organic compounds\(\def\hfill{\hskip 5em}\def\hfil{\hskip 3em}\def\eqno#1{\hfil {#1}}\)

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ISSN: 2056-9890

trans-1,2-Di­methyl­cyclo­hexa­ne

aChemical Crystallography, Central Chemistry Laboratory, University of Oxford, Oxford OX1 3TA, England
*Correspondence e-mail: richard.bream@pmb.ox.ac.uk

(Received 11 January 2006; accepted 23 January 2006; online 27 January 2006)

The title compound, C8H16, a liquid at room temperature, was studied as part of a project to develop a computer-controlled low-temperature crystal-growing device. Single crystals, in P21/n, were obtained at 167 K. The molecule adopts a chair conformation and possesses a non-crystallographic twofold axis of symmetry.

Comment

trans-1,2-Dimethyl­cyclo­hexane, (I)[link] (Fig. 1[link]), was one of eight alkyl­cyclo­hexa­nes whose thermodynamic properties were published in 1949 (Huffman et al., 1949[Huffman, H. M., Todd, S. S. & Oliver, G. D. (1949). J. Am. Chem. Soc. 71, 584-592.]). That work reported a melting point of 184.994 K and showed no evidence for phase changes in the range down to liquid nitro­gen temperatures.

[Scheme 1]

The sample we used was one of several sealed in 0.2 mm Lindeman tubes for preliminary work carried out in 1979. Data had been collected at that time on a Stoe Weissenberg diffractometer and the structure solved, but was not of a publishable quality (Courseille et al., 1979[Courseille, D., Hospital, M., Leroy, F. & Watkin, D. (1979). 5th European Crystallographic Meeting, Copenhagen, Denmark, p. 285.]).

The sample solidified spontaneously to a polycrystalline mass on flash cooling to 120 K. The temperature was then raised to 167 K and the sample was zone-refined into a single crystal using tandem computer-controlled heating elements. The temperature was then slowly reduced to 150 K for data collection.

The mol­ecules are in the chair conformation with the two methyl groups trans-equatorial [τ = −58.0 (2)]. The mol­ecule has an excellent inter­nal twofold axis (r.m.s. positional deviation 0.03 Å, r.m.s. bond length deviation 0.01 Å and r.m.s. torsion angle deviation 1.6° including the refined H atoms). The van der Waals surface is in the form of a slightly elongated disk with alternate layers inclined to each other. The calculated density is not unlike that of the ordered monoclinic phase of cyclo­hexane (0.996 Mg m−3), suggesting that a low specific gravity may be a feature of small chain cyclic hydro­carbons (Kahn et al., 1973[Kahn, R., Fourme, R., Andre, D. & Renaud, M. (1973). Acta Cryst. B29, 131-138.]).

[Figure 1]
Figure 1
The title compound with displacement ellipsoids drawn at the 50% probability level. H atoms are shown as spheres of arbitary radius.
[Figure 2]
Figure 2
An a axis projection of the title compound. One column of mol­ecules has been highlighted in blue for comparison with Fig. 3[link].
[Figure 3]
Figure 3
A projection along the c axis, showing the mol­ecular stacks parallel to the a axis.

Experimental

The material was used as supplied by the Aldrich Chemical Company Inc. in 1979.

Crystal data
  • C8H16

  • Mr = 112.22

  • Monoclinic, P 21 /n

  • a = 5.3403 (4) Å

  • b = 19.4410 (15) Å

  • c = 7.4446 (7) Å

  • β = 92.378 (4)°

  • V = 772.24 (11) Å3

  • Z = 4

  • Dx = 0.965 Mg m−3

  • Mo Kα radiation

  • Cell parameters from 1440 reflections

  • θ = 5–27°

  • μ = 0.05 mm−1

  • T = 150 K

  • Cylinder, colourless

  • 1.00 × 0.20 (radius) mm

Data collection
  • Nonius KappaCCD diffractometer

  • ω scans

  • Absorption correction: multi-scan(DENZO/SCALEPACK; Otwinowski & Minor, 1997[Otwinowski, Z. & Minor, W. (1997). Methods in Enzymology, Vol. 276, Macromolecular Crystallography, Part A, edited by C. W. Carter Jr & R. M. Sweet, pp. 307-326. New York: Academic Press.])Tmin = 0.86, Tmax = 0.97

