The low-melting compounds 1,4-di­ethyl-, 1,2-diethyl- and ethyl­benzene

Crystals of 1,4-diethyl- and 1,2-diethyl­benzene, both C₁₀H₁₄, and ethyl­benzene, C₈H₉, have been grown in situ. The mol­ecules of 1,4-diethyl- and 1,2-diethyl­benzene are located about a centre of inversion and across a twofold axis, respectively. In both mol­ecules, the terminal methyl groups are located on opposite sides of the plane of the aromatic ring. In the crystal structures of all three compounds, mol­ecules are linked together by (Ar)C—H...π and CH₂...π contacts. The methyl H atoms do not form close contacts with any of the aromatic π systems.

S1. Comment

Structural studies of compounds which are not solid under ambient conditions have become more frequent in recent years (Bond, 2003, 2006; Kirchner et al., 2004, 2009, 2010; Nayak et al., 2012; Yufit et al., 2012). The probable main reason for the renaissance of such studies is the increased attention being paid to the origin of intermolecular interactions, which play a major role in the formation of molecular complexes or cocrystals. The synthesis of cocrystals of various active pharmaceutical ingredients (APIs) represents a modern trend in the development of new pharmaceutical forms and the modification of the physical properties of existing ones (Schultheiss & Newman, 2009; Brittain, 2012). Analysis of the crystal structures of small molecules, which are usually liquid under ambient conditions, provides unique information about the relative strains and directional preferences of intermolecular contacts. The limited number of such contacts in the crystal structures of small molecules makes these systems good models for various theoretical calculations (Thakur et al., 2011). As in situ crystallization is a rather time- and effort-consuming process and thus not widely used, the number of nonsolid compounds so far unreported is remarkably high. Herein, the solid-state structures of three ethylbenzene derivatives are reported, namely 1,4-diethylbenzene, (I), 1,2-diethylbenzene, (II), and ethylbenzene, (III).

In the crystal structure of (I) (Fig. 1), the 1,4-diethylbenzene molecule occupies a special position on a centre of symmetry and therefore the ethyl groups are located on opposite sides of the aromatic ring plane. The terminal methyl groups are almost perpendicular to the plane; the corresponding torsion angle is -80.8 (4)°. The molecular geometry is characterized by a well known [see Exner & Böhm (2002), and references therein] decrease of the endo bond angle C1—C2—C3 at the ipso atom C1 to 116.7 (2)°, caused by the combined effect of the ethyl substituents. This contraction is slightly larger than those found in toluene (average 117.9°; Nayak et al., 2010) and p-xylene (117.7°; van Koningsveld et al. 1986). Molecules of (I) are linked together by C—H···π interactions, with the shortest interatomic contact being 2.99 (3) Å between H1 and C2(-x + 1, y + 1/2, -z + 1/2). The second-shortest H···C contact [C4—H4A···C1(x, -y + 1/2, z - 1/2) of 3.20 (3) Å] is observed between the same pair of molecules. These double contacts combine to form the molecules into layers parallel to the (011) plane (Fig. 2).

The molecule of 1,2-diethylbenzene, (II) (Fig. 3), in the crystal structure also occupies a special position on a twofold axis, passing through the middle of the C1—C1ⁱ and C3—C3ⁱ bonds [symmetry code: (i) -x + 1, -y + 1, z]. The perpendicular orientation of the ethyl groups is similar to that found in (I); the C2—C1—C4—C5 torsion angle is -90.88 (11)°. However, in contrast to (I), the steric repulsion between the ortho-ethyl substituents results in a significant difference in the exocyclic bond angles at atom C1 [122.39 (5) and 118.68 (8)°]. Not surprisingly, the molecules of (II) are also linked by C—H···π interactions and the pattern of these interactions is quite similar to that found in (I), namely, a pair of such interactions is present between adjacent molecules. One of these interactions involves an aromatic H atom and the other an H atom of a methylene group. The shortest interatomic distance is C2—H···C3(x + 1/4, -y + 5/4, z + 1/4) = 2.961 (14) Å and this is again formed by an aromatic H atom. In contrast to the crystal structure of (I), in (II) these contacts combine to form the molecules into a three-dimensional framework (Fig. 4).

