Supporting information
Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270107050937/ln3070sup1.cif | |
Structure factor file (CIF format) https://doi.org/10.1107/S0108270107050937/ln3070IIIsup2.hkl |
CCDC reference: 672542
For the preparation of the bis-tosylhydrazone (II) of the pseudo-geminal dialdehyde (I) (Bondarenko et al., 2007, and references therein), a solution of (I) (1.5 g, 5.68 mmol) and p-toluenesulfonic acid hydrazide (3.0 g, 16.12 mmol) in anhydrous tetrahydrofuran (250 ml) was refluxed for 2 h in the presence of a trace of p-toluenesulfonic acid. After cooling to room temperature, the solvent was removed in vacuo and the raw product purified by plate chromatography on silica gel with dichloromethane/ethyl acetate (98:2 v/v). After recrystallization from dichloromethane/ethanol, (II) (3.13 g, 92%) was obtained as colourless needles [m.p. 467 K (decomposition)]. Analysis calculated for C32H32O4N4S2 (600.76): C 63.98, H 5.36%; found: C 62.94, H 4.98%.
For the preparation of (III), a solution of (II) (3.0 g, 5.0 mmol) and sodium methoxide (3.0 g, 93 mmol) in diglyme (150 ml) was heated under reflux for 3 h. After cooling to room temperature, water (200 ml) was added, and the reaction mixture was extracted with ether. The organic phase was separated and dried (calcium chloride), the solvent was removed by rotary evaporation, and the remainder was purified by plate chromatography on silica gel with tetrachloromethane/dichloromethane (9:1 v/v). After recrystallization from dichloromethane/ethanol, (III) (0.85 g, 73%) was obtained as colourless plates (m.p. 430–431 K). 1H NMR (400 MHz, CD2Cl2, int. TMS): δ 7.24 (s, 2H, 9-H), 6.39 (dd, Jo = 7.9 Hz, Jm = 2.1 Hz, 2H, 5-H), 6.33 (d, Jo = 7.9 Hz, 2H, 4-H), 6.23 (d, Jm = 2.1 Hz, 2H, 7-H), 3.05 (m, 4H, ethano bridge), 2.93 (m, 2H, ethano bridge), 2.61 (m, 2H, ethano bridge); 13C NMR (100.6 MHz, CD2Cl2): δ 141.98, 141.45, 139.60 (3 × s, quart. C), 139.21, 138.21, 133.47, 130.82 (4 × s, Ar—C, –HC═CH–), 35.42, 34.29 (t, ethano bridges). Analysis calculated for C18H16 (232.33): C 93.06, H 6.94%; found: C 93.16, H 6.85%. Single crystals were obtained from cyclohexane. Additional spectroscopic data for (II) and (III) are given in the deposited material.
H-atoms positions were calculated, after which the H atoms were refined using a riding model with C—H distances of 0.95 Å for sp2 and 0.99 Å for sp3 C atoms. Uiso(H) values were fixed at 1.2Ueq of the parent C atoms. There is no significant residual electron density that might suggest disorder of the bridges. A rigid-body libration correction (Schomaker & Trueblood, 1968) gave an acceptable Rlib of 0.062 and bond-length corrections of 0.005–0.006 Å; corrected bond lengths are given in the deposited material, but uncorrected values are used in Table 1 and the Comment section. [Please clarify; values in Table 1 ARE the values in the deposited material; should this read Table 2?]
Data collection: DIF4 (Stoe & Cie, 1992); cell refinement: DIF4 (Stoe & Cie, 1992); data reduction: REDU4 (Stoe & Cie, 1992); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: XP (Siemens, 1994); software used to prepare material for publication: SHELXL97 (Sheldrick, 1997).
