The molecule of the title compound, C10H14, displays inversion symmetry. The allenic bond lengths are 1.3067 (16) and 1.3126 (16) Å.
Supporting information
CCDC reference: 182618
Key indicators
- Single-crystal X-ray study
- T = 178 K
- Mean (C-C) = 0.002 Å
- R factor = 0.041
- wR factor = 0.121
- Data-to-parameter ratio = 14.0
checkCIF results
No syntax errors found
ADDSYM reports no extra symmetry
Crystals were grown by sublimation.
A rigid-body libration correction (Shomaker & Trueblood, 1968) was performed
successfully (Rlib 0.078) and gave the following corrected bond
lengths (Å): C1—C2 1.518, C2—C3 1.518, C5—C5i 1.477 Å. The
corrections to the other bonds, C2—C4 and C4—C5, were calculated as zero,
which is consistent with the expected libration pattern of the molecule.
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.
Crystal data top
C10H14 | F(000) = 148 |
Mr = 134.21 | Dx = 0.982 Mg m−3 |
Monoclinic, P21/n | Mo Kα radiation, λ = 0.71073 Å |
a = 4.644 (2) Å | Cell parameters from 50 reflections |
b = 16.278 (6) Å | θ = 10–12.5° |
c = 6.037 (2) Å | µ = 0.06 mm−1 |
β = 96.12 (3)° | T = 178 K |
V = 453.8 (3) Å3 | Prism, colourless |
Z = 2 | 0.70 × 0.25 × 0.25 mm |
Data collection top
Siemens R3 diffractometer | Rint = 0.020 |
Radiation source: fine-focus sealed tube | θmax = 27.5°, θmin = 3.6° |
Graphite monochromator | h = −5→6 |
ω scans | k = −21→21 |
2589 measured reflections | l = −7→7 |
1034 independent reflections | 3 standard reflections every 147 reflections |
810 reflections with I > 2σ(I) | intensity decay: none |
Refinement top
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)] = 0.041 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.121 | All H-atom parameters refined |
S = 1.06 | w = 1/[σ2(Fo2) + (0.0677P)2 + 0.0479P] where P = (Fo2 + 2Fc2)/3 |
1034 reflections | (Δ/σ)max < 0.001 |
74 parameters | Δρmax = 0.14 e Å−3 |
0 restraints | Δρmin = −0.16 e Å−3 |
Crystal data top
C10H14 | V = 453.8 (3) Å3 |
Mr = 134.21 | Z = 2 |
Monoclinic, P21/n | Mo Kα radiation |
a = 4.644 (2) Å | µ = 0.06 mm−1 |
b = 16.278 (6) Å | T = 178 K |
c = 6.037 (2) Å | 0.70 × 0.25 × 0.25 mm |
β = 96.12 (3)° | |
Data collection top
Siemens R3 diffractometer | Rint = 0.020 |
2589 measured reflections | 3 standard reflections every 147 reflections |
1034 independent reflections | intensity decay: none |
810 reflections with I > 2σ(I) | |
Refinement top
R[F2 > 2σ(F2)] = 0.041 | 0 restraints |
wR(F2) = 0.121 | All H-atom parameters refined |
S = 1.06 | Δρmax = 0.14 e Å−3 |
1034 reflections | Δρmin = −0.16 e Å−3 |
74 parameters | |
Special details top
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. |
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top | x | y | z | Uiso*/Ueq | |
C1 | 0.9699 (3) | 0.29882 (7) | 0.2239 (2) | 0.0435 (3) | |
H1A | 0.908 (3) | 0.2896 (9) | 0.057 (3) | 0.062 (4)* | |
H1B | 0.919 (3) | 0.2496 (9) | 0.308 (3) | 0.058 (4)* | |
H1C | 1.186 (3) | 0.3043 (9) | 0.247 (2) | 0.058 (4)* | |
C2 | 0.8269 (2) | 0.37303 (6) | 0.31388 (18) | 0.0354 (3) | |
C3 | 0.9107 (4) | 0.39192 (9) | 0.5565 (2) | 0.0508 (4) | |
H3C | 1.124 (4) | 0.4009 (11) | 0.588 (3) | 0.075 (5)* | |
H3B | 0.871 (4) | 0.3444 (10) | 0.649 (3) | 0.072 (5)* | |
H3A | 0.804 (3) | 0.4399 (11) | 0.605 (3) | 0.070 (5)* | |
C4 | 0.6431 (2) | 0.41832 (7) | 0.18845 (18) | 0.0377 (3) | |
C5 | 0.4587 (2) | 0.46394 (7) | 0.06268 (18) | 0.0383 (3) | |
H5 | 0.252 (3) | 0.4512 (8) | 0.051 (2) | 0.045 (3)* | |