The molecule of ethylbenzene, (III) (Fig. 5), in the crystal structure is in a general position and the conformation of the ethyl group is similar to those in (I) and (II); it is almost perpendicular to the plane of the aromatic ring, the C2—C1—C7—C8 torsion angle being -71.27 (13)°. The contraction of the endo angle at atom C1 in (III) [118.12 (9)°] is slightly less than in the para-substituted compound, (I). The same pairs of intermolecular interactions, namely CH₂···π and (Ar)C—H···π, link molecules of (III) together in loose chains along the [101] direction (Fig. 6), the shortest interatomic distances being C7—H7A···C5(x - 1/2, -y + 1/2, z - 1/2) = 3.008 (13) Å and C2—H2···C4(x - 1/2, -y + 1/2, z - 1/2) = 3.053 (11) Å.

It should be noted that in (I) and (II) the shortest C—H···π contact is formed by an aromatic H atom and the second shortest by a methylene group, and none of the methyl H atoms takes part in short contacts. This corresponds well with the acidity of these H atoms (corresponding NMR chemical shifts RCH₃ < R₂CH₂ < ArH). A similar observation was made during an analysis of the packing motifs of benzyl derivatives (Nayak et al., 2010).

Comparison of the crystal packing of the closely related compounds (I)–(III) shows that all of them display the same pattern of intermolecular interactions; molecules are linked by pairs of C—H···π contacts and in all three the geometric parameters of these contacts are very similar. However, the number and position of the substituents make the resulting patterns quite different, viz. two-dimensional layers in (I), a three-dimensional framework in (II) and one-dimensional chains in (III). It is interesting to note that the difference in the melting points of these compounds [229, 242 and 178 K for (I)–(III), respectively] may reflect the difference in the dimensionality of the packing motifs.

Related literature

For related literature, see: Bond (2003, 2006); Brittain (2012); Bruker (2000); Exner & Böhm (2002); Kirchner et al. (2004, 2009, 2010); Koningsveld et al. (1986); Nayak et al. (2010, 2012); Schultheiss & Newman (2009); Thakur et al. (2011); Yufit & Howard (2005); Yufit et al. (2012).

S2. Experimental

All compounds were purchased from Aldrich and used without further purification. The compounds were sealed in 0.2 mm borosilicate glass capillaries which were mounted on the diffractometer using a special attachment (Yufit & Howard, 2005). The polycrystalline sample of (I) was obtained at 230 K by instantaneous local freezing of the capillary. The capillary was then warmed slowly to 236 K until only a few crystalline seeds could be seen in the capillary, and then cooled slowly to 120 K. The data were collected at this temperature.

Similar procedures ware applied for (II) and (III), which were grown at 227 and 170 K and collected at 220 and 160 K, respectively. In all cases, several spatially separated crystals were present in the capillaries and the reflections from one of them were manually selected for indexing and subsequent integration using the program RLATT (Bruker, 2000).

S3. Refinement

In each case, data were collected using two 180° ω scans in 0.3° steps. Between the scans, each crystal was manually rotated by 180° around the ω axis. This data-collection mode is necessitated by the design of the mounting attachment and does not always provide 100% coverage (Yufit & Howard, 2005).

H atoms were located in difference maps and refined isotropically in (II) and (III). The methyl and methylene H atoms of (I) were refined in riding mode, with C—H = 0.96 and 0.97 Å, respectively, and with U_iso(H) = 1.5 or 1.2U_eq(C), respectively. The aromatic H atoms in (I) were refined isotropically.