Fig. 1. The molecule of (III). Displacement ellipsoids represent 30% probability levels. | |
Fig. 2. The packing of (III), viewed parallel to the z axis in the region z ≈ 1/8. |
C18H16 | Dx = 1.274 Mg m−3 |
Mr = 232.31 | Mo Kα radiation, λ = 0.71073 Å |
Orthorhombic, Pbca | Cell parameters from 50 reflections |
a = 7.6402 (15) Å | θ = 10–11.5° |
b = 11.775 (2) Å | µ = 0.07 mm−1 |
c = 26.927 (5) Å | T = 153 K |
V = 2422.4 (8) Å3 | Tablet, colourless |
Z = 8 | 0.7 × 0.5 × 0.25 mm |
F(000) = 992 |
Stoe STADI-4 diffractometer | Rint = 0.059 |
Radiation source: fine-focus sealed tube | θmax = 25.1°, θmin = 3.0° |
Graphite monochromator | h = −9→0 |
ω/θ scans | k = −14→14 |
4154 measured reflections | l = 0→32 |
2139 independent reflections | 3 standard reflections every 60 min |
1446 reflections with I > 2σ(I) | intensity decay: 5% |
Refinement on F2 | Secondary atom site location: difference Fourier map |
Least-squares matrix: full | Hydrogen site location: inferred from neighbouring sites |
R[F2 > 2σ(F2)] = 0.054 | H-atom parameters constrained |
wR(F2) = 0.150 | w = 1/[σ2(Fo2) + (0.0544P)2 + 0.4953P] where P = (Fo2 + 2Fc2)/3 |
S = 1.10 | (Δ/σ)max < 0.001 |
2139 reflections | Δρmax = 0.23 e Å−3 |
164 parameters | Δρmin = −0.24 e Å−3 |
0 restraints | Extinction correction: SHELXL97 (Sheldrick, 1997), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4 |
Primary atom site location: structure-invariant direct methods | Extinction coefficient: 0.0042 (9) |
C18H16 | V = 2422.4 (8) Å3 |
Mr = 232.31 | Z = 8 |
Orthorhombic, Pbca | Mo Kα radiation |
a = 7.6402 (15) Å | µ = 0.07 mm−1 |
b = 11.775 (2) Å | T = 153 K |
c = 26.927 (5) Å | 0.7 × 0.5 × 0.25 mm |
Stoe STADI-4 diffractometer | Rint = 0.059 |
4154 measured reflections | 3 standard reflections every 60 min |
2139 independent reflections | intensity decay: 5% |
1446 reflections with I > 2σ(I) |
R[F2 > 2σ(F2)] = 0.054 | 0 restraints |
wR(F2) = 0.150 | H-atom parameters constrained |
S = 1.10 | Δρmax = 0.23 e Å−3 |
2139 reflections | Δρmin = −0.24 e Å−3 |
164 parameters |
