Supporting information
Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270107004830/jz3053sup1.cif | |
Structure factor file (CIF format) https://doi.org/10.1107/S0108270107004830/jz3053Isup2.hkl |
CCDC reference: 641815
Compound (I) was prepared as described by Noe et al. (1994). Thin plates were obtained by crystallization from chloroform–hexane (Ratio?) at low temperature.
H atoms were located in a difference Fourier map and refined as riding, with C(sp2)—H = 0.95 Å and Csecondary—H = 0.99 Å, with Uiso(H) = 1.2Ueq(C). Friedel opposites were not merged. The absolute structure was determined from the anomalous scattering contribution of the O atoms, using 1511 Friedel pairs. The thermal motion analysis was performed using the WinGX program package (Farrugia, 1999).
Data collection: CAD-4 Software (Enraf–Nonius, 1989); cell refinement: CAD-4; data reduction: MolEN (Fair, 1990); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: SHELXTL (Sheldrick, 1996); software used to prepare material for publication: SHELXL97.
C21H28O8 | F(000) = 872 |
Mr = 408.43 | Dx = 1.299 Mg m−3 |
Monoclinic, C2 | Cu Kα radiation, λ = 1.54180 Å |
Hall symbol: C 2y | Cell parameters from 25 reflections |
a = 47.506 (8) Å | θ = 36–50° |
b = 5.392 (2) Å | µ = 0.83 mm−1 |
c = 8.288 (2) Å | T = 178 K |
β = 100.38 (2)° | Thin plate, colourless |
V = 2088.3 (10) Å3 | 0.55 × 0.55 × 0.04 mm |
Z = 4 |
Enraf–Nonius CAD-4 diffractometer | 3591 reflections with I > 2σ(I) |
Radiation source: fine-focus sealed tube | Rint = 0.043 |
Graphite monochromator | θmax = 70.0°, θmin = 1.9° |
ω scans | h = −57→57 |
Absorption correction: numerical (SHELXTL; Sheldrick, 1996) | k = −6→5 |
Tmin = 0.601, Tmax = 0.969 | l = −10→9 |
8436 measured reflections | 3 standard reflections every 92 min |
3716 independent reflections | intensity decay: 0.0% |
Refinement on F2 | Hydrogen site location: inferred from neighbouring sites |
Least-squares matrix: full | H-atom parameters constrained |
R[F2 > 2σ(F2)] = 0.036 | w = 1/[σ2(Fo2) + (0.07P)2 + 0.26P] where P = (Fo2 + 2Fc2)/3 |
wR(F2) = 0.100 | (Δ/σ)max = 0.004 |
S = 1.08 | Δρmax = 0.20 e Å−3 |
3716 reflections | Δρmin = −0.15 e Å−3 |
264 parameters | Extinction correction: SHELXL97 (Sheldrick, 1997), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4 |
1 restraint | Extinction coefficient: 0.00080 (13) |
Primary atom site location: structure-invariant direct methods | Absolute structure: Flack (1983), with 1511 Friedel pairs |