Computing details

For all compounds, data collection: SMART (Bruker, 2001); cell refinement: SAINT (Bruker, 2003); data reduction: SAINT (Bruker, 2003); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXTL (Sheldrick, 2008); molecular graphics: OLEX2 (Dolomanov et al., 2009); software used to prepare material for publication: OLEX2 (Dolomanov et al., 2009).

Figures

	Fig. 1. The molecular structure and atom-labelling scheme for (I). Displacement ellipsoids are drawn at the 50% probability level. [Symmetry code: (i) -x + 1, -y, -z + 1.]
	Fig. 2. The layer of molecules of (I) in the crystal structure. Dashed lines indicate close intermolecular contacts (see text).
	Fig. 3. The molecular structure and atom-labelling scheme for (II). Displacement ellipsoids are drawn at the 50% probability level. [Symmetry code: (i) -x + 1, -y + 1, z.]
	Fig. 4. Intermolecular contacts (dashed lines) in the structure of (II).
	Fig. 5. The molecular structure and atom-labelling scheme for (III). Displacement ellipsoids are drawn at the 50% probability level.
	Fig. 6. The chain of molecules in the structure of (III). Dashed lines indicate close intermolecular contacts (see text).

(I) 1,4-Diethylbenzene

Crystal data

C10H14	F(000) = 148
Mr = 134.21	Dx = 0.989 Mg m^−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
a = 9.0919 (9) Å	Cell parameters from 0 reflections
b = 6.0956 (6) Å	θ = 2.5–23.4°
c = 8.9673 (9) Å	µ = 0.06 mm^−1
β = 114.986 (4)°	T = 220 K
V = 450.46 (8) Å^3	Cylinder, colourless
Z = 2	0.5 × 0.3 × 0.3 mm

Data collection

Bruker SMART 6000 CCD area-detector diffractometer	977 independent reflections
Radiation source: sealed X-ray tube, sealed X-ray tube	630 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.039
Detector resolution: 5.6 pixels mm^-1	θmax = 27.0°, θmin = 2.5°
ω scans	h = −11→11
Absorption correction: multi-scan (SADABS; Bruker, 2006)	k = −7→7
Tmin = 0.156, Tmax = 1	l = −11→11
4711 measured 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)] = 0.071	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.277	H atoms treated by a mixture of independent and constrained refinement
S = 1.10	w = 1/[σ^2(Fo^2) + (0.140P)^2 + 0.080P] where P = (Fo^2 + 2Fc^2)/3
977 reflections	(Δ/σ)max < 0.001
55 parameters	Δρmax = 0.14 e Å^−3
0 restraints	Δρmin = −0.18 e Å^−3

Special details

Experimental. SADABS (Version 2.03; Bruker, 2006) was used for absorption correction. R(int) was 0.1408 before and 0.0578 after correction. The Ratio of minimum to maximum transmission is 0.1558. The λ/2 correction factor is 0.0015.

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	0.5056 (3)	0.1892 (4)	0.4243 (3)	0.0830 (9)
C2	0.3737 (3)	0.0551 (4)	0.3468 (3)	0.0743 (8)
C3	0.3709 (3)	−0.1352 (5)	0.4272 (4)	0.0870 (9)
C4	0.2400 (4)	0.1153 (7)	0.1818 (4)	0.1162 (13)
H4A	0.2885	0.1775	0.1136	0.139*
H4B	0.1833	−0.0175	0.1285	0.139*
C5	0.1226 (4)	0.2703 (7)	0.1906 (4)	0.1203 (13)
H5A	0.0762	0.2127	0.2608	0.180*
H5B	0.0383	0.2938	0.0823	0.180*
H5C	0.1756	0.4071	0.2344	0.180*
H1	0.510 (4)	0.317 (6)	0.374 (4)	0.113 (10)*
H3	0.282 (4)	−0.237 (6)	0.365 (4)	0.123 (11)*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
C1	0.0946 (17)	0.0717 (15)	0.0900 (18)	−0.0020 (14)	0.0462 (15)	0.0161 (13)
C2	0.0774 (15)	0.0816 (16)	0.0655 (13)	0.0068 (12)	0.0316 (11)	−0.0035 (10)
C3	0.0770 (16)	0.0786 (17)	0.1002 (19)	−0.0179 (13)	0.0324 (14)	−0.0085 (14)
C4	0.113 (2)	0.146 (3)	0.0752 (18)	0.032 (2)	0.0251 (17)	−0.0058 (17)
C5	0.106 (2)	0.124 (3)	0.104 (2)	0.0240 (19)	0.0174 (19)	−0.0048 (19)

