), P3, XDISK (Nicolet, 1987), SHELXS97 (Sheldrick, 1990), SHELXL97 (Sheldrick, 1997), XP (Siemens, 1994), SHELXL97.
C2—C2i | 1.584 (3) | C9—C9i | 1.590 (3) |
C3—C2—C2i | 112.31 (7) | C7—C6—C5 | 116.50 (13) |
C8—C3—C4 | 116.08 (13) | C7—C6—C9 | 120.95 (12) |
C8—C3—C2 | 118.33 (13) | C5—C6—C9 | 121.63 (12) |
C4—C3—C2 | 124.71 (13) | C6—C9—C9i | 112.88 (7) |
C3—C4—C17—O | −32.2 (2) | C6—C9—C9i—C6i | −5.6 (2) |
C3—C2—C2i—C3i | 14.1 (3) |
Symmetry code: (i) −x+1, y, −z+1/2. |
D—H···A | D—H | H···A | D···A | D—H···A |
C18—H18A···Oii | 0.98 | 2.48 | 3.288 (2) | 139.1 |
Symmetry code: (ii) −x+3/2, y+1/2, −z+1/2. |
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Among the chiral [2.2]paracyclophanes relatively little is known about the 4,13-disubstituted derivatives, otherwise known as `pseudo-meta' compounds. If the two substituents are identical, the compounds may in principle display ideal C2 symmetry. Our interest in these compounds has led us to prepare the title compound, (I), by our established synthetic method (see Experimental); here we report its structure.
The molecule (Fig. 1) displays imposed twofold symmetry, with the twofold axis (at x = 1/2, z = 1/4) passing through the midpoints of C2—C2i and C9—C9i; the atom numbering is standard for one half of a cyclophane molecule. The six-membered rings display the distortion towards a boat form that is typical of [2.2]paracyclophanes, whereby the bridgehead atoms C3 and C6 are displaced by 0.182 (2) and 0.174 (2) Å, respectively, from the plane of the remaining four atoms (mean deviation 0.004 Å). Also typical is the lengthening of the bridge bonds to 1.584 (3) and 1.590 (3) Å. The carbonyl group is rotated out of the corresponding ring plane, with a torsion angle C3—C4—C17—O of -32.2 (2)°. The substituent is associated with some distortion at C3, with a C4—C3—C2 angle of 124.71 (13)°.
The molecules are connected by a weak C18—H18a···O hydrogen bond via a twofold screw axis (at x = 3/4, z = 1/4) to form layers parallel to the xy plane (Fig. 2).