Experimental. Spectroscopic data for bis-tosylhydrazone (II): IR (KBr): ~ν = 3180 (m), 2920 (m), 2840 (m), 1430 (m), 1360 (m), 1320 (m), 1160 (s), 1090 cm-1 (m); MS (70 eV, EI): m/z (%) = 416 [M+—NHTs] (1), 278 (91), 246 (40), 232 (71), 217 (52), 202 (47), 172 (49), 155 (71), 139 (100), 123 (76), 108 (48), 91 (89). Additional spectroscopic data for [2.2.2](1,2,4)cyclophan-9-ene (III): IR (KBr): ~ν = 2950 (w), 2920 (m), 2880 (w), 2840 (m), 1480 (m), 1430 (m), 1395 (m), 920 (m), 815 (m), 730 cm-1 (s); UV (acetonitrile): λmax (lg ε) = 202 (3.30), 220 nm (3.11); MS (70 eV, EI): m/z (%) = 232 [M+] (100), 217 (88), 204 (90), 189 (50), 178 (23), 165 (25), 154 (26), 141 (57), 128 (48), 115 (39), 101 (46), 95 (32), 89 (25). |
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) 4.9418 (0.0057) x + 6.0219 (0.0160) y - 15.2341 (0.0334) z = 2.3993 (0.0230) * 0.0258 (0.0012) C4 * -0.0261 (0.0012) C5 * 0.0257 (0.0012) C7 * -0.0254 (0.0012) C8 - 0.1110 (0.0034) C3 - 0.1356 (0.0035) C6 Rms deviation of fitted atoms = 0.0258 6.1617 (0.0046) x + 5.0281 (0.0165) y - 11.0117 (0.0372) z = 0.9379 (0.0239) Angle to previous plane (with approximate e.s.d.) = 13.74 (0.19) * 0.0282 (0.0012) C11 * -0.0284 (0.0012) C12 * 0.0285 (0.0012) C14 * -0.0284 (0.0012) C15 0.1457 (0.0036) C13 0.1148 (0.0037) C16 Rms deviation of fitted atoms = 0.0284 |
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 | ||
C1 | 0.4439 (4) | 0.4984 (2) | 0.33019 (9) | 0.0520 (7) | |
H1A | 0.3450 | 0.4850 | 0.3072 | 0.062* | |
H1B | 0.4872 | 0.4235 | 0.3415 | 0.062* | |
C2 | 0.5954 (4) | 0.5619 (2) | 0.30150 (10) | 0.0529 (7) | |
H2A | 0.7012 | 0.5134 | 0.3013 | 0.063* | |
H2B | 0.5592 | 0.5739 | 0.2666 | 0.063* | |
C3 | 0.6403 (3) | 0.6755 (2) | 0.32451 (8) | 0.0408 (6) | |
C4 | 0.7703 (3) | 0.6831 (2) | 0.36072 (9) | 0.0468 (7) | |
H4 | 0.8631 | 0.6294 | 0.3610 | 0.056* | |
C5 | 0.7654 (4) | 0.7678 (2) | 0.39603 (9) | 0.0489 (7) | |
H5 | 0.8510 | 0.7690 | 0.4216 | 0.059* | |
C6 | 0.6374 (4) | 0.8515 (2) | 0.39475 (9) | 0.0434 (6) | |
C7 | 0.5338 (3) | 0.8570 (2) | 0.35276 (8) | 0.0411 (6) | |
H7 | 0.4655 | 0.9231 | 0.3469 | 0.049* | |
C8 | 0.5273 (3) | 0.7675 (2) | 0.31860 (8) | 0.0378 (6) | |
C9 | 0.3577 (4) | 0.7523 (2) | 0.29159 (9) | 0.0480 (7) | |
H9 | 0.3411 | 0.7788 | 0.2586 | 0.058* | |
C10 | 0.2314 (4) | 0.6994 (2) | 0.31666 (9) | 0.0479 (7) | |
H10 | 0.1191 | 0.6867 | 0.3026 | 0.057* | |
