γ-Terpinene

The crystal structure of γ-terpinene, C₁₀H₁₆, has been determined at 150 (2) K following in situ crystal growth from the liquid. The mol­ecule lies on a mirror plane in the space group Pnma and forms stacks which pack in a herring-bone-type arrangement.

Key indicators

• Single-crystal X-ray study
• T = 150 K
• Mean [sigma](C-C) = 0.002 Å
• R factor = 0.049
• wR factor = 0.139
• Data-to-parameter ratio = 15.7

checkCIF results

No syntax errors found

ADDSYM reports no extra symmetry


 Alert Level C:



ABSTM_02  Alert C The ratio of expected to reported Tmax/Tmin(RR') is < 0.90
          Tmin and Tmax reported:      0.809     0.986
          Tmin' and Tmax expected:      1.000     1.000
          RR' =      0.820
          Please check that your absorption correction is appropriate.


 0 Alert Level A = Potentially serious problem

 0 Alert Level B = Potential problem

 1 Alert Level C = Please check

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S1. Comment

γ-Terpinene (I) occurs in nature and can be obtained, for example, from coriander oil, lemon oil and cumin oil. An account of its history and the determination of its structure using the techniques of classical organic chemistry is given by Simonsen & Owen (1947). This work forms part of a continuing study devoted to improving the techniques for determining the crystal structures of substances which are liquids at room temperature (see, for example, Davies & Bond, 2001).

S2. Experimental

γ-Terpinene (97%) was obtained from the Aldrich company and used without further purification. The crystal was grown in a 0.3 mm glass capillary tube at 210 K (a temperature only slightly less than the melting point of the solid in the capillary tube). With the axis of the capillary parallel to the ϕ axis and horizontal on the instrument, the crystal was obtained by moving a plug of solid material up and down the tube (the movement being controlled with the standard height adjustment of the goniometer head). The length of the cylindrical crystal was not estimated, but it exceeded the 0.35 mm collimator diameter. Data were collected at 150 K.

S3. Refinement

Hydrogen atoms were placed geometrically and refined using a riding model with an isotropic displacement parameter fixed at 1.2 times U_eq for the carbon to which they are attached.

Computing details

Data collection: COLLECT (Nonius, 1998); cell refinement: HKL SCALEPACK (Otwinowski & Minor, 1997); data reduction: HKL DENZO (Otwinowski & Minor, 1997) and SCALEPACK; program(s) used to solve structure: SIR92 (Altomare et al., 1994); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: XP (Sheldrick, 1993) and CAMERON (Watkin et al., 1996); software used to prepare material for publication: SHELXL97.

Figures

	Fig. 1. Molecular structure of (I), showing displacement ellipsoids at the 50% probability level (XP; Sheldrick, 1993).
	Fig. 2. Projection on to (010), showing stacks of (I) packed in a herring-bone type arrangement (CAMERON; Watkin et al., 1996).

1-isopropyl-4-methyl-1,4-cyclohexadiene

Crystal data

C10H16	Dx = 1.015 Mg m^−3
Mr = 136.23	Mo Kα radiation, λ = 0.7107 Å
Orthorhombic, Pnma	Cell parameters from 4398 reflections
a = 18.1968 (13) Å	θ = 1.0–27.5°
b = 7.2601 (5) Å	µ = 0.06 mm^−1
c = 6.7498 (3) Å	T = 150 K
V = 891.72 (10) Å^3	Cylinder, colourless
Z = 4	0.15 mm (radius)
F(000) = 304

Data collection

Nonius KappaCCD diffractometer	829 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	Rint = 0.056
Thin–slice ω and ϕ scans	θmax = 27.5°, θmin = 3.6°
Absorption correction: multi-scan (SORTAV; Blessing, 1995)	h = −21→23
Tmin = 0.809, Tmax = 0.986	k = −7→9
5877 measured reflections	l = −8→7
1102 independent reflections

Refinement

Refinement on F^2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.049	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.139	H-atom parameters constrained
S = 1.06	w = 1/[σ^2(Fo^2) + (0.0688P)^2 + 0.1715P] where P = (Fo^2 + 2Fc^2)/3
1102 reflections	(Δ/σ)max = 0.001
70 parameters	Δρmax = 0.19 e Å^−3
0 restraints	Δρmin = −0.23 e Å^−3

Special details

Experimental. Grown in situ in a 0.30 mm Lindemann tube at 210 K.

