Methyl­cyclo­penta­ne

Bream, R.; Watkin, D.; Cowley, A.

doi:10.1107/S1600536806006003

organic compounds

CRYSTALLOGRAPHIC
COMMUNICATIONS

ISSN: 2056-9890

Volume 62| Part 4| April 2006| Pages o1211-o1212

https://doi.org/10.1107/S1600536806006003

Methylcyclopentane

Richard Bream,^a ^* David Watkin ^a and Andrew Cowley ^a

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

(Received 13 February 2006; accepted 17 February 2006; online 3 March 2006)

Methylcyclopentane, C₆H₁₂, a liquid at room temperature, was studied as part of a project to develop a computer-controlled low-temperature crystal-growing device. A single crystal was obtained at 115 K. The ring has an envelope conformation, with a pseudo-equatorial methyl substituent on the flap atom.

Comment

The melting point of methylcyclopentane is noted by the CRC Handbook of Chemistry and Physics as being −142.4° C (130.8 K) (Weast, 1978 ). A sample solidified spontaneously to a polycrystalline mass on flash-cooling to 115 K, and was then zone refined into a single crystal using tandem computer-controlled heating elements. Data collection was completed at 110 K

The molecule is in the envelope conformation (Fig. 1), with the four atoms C2—C5 almost coplanar (maximum deviation 0.04 Å) and a pseudo-equatorial methyl group attached to the flap atom C1. The crystal structure consists of molecular stacks formed by unit-cell translations along the a axis (Figs. 2 and 3).

The calculated density is not unlike that of the ordered monoclinic phase of cyclohexane (0.996 Mg m⁻³), suggesting that a low density may be a feature of small cyclic hydrocarbons (Kahn et al., 1973 ).

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
An a-axis projection of the title compound. One column of molecules has been highlighted in blue for comparison with Fig. 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 Acros Organics. A 2.0 mm column was flame-sealed in a 0.3 mm diameter Lindemann tube and crystallized as described above.

Crystal data

C₆H₁₂
M_r = 84.16
Monoclinic, P 2₁ /n
a = 5.3934 (2) Å
b = 11.1439 (5) Å
c = 9.7047 (5) Å
β = 98.0288 (17)°
V = 577.57 (5) Å³
Z = 4
D_x = 0.968 Mg m⁻³
Mo Kα radiation
Cell parameters from 1447 reflections
θ = 5–28°
μ = 0.05 mm⁻¹
T = 110 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 )T_min = 0.69, T_max = 0.98
7788 measured reflections
1412 independent reflections
1408 reflections with I > 3σ(I)
R_int = 0.063
θ_max = 28.3°
h = −7 → 7
k = −14 → 14
l = −12 → 12

Refinement

Refinement on F²
R[F² > 2σ(F²)] = 0.070
wR(F²) = 0.097
S = 0.94
1408 reflections
55 parameters
H-atom parameters constrained
w = 1/[σ²(F²) + (0.03P)² + 0.1P] where P = [max(F_o²,0) + 2F_c²]/3
(Δ/σ)_max < 0.001
Δρ_max = 0.28 e Å⁻³
Δρ_min = −0.22 e Å⁻³

Table 1
Selected geometric parameters (Å, °)

C1—C2	1.5290 (14)
C1—C5	1.5274 (14)
C1—C6	1.5171 (14)
C2—C3	1.5344 (14)
C3—C4	1.5402 (15)
C4—C5	1.5286 (14)

C2—C1—C5	101.82 (8)
C2—C1—C6	114.77 (8)
C5—C1—C6	115.00 (8)
C1—C2—C3	105.28 (8)
C2—C3—C4	105.88 (8)
C3—C4—C5	105.39 (8)
C4—C5—C1	104.05 (8)

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 in the range 0.93–0.98 Å) and displacement parameters [U_iso(H) in the range 1.2–1.5 times U_eq of the parent atom], after which they were refined with riding constraints.

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.

Supporting information

Crystal structure: contains datablocks global, I. DOI: https://doi.org/10.1107/S1600536806006003/cf2008sup1.cif

Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S1600536806006003/cf2008Isup2.hkl

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.

methylcyclopentane top

Crystal data top

C₆H₁₂	D_x = 0.968 Mg m⁻³
M_r = 84.16	Melting point: 130.8 K
Monoclinic, P2₁/n	Mo Kα radiation, λ = 0.71073 Å
a = 5.3934 (2) Å	Cell parameters from 1447 reflections
b = 11.1439 (5) Å	θ = 5–28°
c = 9.7047 (5) Å	µ = 0.05 mm⁻¹
β = 98.0288 (17)°	T = 110 K
V = 577.57 (5) Å³	Cylinder, colourless
Z = 4	1.00 × 0.20 (radius) mm
F(000) = 192