C11 | 0.2754 (3) | 0.6611 (2) | 0.36823 (8) | 0.0400 (6) | |
C12 | 0.2670 (3) | 0.7420 (2) | 0.40560 (8) | 0.0401 (6) | |
H12 | 0.1861 | 0.8029 | 0.4027 | 0.048* | |
C13 | 0.3745 (3) | 0.7358 (2) | 0.44710 (8) | 0.0410 (6) | |
C14 | 0.4563 (3) | 0.6321 (2) | 0.45617 (9) | 0.0450 (7) | |
H14 | 0.5144 | 0.6199 | 0.4869 | 0.054* | |
C15 | 0.4538 (4) | 0.5468 (2) | 0.42101 (9) | 0.0457 (7) | |
H15 | 0.5036 | 0.4749 | 0.4287 | 0.055* | |
C16 | 0.3793 (3) | 0.5646 (2) | 0.37445 (9) | 0.0410 (6) | |
C17 | 0.4362 (4) | 0.8437 (2) | 0.47209 (9) | 0.0539 (7) | |
H17A | 0.4859 | 0.8242 | 0.5050 | 0.065* | |
H17B | 0.3340 | 0.8937 | 0.4777 | 0.065* | |
C18 | 0.5780 (4) | 0.9112 (2) | 0.44136 (9) | 0.0563 (8) | |
H18A | 0.5292 | 0.9862 | 0.4322 | 0.068* | |
H18B | 0.6812 | 0.9247 | 0.4628 | 0.068* |
U11 | U22 | U33 | U12 | U13 | U23 | |
C1 | 0.0636 (18) | 0.0350 (13) | 0.0573 (16) | −0.0064 (15) | 0.0039 (15) | −0.0013 (12) |
C2 | 0.0670 (19) | 0.0408 (14) | 0.0509 (14) | 0.0051 (15) | 0.0134 (14) | −0.0006 (12) |
C3 | 0.0450 (15) | 0.0381 (14) | 0.0394 (13) | −0.0023 (13) | 0.0111 (12) | 0.0061 (11) |
C4 | 0.0333 (14) | 0.0469 (15) | 0.0603 (15) | 0.0011 (13) | 0.0115 (13) | 0.0169 (13) |
C5 | 0.0386 (15) | 0.0567 (17) | 0.0515 (14) | −0.0142 (14) | −0.0051 (12) | 0.0140 (14) |
C6 | 0.0446 (15) | 0.0385 (14) | 0.0471 (14) | −0.0137 (13) | −0.0004 (12) | 0.0043 (12) |
C7 | 0.0477 (16) | 0.0333 (13) | 0.0425 (13) | −0.0039 (12) | 0.0004 (12) | 0.0071 (11) |
C8 | 0.0449 (14) | 0.0371 (14) | 0.0314 (11) | −0.0035 (12) | 0.0041 (10) | 0.0066 (10) |
C9 | 0.0624 (18) | 0.0438 (14) | 0.0378 (13) | 0.0061 (15) | −0.0071 (13) | −0.0010 (12) |
C10 | 0.0436 (15) | 0.0493 (15) | 0.0508 (14) | 0.0021 (14) | −0.0088 (13) | −0.0077 (13) |
C11 | 0.0325 (14) | 0.0403 (14) | 0.0472 (14) | −0.0043 (12) | 0.0001 (11) | 0.0000 (12) |
C12 | 0.0313 (13) | 0.0432 (14) | 0.0457 (13) | 0.0028 (12) | 0.0069 (11) | −0.0003 (11) |
C13 | 0.0395 (14) | 0.0473 (15) | 0.0361 (12) | −0.0030 (13) | 0.0075 (11) | 0.0006 (11) |
C14 | 0.0454 (16) | 0.0528 (16) | 0.0368 (13) | −0.0040 (14) | 0.0027 (12) | 0.0152 (12) |
C15 | 0.0495 (16) | 0.0356 (13) | 0.0521 (14) | −0.0007 (13) | 0.0088 (13) | 0.0137 (12) |
C16 | 0.0427 (15) | 0.0321 (12) | 0.0480 (14) | −0.0087 (12) | 0.0034 (12) | 0.0036 (11) |