Geometric parameters (Å, º)

C1—C2	1.372 (4)	C4—C5	1.452 (5)
C1—C3^i	1.371 (4)	C4—H4A	0.9700
C1—H1	0.91 (3)	C4—H4B	0.9700
C2—C3	1.372 (4)	C5—H5A	0.9600
C2—C4	1.511 (4)	C5—H5B	0.9600
C3—C1^i	1.371 (4)	C5—H5C	0.9600
C3—H3	0.98 (3)
C2—C1—C3^i	122.0 (2)	C2—C4—H4A	108.7
C2—C1—H1	118 (2)	C5—C4—H4B	108.7
C3^i—C1—H1	120 (2)	C2—C4—H4B	108.7
C3—C2—C1	116.3 (2)	H4A—C4—H4B	107.6
C3—C2—C4	122.3 (3)	C4—C5—H5A	109.5
C1—C2—C4	121.4 (3)	C4—C5—H5B	109.5
C2—C3—C1^i	121.6 (2)	H5A—C5—H5B	109.5
C2—C3—H3	115 (2)	C4—C5—H5C	109.5
C1^i—C3—H3	123 (2)	H5A—C5—H5C	109.5
C5—C4—C2	114.3 (2)	H5B—C5—H5C	109.5
C5—C4—H4A	108.7
C3^i—C1—C2—C3	0.9 (4)	C4—C2—C3—C1^i	179.0 (2)
C3^i—C1—C2—C4	−179.0 (2)	C3—C2—C4—C5	99.3 (4)
C1—C2—C3—C1^i	−0.9 (4)	C1—C2—C4—C5	−80.8 (4)

Symmetry code: (i) −x+1, −y, −z+1.

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
C1—H1···C2^ii	0.91 (3)	2.99 (3)	3.787 (3)	148 (3)
C4—H4A···C1^iii	0.97	3.20	4.159 (5)	168

Symmetry codes: (ii) −x+1, y+1/2, −z+1/2; (iii) x, −y+1/2, z−1/2.

(II) 1,2-Diethylbenzene

Crystal data

C10H14	Dx = 1.064 Mg m^−3
Mr = 134.21	Mo Kα radiation, λ = 0.71073 Å
Orthorhombic, Fdd2	Cell parameters from 0 reflections
a = 13.556 (3) Å	θ = 2.6–30.5°
b = 15.931 (3) Å	µ = 0.06 mm^−1
c = 7.7562 (16) Å	T = 120 K
V = 1675.0 (6) Å^3	Cylinder, colourless
Z = 8	0.3 × 0.3 × 0.3 mm
F(000) = 592

Data collection

Bruker SMART 6000 CCD area-detector diffractometer	625 independent reflections
Radiation source: sealed X-ray tube, sealed X-ray tube	618 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.022
Detector resolution: 5.6 pixels mm^-1	θmax = 29.5°, θmin = 3.3°
ω scans	h = −18→18
Absorption correction: multi-scan (SADABS; Bruker, 2006)	k = −21→22
Tmin = 0.794, Tmax = 1	l = −10→10
5125 measured reflections

