1,4-Bis(triisopropyl­silyl)buta-1,3-diyne and 1,4-bis­(biphenyl-4-yl)buta-1,3-diyne

We report the single crystal structures of 1,4-bis­(triisopropyl­silyl)buta-1,3-diyne, C₂₂H₄₂Si₂, and 1,4-bis­(biphenyl-4-yl)buta-1,3-diyne, C₂₈H₁₈, the packing in both of which illustrates the versatility of weak C—H...π supra­molecular inter­actions in dictating the overall solid-state structures.

S1. Comment

We have been interested in the development of polyalkyne-based stars and dendrimers and their reactions with Co₂(CO)₈ to produce organometallic cluster-decorated architectures (Constable et al., 2006). We have used Sonogashira palladium-catalysed cross-coupling reactions (Sonogashira et al., 1975; Sonogashira, 2002) for the divergent assembly of polyalkynes containing rigid frameworks with well defined structures. Under Sonogashira conditions, reactions between terminal alkynes (RC≡CH) and aryl halides can give rise to diynes, RC≡C—C≡CR, as side-products (these most often arise from bromo precursors) (Sonogashira et al. 1975; Sonogashira 2002). Related reactions (Liu & Burton, 1997) or modified Sonogashira conditions (Rossi et al., 1985) have been used for the specific formation of diynes. Two molecular cores that we have investigated are hexakis[(triisopropylsilyl)ethynyl]benzene and 4,4'-bis(biphenyl-4-ylethynyl)biphenyl. During attempts to synthesize these compounds, we found that 1,4-bis(triisopropylsilyl)buta-1,3-diyne, (I), and 1,4-di(biphenyl-4-yl)buta-1,3-diyne, (II), could be produced quantitatively.

With the aim of preparing C₆(C≡CSiⁱPr₃)₆, we treated C₆I₆ with six equivalents of ⁱPr₃SiC≡CH under Sonogashira cross-coupling conditions. Instead of the desired product, compound (I) was formed quantitatively under the conditions shown in the scheme. This was also the case when C₆Br₆ was used as the precursor. Similarly (see scheme), the palladium-catalysed cross-coupling reaction between 4-ethynylbiphenyl and 4,4'-dibromobiphenyl led to the quantitative formation of (II). Compounds (I) and (II) have previously been reported (Eisler et al., 2005; Hlavatý et al., 2002; Ried & Saxena, 1970; Toda & Tokumaru, 1990), but have not, to our knowledge, been structurally characterized. Here, we report their single-crystal structures, which illustrate a number of facets of weak C—H···π interactions in dictating solid-state structures. Such hydrogen bonds are now well established as important components in solid-state supramolecular assemblies (Desiraju, 2002, 2005; Desiraju & Steiner, 1999; Nishio, 2004; Nishio et al., 1998; Steiner, 2002), and their role in organic reactions has recently been assessed (Nishio, 2005).

X-ray quality crystals of (I) were grown from a CH₂Cl₂ solution. Fig. 1 shows the structure of the centrosymmetric molecule of (I). The carbon backbone is linear, as observed for Me₃Si(C≡C)₂SiMe₃ (Carré et al., 2003) and ⁱPr₃Si(C≡ C)_nSiⁱPr₃ (n = 4, 5 or 6; Eisler et al., 2005), in contrast with the curved backbone of ⁱPr₃Si(C≡C)₈SiⁱPr₃ (Eisler et al., 2005). The C—Si—C bond angles lie in the range 105.97 (9)–116.94 (13)°.

Molecules of (I) pack in rows (Fig. 2a), such that the distance between the least-squares planes containing adjacent rows of SiCCCCSi chains is 5.8 Å. Adjacent chains are interlocked, with the packing being supported by close methyl C—H to alkyne π interactions (C8—H83···C1 = 2.9 Å and C8—H83···C2 = 3.1 Å). This leads to the presence of close (repulsive) H···H contacts (Me₂C—H61···H61—CMe₂ = 2.7 Å). A second set of C—H···π interactions operates between molecules within each row (Fig. 2b). Their evolution gives rise to short H···H contacts between pairs of molecules.