C17 | 0.0610 (19) | 0.0567 (17) | 0.0440 (14) | −0.0029 (16) | 0.0023 (14) | −0.0099 (13) |
C18 | 0.068 (2) | 0.0504 (16) | 0.0506 (15) | −0.0175 (16) | −0.0066 (15) | −0.0068 (13) |
C1—C16 | 1.508 (3) | C9—H9 | 0.9500 |
C1—C2 | 1.580 (4) | C10—C11 | 1.498 (3) |
C1—H1A | 0.9900 | C10—H10 | 0.9500 |
C1—H1B | 0.9900 | C11—C12 | 1.387 (3) |
C2—C3 | 1.513 (3) | C11—C16 | 1.395 (3) |
C2—H2A | 0.9900 | C12—C13 | 1.389 (3) |
C2—H2B | 0.9900 | C12—H12 | 0.9500 |
C3—C8 | 1.394 (3) | C13—C14 | 1.393 (4) |
C3—C4 | 1.395 (3) | C13—C17 | 1.513 (3) |
C4—C5 | 1.379 (4) | C14—C15 | 1.380 (3) |
C4—H4 | 0.9500 | C14—H14 | 0.9500 |
C5—C6 | 1.389 (4) | C15—C16 | 1.393 (3) |
C5—H5 | 0.9500 | C15—H15 | 0.9500 |
C6—C7 | 1.381 (3) | C17—C18 | 1.578 (4) |
C6—C18 | 1.508 (3) | C17—H17A | 0.9900 |
C7—C8 | 1.400 (3) | C17—H17B | 0.9900 |
C7—H7 | 0.9500 | C18—H18A | 0.9900 |
C8—C9 | 1.497 (4) | C18—H18B | 0.9900 |
C9—C10 | 1.332 (4) | ||
C16—C1—C2 | 112.4 (2) | C9—C10—C11 | 116.6 (2) |
C16—C1—H1A | 109.1 | C9—C10—H10 | 121.7 |
C2—C1—H1A | 109.1 | C11—C10—H10 | 121.7 |
C16—C1—H1B | 109.1 | C12—C11—C16 | 119.9 (2) |
C2—C1—H1B | 109.1 | C12—C11—C10 | 117.0 (2) |
H1A—C1—H1B | 107.9 | C16—C11—C10 | 119.0 (2) |
C3—C2—C1 | 112.6 (2) | C11—C12—C13 | 121.3 (2) |
C3—C2—H2A | 109.1 | C11—C12—H12 | 119.3 |
C1—C2—H2A | 109.1 | C13—C12—H12 | 119.3 |
C3—C2—H2B | 109.1 | C12—C13—C14 | 116.9 (2) |
C1—C2—H2B | 109.1 | C12—C13—C17 | 119.9 (2) |
H2A—C2—H2B | 107.8 | C14—C13—C17 | 121.2 (2) |
C8—C3—C4 | 118.1 (2) | C15—C14—C13 | 120.8 (2) |
C8—C3—C2 | 120.0 (2) | C15—C14—H14 | 119.6 |
C4—C3—C2 | 120.3 (2) | C13—C14—H14 | 119.6 |
C5—C4—C3 | 120.6 (2) | C14—C15—C16 | 120.8 (2) |
C5—C4—H4 | 119.7 | C14—C15—H15 | 119.6 |
C3—C4—H4 | 119.7 | C16—C15—H15 | 119.6 |
C4—C5—C6 | 121.0 (2) | C15—C16—C11 | 117.6 (2) |
C4—C5—H5 | 119.5 | C15—C16—C1 | 119.9 (2) |
C6—C5—H5 | 119.5 | C11—C16—C1 | 120.8 (2) |
C7—C6—C5 | 117.2 (2) | C13—C17—C18 | 113.8 (2) |
C7—C6—C18 | 119.1 (2) | C13—C17—H17A | 108.8 |
C5—C6—C18 | 121.4 (2) | C18—C17—H17A | 108.8 |
C6—C7—C8 | 121.5 (2) | C13—C17—H17B | 108.8 |
C6—C7—H7 | 119.2 | C18—C17—H17B | 108.8 |
C8—C7—H7 | 119.2 | H17A—C17—H17B | 107.7 |
C3—C8—C7 | 119.2 (2) | C6—C18—C17 | 114.0 (2) |