Secondary atom site location: difference Fourier map | Absolute structure parameter: 0.12 (15) |
C21H28O8 | V = 2088.3 (10) Å3 |
Mr = 408.43 | Z = 4 |
Monoclinic, C2 | Cu Kα radiation |
a = 47.506 (8) Å | µ = 0.83 mm−1 |
b = 5.392 (2) Å | T = 178 K |
c = 8.288 (2) Å | 0.55 × 0.55 × 0.04 mm |
β = 100.38 (2)° |
Enraf–Nonius CAD-4 diffractometer | 3591 reflections with I > 2σ(I) |
Absorption correction: numerical (SHELXTL; Sheldrick, 1996) | Rint = 0.043 |
Tmin = 0.601, Tmax = 0.969 | 3 standard reflections every 92 min |
8436 measured reflections | intensity decay: 0.0% |
3716 independent reflections |
R[F2 > 2σ(F2)] = 0.036 | H-atom parameters constrained |
wR(F2) = 0.100 | Δρmax = 0.20 e Å−3 |
S = 1.08 | Δρmin = −0.15 e Å−3 |
3716 reflections | Absolute structure: Flack (1983), with 1511 Friedel pairs |
264 parameters | Absolute structure parameter: 0.12 (15) |
1 restraint |
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. |
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 | ||
O1 | 0.38902 (2) | 0.1043 (2) | 0.32502 (11) | 0.0415 (3) | |
O2 | 0.407524 (18) | 0.1299 (2) | 0.08172 (10) | 0.0362 (2) | |
O3 | 0.456702 (18) | 0.1167 (2) | 0.18980 (10) | 0.0356 (2) | |
O4 | 0.475385 (17) | 0.1237 (2) | −0.05420 (9) | 0.0350 (2) | |
O5 | 0.375388 (19) | 0.5635 (2) | 0.65927 (10) | 0.0376 (3) | |
O6 | 0.424644 (18) | 0.60453 (19) | 0.75902 (10) | 0.0360 (2) | |
O7 | 0.441967 (18) | 0.6226 (2) | 0.51124 (10) | 0.0362 (2) | |
O8 | 0.490993 (18) | 0.6335 (2) | 0.62303 (10) | 0.0351 (2) | |
C1 | 0.33698 (3) | 0.1333 (3) | 0.22644 (15) | 0.0370 (3) | |
C2 | 0.33454 (3) | 0.3462 (3) | 0.31737 (16) | 0.0357 (3) | |
H2 | 0.3502 | 0.3972 | 0.3983 | 0.043* | |
C3 | 0.30968 (3) | 0.4854 (4) | 0.29227 (19) | 0.0482 (4) | |
H3 | 0.3085 | 0.6306 | 0.3556 | 0.058* | |
C4 | 0.28690 (3) | 0.4148 (5) | 0.1770 (2) | 0.0649 (6) | |
H4 | 0.2698 | 0.5096 | 0.1604 | 0.078* | |
C5 | 0.28886 (4) | 0.2051 (5) | 0.0845 (2) | 0.0736 (7) | |
H5 | 0.2730 | 0.1561 | 0.0038 | 0.088* | |
C6 | 0.31382 (4) | 0.0645 (4) | 0.10822 (17) | 0.0577 (5) | |
H6 | 0.3150 | −0.0790 | 0.0432 | 0.069* | |
C7 | 0.36332 (3) | −0.0264 (3) | 0.2605 (2) | 0.0487 (4) | |
H7A | 0.3603 | −0.1575 | 0.3393 | 0.058* | |
H7B | 0.3658 | −0.1090 | 0.1572 | 0.058* | |
C8 | 0.39871 (3) | 0.2614 (3) | 0.21240 (15) | 0.0348 (3) | |
H8A | 0.4150 | 0.3605 | 0.2702 | 0.042* | |
H8B | 0.3832 | 0.3777 | 0.1668 | 0.042* | |
C9 | 0.43180 (3) | −0.0219 (3) | 0.13034 (15) | 0.0375 (3) | |
H9A | 0.4281 | −0.1371 | 0.2171 | 0.045* | |
