Supporting information
Crystallographic Information File (CIF) https://doi.org/10.1107/S160053680300134X/bt6231sup1.cif | |
Structure factor file (CIF format) https://doi.org/10.1107/S160053680300134X/bt6231Isup2.hkl |
CCDC reference: 204711
Key indicators
- Single-crystal X-ray study
- T = 178 K
- Mean (C-C) = 0.002 Å
- R factor = 0.038
- wR factor = 0.099
- Data-to-parameter ratio = 13.0
checkCIF results
No syntax errors found ADDSYM reports no extra symmetry
Alert Level C:
PLAT_371 Alert C Long C(sp2)-C(sp1) Bond C(6) - C(19) = 1.43 Ang. PLAT_710 Alert C Delete 1-2-3 or 2-3-4 (CIF) Linear Torsion Angle # 65 C5 -C6 -C19 -N1 108.00 6.00 1.555 1.555 1.555 1.555 PLAT_710 Alert C Delete 1-2-3 or 2-3-4 (CIF) Linear Torsion Angle # 66 C7 -C6 -C19 -N1 -69.00 7.00 1.555 1.555 1.555 1.555 PLAT_710 Alert C Delete 1-2-3 or 2-3-4 (CIF) Linear Torsion Angle # 67 C6 -C7 -C20 -N2 -66.00 3.00 1.555 1.555 1.555 1.555 PLAT_710 Alert C Delete 1-2-3 or 2-3-4 (CIF) Linear Torsion Angle # 68 C8 -C7 -C20 -N2 178.00100.00 1.555 1.555 1.555 1.555 PLAT_710 Alert C Delete 1-2-3 or 2-3-4 (CIF) Linear Torsion Angle # 69 C1 -C7 -C20 -N2 68.00 3.00 1.555 1.555 1.555 1.555
0 Alert Level A = Potentially serious problem
0 Alert Level B = Potential problem
6 Alert Level C = Please check
A toluene solution of (1) was heated at 503 K for 24 h in a sealed ampoule, leading to two isomerization products in the ratio 9:1. These were separated by thick-layer chromatography and the major product [(2); 10% yield] was recrystallized from chloroform/pentane (Witulski, 1992).
H atoms were included using a riding model with fixed C—H bond lengths (sp2 C—H = 0.95 Å and methine C—H = 1.00 Å); Uiso(H) values were fixed at 1.2Ueq of the parent atom.
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, 1996); software used to prepare material for publication: SHELXL97.
C20H12N2 | F(000) = 1168 |
Mr = 280.32 | Dx = 1.272 Mg m−3 |
Monoclinic, C2/c | Mo Kα radiation, λ = 0.71073 Å |
a = 15.834 (5) Å | Cell parameters from 50 reflections |
b = 8.196 (3) Å | θ = 10–11.5° |
c = 22.849 (7) Å | µ = 0.08 mm−1 |
β = 99.11 (3)° | T = 178 K |
V = 2927.8 (17) Å3 | Prism, colourless |
Z = 8 | 0.7 × 0.4 × 0.4 mm |
Nicolet R3 diffractometer | Rint = 0.026 |
Radiation source: fine-focus sealed tube | θmax = 25.1°, θmin = 3.0° |
Graphite monochromator | h = −18→18 |
ω scans | k = −9→1 |
2674 measured reflections | l = −27→0 |