C3—C8—C9 | 119.9 (2) | C6—C18—H18A | 108.7 |
C7—C8—C9 | 116.1 (2) | C17—C18—H18A | 108.7 |
C10—C9—C8 | 115.9 (2) | C6—C18—H18B | 108.7 |
C10—C9—H9 | 122.1 | C17—C18—H18B | 108.7 |
C8—C9—H9 | 122.1 | H18A—C18—H18B | 107.6 |
C16—C1—C2—C3 | −0.6 (3) | C16—C11—C12—C13 | 7.1 (4) |
C1—C2—C3—C8 | −73.9 (3) | C10—C11—C12—C13 | −149.8 (2) |
C1—C2—C3—C4 | 91.2 (3) | C11—C12—C13—C14 | −16.3 (3) |
C8—C3—C4—C5 | 12.9 (3) | C11—C12—C13—C17 | 147.7 (3) |
C2—C3—C4—C5 | −152.4 (2) | C12—C13—C14—C15 | 10.7 (4) |
C3—C4—C5—C6 | −3.9 (4) | C17—C13—C14—C15 | −153.1 (2) |
C4—C5—C6—C7 | −10.1 (3) | C13—C14—C15—C16 | 4.1 (4) |
C4—C5—C6—C18 | 152.8 (2) | C14—C15—C16—C11 | −13.5 (4) |
C5—C6—C7—C8 | 15.2 (4) | C14—C15—C16—C1 | 152.3 (2) |
C18—C6—C7—C8 | −148.2 (2) | C12—C11—C16—C15 | 7.9 (4) |
C4—C3—C8—C7 | −7.9 (3) | C10—C11—C16—C15 | 164.4 (2) |
C2—C3—C8—C7 | 157.5 (2) | C12—C11—C16—C1 | −157.7 (2) |
C4—C3—C8—C9 | −162.5 (2) | C10—C11—C16—C1 | −1.1 (4) |
C2—C3—C8—C9 | 2.9 (3) | C2—C1—C16—C15 | −91.6 (3) |
C6—C7—C8—C3 | −6.3 (4) | C2—C1—C16—C11 | 73.7 (3) |
C6—C7—C8—C9 | 149.3 (2) | C12—C13—C17—C18 | −72.1 (3) |
C3—C8—C9—C10 | 75.8 (3) | C14—C13—C17—C18 | 91.2 (3) |
C7—C8—C9—C10 | −79.5 (3) | C7—C6—C18—C17 | 80.0 (3) |
C8—C9—C10—C11 | −0.5 (3) | C5—C6—C18—C17 | −82.7 (3) |
C9—C10—C11—C12 | 81.1 (3) | C13—C17—C18—C6 | −4.7 (3) |
C9—C10—C11—C16 | −76.1 (3) |
Experimental details
Crystal data | |
Chemical formula | C18H16 |
Mr | 232.31 |
Crystal system, space group | Orthorhombic, Pbca |
Temperature (K) | 153 |
a, b, c (Å) | 7.6402 (15), 11.775 (2), 26.927 (5) |
V (Å3) | 2422.4 (8) |
Z | 8 |
Radiation type | Mo Kα |
µ (mm−1) | 0.07 |
Crystal size (mm) | 0.7 × 0.5 × 0.25 |
Data collection | |
Diffractometer | Stoe STADI-4 diffractometer |
Absorption correction | – |
No. of measured, independent and observed [I > 2σ(I)] reflections | 4154, 2139, 1446 |
Rint | 0.059 |
(sin θ/λ)max (Å−1) | 0.596 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.054, 0.150, 1.10 |
No. of reflections | 2139 |
No. of parameters | 164 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 0.23, −0.24 |
Computer programs: DIF4 (Stoe & Cie, 1992), REDU4 (Stoe & Cie, 1992), SHELXS97 (Sheldrick, 1997), SHELXL97 (Sheldrick, 1997), XP (Siemens, 1994).