H9B | 0.4350 | −0.1226 | 0.0355 | 0.045* | |
C10 | 0.46634 (2) | 0.2659 (3) | 0.07022 (14) | 0.0345 (3) | |
H10A | 0.4507 | 0.3776 | 0.0199 | 0.041* | |
H10B | 0.4824 | 0.3703 | 0.1243 | 0.041* | |
C11 | 0.5000 | −0.0218 (4) | 0.0000 | 0.0365 (4) | |
H11A | 0.4965 | −0.1299 | 0.0909 | 0.044* | |
C12 | 0.33434 (3) | 0.7404 (3) | 0.74043 (15) | 0.0388 (3) | |
C13 | 0.31284 (3) | 0.5872 (3) | 0.77704 (18) | 0.0452 (4) | |
H13 | 0.3177 | 0.4406 | 0.8395 | 0.054* | |
C14 | 0.28439 (3) | 0.6473 (4) | 0.72284 (19) | 0.0506 (4) | |
H14 | 0.2698 | 0.5439 | 0.7507 | 0.061* | |
C15 | 0.27713 (3) | 0.8547 (3) | 0.6294 (2) | 0.0485 (4) | |
H15 | 0.2576 | 0.8929 | 0.5904 | 0.058* | |
C16 | 0.29827 (3) | 1.0079 (4) | 0.59181 (19) | 0.0492 (4) | |
H16 | 0.2933 | 1.1520 | 0.5271 | 0.059* | |
C17 | 0.32667 (3) | 0.9521 (3) | 0.64808 (17) | 0.0458 (4) | |
H17 | 0.3411 | 1.0598 | 0.6233 | 0.055* | |
C18 | 0.36524 (3) | 0.6737 (4) | 0.79578 (16) | 0.0486 (4) | |
H18A | 0.3765 | 0.8240 | 0.8330 | 0.058* | |
H18B | 0.3673 | 0.5551 | 0.8883 | 0.058* | |
C19 | 0.40162 (3) | 0.4415 (3) | 0.70341 (15) | 0.0367 (3) | |
H19A | 0.4057 | 0.3482 | 0.6074 | 0.044* | |
H19B | 0.4001 | 0.3202 | 0.7912 | 0.044* | |
C20 | 0.43197 (3) | 0.7586 (3) | 0.63567 (15) | 0.0364 (3) | |
H20A | 0.4470 | 0.8765 | 0.6859 | 0.044* | |
H20B | 0.4150 | 0.8564 | 0.5858 | 0.044* | |
C21 | 0.46692 (3) | 0.4839 (3) | 0.56643 (15) | 0.0363 (3) | |
H21A | 0.4710 | 0.3784 | 0.4755 | 0.044* | |
H21B | 0.4636 | 0.3731 | 0.6563 | 0.044* | |
C22 | 0.5000 | 0.7800 (4) | 0.5000 | 0.0358 (4) | |
H22A | 0.4840 | 0.8881 | 0.4489 | 0.043* |
U11 | U22 | U33 | U12 | U13 | U23 | |
O1 | 0.0431 (5) | 0.0518 (7) | 0.0334 (4) | 0.0098 (5) | 0.0165 (4) | 0.0096 (5) |
O2 | 0.0347 (4) | 0.0502 (6) | 0.0248 (4) | −0.0032 (5) | 0.0083 (3) | 0.0010 (4) |
O3 | 0.0349 (4) | 0.0494 (6) | 0.0234 (4) | 0.0041 (4) | 0.0079 (3) | 0.0006 (4) |
O4 | 0.0343 (5) | 0.0490 (6) | 0.0226 (4) | −0.0050 (4) | 0.0075 (3) | 0.0000 (4) |
O5 | 0.0346 (5) | 0.0546 (7) | 0.0247 (4) | 0.0001 (4) | 0.0085 (3) | −0.0048 (4) |
O6 | 0.0344 (4) | 0.0484 (6) | 0.0250 (4) | 0.0046 (4) | 0.0048 (3) | −0.0012 (4) |
O7 | 0.0364 (5) | 0.0479 (6) | 0.0246 (4) | −0.0024 (4) | 0.0063 (3) | 0.0004 (4) |
O8 | 0.0368 (4) | 0.0453 (6) | 0.0238 (4) | 0.0043 (4) | 0.0067 (3) | −0.0003 (4) |
C1 | 0.0432 (7) | 0.0420 (8) | 0.0299 (6) | −0.0106 (6) | 0.0174 (5) | 0.0007 (6) |
C2 | 0.0354 (6) | 0.0408 (8) | 0.0321 (6) | −0.0034 (6) | 0.0090 (5) | −0.0001 (5) |