Refinement

Refinement on F^2	Hydrogen site location: difference Fourier map
Least-squares matrix: full	All H-atom parameters refined
R[F^2 > 2σ(F^2)] = 0.035	w = 1/[σ^2(Fo^2) + (0.080P)^2 + 0.150P] where P = (Fo^2 + 2Fc^2)/3
wR(F^2) = 0.091	(Δ/σ)max < 0.001
S = 1.06	Δρmax = 0.28 e Å^−3
625 reflections	Δρmin = −0.17 e Å^−3
75 parameters	Extinction correction: SHELXTL (Sheldrick, 2008), Fc^* = kFc[1 + 0.001Fc^2λ^3/sin(2θ)]^-1/4
1 restraint	Extinction coefficient: 0.014 (3)
Primary atom site location: structure-invariant direct methods	Absolute structure: Flack (1983), with how many Friedel pairs?
Secondary atom site location: difference Fourier map	Absolute structure parameter: 6 (10)

Special details

Experimental. SADABS (Version 2.03; Bruker, 2006) was used for absorption correction. R(int) was 0.1181 before and 0.0254 after correction. The Ratio of minimum to maximum transmission is 0.7937. The λ/2 correction factor is 0.0015.

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	0.53784 (6)	0.53015 (5)	0.27702 (10)	0.0191 (3)
C2	0.57456 (7)	0.55885 (6)	0.11920 (13)	0.0238 (3)
C3	0.53774 (8)	0.52946 (6)	−0.03657 (12)	0.0271 (3)
C4	0.58307 (8)	0.56323 (6)	0.44110 (14)	0.0247 (3)
C5	0.66855 (9)	0.50907 (8)	0.50440 (19)	0.0319 (3)
H2	0.6300 (10)	0.6003 (9)	0.120 (2)	0.027 (3)*
H3	0.5661 (13)	0.5467 (12)	−0.142 (3)	0.036 (4)*
H4A	0.5337 (13)	0.5664 (14)	0.535 (3)	0.041 (5)*
H4B	0.6076 (13)	0.6205 (11)	0.425 (3)	0.041 (4)*
H5A	0.6484 (15)	0.4538 (13)	0.529 (3)	0.041 (5)*
H5B	0.6969 (14)	0.5328 (13)	0.606 (3)	0.042 (5)*
H5C	0.7253 (15)	0.5047 (14)	0.413 (3)	0.050 (6)*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
C1	0.0181 (4)	0.0180 (5)	0.0213 (4)	0.0006 (3)	−0.0007 (3)	−0.0008 (3)
C2	0.0231 (4)	0.0223 (5)	0.0261 (6)	−0.0007 (3)	0.0030 (4)	0.0022 (3)
C3	0.0318 (6)	0.0288 (6)	0.0207 (5)	0.0042 (4)	0.0039 (4)	0.0032 (4)
C4	0.0243 (5)	0.0249 (5)	0.0248 (5)	−0.0003 (3)	−0.0036 (3)	−0.0040 (3)
C5	0.0280 (5)	0.0371 (6)	0.0307 (5)	0.0027 (4)	−0.0088 (4)	−0.0007 (4)

Geometric parameters (Å, º)

C1—C1^i	1.4054 (17)	C4—C5	1.5258 (15)
C1—C2	1.3982 (13)	C4—H4A	0.99 (2)
C1—C4	1.5077 (13)	C4—H4B	0.978 (18)
C2—C3	1.3885 (15)	C5—H5A	0.94 (2)
C2—H2	1.000 (14)	C5—H5B	0.96 (2)
C3—C3^i	1.388 (2)	C5—H5C	1.05 (2)
C3—H3	0.94 (2)
C1^i—C1—C4	122.39 (5)	C1—C4—H4B	110.9 (14)
C2—C1—C1^i	118.90 (5)	C5—C4—H4A	107.8 (13)
C2—C1—C4	118.68 (8)	C5—C4—H4B	108.1 (11)
C1—C2—H2	118.4 (11)	H4A—C4—H4B	105.9 (18)
C3—C2—C1	121.57 (8)	C4—C5—H5A	111.9 (13)
C3—C2—H2	120.0 (11)	C4—C5—H5B	110.3 (12)
C2—C3—H3	120.5 (12)	C4—C5—H5C	112.3 (12)
C3^i—C3—C2	119.53 (6)	H5A—C5—H5B	108.5 (19)
C3^i—C3—H3	119.9 (12)	H5A—C5—H5C	106.7 (19)
C1—C4—C5	112.51 (9)	H5B—C5—H5C	106.8 (16)
C1—C4—H4A	111.3 (12)
C2—C1—C4—C5	−90.88 (11)