C1—C2 | 1.580 (4) | C17—C18 | 1.578 (4) |
C9—C10 | 1.332 (4) | ||
C16—C1—C2 | 112.4 (2) | C9—C10—C11 | 116.6 (2) |
C3—C2—C1 | 112.6 (2) | C12—C13—C14 | 116.9 (2) |
C8—C3—C4 | 118.1 (2) | C15—C16—C11 | 117.6 (2) |
C7—C6—C5 | 117.2 (2) | C13—C17—C18 | 113.8 (2) |
C10—C9—C8 | 115.9 (2) | C6—C18—C17 | 114.0 (2) |
C3···C16 | 2.737 (3) |
C4···C15 | 3.326 (3) |
C5···C14 | 3.280 (3) |
C6···C13 | 2.807 (3) |
C7···C12 | 2.831 (3) |
C8···C11 | 2.657 (3) |
In contrast to to the [2n]cyclophanes with saturated bridges – from [22]paracyclophane (review article: Hopf & Kleinschroth, 1982) to superphane ([26]paracyclophane; review article: Gleiter & Roers, 2004) – relatively little is known about the chemical behavior and the structural properties of cyclophanes with unsaturated bridges (`cyclophenes'). We report here the preparation and the structural properties of [2.2.2](1,2,4)cyclophan-9-ene, (III), a triply bridged cyclophane in which one of the ethano bridges of its saturated analogue has been replaced by a double bond. The unsaturated analogue of superphane, superphene, a hydrocarbon with six adjacent unsaturated bridges, is so far unknown. A search of the Cambridge Structural Database (Allen, 2002) revealed no other cyclophene of the [2.2.2](1,2,4) type.
The molecule of (III) is shown in Fig. 1; selected molecular dimensions are presented in Table 1. The molecule may be regarded as a derivative of [2.2]paracyclophane (bridgehead atoms C3, C6, C13 and C16); as we have previously noted in such derivatives with extra bridges (Bondarenko et al., 2007, and references therein) the molecular geometry is changed surprisingly little by the extra bridge. Typical features of [2.2]paracyclophanes are elongated single bonds in the bridges, widened sp3 angles at the bridge atoms, narrowed sp2 angles in the six-membered rings at the bridgehead atoms, and flattened boat conformations of the rings, with the bridgehead atoms displaced by ca 0.10–0.15 Å from the mean plane of the other four atoms towards the centre of the molecule. All these features are observed in (III) (Table 1), except that the deviations of the bridgehead atoms are slightly smaller [0.111 (3) Å for C3, 0.136 (3) Å for C6, 0.146 (4) Å for C13 and 0.115 (4) Å for C16].
However, whereas the rings in normal [2.2]paracyclophanes are parallel, those in (III) are significantly rotated, with an interplanar angle of 13.7 (2)°; this is also an effect that we have noted before (Bondarenko et al., 2007, and references therein), and is presumably connected with the extra bridge C9═C10. The bridge is not elongated with respect to normal C═C distances, but the angles at the bridge atoms are significantly narrower than ideal sp2 angles. This leads to an extremely short contact of 2.657 (3) Å between the formally nonbonded atoms C8 and C11, whereas the ring rotation causes atoms C4 and C5 to be farther than usual (> 3.2 Å) from their counterparts (Table 2).
The crystal packing involves layers of molecules parallel to the xy plane, with four layers per cell at z ≈ 1/8, 3/8, 5/8 and 7/8. One such layer is shown in Fig. 2. The molecules are arranged in a hexagonally close-packed pattern; connecting the centroids of adjacent molecules, which are related by the b glide planes, forms a rhombus with sides of ca 7.0 Å and angles of 66 and 113°. The approximately equidimensional nature of the molecules of simple [2.2]paracyclophane derivatives often leads to such layer structures, in which the two cell constants associated with the layer are, as here, often ca 7 and 11 Å. We have called this the `7,11'-packing pattern (El Shaieb et al., 2003; Jones et al., 2007). In many cases, adjacent molecules are connected by C—H···π contacts, sometimes extremely short, but in (III) there are no H···(C9═C10) contacts shorter than 3.17 Å and no H···(ring centroid) contacts greater than 3.34 Å.