C3 | 0.0455 (8) | 0.0540 (10) | 0.0504 (8) | 0.0069 (7) | 0.0226 (6) | 0.0147 (7) |
C4 | 0.0368 (8) | 0.0941 (17) | 0.0640 (11) | 0.0003 (9) | 0.0097 (7) | 0.0371 (12) |
C5 | 0.0492 (9) | 0.1164 (19) | 0.0475 (9) | −0.0357 (11) | −0.0118 (7) | 0.0258 (11) |
C6 | 0.0724 (11) | 0.0698 (12) | 0.0321 (7) | −0.0338 (9) | 0.0127 (7) | −0.0047 (7) |
C7 | 0.0565 (9) | 0.0378 (9) | 0.0601 (9) | −0.0018 (7) | 0.0331 (7) | 0.0000 (7) |
C8 | 0.0338 (6) | 0.0398 (8) | 0.0323 (7) | −0.0003 (6) | 0.0099 (5) | 0.0016 (6) |
C9 | 0.0425 (7) | 0.0407 (8) | 0.0325 (7) | 0.0001 (6) | 0.0152 (5) | −0.0008 (6) |
C10 | 0.0317 (6) | 0.0400 (8) | 0.0321 (7) | −0.0003 (5) | 0.0068 (5) | 0.0006 (5) |
C11 | 0.0415 (10) | 0.0405 (11) | 0.0303 (9) | 0.000 | 0.0140 (7) | 0.000 |
C12 | 0.0431 (7) | 0.0475 (8) | 0.0289 (6) | 0.0010 (6) | 0.0148 (5) | −0.0062 (6) |
C13 | 0.0549 (8) | 0.0396 (9) | 0.0442 (7) | 0.0013 (7) | 0.0175 (6) | 0.0023 (7) |
C14 | 0.0474 (8) | 0.0524 (10) | 0.0570 (9) | −0.0098 (7) | 0.0230 (6) | −0.0022 (8) |
C15 | 0.0409 (7) | 0.0536 (10) | 0.0544 (9) | 0.0055 (7) | 0.0180 (6) | −0.0032 (7) |
C16 | 0.0548 (8) | 0.0449 (9) | 0.0509 (8) | 0.0072 (7) | 0.0178 (6) | 0.0066 (7) |
C17 | 0.0474 (8) | 0.0491 (9) | 0.0451 (8) | −0.0058 (7) | 0.0201 (6) | 0.0016 (7) |
C18 | 0.0456 (7) | 0.0738 (12) | 0.0278 (6) | 0.0068 (8) | 0.0103 (5) | −0.0100 (7) |
C19 | 0.0400 (7) | 0.0410 (9) | 0.0310 (6) | −0.0006 (6) | 0.0115 (5) | −0.0002 (6) |
C20 | 0.0354 (7) | 0.0391 (8) | 0.0351 (7) | 0.0032 (6) | 0.0077 (5) | 0.0008 (6) |
C21 | 0.0414 (7) | 0.0374 (8) | 0.0323 (7) | 0.0002 (6) | 0.0125 (6) | −0.0006 (5) |
C22 | 0.0359 (9) | 0.0377 (11) | 0.0332 (9) | 0.000 | 0.0049 (7) | 0.000 |
O1—C8 | 1.3985 (16) | C8—H8B | 0.9900 |
O1—C7 | 1.4276 (19) | C9—H9A | 0.9900 |
O2—C9 | 1.4125 (18) | C9—H9B | 0.9900 |
O2—C8 | 1.4192 (16) | C10—H10A | 0.9900 |
O3—C9 | 1.4109 (18) | C10—H10B | 0.9900 |
O3—C10 | 1.4150 (16) | C11—O4i | 1.4125 (16) |
O4—C10 | 1.4124 (16) | C11—H11A | 0.9900 |
O4—C11 | 1.4127 (16) | C11—H11Ai | 0.9900 |
O5—C19 | 1.3981 (16) | C12—C17 | 1.386 (2) |
O5—C18 | 1.4360 (16) | C12—C13 | 1.389 (2) |
O6—C20 | 1.4088 (17) | C12—C18 | 1.5008 (19) |
O6—C19 | 1.4141 (17) | C13—C14 | 1.384 (2) |
O7—C21 | 1.4067 (17) | C13—H13 | 0.9500 |
O7—C20 | 1.4156 (16) | C14—C15 | 1.369 (2) |
O8—C21 | 1.4091 (17) | C14—H14 | 0.9500 |
O8—C22 | 1.4156 (15) | C15—C16 | 1.379 (2) |
C1—C6 | 1.386 (2) | C15—H15 | 0.9500 |
C1—C2 | 1.390 (2) | C16—C17 | 1.379 (2) |