  • 2938 measured reflections

  • 1679 independent reflections

  • 1677 reflections with I > −3σ(I)

  • Rint = 0.039

  • θmax = 27.4°

  • h = −6 → 6

  • k = −25 → 22

  • l = −9 → 9

Refinement
  • Refinement on F2

  • R[F2 > 2σ(F2)] = 0.083

  • wR(F2) = 0.149

  • S = 1.01

  • 1677 reflections

  • 73 parameters

  • H-atom parameters constrained

  • w = 1/[σ2(F2) + (0.05P)2 + 0.29P] where P = [max(Fo2,0) + 2Fc2]/3

  • (Δ/σ)max = 0.004

  • Δρmax = 0.23 e Å−3

  • Δρmin = −0.20 e Å−3

Table 1
Selected geometric parameters (Å, °)

C1—C2 1.531 (2)
C1—C6 1.531 (2)
C1—C8 1.529 (2)
C2—C3 1.529 (2)
C2—C7 1.531 (2)
C3—C4 1.526 (2)
C4—C5 1.521 (2)
C5—C6 1.526 (2)
C2—C1—C6 110.81 (12)
C2—C1—C8 113.12 (13)
C6—C1—C8 110.15 (12)
C1—C2—C3 110.76 (12)
C1—C2—C7 112.87 (12)
C3—C2—C7 110.38 (12)
C2—C3—C4 112.76 (12)
C3—C4—C5 110.67 (12)
C4—C5—C6 111.00 (13)
C1—C6—C5 112.93 (12)

The H atoms were all located in a difference map and then repositioned geometrically. They were initially refined with soft restraints on the bond lengths and angles to regularize their geometry (C—H = 0.93–0.98 Å) and displacement parameters [Uiso(H) = 1.2–1.5Ueq(C)], after which their positions were refined with riding constraints.

Data collection: COLLECT (Nonius, 2001[Nonius (2001). COLLECT. Nonius BV, Delft, The Netherlands.]); cell refinement: DENZO/SCALEPACK; data reduction: DENZO/SCALEPACK (Otwinowski & Minor, 1997[Otwinowski, Z. & Minor, W. (1997). Methods in Enzymology, Vol. 276, Macromolecular Crystallography, Part A, edited by C. W. Carter Jr & R. M. Sweet, pp. 307-326. New York: Academic Press.]); program(s) used to solve structure: SIR92 (Altomare et al., 1994[Altomare, A., Cascarano, G., Giacovazzo, G., Guagliardi, A., Burla, M. C., Polidori, G. & Camalli, M. (1994). J. Appl. Cryst. 27, 435.]); program(s) used to refine structure: CRYSTALS (Betteridge et al., 2003[Betteridge, P. W., Carruthers, J. R., Cooper, R. I., Prout, K. & Watkin, D. J. (2003). J. Appl. Cryst. 36, 1487.]); molecular graphics: CAMERON (Watkin et al., 1996[Watkin, D. J., Prout, C. K. & Pearce, L. J. (1996). CAMERON. Chemical Crystallography Laboratory, Oxford, England.]); software used to prepare material for publication: CRYSTALS.

Supporting information


Comment top

trans-1,2-Dimethylcyclohexane, (I) (Fig. 1), was one of eight alkylcyclohexanes whose thermodynamic properties were published in 1949 (Huffman et al., 1949). That work reported a melting point of 457.994 K and showed no evidence for phase changes in the range down to liquid nitrogen temperatures.

The sample we used was one of several sealed in 0.2 mm Lindeman tubes for preliminary work carried out in 1979. Data had been collected at that time on a Stoe Weissenberg diffractometer and the structure solved, but was not of a publishable quality (Courseille et al., 1979).