The structures of a number of molecules closely related to (I) have been determined and comparisons of the solid-state packing are instructive. A search of the Cambridge Structural Database (CSD, Version 5.2.7; Allen, 2002; Bruno et al., 2002) for molecules containing an E—C≡ C—C≡ C–E unit (E is Si, Sn, Ge or Pb) gave only 14 hits (Brouty et al., 1980; Brunel et al., 2001; Carré et al., 1999, 2003; Dam et al., 1998; Neugebauer et al., 2000). Among these are two polymorphs of Me₃SiC≡CC≡CSiMe₃ (structures determined at 120 and 203 K; Carré et al., 2003). The packing of the molecules in both polymorphs differs from that in (I). Although the molecules are interlocked by virtue of the close approach of SiMe₃ and alkyne groups, molecules in both polymorphs of Me₃SiC≡CC≡ CSiMe₃ form grid-like assemblies, in contrast with the parallel alignment of molecules observed in the solid state of (I).

Compound (I) is a member of a family of polyynes, ⁱPr₃Si(C≡ C)_nSiⁱPr₃ (n = 4, 5, 6 and 8; Eisler et al., 2005). The solid-state packing of ⁱPr₃Si(C≡ C)₄SiⁱPr₃ resembles that of (I), with molecules organized in offset rows, while for ⁱPr₃Si(C≡ C)₅SiⁱPr₃ and ⁱPr₃Si(C≡C)₆SiⁱPr₃, a herringbone assembly is observed. In ⁱPr₃Si(C≡C)₈SiⁱPr₃, the polyyne backbone is significantly curved and the molecular packing is less readily compared with that of the smaller polyynes (Eisler et al., 2005).

Crystals of (II) were grown from a CH₂Cl₂ solution, and the molecular structure is shown in Fig. 3. The molecule is slightly bowed and the aryl rings are twisted with respect to one another, so that the angles between the least-squares planes of the rings containing atoms C6 and C7, atoms C7 and C22, and atoms C22 and C23 are 28.70 (7), 61.07 (6) and 44.22 (6)°, respectively. The origin of these ring orientations can be traced to the intermolecular C—H···π interactions listed in Table 3. The basic motif in the solid state is a dimeric unit (Fig. 4a), in which both C—H_aryl···π_alkyne and C—H_aryl···π_aryl interactions are present (Table 3).

The dimers further assemble into layers (Fig. 4b), again with C—H···π interactions playing a role (Table 3). Stacking of planes of molecules into the three-dimensional lattice is also supported by C—H···π contacts (Table 3). The molecular structure of (II) shows interesting contrasts with that of 1,4-diphenylbuta-1,3-diyne (Fronczek & Erickson, 1995; Surette et al., 1994). Molecules of the latter are planar in the solid state and pack in a herringbone arrangement. Whereas C—H···π contacts control the ring orientations and packing in (II), π-stacking interactions are important in 1,4-diphenylbuta-1,3-diyne. Also related to (II) is 4-ethynylbiphenyl (Mague et al., 1997). As in (II), the biphenyl unit of 4-ethynylbiphenyl is non-planar. The authors (Mague et al., 1997) describe the structure as containing "no significant intermolecular interactions", although inspection of the data indicate the presence of weak C—H_alkyne···π_aryl contacts.

In conclusion, we have investigated the solid-state structures of two simple diynes and in both cases find that weak C—H···π contacts control the molecular packing. In the case of 1,4-di(biphenyl-4-yl)buta-1,3-diyne, a combination of C—H_aryl···π_alkyne and C—H_aryl···π_aryl interactions operate at the expense of π-stacking interactions.