C1—C7 | 1.503 (2) | C16—H16 | 0.9500 |
C2—C3 | 1.383 (2) | C17—H17 | 0.9500 |
C2—H2 | 0.9500 | C18—H18A | 0.9900 |
C3—C4 | 1.363 (3) | C18—H18B | 0.9900 |
C3—H3 | 0.9500 | C19—H19A | 0.9900 |
C4—C5 | 1.379 (3) | C19—H19B | 0.9900 |
C4—H4 | 0.9500 | C20—H20A | 0.9900 |
C5—C6 | 1.391 (3) | C20—H20B | 0.9900 |
C5—H5 | 0.9500 | C21—H21A | 0.9900 |
C6—H6 | 0.9500 | C21—H21B | 0.9900 |
C7—H7A | 0.9900 | C22—O8ii | 1.4156 (15) |
C7—H7B | 0.9900 | C22—H22A | 0.9900 |
C8—H8A | 0.9900 | C22—H22Aii | 0.9900 |
C8—O1—C7 | 114.26 (10) | O4—C11—H11A | 109.1 |
C9—O2—C8 | 114.19 (9) | O4i—C11—H11Ai | 109.1 |
C9—O3—C10 | 114.40 (9) | O4—C11—H11Ai | 109.1 |
C10—O4—C11 | 114.37 (8) | H11A—C11—H11Ai | 107.8 |
C19—O5—C18 | 113.47 (10) | C17—C12—C13 | 118.68 (13) |
C20—O6—C19 | 114.06 (9) | C17—C12—C18 | 120.79 (14) |
C21—O7—C20 | 114.36 (9) | C13—C12—C18 | 120.51 (15) |
C21—O8—C22 | 114.34 (8) | C14—C13—C12 | 120.21 (15) |
C6—C1—C2 | 118.11 (15) | C14—C13—H13 | 119.9 |
C6—C1—C7 | 120.50 (15) | C12—C13—H13 | 119.9 |
C2—C1—C7 | 121.31 (12) | C15—C14—C13 | 120.46 (14) |
C3—C2—C1 | 121.28 (14) | C15—C14—H14 | 119.8 |
C3—C2—H2 | 119.4 | C13—C14—H14 | 119.8 |
C1—C2—H2 | 119.4 | C14—C15—C16 | 119.86 (15) |
C4—C3—C2 | 120.21 (18) | C14—C15—H15 | 120.1 |
C4—C3—H3 | 119.9 | C16—C15—H15 | 120.1 |
C2—C3—H3 | 119.9 | C15—C16—C17 | 120.07 (15) |
C3—C4—C5 | 119.59 (18) | C15—C16—H16 | 120.0 |
C3—C4—H4 | 120.2 | C17—C16—H16 | 120.0 |
C5—C4—H4 | 120.2 | C16—C17—C12 | 120.70 (14) |
C4—C5—C6 | 120.67 (15) | C16—C17—H17 | 119.7 |
C4—C5—H5 | 119.7 | C12—C17—H17 | 119.7 |
C6—C5—H5 | 119.7 | O5—C18—C12 | 107.88 (10) |
C1—C6—C5 | 120.14 (18) | O5—C18—H18A | 110.1 |
C1—C6—H6 | 119.9 | C12—C18—H18A | 110.1 |
C5—C6—H6 | 119.9 | O5—C18—H18B | 110.1 |
O1—C7—C1 | 114.49 (13) | C12—C18—H18B | 110.1 |
O1—C7—H7A | 108.6 | H18A—C18—H18B | 108.4 |
C1—C7—H7A | 108.6 | O5—C19—O6 | 113.18 (12) |
O1—C7—H7B | 108.6 | O5—C19—H19A | 108.9 |
C1—C7—H7B | 108.6 | O6—C19—H19A | 108.9 |
H7A—C7—H7B | 107.6 | O5—C19—H19B | 108.9 |
O1—C8—O2 | 112.61 (12) | O6—C19—H19B | 108.9 |
O1—C8—H8A | 109.1 | H19A—C19—H19B | 107.8 |
O2—C8—H8A | 109.1 | O6—C20—O7 | 112.47 (13) |
O1—C8—H8B | 109.1 | O6—C20—H20A | 109.1 |
O2—C8—H8B | 109.1 | O7—C20—H20A | 109.1 |
H8A—C8—H8B | 107.8 | O6—C20—H20B | 109.1 |
O3—C9—O2 | 112.51 (14) | O7—C20—H20B | 109.1 |
O3—C9—H9A | 109.1 | H20A—C20—H20B | 107.8 |
O2—C9—H9A | 109.1 | O7—C21—O8 | 112.93 (14) |
O3—C9—H9B | 109.1 | O7—C21—H21A | 109.0 |
O2—C9—H9B | 109.1 | O8—C21—H21A | 109.0 |