2596 independent reflections | 3 standard reflections every 147 reflections |
1938 reflections with I > 2σ(I) | intensity decay: none |
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)] = 0.038 | H-atom parameters constrained |
wR(F2) = 0.099 | w = 1/[σ2(Fo2) + (0.0374P)2 + 2.4161P] where P = (Fo2 + 2Fc2)/3 |
S = 1.05 | (Δ/σ)max < 0.001 |
2596 reflections | Δρmax = 0.18 e Å−3 |
200 parameters | Δρmin = −0.17 e Å−3 |
0 restraints | Extinction correction: SHELXL97, Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4 |
Primary atom site location: structure-invariant direct methods | Extinction coefficient: 0.0026 (4) |
C20H12N2 | V = 2927.8 (17) Å3 |
Mr = 280.32 | Z = 8 |
Monoclinic, C2/c | Mo Kα radiation |
a = 15.834 (5) Å | µ = 0.08 mm−1 |
b = 8.196 (3) Å | T = 178 K |
c = 22.849 (7) Å | 0.7 × 0.4 × 0.4 mm |
β = 99.11 (3)° |
Nicolet R3 diffractometer | Rint = 0.026 |
2674 measured reflections | 3 standard reflections every 147 reflections |
2596 independent reflections | intensity decay: none |
1938 reflections with I > 2σ(I) |
R[F2 > 2σ(F2)] = 0.038 | 0 restraints |
wR(F2) = 0.099 | H-atom parameters constrained |
S = 1.05 | Δρmax = 0.18 e Å−3 |
2596 reflections | Δρmin = −0.17 e Å−3 |
200 parameters |
Experimental. 9,10-Dicyano-dibenzoisobullvalene |
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 | ||
C1 | 0.62156 (10) | 0.4401 (2) | 0.37959 (7) | 0.0289 (4) | |
H1 | 0.5901 | 0.3389 | 0.3876 | 0.035* | |
C2 | 0.56634 (10) | 0.5927 (2) | 0.37461 (7) | 0.0283 (4) | |
C3 | 0.59356 (10) | 0.7307 (2) | 0.34623 (7) | 0.0271 (4) | |
C4 | 0.66646 (10) | 0.7094 (2) | 0.31056 (7) | 0.0288 (4) | |
H4 | 0.6948 | 0.8144 | 0.3027 | 0.035* | |
C5 | 0.62233 (11) | 0.6265 (2) | 0.25504 (7) | 0.0305 (4) | |
H5 | 0.5987 | 0.6808 | 0.2195 | 0.037* | |
C6 | 0.62157 (10) | 0.4659 (2) | 0.26351 (7) | 0.0296 (4) | |
C7 | 0.66999 (10) | 0.4247 (2) | 0.32454 (7) | 0.0278 (4) | |
C8 | 0.73065 (10) | 0.5747 (2) | 0.33685 (7) | 0.0285 (4) | |
H8 | 0.7809 | 0.5670 | 0.3154 | 0.034* | |
C9 | 0.75689 (10) | 0.5694 (2) | 0.40309 (7) | 0.0293 (4) | |
C10 | 0.69658 (11) | 0.4803 (2) | 0.42803 (7) | 0.0299 (4) | |
C11 | 0.49434 (11) | 0.6034 (2) | 0.40200 (7) | 0.0320 (4) | |
H11 | 0.4751 | 0.5101 | 0.4208 | 0.038* | |
C12 | 0.45032 (11) | 0.7503 (2) | 0.40203 (7) | 0.0349 (4) | |
H12 | 0.4015 | 0.7575 | 0.4213 | 0.042* | |
C13 | 0.47727 (11) | 0.8854 (2) | 0.37419 (7) | 0.0349 (4) | |
H13 | 0.4470 | 0.9854 | 0.3743 | 0.042* | |
