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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

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S1600536802002696/bt6111sup1.cif
Contains datablocks I, global

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S1600536802002696/bt6111Isup2.hkl
Contains datablock I

CCDC reference: 182618

Key indicators

  • Single-crystal X-ray study
  • T = 178 K
  • Mean [sigma](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








Comment top

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 CC 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).

Experimental top

Crystals were grown by sublimation.

Refinement top

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.

Computing details top

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.

Figures top
[Figure 1] Fig. 1. The molecule of the title compound in the crystal. Ellipsoids represent 50% probability levels.
[Figure 2] Fig. 2. Packing diagram of the title compound projected along the x axis. Radii are arbitrary.
(I) top
Crystal data top
C10H14F(000) = 148
Mr = 134.21Dx = 0.982 Mg m3
Monoclinic, P21/nMo Kα radiation, λ = 0.71073 Å
a = 4.644 (2) ÅCell parameters from 50 reflections
b = 16.278 (6) Åθ = 10–12.5°
c = 6.037 (2) ŵ = 0.06 mm1
β = 96.12 (3)°T = 178 K
V = 453.8 (3) Å3Prism, colourless
Z = 20.70 × 0.25 × 0.25 mm
Data collection top
Siemens R3
diffractometer
Rint = 0.020
Radiation source: fine-focus sealed tubeθmax = 27.5°, θmin = 3.6°
Graphite monochromatorh = 56
ω scansk = 2121
2589 measured reflectionsl = 77
1034 independent reflections3 standard reflections every 147 reflections
810 reflections with I > 2σ(I) intensity decay: none
Refinement top
Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.041Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.121All 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 parametersΔρmax = 0.14 e Å3
0 restraintsΔρmin = 0.16 e Å3
Crystal data top
C10H14V = 453.8 (3) Å3
Mr = 134.21Z = 2
Monoclinic, P21/nMo Kα radiation
a = 4.644 (2) ŵ = 0.06 mm1
b = 16.278 (6) ÅT = 178 K
c = 6.037 (2) Å0.70 × 0.25 × 0.25 mm
β = 96.12 (3)°
Data collection top
Siemens R3
diffractometer
Rint = 0.020
2589 measured reflections3 standard reflections every 147 reflections
1034 independent reflections intensity decay: none
810 reflections with I > 2σ(I)
Refinement top
R[F2 > 2σ(F2)] = 0.0410 restraints
wR(F2) = 0.121All H-atom parameters refined
S = 1.06Δρmax = 0.14 e Å3
1034 reflectionsΔρmin = 0.16 e Å3
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
xyzUiso*/Ueq
C10.9699 (3)0.29882 (7)0.2239 (2)0.0435 (3)
H1A0.908 (3)0.2896 (9)0.057 (3)0.062 (4)*
H1B0.919 (3)0.2496 (9)0.308 (3)0.058 (4)*
H1C1.186 (3)0.3043 (9)0.247 (2)0.058 (4)*
C20.8269 (2)0.37303 (6)0.31388 (18)0.0354 (3)
C30.9107 (4)0.39192 (9)0.5565 (2)0.0508 (4)
H3C1.124 (4)0.4009 (11)0.588 (3)0.075 (5)*
H3B0.871 (4)0.3444 (10)0.649 (3)0.072 (5)*
H3A0.804 (3)0.4399 (11)0.605 (3)0.070 (5)*
C40.6431 (2)0.41832 (7)0.18845 (18)0.0377 (3)
C50.4587 (2)0.46394 (7)0.06268 (18)0.0383 (3)
H50.252 (3)0.4512 (8)0.051 (2)0.045 (3)*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
C10.0457 (7)0.0366 (6)0.0467 (7)0.0021 (5)0.0024 (5)0.0007 (5)
C20.0357 (6)0.0343 (5)0.0359 (6)0.0042 (4)0.0017 (4)0.0034 (4)
C30.0689 (9)0.0458 (7)0.0362 (6)0.0017 (6)0.0016 (6)0.0028 (5)
C40.0371 (6)0.0385 (6)0.0381 (6)0.0011 (4)0.0057 (4)0.0003 (4)
C50.0332 (6)0.0411 (6)0.0409 (6)0.0017 (4)0.0051 (4)0.0020 (4)
Geometric parameters (Å, º) top
C1—C21.5076 (17)C3—H3C1.001 (19)
C1—H1A1.026 (17)C3—H3B0.986 (17)
C1—H1B0.990 (16)C3—H3A0.987 (18)
C1—H1C1.004 (15)C4—C51.3126 (16)
C2—C41.3067 (16)C5—C5i1.470 (2)
C2—C31.5067 (17)C5—H50.977 (13)
C2—C1—H1A112.5 (8)C2—C3—H3B110.4 (10)
C2—C1—H1B109.0 (9)H3C—C3—H3B104.5 (14)
H1A—C1—H1B109.1 (11)C2—C3—H3A111.4 (9)
C2—C1—H1C110.6 (9)H3C—C3—H3A110.3 (14)
H1A—C1—H1C108.6 (12)H3B—C3—H3A108.7 (14)
H1B—C1—H1C106.8 (12)C2—C4—C5179.89 (13)
C4—C2—C3122.22 (11)C4—C5—C5i124.04 (13)
C4—C2—C1121.93 (10)C4—C5—H5119.8 (8)
C3—C2—C1115.85 (10)C5i—C5—H5116.2 (8)
C2—C3—H3C111.3 (10)
Symmetry code: (i) x+1, y+1, z.

Experimental details

Crystal data
Chemical formulaC10H14
Mr134.21
Crystal system, space groupMonoclinic, P21/n
Temperature (K)178
a, b, c (Å)4.644 (2), 16.278 (6), 6.037 (2)
β (°) 96.12 (3)
V3)453.8 (3)
Z2
Radiation typeMo Kα
µ (mm1)0.06
Crystal size (mm)0.70 × 0.25 × 0.25
Data collection
DiffractometerSiemens R3
diffractometer
Absorption correction
No. of measured, independent and
observed [I > 2σ(I)] reflections
2589, 1034, 810
Rint0.020
(sin θ/λ)max1)0.650
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.041, 0.121, 1.06
No. of reflections1034
No. of parameters74
H-atom treatmentAll H-atom parameters refined
Δρmax, Δρmin (e Å3)0.14, 0.16

Computer programs: P3 (Nicolet, 1987), P3, XDISK (Nicolet, 1987), SHELXS97 (Sheldrick, 1990), SHELXL97 (Sheldrick, 1997), XP (Siemens, 1994), SHELXL97.

Selected geometric parameters (Å, º) top
C1—C21.5076 (17)C4—C51.3126 (16)
C2—C41.3067 (16)C5—C5i1.470 (2)
C2—C31.5067 (17)
C4—C2—C3122.22 (11)C2—C4—C5179.89 (13)
C4—C2—C1121.93 (10)C4—C5—C5i124.04 (13)
C3—C2—C1115.85 (10)
Symmetry code: (i) x+1, y+1, z.
 

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