H9A—C9—H9B | 107.8 | O7—C21—H21B | 109.0 |
O4—C10—O3 | 112.48 (13) | O8—C21—H21B | 109.0 |
O4—C10—H10A | 109.1 | H21A—C21—H21B | 107.8 |
O3—C10—H10A | 109.1 | O8ii—C22—O8 | 112.17 (17) |
O4—C10—H10B | 109.1 | O8ii—C22—H22A | 109.2 |
O3—C10—H10B | 109.1 | O8—C22—H22A | 109.2 |
H10A—C10—H10B | 107.8 | O8ii—C22—H22Aii | 109.2 |
O4i—C11—O4 | 112.51 (18) | O8—C22—H22Aii | 109.2 |
O4i—C11—H11A | 109.1 | H22A—C22—H22Aii | 107.9 |
C6—C1—C2—C3 | 0.53 (19) | C17—C12—C13—C14 | −0.5 (2) |
C7—C1—C2—C3 | −176.29 (13) | C18—C12—C13—C14 | −178.72 (14) |
C1—C2—C3—C4 | 0.2 (2) | C12—C13—C14—C15 | 1.6 (2) |
C2—C3—C4—C5 | −0.6 (2) | C13—C14—C15—C16 | −1.4 (2) |
C3—C4—C5—C6 | 0.2 (3) | C14—C15—C16—C17 | 0.1 (2) |
C2—C1—C6—C5 | −0.8 (2) | C15—C16—C17—C12 | 1.0 (2) |
C7—C1—C6—C5 | 176.02 (14) | C13—C12—C17—C16 | −0.8 (2) |
C4—C5—C6—C1 | 0.5 (2) | C18—C12—C17—C16 | 177.40 (14) |
C8—O1—C7—C1 | −70.30 (15) | C19—O5—C18—C12 | −166.02 (13) |
C6—C1—C7—O1 | 153.78 (13) | C17—C12—C18—O5 | −78.76 (18) |
C2—C1—C7—O1 | −29.47 (18) | C13—C12—C18—O5 | 99.43 (15) |
C7—O1—C8—O2 | −66.13 (14) | C18—O5—C19—O6 | −67.62 (14) |
C9—O2—C8—O1 | −65.52 (14) | C20—O6—C19—O5 | −68.85 (13) |
C10—O3—C9—O2 | −66.41 (13) | C19—O6—C20—O7 | −63.70 (13) |
C8—O2—C9—O3 | −65.90 (13) | C21—O7—C20—O6 | −61.37 (14) |
C11—O4—C10—O3 | −65.99 (13) | C20—O7—C21—O8 | −66.00 (14) |
C9—O3—C10—O4 | −65.11 (13) | C22—O8—C21—O7 | −65.72 (13) |
C10—O4—C11—O4i | −65.55 (9) | C21—O8—C22—O8ii | −63.05 (9) |
Symmetry codes: (i) −x+1, y, −z; (ii) −x+1, y, −z+1. |
D—H···A | D—H | H···A | D···A | D—H···A |
C2—H2···O5 | 0.95 | 2.45 | 3.345 (2) | 158 |
C8—H8A···O7 | 0.99 | 2.59 | 3.510 (2) | 155 |
C10—H10A···O6iii | 0.99 | 2.60 | 3.474 (2) | 148 |
C19—H19B···O2iv | 0.99 | 2.58 | 3.524 (2) | 159 |
C22—H22A···O3v | 0.99 | 2.61 | 3.497 (2) | 149 |
C3—H3···Cg2 | 0.95 | 2.90 | 3.702 | 143 |
C6—H6···Cg2vi | 0.95 | 3.00 | 3.745 | 137 |
C13—H13···Cg1iv | 0.95 | 3.19 | 3.905 | 134 |
C16—H16···Cg1v | 0.95 | 3.06 | 3.705 | 126 |
Symmetry codes: (iii) x, y, z−1; (iv) x, y, z+1; (v) x, y+1, z; (vi) x, y−1, z−1. |
Experimental details
Crystal data | |
Chemical formula | C21H28O8 |
Mr | 408.43 |
Crystal system, space group | Monoclinic, C2 |
Temperature (K) | 178 |
a, b, c (Å) | 47.506 (8), 5.392 (2), 8.288 (2) |
β (°) | 100.38 (2) |
V (Å3) | 2088.3 (10) |
Z | 4 |
Radiation type | Cu Kα |
µ (mm−1) | 0.83 |
Crystal size (mm) | 0.55 × 0.55 × 0.04 |
Data collection | |
Diffractometer | Enraf–Nonius CAD-4 diffractometer |