C14 | 0.54855 (11) | 0.8754 (2) | 0.34606 (7) | 0.0309 (4) | |
H14 | 0.5666 | 0.9685 | 0.3266 | 0.037* | |
C15 | 0.82791 (11) | 0.6344 (2) | 0.43847 (8) | 0.0357 (4) | |
H15 | 0.8684 | 0.6974 | 0.4217 | 0.043* | |
C16 | 0.83880 (13) | 0.6055 (2) | 0.49907 (8) | 0.0422 (5) | |
H16 | 0.8874 | 0.6485 | 0.5240 | 0.051* | |
C17 | 0.77980 (13) | 0.5150 (2) | 0.52326 (8) | 0.0447 (5) | |
H17 | 0.7889 | 0.4948 | 0.5647 | 0.054* | |
C18 | 0.70698 (12) | 0.4524 (2) | 0.48829 (8) | 0.0381 (4) | |
H18 | 0.6657 | 0.3924 | 0.5054 | 0.046* | |
C19 | 0.58425 (11) | 0.3468 (2) | 0.22176 (8) | 0.0350 (4) | |
C20 | 0.71256 (11) | 0.2655 (2) | 0.32669 (7) | 0.0313 (4) | |
N1 | 0.55640 (11) | 0.2497 (2) | 0.18800 (8) | 0.0510 (5) | |
N2 | 0.74157 (10) | 0.1374 (2) | 0.32778 (7) | 0.0424 (4) |
U11 | U22 | U33 | U12 | U13 | U23 | |
C1 | 0.0314 (9) | 0.0267 (9) | 0.0301 (9) | 0.0004 (7) | 0.0096 (7) | 0.0014 (7) |
C2 | 0.0298 (9) | 0.0297 (9) | 0.0256 (8) | 0.0005 (7) | 0.0052 (7) | −0.0022 (7) |
C3 | 0.0284 (8) | 0.0292 (9) | 0.0237 (8) | −0.0014 (7) | 0.0039 (6) | −0.0022 (7) |
C4 | 0.0309 (9) | 0.0285 (9) | 0.0283 (8) | −0.0018 (7) | 0.0084 (7) | 0.0016 (7) |
C5 | 0.0310 (9) | 0.0377 (10) | 0.0238 (8) | 0.0011 (8) | 0.0077 (7) | 0.0008 (7) |
C6 | 0.0272 (9) | 0.0357 (10) | 0.0266 (8) | −0.0004 (7) | 0.0065 (7) | −0.0038 (7) |
C7 | 0.0272 (9) | 0.0300 (9) | 0.0267 (8) | 0.0011 (7) | 0.0058 (7) | −0.0022 (7) |
C8 | 0.0256 (8) | 0.0310 (9) | 0.0297 (9) | −0.0004 (7) | 0.0072 (7) | −0.0024 (7) |
C9 | 0.0297 (9) | 0.0295 (9) | 0.0288 (9) | 0.0055 (7) | 0.0048 (7) | −0.0021 (7) |
C10 | 0.0352 (9) | 0.0274 (9) | 0.0271 (8) | 0.0055 (7) | 0.0056 (7) | 0.0000 (7) |
C11 | 0.0308 (9) | 0.0351 (10) | 0.0314 (9) | −0.0017 (7) | 0.0096 (7) | 0.0011 (7) |
C12 | 0.0305 (9) | 0.0424 (11) | 0.0329 (9) | 0.0047 (8) | 0.0084 (7) | −0.0011 (8) |
C13 | 0.0346 (10) | 0.0357 (10) | 0.0341 (10) | 0.0070 (8) | 0.0048 (8) | −0.0027 (8) |
C14 | 0.0347 (9) | 0.0303 (9) | 0.0270 (9) | −0.0001 (8) | 0.0032 (7) | 0.0003 (7) |
C15 | 0.0334 (9) | 0.0353 (10) | 0.0371 (10) | 0.0034 (8) | 0.0021 (8) | −0.0074 (8) |
C16 | 0.0428 (11) | 0.0450 (12) | 0.0351 (10) | 0.0085 (9) | −0.0055 (8) | −0.0073 (9) |
C17 | 0.0583 (13) | 0.0455 (12) | 0.0276 (9) | 0.0122 (10) | −0.0019 (9) | −0.0008 (8) |
C18 | 0.0476 (11) | 0.0346 (10) | 0.0331 (10) | 0.0079 (9) | 0.0091 (8) | 0.0047 (8) |