Atomic displacement parameters (Å2) top | U11 | U22 | U33 | U12 | U13 | U23 |
C1 | 0.0457 (7) | 0.0366 (6) | 0.0467 (7) | 0.0021 (5) | −0.0024 (5) | 0.0007 (5) |
C2 | 0.0357 (6) | 0.0343 (5) | 0.0359 (6) | −0.0042 (4) | 0.0017 (4) | 0.0034 (4) |
C3 | 0.0689 (9) | 0.0458 (7) | 0.0362 (6) | −0.0017 (6) | −0.0016 (6) | 0.0028 (5) |
C4 | 0.0371 (6) | 0.0385 (6) | 0.0381 (6) | −0.0011 (4) | 0.0057 (4) | −0.0003 (4) |
C5 | 0.0332 (6) | 0.0411 (6) | 0.0409 (6) | 0.0017 (4) | 0.0051 (4) | 0.0020 (4) |
Geometric parameters (Å, º) top
C1—C2 | 1.5076 (17) | C3—H3C | 1.001 (19) |
C1—H1A | 1.026 (17) | C3—H3B | 0.986 (17) |
C1—H1B | 0.990 (16) | C3—H3A | 0.987 (18) |
C1—H1C | 1.004 (15) | C4—C5 | 1.3126 (16) |
C2—C4 | 1.3067 (16) | C5—C5i | 1.470 (2) |
C2—C3 | 1.5067 (17) | C5—H5 | 0.977 (13) |
| | | |
C2—C1—H1A | 112.5 (8) | C2—C3—H3B | 110.4 (10) |
C2—C1—H1B | 109.0 (9) | H3C—C3—H3B | 104.5 (14) |
H1A—C1—H1B | 109.1 (11) | C2—C3—H3A | 111.4 (9) |
C2—C1—H1C | 110.6 (9) | H3C—C3—H3A | 110.3 (14) |
H1A—C1—H1C | 108.6 (12) | H3B—C3—H3A | 108.7 (14) |
H1B—C1—H1C | 106.8 (12) | C2—C4—C5 | 179.89 (13) |
C4—C2—C3 | 122.22 (11) | C4—C5—C5i | 124.04 (13) |
C4—C2—C1 | 121.93 (10) | C4—C5—H5 | 119.8 (8) |
C3—C2—C1 | 115.85 (10) | C5i—C5—H5 | 116.2 (8) |
C2—C3—H3C | 111.3 (10) | | |
Symmetry code: (i) −x+1, −y+1, −z. |
Experimental details
Crystal data |
Chemical formula | C10H14 |
Mr | 134.21 |
Crystal system, space group | Monoclinic, P21/n |
Temperature (K) | 178 |
a, b, c (Å) | 4.644 (2), 16.278 (6), 6.037 (2) |
β (°) | 96.12 (3) |
V (Å3) | 453.8 (3) |
Z | 2 |
Radiation type | Mo Kα |
µ (mm−1) | 0.06 |
Crystal size (mm) | 0.70 × 0.25 × 0.25 |
|
Data collection |
Diffractometer | Siemens R3 diffractometer |
Absorption correction | – |
No. of measured, independent and observed [I > 2σ(I)] reflections | 2589, 1034, 810 |
Rint | 0.020 |
(sin θ/λ)max (Å−1) | 0.650 |
|
Refinement |
R[F2 > 2σ(F2)], wR(F2), S | 0.041, 0.121, 1.06 |
No. of reflections | 1034 |
No. of parameters | 74 |
H-atom treatment | All H-atom parameters refined |
Δρmax, Δρmin (e Å−3) | 0.14, −0.16 |
Selected geometric parameters (Å, º) topC1—C2 | 1.5076 (17) | C4—C5 | 1.3126 (16) |
C2—C4 | 1.3067 (16) | C5—C5i | 1.470 (2) |
C2—C3 | 1.5067 (17) | | |
| | | |
C4—C2—C3 | 122.22 (11) | C2—C4—C5 | 179.89 (13) |
C4—C2—C1 | 121.93 (10) | C4—C5—C5i | 124.04 (13) |
C3—C2—C1 | 115.85 (10) | | |
Symmetry code: (i) −x+1, −y+1, −z. |
Conjugated bis-allenes are interesting starting materials in organic chemistry and have been used, in particular, as diene components in Diels–Alder addition (for a summary, see Hopf, 2000). In a study of the behaviour of bis-allenes in ionic reaction, we have prepared one of the oldest known bis-allenes, the title compound 2,7-dimethyl-octa-2,3,5,6-tetraene, (I) (Skattebøl & Solomon, 1965), and subjected it to structure determination.
The molecule (Fig. 1) displays crystallographic inversion symmetry, because of which the standard IUPAC numbering was not used. Molecular dimensions may be regarded as normal [cf. e.g. the standard allenic C═C bond length of 1.307 Å (Allen et al., 1987)]. The allenic angle C2—C4—C5 is essentially linear at 179.89 (13)° and the angle C4—C5—C5i 124.04 (13)° somewhat wider than the standard sp2 value [symmetry code: (i) 1 - x, 1 - y, -z]. The shortest intermolecular contact is H1A···H1C(-0.5 + x, 0.5 - y, -0.5 + z) 2.55 (2) Å, and the molecules pack in the common herring-bone pattern (Fig. 2).