Absorption correction | Numerical (SHELXTL; Sheldrick, 1996) |
Tmin, Tmax | 0.601, 0.969 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 8436, 3716, 3591 |
Rint | 0.043 |
(sin θ/λ)max (Å−1) | 0.609 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.036, 0.100, 1.08 |
No. of reflections | 3716 |
No. of parameters | 264 |
No. of restraints | 1 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 0.20, −0.15 |
Absolute structure | Flack (1983), with 1511 Friedel pairs |
Absolute structure parameter | 0.12 (15) |
Computer programs: CAD-4 Software (Enraf–Nonius, 1989), CAD-4, MolEN (Fair, 1990), SHELXS97 (Sheldrick, 1997), SHELXL97 (Sheldrick, 1997), SHELXTL (Sheldrick, 1996), SHELXL97.
D—H···A | D—H | H···A | D···A | D—H···A |
C2—H2···O5 | 0.95 | 2.45 | 3.345 (2) | 158 |
C8—H8A···O7 | 0.99 | 2.59 | 3.510 (2) | 155 |
C10—H10A···O6i | 0.99 | 2.60 | 3.474 (2) | 148 |
C19—H19B···O2ii | 0.99 | 2.58 | 3.524 (2) | 159 |
C22—H22A···O3iii | 0.99 | 2.61 | 3.497 (2) | 149 |
C3—H3···Cg2 | 0.95 | 2.90 | 3.702 | 143 |
C6—H6···Cg2iv | 0.95 | 3.00 | 3.745 | 137 |
C13—H13···Cg1ii | 0.95 | 3.19 | 3.905 | 134 |
C16—H16···Cg1iii | 0.95 | 3.06 | 3.705 | 126 |
Symmetry codes: (i) x, y, z−1; (ii) x, y, z+1; (iii) x, y+1, z; (iv) x, y−1, z−1. |
The synthesis of polyoxymethylene helices that are terminated at both ends by phenyl groups has been reported by Noe et al. (1994). We have previously reported the crystal structure of 1,13-diphenyl-2,4,6,8,10,12-hexaoxatridecane (Noe et al., 1994). Here, we report the structure of the related title compound, (I).
Crystals of (I) undergo a reversible phase transition at approximately 155 K, accompanied by a splitting of the reflection profiles in the low-temperature phase. The structure determination of (I) was performed at 178 K, which is well above the phase-transition temperature. The crystal structure of (I) is isomorphous with that of 1,13-diphenyl-2,4,6,8,10,12-hexaoxatridecane (Noe et al., 1994).
The molecular structure of compound (I) is shown in Fig. 1. The compound crystallizes with two independent molecules (A and B), each displaying crystallographic twofold symmetry, with the axis passing through the central CH2 group. The helical molecule has a chiral axis and both independent molecules have the same chirality. There should be no preference for the molecules to adopt left- or right-handed helices, and thus the bulk material is expected to be a racemate that crystallizes into equal amounts of enantiomorphous crystals.