C19 | 0.0324 (9) | 0.0383 (10) | 0.0339 (10) | 0.0041 (8) | 0.0036 (8) | −0.0053 (8) |
C20 | 0.0298 (9) | 0.0345 (10) | 0.0307 (9) | −0.0016 (8) | 0.0084 (7) | −0.0030 (8) |
N1 | 0.0527 (11) | 0.0486 (10) | 0.0487 (10) | 0.0023 (9) | −0.0009 (8) | −0.0153 (9) |
N2 | 0.0442 (9) | 0.0359 (9) | 0.0498 (10) | 0.0050 (8) | 0.0159 (8) | −0.0010 (8) |
C1—C2 | 1.520 (2) | C9—C15 | 1.383 (2) |
C1—C10 | 1.526 (2) | C9—C10 | 1.394 (2) |
C1—C7 | 1.578 (2) | C10—C18 | 1.380 (2) |
C1—H1 | 1.0000 | C11—C12 | 1.391 (2) |
C2—C11 | 1.387 (2) | C11—H11 | 0.9500 |
C2—C3 | 1.405 (2) | C12—C13 | 1.378 (2) |
C3—C14 | 1.383 (2) | C12—H12 | 0.9500 |
C3—C4 | 1.525 (2) | C13—C14 | 1.387 (2) |
C4—C5 | 1.509 (2) | C13—H13 | 0.9500 |
C4—C8 | 1.555 (2) | C14—H14 | 0.9500 |
C4—H4 | 1.0000 | C15—C16 | 1.388 (3) |
C5—C6 | 1.331 (2) | C15—H15 | 0.9500 |
C5—H5 | 0.9500 | C16—C17 | 1.375 (3) |
C6—C19 | 1.426 (2) | C16—H16 | 0.9500 |
C6—C7 | 1.519 (2) | C17—C18 | 1.393 (3) |
C7—C20 | 1.466 (2) | C17—H17 | 0.9500 |
C7—C8 | 1.558 (2) | C18—H18 | 0.9500 |
C8—C9 | 1.506 (2) | C19—N1 | 1.147 (2) |
C8—H8 | 1.0000 | C20—N2 | 1.144 (2) |
C2—C1—C10 | 104.45 (13) | C4—C8—H8 | 112.1 |
C2—C1—C7 | 110.65 (13) | C7—C8—H8 | 112.1 |
C10—C1—C7 | 100.06 (13) | C15—C9—C10 | 120.60 (16) |
C2—C1—H1 | 113.5 | C15—C9—C8 | 130.24 (16) |
C10—C1—H1 | 113.5 | C10—C9—C8 | 109.15 (14) |
C7—C1—H1 | 113.5 | C18—C10—C9 | 120.89 (16) |
C11—C2—C3 | 119.44 (15) | C18—C10—C1 | 130.13 (16) |
C11—C2—C1 | 121.48 (15) | C9—C10—C1 | 108.76 (14) |
C3—C2—C1 | 118.82 (14) | C2—C11—C12 | 120.14 (16) |
C14—C3—C2 | 119.73 (15) | C2—C11—H11 | 119.9 |
C14—C3—C4 | 122.01 (15) | C12—C11—H11 | 119.9 |
C2—C3—C4 | 117.90 (14) | C13—C12—C11 | 120.22 (16) |
C5—C4—C3 | 102.23 (13) | C13—C12—H12 | 119.9 |
C5—C4—C8 | 101.09 (13) | C11—C12—H12 | 119.9 |
C3—C4—C8 | 112.25 (13) | C12—C13—C14 | 120.05 (16) |
C5—C4—H4 | 113.4 | C12—C13—H13 | 120.0 |
C3—C4—H4 | 113.4 | C14—C13—H13 | 120.0 |
C8—C4—H4 | 113.4 | C3—C14—C13 | 120.41 (16) |
C6—C5—C4 | 109.66 (15) | C3—C14—H14 | 119.8 |
C6—C5—H5 | 125.2 | C13—C14—H14 | 119.8 |
C4—C5—H5 | 125.2 | C9—C15—C16 | 118.57 (18) |
C5—C6—C19 | 126.30 (16) | C9—C15—H15 | 120.7 |
C5—C6—C7 | 109.81 (15) | C16—C15—H15 | 120.7 |
C19—C6—C7 | 123.86 (15) | C17—C16—C15 | 120.53 (18) |
C20—C7—C6 | 113.04 (14) | C17—C16—H16 | 119.7 |
C20—C7—C8 | 115.43 (14) | C15—C16—H16 | 119.7 |
C6—C7—C8 | 101.37 (13) | C16—C17—C18 | 121.41 (17) |
C20—C7—C1 | 108.87 (13) | C16—C17—H17 | 119.3 |