Symmetry code: (i) −x+1, −y+1, z.

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
C2—H2···C3^ii	1.000 (14)	2.961 (14)	3.9397 (15)	166.3 (14)
C4—H4B···C1^iii	0.978 (18)	3.017 (18)	3.9305 (14)	155.8 (18)

Symmetry codes: (ii) x+1/4, −y+5/4, z+1/4; (iii) −x+5/4, y+1/4, z+1/4.

(III) Ethylbenzene

Crystal data

C8H10	F(000) = 232
Mr = 106.16	Dx = 1.067 Mg m^−3
Monoclinic, P21/n	Melting point: 178 K
Hall symbol: -P 2yn	Mo Kα radiation, λ = 0.71073 Å
a = 5.6138 (5) Å	Cell parameters from 999 reflections
b = 14.970 (1) Å	θ = 2.7–29.0°
c = 8.0481 (10) Å	µ = 0.06 mm^−1
β = 102.18 (2)°	T = 160 K
V = 661.13 (11) Å^3	Cylinder, colourless
Z = 4	0.50 × 0.30 × 0.30 mm

Data collection

Bruker SMART 6000 CCD area-detector diffractometer	1215 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	Rint = 0.022
Graphite monochromator	θmax = 29.0°, θmin = 2.7°
0.30° ω scans	h = −6→6
5060 measured reflections	k = −20→20
1455 independent reflections	l = −10→10

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)] = 0.038	Hydrogen site location: difference Fourier map
wR(F^2) = 0.117	All H-atom parameters refined
S = 1.01	w = 1/[σ^2(Fo^2) + (0.070P)^2 + 0.070P] where P = (Fo^2 + 2Fc^2)/3
1455 reflections	(Δ/σ)max < 0.001
113 parameters	Δρmax = 0.23 e Å^−3
0 restraints	Δρmin = −0.10 e Å^−3