The sample solidified spontaneously to a polycrystalline mass on flash cooling to 120 K. The temperature was then raised to 167 K and the sample was zone refined into a single-crystal using tandem computer-controlled heating elements. The temperature was then slowly reduced to 150 K for data collection.

The molecules are in the chair conformation with the two methyl groups trans-equatorial [τ = −58.0 (2)]. The molecule has an excellent internal twofold axis (r.m.s. positional deviation 0.03 Å, r.m.s. bond length deviation 0.01 Å and r.m.s. torsion angle deviation 1.6° including the refined H atoms). The van der Waals surface is in the form of a slightly elongated disk with alternate layers inclined to each other. The calculated density is not unlike that of the ordered monoclinic phase of cyclohexane (0.996 Mg m−3), suggesting that a low specific gravity may be a feature of small chain cyclic hydrocarbons (Kahn et al., 1973).

Experimental top

The material was used as supplied by the Aldrich Chemical Company Inc. in 1979.

Refinement top

The H atoms were all located in a difference map and then repositioned geometrically. The H atoms were initially refined with soft restraints on the bond lengths and angles to regularize their geometry (C—H = 0.93–0.98 Å) and displacement parameters [Uiso(H) = 1.2–1.5Ueq(C)], after which their positions were refined with riding constraints.

Computing details top

Data collection: COLLECT (Nonius, 2001); cell refinement: DENZO/SCALEPACK; data reduction: DENZO/SCALEPACK (Otwinowski & Minor, 1997); program(s) used to solve structure: SIR92 (Altomare et al., 1994); program(s) used to refine structure: CRYSTALS (Betteridge et al., 2003); molecular graphics: CAMERON (Watkin et al., 1996); software used to prepare material for publication: CRYSTALS.