The two independent molecules in (I) have different orientations of the terminal benzyl groups. The phenyl group of molecule A is synperiplanar with the C7—O1 bond [torsion angle C2—C1—C7—O1 = -29.47 (18)°], while the phenyl group of molecule B is almost perpendicular to the C18—O5 bond [torsion angle C17—C12—C18—O5 = -78.76 (18)°]. An almost constant C—O bond length, varying between 1.4067 (17) and 1.4192 (16) Å with an average of 1.413 Å, is observed in the regions C8–C8(1 - x, y, -z) and C19—C19(1 - x, y, 1 - z). The polyoxymethylene helices (without the benzyl groups) behave as rigid bodies with rather large librational motion along the helix axis [51 (2)°2 for molecule A and 45 (2)°2 for molecule B] but with almost no librational motion about axes perpendicular to the molecular axis. The average C—O bond length, corrected for librational motion, is 1.419 Å. A value of 1.420 Å was observed in the structure of the related compound 1,15-diphenylheptaoxapentadecane (Bats et al., 2001). These values are in good agreement with the C—O bond lengths of 1.423 and 1.417 Å obtained from ab initio calculations of dimethoxymethane (Jeffrey et al., 1978) and 1,3-dimethoxydimethyl ether (Sawanobori et al., 2001). A major factor stabilizing the helix structure is the stereoelectronic effect (Kirby, 1983; Deslongchamps, 1984), which results in a preference of gauche conformations (all-g+ or all-g-) over trans conformations for the conjugated C—O bonds. The helix is also stabilized by intramolecular 1→4 C—H···O interactions. The helix of molecule A shows 14 such interactions with H···O distances between 2.54 and 2.57 Å, while the helix of molecule B shows 12 interactions with H···O distances between 2.50 and 2.61 Å.
No stereoelectronic effects are expected for the terminal O—Cbenzyl bonds. Those bond lengths are 1.4276 (19) and 1.4360 (16) Å, respectively, and thus are significantly longer than the remaining C—O bonds. The O1—C8 and O5—C19 bonds in (I) are surprisingly short, at 1.3985 (16) and 1.3981 (16) Å, respectively. This bond shortening at the ends of the helices is significant, but its origin is not clearly understood. However, this bond-length variation is reproduced in the ab initio calculation of 1,3-dimethoxydimethyl ether (Sawanobori et al., 2001).
The C—O—C bond angles in (I) range between 113.47 (10) and 114.40 (9)° and are almost constant, with an average value of 114.20°. The O—C—O angles range between 112.17 (17) and 113.18 (12)° and these values are also almost constant, with an average value of 112.62°. The C—O—C—O torsion angles vary between -61.37 (14) and -68.85 (13)°, with an average value of -65.50°. Almost constant torsion angles, corresponding to an undisturbed helix, are found in molecule A. The helix of molecule B is slightly bent, resulting in deviations of the C—O—C—O torsion angles by up to 4° from their average value.
The crystal packing in (I), shown in Fig. 2, is stabilized by a number of intermolecular C—H···O and C—H···π(phenyl) interactions. Each molecule A is connected to four symmetry-related molecules B, and each molecule B is connected to four symmetry-related molecules A. There are no contacts between molecules A or between molecules B. The molecules are arranged by these intermolecular interactions to form layers parallel to (100). The C—H···O contacts with H···O distances of less than 2.61 Å are reported in Table 1. This cut-off value was chosen arbitrarily and there are several additional contacts with still longer distances. The molecules in the layers are also connected by weak intermolecular C(phenyl)—H···π(phenyl) interactions, which have been included in Table 1 (Cg1 and Cg2 represent the centroids of the phenyl rings of molecules A and B). The C—H donor groups do not point to the midpoint of the acceptor phenyl groups but instead are closer to individual C atoms of the acceptor rings. The shortest H···C distances for the four contacts are 2.92, 2.84, 2.94 and 2.86 Å. There are no short intermolecular contacts between the layers along the a direction.