S2. Experimental

Compound (I), previously prepared directly (Eisler et al., 2005; Hlavatý et al., 2002), was the product of an unsuccessful attempt to prepare C₆(CCSiⁱPr₃)₆. C₆I₆ (1.00 g, 1.20 mmol), CuCl (17.8 mg, 0.18 mmol) and [Pd(PPh₃)₂Cl₂] (126 mg, 0.18 mmol) were added to Et₃N (75 ml), and after the addition of ⁱPr₃SiC≡CH (2.13 ml, 9.60 mmol) the mixture was stirred at 333 K for 12 h under argon. The solvent was removed and the residue was extracted with 30% CH₂Cl₂ in hexanes (200 ml). The product was purified by column chromatography (alumina, hexanes) and (I) was collected as a dark-yellow solid (1.74 g, 100%; m.p. 369 K). FAB–MS m/z 362 ([M]⁺), 319 ([M - ⁱPr], base peak); ¹H NMR (400 MHz, CDCl₃, δ, p.p.m.): 1.09 (s, TIPS); ¹³C NMR (125 MHz, CDCl₃, δ, p.p.m.): 90.2 (C≡C), 81.6 (C≡C), 18.6 (CH), 11.3 (CH₃); IR (solid, ν, cm^-1): 2943 (s), 2866 (s), 2050 (s), 1458 (s), 1383 (s), 1365 (s), 1230 (m), 1011 (s), 991 (s), 881 (vs), 663 (vs), 625 (vs). Crystals were grown from a solution in CH₂Cl₂.

The route to compound (II) was optimized during attempts to prepare 4,4'-bis(biphenyl-4-ylethynyl)biphenyl. 4,4'-Dibromobiphenyl (233 mg, 1.00 mmol), CuCl (14.9 mg, 0.15 mmol) and [Pd(PPh₃)₂Cl₂] (105 mg, 0.15 mmol) were added to Et₃N (40 ml), and after the addition of 4-ethynylbiphenyl (Foroozesh et al., 1997) (196 mg, 1.10 mmol) the mixture was stirred at 333 K for 18 h under argon. The solvent was removed, the residue was redissolved in hexanes (150 ml) and the mixture was filtered. The product was purified by column chromatography (alumina, hexanes–CH₂Cl₂, 1:4) to yield (II) as a yellow solid (195 mg, 100%; m.p. 513 K). FAB–MS m/z 354 ([M]⁺, base peak), 177 ([M - PhC₆H₄CC]⁺); ¹H NMR (400 MHz, CDCl₃, δ, p.p.m.): 7.60 [m, 12H, H(B2,B3,A2)], 7.46 [m, 4H, H(A3)], 7.38 [t, 2H, H(A4)]; ¹³C NMR (125 MHz, CDCl₃, δ, p.p.m.): 141.9 [C(1A/1B)], 140.0 [C(1B/1A)], 132.9 [C(3B)], 128.9 [C(3A)], 127.9 [C(4A)], 127.1 [C(2A)], 127.0 [C(2B)], 120.6 [C(4B)], 81.8 [C(ArC≡ C)], 74.6 [C(ArC≡C); IR (solid, ν, cm^-1): 3059 (w), 3036 (w), 2133 (w), 1599 (m), 1481 (s), 1448 (s), 839 (vs), 762 (vs), 721 (vs), 696 (vs). Crystals of (II) were grown from a solution in CH₂Cl₂.

S3. Refinement

All H atoms were treated as riding, with C—H distances of 1.00 Å and with U_iso(H) = 1.2U_eq(C).

Computing details

For both compounds, data collection: COLLECT (Nonius, 2001); cell refinement: DENZO and SCALEPACK (Otwinowski & Minor, 1997); data reduction: DENZO and SCALEPACK; program(s) used to solve structure: SIR92 (Altomare et al., 1994); program(s) used to refine structure: CRYSTALS (Betteridge et al., 2003); molecular graphics: ORTEP-3 (Farrugia, 1997); software used to prepare material for publication: CRYSTALS.