Figures top
[Figure 1] Fig. 1. The title compound with displacement ellipsoids drawn at the 50% probability level. H atoms are shown as spheres of arbitary radius.
[Figure 2] Fig. 2. An a axis projection of the title compound. One column of molecules has been highlighted in blue for comparison with Fig. 3.
[Figure 3] Fig. 3. A projection of along the c axis, showing the molecular stacks parallel to the a axis.
trans-1,2-dimethyl-cyclohexane top
Crystal data top
C8H16Dx = 0.965 Mg m3
Mr = 112.22Melting point: 184.994 K
Monoclinic, P21/nMo Kα radiation, λ = 0.71073 Å
a = 5.3403 (4) ÅCell parameters from 1440 reflections
b = 19.4410 (15) Åθ = 5–27°
c = 7.4446 (7) ŵ = 0.05 mm1
β = 92.378 (4)°T = 150 K
V = 772.24 (11) Å3Cylinder, colourless
Z = 41.00 × 0.20 (radius) mm
F(000) = 256
Data collection top
Nonius KappaCCD
diffractometer
1677 reflections with I > 3σ(I)
Graphite monochromatorRint = 0.039
ω scansθmax = 27.4°, θmin = 5.2°
Absorption correction: multi-scan
(DENZO/SCALEPACK; Otwinowski & Minor, 1997)
h = 66
Tmin = 0.86, Tmax = 0.97k = 2522
2938 measured reflectionsl = 99
1679 independent reflections
Refinement top
Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullHydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.083H-atom parameters constrained
wR(F2) = 0.149 w = 1/[σ2(F2) + (0.05P)2 + 0.29P]
where P = [max(Fo2,0) + 2Fc2]/3
S = 1.01(Δ/σ)max = 0.004
1677 reflectionsΔρmax = 0.23 e Å3
73 parametersΔρmin = 0.20 e Å3
0 restraints
Crystal data top
C8H16V = 772.24 (11) Å3
Mr = 112.22Z = 4
Monoclinic, P21/nMo Kα radiation
a = 5.3403 (4) ŵ = 0.05 mm1
b = 19.4410 (15) ÅT = 150 K
c = 7.4446 (7) Å1.00 × 0.20 (radius) mm
β = 92.378 (4)°
Data collection top
Nonius KappaCCD
diffractometer
1679 independent reflections
Absorption correction: multi-scan
(DENZO/SCALEPACK; Otwinowski & Minor, 1997)
1677 reflections with I > 3σ(I)
Tmin = 0.86, Tmax = 0.97Rint = 0.039
2938 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0830 restraints
wR(F2) = 0.149H-atom parameters constrained
S = 1.01Δρmax = 0.23 e Å3
1677 reflectionsΔρmin = 0.20 e Å3
73 parameters
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
C10.7205 (3)0.10079 (7)0.29818 (19)0.0409
C20.4530 (3)0.12850 (7)0.27380 (19)0.0393
C30.4130 (3)0.18962 (8)0.39864 (19)0.0422
C40.4752 (3)0.17273 (8)0.5957 (2)0.0445
C50.7418 (3)0.14581 (8)0.6199 (2)0.0451
C60.7843 (3)0.08472 (8)0.4962 (2)0.0431
C70.3833 (4)0.14810 (9)0.0788 (2)0.0508
C80.7683 (4)0.03765 (9)0.1821 (2)0.0532
H110.83730.13840.26180.0482*
H210.33940.09050.31030.0464*
H310.52180.22790.36340.0510*
H320.23590.20550.38370.0504*
H410.45190.21480.66860.0539*
H420.35750.13640.63210.0538*
H510.77890.13220.74910.0538*
H520.85560.18410.59090.0538*
H610.96270.07040.51020.0513*
H620.67900.04650.53040.0527*
H710.21440.17000.07270.0746*
H720.50420.18150.03970.0756*
H730.38270.10690.00050.0756*
H810.94070.02040.20940.0792*
H820.75350.04970.05480.0792*
H830.64660.00270.20820.0802*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
C10.0482 (9)0.0385 (8)0.0364 (8)0.0018 (6)0.0068 (7)0.0021 (6)
C20.0477 (9)0.0398 (8)0.0307 (7)0.0016 (6)0.0032 (6)0.0001 (6)
C30.0481 (9)0.0435 (8)0.0353 (8)0.0038 (7)0.0043 (6)0.0003 (6)
C40.0514 (10)0.0502 (9)0.0323 (8)0.0010 (7)0.0046 (7)0.0044 (7)
C50.0514 (10)0.0507 (9)0.0331 (8)0.0014 (7)0.0013 (6)0.0031 (7)
C60.0463 (9)0.0419 (8)0.0408 (9)0.0008 (7)0.0001 (7)0.0004 (6)
C70.0678 (11)0.0524 (9)0.0320 (8)0.0048 (8)0.0011 (7)0.0008 (7)
C80.0616 (11)0.0515 (10)0.0466 (9)0.0075 (8)0.0029 (8)0.0104 (8)
Geometric parameters (Å, º) top
C1—C21.531 (2)C4—H420.990
C1—C61.531 (2)C5—C61.526 (2)
C1—C81.529 (2)C5—H511.009
C1—H111.005C5—H520.990
C2—C31.529 (2)C6—H610.994
C2—C71.531 (2)C6—H620.972
C2—H211.001C7—H710.997
C3—C41.526 (2)C7—H720.969
C3—H310.986C7—H730.991
C3—H320.997C8—H810.993
C4—C51.521 (2)C8—H820.977
C4—H410.992C8—H830.966
C2—C1—C6110.81 (12)C4—C5—C6111.00 (13)
C2—C1—C8113.12 (13)C4—C5—H51110.4
C6—C1—C8110.15 (12)C6—C5—H51110.1
C2—C1—H11107.4C4—C5—H52107.2
C6—C1—H11107.0C6—C5—H52110.2
C8—C1—H11108.1H51—C5—H52107.8
C1—C2—C3110.76 (12)C1—C6—C5112.93 (12)
C1—C2—C7112.87 (12)C1—C6—H61109.4
C3—C2—C7110.38 (12)C5—C6—H61108.7
C1—C2—H21106.3C1—C6—H62107.5
C3—C2—H21107.9C5—C6—H62109.6
C7—C2—H21108.4H61—C6—H62108.7
C2—C3—C4112.76 (12)C2—C7—H71109.5
C2—C3—H31109.0C2—C7—H72108.2
C4—C3—H31108.1H71—C7—H72108.2
C2—C3—H32109.2C2—C7—H73110.6
C4—C3—H32109.9H71—C7—H73109.7
H31—C3—H32107.6H72—C7—H73110.5
C3—C4—C5110.67 (12)C1—C8—H81109.3
C3—C4—H41108.7C1—C8—H82110.3
C5—C4—H41110.9H81—C8—H82108.5
C3—C4—H42107.5C1—C8—H83108.8
C5—C4—H42108.9H81—C8—H83110.3
H41—C4—H42110.1H82—C8—H83109.7