Data collection top

Nonius KappaCCD diffractometer	1408 reflections with I > −3.0σ(I)
Graphite monochromator	R_int = 0.063
ω scans	θ_max = 28.3°, θ_min = 5.3°
Absorption correction: multi-scan (DENZO/SCALEPACK; Otwinowski & Minor, 1997)	h = −7→7
T_min = 0.69, T_max = 0.98	k = −14→14
7788 measured reflections	l = −12→12
1412 independent reflections

Refinement top

Refinement on F²	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F² > 2σ(F²)] = 0.070	H-atom parameters constrained
wR(F²) = 0.097	w = 1/[σ²(F²) + (0.03P)² + 0.1P] where P = [max(F_o²,0) + 2F_c²]/3
S = 0.94	(Δ/σ)_max < 0.001
1408 reflections	Δρ_max = 0.28 e Å⁻³
55 parameters	Δρ_min = −0.22 e Å⁻³
0 restraints

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å²) top

	x	y	z	U_iso*/U_eq
C1	1.03029 (18)	0.25222 (9)	0.78471 (10)	0.0284
C2	1.0448 (2)	0.19129 (9)	0.64490 (11)	0.0347
C3	1.2171 (2)	0.08259 (10)	0.67904 (11)	0.0350
C4	1.22182 (19)	0.05906 (10)	0.83578 (11)	0.0343
C5	1.02749 (18)	0.14454 (9)	0.88184 (11)	0.0313
C6	0.81288 (19)	0.33855 (10)	0.78504 (12)	0.0360
H11	1.1857	0.2957	0.8138	0.0340*
H21	1.1039	0.2457	0.5789	0.0431*
H22	0.8742	0.1633	0.6054	0.0443*
H31	1.3876	0.1010	0.6582	0.0454*
H32	1.1534	0.0141	0.6260	0.0435*
H41	1.3888	0.0781	0.8855	0.0414*
H42	1.1882	−0.0251	0.8563	0.0421*
H51	1.0629	0.1677	0.9795	0.0402*
H52	0.8593	0.1062	0.8656	0.0385*
H61	0.8146	0.3762	0.8788	0.0540*
H62	0.8215	0.4062	0.7163	0.0519*
H63	0.6522	0.2949	0.7605	0.0531*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
C1	0.0268 (5)	0.0270 (5)	0.0316 (6)	−0.0033 (4)	0.0046 (4)	0.0004 (4)
C2	0.0411 (6)	0.0343 (6)	0.0297 (6)	0.0059 (5)	0.0078 (4)	0.0033 (4)
C3	0.0380 (6)	0.0309 (6)	0.0366 (6)	0.0042 (5)	0.0067 (4)	0.0009 (4)
C4	0.0341 (5)	0.0316 (5)	0.0364 (6)	0.0002 (4)	0.0024 (4)	0.0058 (5)
C5	0.0320 (5)	0.0333 (5)	0.0286 (6)	−0.0044 (4)	0.0044 (4)	0.0021 (4)
C6	0.0348 (6)	0.0338 (6)	0.0405 (6)	0.0017 (5)	0.0085 (4)	−0.0023 (5)

Geometric parameters (Å, º) top

C1—C2	1.5290 (14)	C3—H32	0.957
C1—C5	1.5274 (14)	C4—C5	1.5286 (14)
C1—C6	1.5171 (14)	C4—H41	0.984
C1—H11	0.975	C4—H42	0.981
C2—C3	1.5344 (14)	C5—H51	0.975
C2—H21	0.967	C5—H52	0.995
C2—H22	0.996	C6—H61	1.001
C3—C4	1.5402 (15)	C6—H62	1.013
C3—H31	0.990	C6—H63	0.993

C2—C1—C5	101.82 (8)	C3—C4—C5	105.39 (8)
C2—C1—C6	114.77 (8)	C3—C4—H41	109.6
C5—C1—C6	115.00 (8)	C5—C4—H41	109.9
C2—C1—H11	109.2	C3—C4—H42	112.6
C5—C1—H11	107.1	C5—C4—H42	112.5
C6—C1—H11	108.5	H41—C4—H42	106.8
C1—C2—C3	105.28 (8)	C4—C5—C1	104.05 (8)
C1—C2—H21	111.8	C4—C5—H51	113.6
C3—C2—H21	113.1	C1—C5—H51	112.0
C1—C2—H22	108.7	C4—C5—H52	109.5
C3—C2—H22	109.6	C1—C5—H52	109.1
H21—C2—H22	108.3	H51—C5—H52	108.5
C2—C3—C4	105.88 (8)	C1—C6—H61	111.0
C2—C3—H31	110.1	C1—C6—H62	111.4
C4—C3—H31	110.5	H61—C6—H62	107.0
C2—C3—H32	110.6	C1—C6—H63	109.8
C4—C3—H32	110.5	H61—C6—H63	108.7
H31—C3—H32	109.2	H62—C6—H63	109.0

References

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