Figures

	Fig. 1. The molecular structure of (I), showing the atom-numbering scheme. Displacement ellipsoids are drawn at the 30% probability level and H atoms are shown as small spheres of arbitary radii. Unlabelled atoms and symmetry code (i) are generated by the symmetry operator (-x + 2, -y + 1, -z + 1).
	Fig. 2. (a) The packing of molecules of (I), showing parts of two offset rows. (b) C—H···π interactions between adjacent molecules in a row (C2^i···H53^ii = 3.2 Å; C1^i···H53^ii = 2.9 Å; C1···H53^ii = 3.1 Å). [Symmetry codes: (i) -x + 2, -y + 1, -z + 1; (ii) 1 - x, 1 - y, 1 - z.]
	Fig. 3. The molecular structure of (II), showing the atom-numbering scheme. Displacement ellipsoids are drawn at the 50% probability level and H atoms are shown as small spheres of arbitary radii.
	Fig. 4. (a) The dimeric motif in the solid-state structure of (II). [Symmetry code (i) 1 - x, 1 - y, -z.] (b) The packing of molecules of (II) into layers. Two dimeric units are shown in the middle of the figure.

(I) 1,4-bis(triisopropylsilyl)buta-1,3-diyne

Crystal data

C22H42Si2	Z = 1
Mr = 362.75	F(000) = 202
Triclinic, P1	Dx = 1.006 Mg m^−3
Hall symbol: -P 1	Mo Kα radiation, λ = 0.71073 Å
a = 7.2397 (4) Å	Cell parameters from 3524 reflections
b = 7.8151 (5) Å	θ = 3–30°
c = 10.9548 (5) Å	µ = 0.15 mm^−1
α = 86.680 (5)°	T = 173 K
β = 80.485 (4)°	Plate, colourless
γ = 78.542 (4)°	0.30 × 0.16 × 0.14 mm
V = 598.90 (6) Å^3

Data collection

Nonius KappaCCD area-detector diffractometer	2019 reflections with I > 3σ(I)
Graphite monochromator	Rint = 0.069
φ and ω scans	θmax = 30.0°, θmin = 3.2°
Absorption correction: multi-scan DENZO and SCALEPACK (Otwinowski & Minor, 1997)	h = −10→10
Tmin = 0.98, Tmax = 0.98	k = −10→10
29988 measured reflections	l = −15→15
3478 independent reflections

Refinement

Refinement on F	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F^2 > 2σ(F^2)] = 0.050	H-atom parameters constrained
wR(F^2) = 0.054	Method, part 1, Chebychev polynomial, (Watkin, 1994; Prince, 1982) [weight] = 1.0/[A0T0(x) + A1T1(x) ··· + An-1Tn-1(x)], where Ai are the Chebychev coefficients listed below and x = F /Fmax Method = robust weighting (Prince, 1982) W = [weight][1-(ΔF/6σF)^2]^2 Ai are 1.89 -0.168 1.21
S = 1.09	(Δ/σ)max = 0.007
2019 reflections	Δρmax = 0.93 e Å^−3
109 parameters	Δρmin = −0.64 e Å^−3
0 restraints