C6—C7—C1 | 118.38 (13) | C18—C17—H17 | 119.3 |
C8—C7—C1 | 98.99 (13) | C10—C18—C17 | 117.97 (18) |
C9—C8—C4 | 117.90 (13) | C10—C18—H18 | 121.0 |
C9—C8—C7 | 102.89 (13) | C17—C18—H18 | 121.0 |
C4—C8—C7 | 98.28 (13) | N1—C19—C6 | 178.15 (19) |
C9—C8—H8 | 112.1 | N2—C20—C7 | 176.35 (18) |
C10—C1—C2—C11 | −99.04 (18) | C20—C7—C8—C4 | 162.38 (14) |
C7—C1—C2—C11 | 154.11 (15) | C6—C7—C8—C4 | 39.86 (14) |
C10—C1—C2—C3 | 75.00 (18) | C1—C7—C8—C4 | −81.65 (13) |
C7—C1—C2—C3 | −31.9 (2) | C4—C8—C9—C15 | −96.1 (2) |
C11—C2—C3—C14 | 0.2 (2) | C7—C8—C9—C15 | 157.18 (17) |
C1—C2—C3—C14 | −173.99 (14) | C4—C8—C9—C10 | 85.08 (18) |
C11—C2—C3—C4 | −173.04 (15) | C7—C8—C9—C10 | −21.67 (17) |
C1—C2—C3—C4 | 12.8 (2) | C15—C9—C10—C18 | −1.1 (3) |
C14—C3—C4—C5 | −97.02 (18) | C8—C9—C10—C18 | 177.90 (15) |
C2—C3—C4—C5 | 76.03 (17) | C15—C9—C10—C1 | 174.09 (15) |
C14—C3—C4—C8 | 155.44 (15) | C8—C9—C10—C1 | −6.93 (18) |
C2—C3—C4—C8 | −31.5 (2) | C2—C1—C10—C18 | 92.0 (2) |
C3—C4—C5—C6 | −86.22 (16) | C7—C1—C10—C18 | −153.41 (18) |
C8—C4—C5—C6 | 29.71 (17) | C2—C1—C10—C9 | −82.55 (16) |
C4—C5—C6—C19 | 178.75 (15) | C7—C1—C10—C9 | 32.01 (17) |
C4—C5—C6—C7 | −3.36 (19) | C3—C2—C11—C12 | −0.9 (2) |
C5—C6—C7—C20 | −148.48 (15) | C1—C2—C11—C12 | 173.08 (15) |
C19—C6—C7—C20 | 29.5 (2) | C2—C11—C12—C13 | 0.9 (3) |
C5—C6—C7—C8 | −24.32 (17) | C11—C12—C13—C14 | −0.1 (3) |
C19—C6—C7—C8 | 153.62 (15) | C2—C3—C14—C13 | 0.6 (2) |
C5—C6—C7—C1 | 82.52 (19) | C4—C3—C14—C13 | 173.54 (15) |
C19—C6—C7—C1 | −99.53 (19) | C12—C13—C14—C3 | −0.7 (2) |
C2—C1—C7—C20 | −172.02 (13) | C10—C9—C15—C16 | 1.5 (3) |
C10—C1—C7—C20 | 78.24 (15) | C8—C9—C15—C16 | −177.21 (16) |
C2—C1—C7—C6 | −41.1 (2) | C9—C15—C16—C17 | −0.4 (3) |
C10—C1—C7—C6 | −150.85 (14) | C15—C16—C17—C18 | −1.2 (3) |
C2—C1—C7—C8 | 67.08 (15) | C9—C10—C18—C17 | −0.5 (3) |
C10—C1—C7—C8 | −42.65 (14) | C1—C10—C18—C17 | −174.51 (17) |
C5—C4—C8—C9 | −151.13 (14) | C16—C17—C18—C10 | 1.6 (3) |
C3—C4—C8—C9 | −42.87 (19) | C5—C6—C19—N1 | 108 (6) |
C5—C4—C8—C7 | −41.74 (14) | C7—C6—C19—N1 | −69 (7) |
C3—C4—C8—C7 | 66.53 (15) | C6—C7—C20—N2 | −66 (3) |
C20—C7—C8—C9 | −76.39 (16) | C8—C7—C20—N2 | 178 (100) |
C6—C7—C8—C9 | 161.08 (12) | C1—C7—C20—N2 | 68 (3) |
C1—C7—C8—C9 | 39.57 (15) |
D—H···A | D—H | H···A | D···A | D—H···A |
C13—H13···N1i | 0.95 | 2.59 | 3.314 (3) | 134 |
Symmetry code: (i) −x+1, y+1, −z+1/2. |
Experimental details
Crystal data | |
Chemical formula | C20H12N2 |