Special details

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	0.26089 (18)	0.14402 (6)	0.05894 (11)	0.0326 (3)
C2	0.1119 (2)	0.17626 (6)	0.16338 (12)	0.0363 (3)
C3	0.1719 (2)	0.16322 (6)	0.33831 (13)	0.0395 (3)
C4	0.3822 (2)	0.11725 (7)	0.41133 (12)	0.0410 (3)
C5	0.5330 (2)	0.08546 (7)	0.30982 (13)	0.0408 (3)
C6	0.4733 (2)	0.09897 (6)	0.13472 (13)	0.0362 (3)
C7	0.1900 (2)	0.15482 (7)	−0.13190 (12)	0.0402 (3)
C8	−0.0229 (2)	0.09510 (8)	−0.21238 (13)	0.0472 (3)
H2	−0.038 (2)	0.2090 (8)	0.1140 (14)	0.042 (3)*
H3	0.064 (2)	0.1871 (8)	0.4101 (15)	0.046 (3)*
H4	0.422 (2)	0.1079 (8)	0.5363 (18)	0.053 (3)*
H5	0.686 (2)	0.0526 (8)	0.3584 (16)	0.047 (3)*
H6	0.582 (2)	0.0760 (8)	0.0609 (16)	0.046 (3)*
H71	0.148 (2)	0.2182 (9)	−0.1623 (15)	0.054 (4)*
H72	0.332 (3)	0.1391 (9)	−0.1832 (19)	0.054 (4)*
H81	−0.177 (3)	0.1138 (11)	−0.168 (2)	0.074 (5)*
H82	−0.060 (3)	0.1039 (9)	−0.3409 (19)	0.060 (4)*
H83	0.015 (2)	0.0302 (10)	−0.1845 (18)	0.066 (4)*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
C1	0.0366 (6)	0.0310 (4)	0.0301 (4)	−0.0067 (3)	0.0067 (4)	−0.0016 (3)
C2	0.0379 (6)	0.0356 (5)	0.0353 (5)	0.0010 (4)	0.0072 (4)	0.0014 (4)
C3	0.0463 (7)	0.0400 (5)	0.0344 (5)	−0.0013 (4)	0.0131 (5)	−0.0035 (4)
C4	0.0498 (7)	0.0408 (5)	0.0303 (5)	−0.0049 (4)	0.0036 (4)	−0.0009 (4)
C5	0.0390 (7)	0.0389 (5)	0.0410 (5)	0.0007 (4)	0.0007 (5)	−0.0009 (4)
C6	0.0357 (6)	0.0358 (5)	0.0379 (5)	−0.0030 (4)	0.0098 (4)	−0.0055 (4)
C7	0.0465 (7)	0.0446 (5)	0.0301 (5)	−0.0063 (4)	0.0093 (5)	0.0020 (4)
C8	0.0506 (8)	0.0567 (7)	0.0311 (5)	−0.0085 (5)	0.0012 (5)	−0.0009 (4)

Geometric parameters (Å, º)

C1—C6	1.3933 (14)	C5—C6	1.3927 (14)
C1—C2	1.3912 (15)	C5—H5	0.994 (13)
C1—C7	1.5118 (13)	C6—H6	1.000 (13)
C2—C3	1.3905 (13)	C7—C8	1.5234 (15)
C2—H2	0.983 (12)	C7—H71	0.995 (13)
C3—C4	1.3858 (15)	C7—H72	0.999 (16)
C3—H3	0.986 (13)	C8—H81	1.042 (18)
C4—C5	1.3791 (16)	C8—H82	1.020 (14)
C4—H4	0.993 (14)	C8—H83	1.011 (15)
C6—C1—C2	118.12 (9)	C1—C6—C5	120.95 (10)
C6—C1—C7	120.94 (10)	C1—C6—H6	118.7 (7)
C2—C1—C7	120.91 (9)	C5—C6—H6	120.3 (7)
C3—C2—C1	121.00 (10)	C1—C7—C8	112.58 (9)
C3—C2—H2	118.9 (7)	C1—C7—H71	110.5 (7)
C1—C2—H2	120.1 (7)	C8—C7—H71	109.3 (7)
C4—C3—C2	120.11 (10)	C1—C7—H72	109.4 (8)
C4—C3—H3	120.2 (7)	C8—C7—H72	107.9 (8)
C2—C3—H3	119.7 (7)	H71—C7—H72	107.0 (10)
C5—C4—C3	119.64 (9)	C7—C8—H81	109.4 (9)
C5—C4—H4	121.0 (8)	C7—C8—H82	109.3 (8)
C3—C4—H4	119.4 (8)	H81—C8—H82	107.6 (12)
C4—C5—C6	120.16 (10)	C7—C8—H83	111.0 (8)
C4—C5—H5	121.6 (7)	H81—C8—H83	109.7 (12)
C6—C5—H5	118.3 (7)	H82—C8—H83	109.7 (12)
C2—C1—C7—C8	−71.27 (13)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
C2—H2···C4^i	0.983 (12)	3.053 (11)	3.7722 (14)	131.1 (8)
C7—H71···C5^i	0.995 (13)	3.008 (13)	3.9924 (15)	170.3 (9)

Symmetry code: (i) x−1/2, −y+1/2, z−1/2.