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
C1	0.9569 (2)	0.4465 (2)	0.54262 (17)	0.0297
C2	0.8806 (3)	0.3535 (3)	0.61763 (18)	0.0325
C3	0.4976 (3)	0.2698 (3)	0.7054 (2)	0.0410
C4	0.4047 (4)	0.4570 (4)	0.7391 (3)	0.0594
C5	0.4776 (4)	0.2384 (4)	0.5727 (3)	0.0573
C6	0.8595 (3)	−0.0168 (3)	0.68257 (19)	0.0388
C7	1.0699 (4)	−0.0721 (4)	0.6943 (3)	0.0610
C8	0.7444 (5)	−0.1499 (3)	0.7470 (3)	0.0674
C9	0.7757 (4)	0.2751 (4)	0.8877 (2)	0.0596
C10	0.6525 (5)	0.1876 (4)	0.9890 (2)	0.0615
C11	0.9605 (7)	0.2834 (8)	0.9147 (3)	0.1148
Si1	0.75346 (8)	0.21347 (8)	0.72851 (5)	0.0297
H31	0.4287	0.1908	0.7629	0.0483*
H41	0.4181	0.4768	0.8264	0.0670*
H42	0.4688	0.5396	0.6820	0.0670*
H43	0.2663	0.4776	0.7313	0.0670*
H51	0.5388	0.1153	0.5510	0.0709*
H52	0.5419	0.3206	0.5153	0.0709*
H53	0.3393	0.2586	0.5645	0.0709*
H61	0.8522	−0.0164	0.5922	0.0438*
H71	1.1419	0.0169	0.6516	0.0681*
H72	1.0841	−0.0815	0.7839	0.0681*
H73	1.1219	−0.1879	0.6553	0.0681*
H81	0.6071	−0.1104	0.7378	0.0764*
H82	0.7563	−0.1599	0.8369	0.0764*
H83	0.7942	−0.2662	0.7083	0.0764*
H91	0.7203	0.4029	0.8872	0.0746*
H101	0.5256	0.1890	0.9637	0.0758*
H102	0.6338	0.2519	1.0677	0.0758*
H103	0.7177	0.0641	1.0019	0.0758*
H111	1.0319	0.3429	0.8443	0.1414*
H112	0.9478	0.3494	0.9921	0.1414*
H113	1.0317	0.1616	0.9263	0.1414*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
C1	0.0239 (8)	0.0318 (10)	0.0326 (9)	−0.0062 (7)	−0.0017 (7)	0.0007 (7)
C2	0.0277 (9)	0.0334 (10)	0.0354 (10)	−0.0081 (8)	0.0000 (7)	0.0021 (8)
C3	0.0278 (9)	0.0357 (11)	0.0566 (13)	−0.0100 (8)	0.0054 (9)	0.0002 (9)
C4	0.0435 (13)	0.0436 (14)	0.0807 (19)	0.0029 (11)	0.0084 (12)	−0.0058 (13)
C5	0.0394 (12)	0.0649 (17)	0.0713 (17)	−0.0095 (12)	−0.0187 (12)	−0.0064 (14)
C6	0.0429 (11)	0.0323 (10)	0.0345 (10)	−0.0028 (9)	0.0057 (8)	0.0043 (8)
C7	0.0546 (15)	0.0534 (16)	0.0620 (16)	0.0157 (13)	−0.0053 (12)	0.0055 (13)
C8	0.088 (2)	0.0300 (12)	0.0721 (18)	−0.0165 (12)	0.0280 (15)	−0.0034 (11)
C9	0.0759 (18)	0.0780 (19)	0.0339 (11)	−0.0474 (16)	0.0060 (11)	−0.0040 (11)
C10	0.083 (2)	0.0739 (19)	0.0320 (11)	−0.0399 (16)	0.0080 (12)	−0.0008 (11)
C11	0.131 (4)	0.199 (5)	0.0512 (18)	−0.116 (4)	−0.018 (2)	0.000 (2)
Si1	0.0289 (3)	0.0302 (3)	0.0291 (3)	−0.0106 (2)	0.00341 (18)	0.00170 (18)

Geometric parameters (Å, º)