Mr | 280.32 |
Crystal system, space group | Monoclinic, C2/c |
Temperature (K) | 178 |
a, b, c (Å) | 15.834 (5), 8.196 (3), 22.849 (7) |
β (°) | 99.11 (3) |
V (Å3) | 2927.8 (17) |
Z | 8 |
Radiation type | Mo Kα |
µ (mm−1) | 0.08 |
Crystal size (mm) | 0.7 × 0.4 × 0.4 |
Data collection | |
Diffractometer | Nicolet R3 diffractometer |
Absorption correction | – |
No. of measured, independent and observed [I > 2σ(I)] reflections | 2674, 2596, 1938 |
Rint | 0.026 |
(sin θ/λ)max (Å−1) | 0.596 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.038, 0.099, 1.05 |
No. of reflections | 2596 |
No. of parameters | 200 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 0.18, −0.17 |
Computer programs: P3 (Nicolet, 1987), P3, XDISK (Nicolet, 1987), SHELXS97 (Sheldrick, 1990), SHELXL97 (Sheldrick, 1997), XP (Siemens, 1996), SHELXL97.
C1—C7 | 1.578 (2) | C5—C6 | 1.331 (2) |
C6—C5—C4 | 109.66 (15) | C4—C8—C7 | 98.28 (13) |
C5—C6—C7 | 109.81 (15) | C15—C9—C8 | 130.24 (16) |
C8—C7—C1 | 98.99 (13) | C18—C10—C1 | 130.13 (16) |
D—H···A | D—H | H···A | D···A | D—H···A |
C13—H13···N1i | 0.95 | 2.59 | 3.314 (3) | 134 |
Symmetry code: (i) −x+1, y+1, −z+1/2. |
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Recently, we described the crystal structure of 9,10-dicyanodibenzoisobullvalene [(1); Jones et al., 2003]. Since the polycyclic carbon skeleton of (1) contains a vinylcyclopropane subunit, which, in principle, can undergo a ring-opening reaction, we decided to pyrolyze (1) (Witulski, 1992). We describe here the structure of the main isomerization product, (2).
The molecule of (2) is shown in Fig. 1. The strain imposed by the fused-ring system is apparent in, for example, the lengthened single bond C1—C7, the narrow sp2 angles C4—C5—C6/C5—C6—C7 and sp3 angles C1—C7—C8/C4—C8—C7, and the widened sp3 angles C8—C9—C15/C1—C10—C18 (Table 1).
The molecules are linked to form ribbons parallel to the b axis by a weak C—H···N hydrogen bond (Table 2) and then, more strikingly, crosslinked by two C—H···π interactions to the centroid (cent) of the ring C2/C3/C11–C14, to form layers perpendicular to [101]; C5—H5···cent, with H···cent = 2.55 Å and C—H···cent = 153° for the operator 1 − x, y, 0.5 − z, and C16—H16···cent, with H···cent = 2.58 Å and C—H···cent = 155° for the operator 1.5 − x, 1.5 − y, −z. The C—H distances were normalized to 1.08 Å to calculate these values. The packing diagram is shown as Fig. 2.