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 (Ų)

	x	y	z	Uiso*/Ueq
C1	1.02376 (10)	0.2500	0.3824 (3)	0.0310 (4)
C2	1.02268 (10)	0.2500	0.1860 (3)	0.0314 (4)
H2	1.0685	0.2500	0.1187	0.038*
C3	0.95400 (9)	0.2500	0.0626 (2)	0.0301 (4)
H3	0.9554 (7)	0.139 (2)	−0.0279 (19)	0.036*
C4	0.88415 (9)	0.2500	0.1816 (2)	0.0244 (4)
C5	0.88555 (10)	0.2500	0.3789 (2)	0.0285 (4)
H5	0.8398	0.2500	0.4467	0.034*
C6	0.95421 (10)	0.2500	0.5016 (3)	0.0322 (5)
H6	0.9537 (8)	0.139 (2)	0.5946 (19)	0.039*
C7	1.09428 (13)	0.2500	0.4999 (4)	0.0453 (6)
H7A	1.1403 (15)	0.2500	0.411 (4)	0.068*
H7B	1.0948 (10)	0.363 (3)	0.585 (2)	0.068*
C8	0.81188 (9)	0.2500	0.0692 (2)	0.0283 (4)
H8	0.7716	0.2500	0.1699	0.034*
C9	0.80236 (7)	0.4234 (2)	−0.0569 (2)	0.0406 (4)
H9A	0.7528	0.4252	−0.1137	0.061*
H9B	0.8388	0.4233	−0.1639	0.061*
H9C	0.8094	0.5327	0.0261	0.061*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
C1	0.0365 (10)	0.0192 (9)	0.0373 (10)	0.000	−0.0112 (7)	0.000
C2	0.0285 (9)	0.0297 (10)	0.0359 (10)	0.000	−0.0009 (7)	0.000
C3	0.0309 (9)	0.0366 (10)	0.0226 (8)	0.000	0.0003 (7)	0.000
C4	0.0301 (9)	0.0211 (8)	0.0221 (8)	0.000	0.0006 (6)	0.000
C5	0.0347 (9)	0.0277 (9)	0.0231 (8)	0.000	0.0026 (7)	0.000
C6	0.0486 (11)	0.0262 (10)	0.0216 (8)	0.000	−0.0071 (7)	0.000
C7	0.0488 (12)	0.0324 (11)	0.0548 (13)	0.000	−0.0247 (10)	0.000
C8	0.0266 (8)	0.0326 (10)	0.0256 (8)	0.000	−0.0003 (6)	0.000
C9	0.0361 (7)	0.0469 (9)	0.0390 (7)	0.0057 (6)	−0.0043 (5)	0.0103 (6)

Geometric parameters (Å, º)

C1—C2	1.326 (2)	C4—C5	1.332 (2)
C1—C6	1.499 (3)	C4—C8	1.518 (2)
C1—C7	1.508 (2)	C5—C6	1.499 (2)
C2—C3	1.502 (2)	C8—C9^i	1.5294 (17)
C3—C4	1.503 (2)	C8—C9	1.5294 (17)
C2—C1—C6	121.58 (15)	C3—C4—C8	117.74 (13)
C2—C1—C7	122.55 (18)	C4—C5—C6	124.64 (16)
C6—C1—C7	115.87 (16)	C5—C6—C1	114.04 (14)
C1—C2—C3	124.52 (16)	C4—C8—C9^i	112.10 (9)
C2—C3—C4	114.05 (14)	C4—C8—C9	112.10 (9)
C5—C4—C3	121.18 (15)	C9^i—C8—C9	110.77 (15)
C5—C4—C8	121.08 (15)
C6—C1—C2—C3	0.0	C4—C5—C6—C1	0.0
C7—C1—C2—C3	180.0	C2—C1—C6—C5	0.0
C1—C2—C3—C4	0.0	C7—C1—C6—C5	180.0
C2—C3—C4—C5	0.0	C5—C4—C8—C9^i	−117.34 (10)
C2—C3—C4—C8	180.0	C3—C4—C8—C9^i	62.66 (10)
C3—C4—C5—C6	0.0	C5—C4—C8—C9	117.34 (10)
C8—C4—C5—C6	180.0	C3—C4—C8—C9	−62.66 (10)

Symmetry code: (i) x, −y+1/2, z.