Experimental details

Crystal data
Chemical formulaC8H16
Mr112.22
Crystal system, space groupMonoclinic, P21/n
Temperature (K)150
a, b, c (Å)5.3403 (4), 19.4410 (15), 7.4446 (7)
β (°) 92.378 (4)
V3)772.24 (11)
Z4
Radiation typeMo Kα
µ (mm1)0.05
Crystal size (mm)1.00 × 0.20 (radius)
Data collection
DiffractometerNonius KappaCCD
diffractometer
Absorption correctionMulti-scan
(DENZO/SCALEPACK; Otwinowski & Minor, 1997)
Tmin, Tmax0.86, 0.97
No. of measured, independent and
observed [I > 3σ(I)] reflections
2938, 1679, 1677
Rint0.039
(sin θ/λ)max1)0.647
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.083, 0.149, 1.01
No. of reflections1677
No. of parameters73
H-atom treatmentH-atom parameters constrained
Δρmax, Δρmin (e Å3)0.23, 0.20

Computer programs: COLLECT (Nonius, 2001), DENZO/SCALEPACK (Otwinowski & Minor, 1997), SIR92 (Altomare et al., 1994), CRYSTALS (Betteridge et al., 2003), CAMERON (Watkin et al., 1996), CRYSTALS.

Selected geometric parameters (Å, º) top
C1—C21.531 (2)C2—C71.531 (2)
C1—C61.531 (2)C3—C41.526 (2)
C1—C81.529 (2)C4—C51.521 (2)
C2—C31.529 (2)C5—C61.526 (2)
C2—C1—C6110.81 (12)C3—C2—C7110.38 (12)
C2—C1—C8113.12 (13)C2—C3—C4112.76 (12)
C6—C1—C8110.15 (12)C3—C4—C5110.67 (12)
C1—C2—C3110.76 (12)C4—C5—C6111.00 (13)
C1—C2—C7112.87 (12)C1—C6—C5112.93 (12)
 

References

First citationAltomare, A., Cascarano, G., Giacovazzo, G., Guagliardi, A., Burla, M. C., Polidori, G. & Camalli, M. (1994). J. Appl. Cryst. 27, 435. CrossRef Web of Science IUCr Journals
First citationBetteridge, P. W., Carruthers, J. R., Cooper, R. I., Prout, K. & Watkin, D. J. (2003). J. Appl. Cryst. 36, 1487. Web of Science CrossRef IUCr Journals
First citationCourseille, D., Hospital, M., Leroy, F. & Watkin, D. (1979). 5th European Crystallographic Meeting, Copenhagen, Denmark, p. 285.
First citationHuffman, H. M., Todd, S. S. & Oliver, G. D. (1949). J. Am. Chem. Soc. 71, 584–592. CrossRef CAS Web of Science
First citationKahn, R., Fourme, R., Andre, D. & Renaud, M. (1973). Acta Cryst. B29, 131–138. CSD CrossRef CAS IUCr Journals Web of Science
First citationNonius (2001). COLLECT. Nonius BV, Delft, The Netherlands.
First citationOtwinowski, Z. & Minor, W. (1997). Methods in Enzymology, Vol. 276, Macromolecular Crystallography, Part A, edited by C. W. Carter Jr & R. M. Sweet, pp. 307–326. New York: Academic Press.
First citationWatkin, D. J., Prout, C. K. & Pearce, L. J. (1996). CAMERON. Chemical Crystallography Laboratory, Oxford, England.

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