C1—C1^i	1.373 (3)	C7—H71	1.000
C1—C2	1.204 (2)	C7—H72	1.000
C2—Si1	1.8432 (18)	C7—H73	1.000
C3—C4	1.523 (3)	C8—H81	1.000
C3—C5	1.523 (4)	C8—H82	1.000
C3—Si1	1.873 (2)	C8—H83	1.000
C3—H31	1.000	C9—C10	1.524 (3)
C4—H41	1.000	C9—C11	1.432 (5)
C4—H42	1.000	C9—Si1	1.876 (2)
C4—H43	1.000	C9—H91	1.000
C5—H51	1.000	C10—H101	1.000
C5—H52	1.000	C10—H102	1.000
C5—H53	1.000	C10—H103	1.000
C6—C7	1.523 (3)	C11—H111	1.000
C6—C8	1.530 (3)	C11—H112	1.000
C6—Si1	1.873 (2)	C11—H113	1.000
C6—H61	1.000
C1^i—C1—C2	179.6 (3)	H72—C7—H73	109.5
C1—C2—Si1	177.18 (18)	C6—C8—H81	109.4
C4—C3—C5	109.7 (2)	C6—C8—H82	109.5
C4—C3—Si1	112.72 (17)	H81—C8—H82	109.5
C5—C3—Si1	111.02 (15)	C6—C8—H83	109.5
C4—C3—H31	107.5	H81—C8—H83	109.5
C5—C3—H31	109.3	H82—C8—H83	109.5
Si1—C3—H31	106.4	C10—C9—C11	114.6 (3)
C3—C4—H41	109.4	C10—C9—Si1	112.41 (18)
C3—C4—H42	109.5	C11—C9—Si1	119.0 (2)
H41—C4—H42	109.5	C10—C9—H91	107.6
C3—C4—H43	109.5	C11—C9—H91	98.7
H41—C4—H43	109.5	Si1—C9—H91	101.9
H42—C4—H43	109.5	C9—C10—H101	109.6
C3—C5—H51	109.4	C9—C10—H102	109.6
C3—C5—H52	109.4	H101—C10—H102	109.5
H51—C5—H52	109.5	C9—C10—H103	109.2
C3—C5—H53	109.6	H101—C10—H103	109.5
H51—C5—H53	109.5	H102—C10—H103	109.5
H52—C5—H53	109.5	C9—C11—H111	109.7
C7—C6—C8	111.1 (2)	C9—C11—H112	110.1
C7—C6—Si1	113.98 (18)	H111—C11—H112	109.5
C8—C6—Si1	113.26 (15)	C9—C11—H113	108.6
C7—C6—H61	106.4	H111—C11—H113	109.5
C8—C6—H61	107.4	H112—C11—H113	109.5
Si1—C6—H61	104.0	C9—Si1—C6	116.94 (13)
C6—C7—H71	109.5	C9—Si1—C3	109.87 (12)
C6—C7—H72	109.4	C6—Si1—C3	110.38 (10)
H71—C7—H72	109.5	C9—Si1—C2	106.99 (10)
C6—C7—H73	109.4	C6—Si1—C2	105.97 (9)
H71—C7—H73	109.5	C3—Si1—C2	106.00 (9)

Symmetry code: (i) −x+2, −y+1, −z+1.

(II) 1,4-bis(biphenyl-4-yl)buta-1,3-diyne

Crystal data

C28H18	F(000) = 744
Mr = 354.45	Dx = 1.230 Mg m^−3
Monoclinic, P21/n	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2yn	Cell parameters from 10543 reflections
a = 6.6723 (2) Å	θ = 1–30°
b = 11.0320 (3) Å	µ = 0.07 mm^−1
c = 26.0094 (7) Å	T = 173 K
β = 91.2833 (14)°	Block, colourless
V = 1914.04 (9) Å^3	0.27 × 0.22 × 0.20 mm
Z = 4

Data collection

Nonius KappaCCD area-detector diffractometer	2992 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.081
φ and ω scans	θmax = 30.1°, θmin = 1.6°
Absorption correction: multi-scan DENZO and SCALEPACK (Otwinowski & Minor, 1997)	h = −9→9
Tmin = 0.98, Tmax = 0.99	k = −15→15
21205 measured reflections	l = −36→36
5625 independent reflections

Refinement

Refinement on F	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F^2 > 2σ(F^2)] = 0.040	H-atom parameters constrained
wR(F^2) = 0.047	Method = modified Sheldrick (Reference ), w = 1/[σ^2(F^2) + (0.03P)^2], where P = [max(Fo^2,0) + 2Fc^2]/3
S = 0.99	(Δ/σ)max = 0.004
2992 reflections	Δρmax = 0.13 e Å^−3
253 parameters	Δρmin = −0.18 e Å^−3
0 restraints

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
C1	−0.5927 (2)	0.68368 (12)	−0.28227 (5)	0.0404
C2	−0.7262 (2)	0.74412 (13)	−0.31455 (6)	0.0443
C3	−0.8638 (2)	0.82376 (13)	−0.29479 (6)	0.0473
C4	−0.8675 (2)	0.84263 (14)	−0.24233 (6)	0.0469
C5	−0.7337 (2)	0.78279 (13)	−0.20981 (6)	0.0417
C6	−0.5927 (2)	0.70190 (12)	−0.22909 (5)	0.0360
C7	−0.44585 (19)	0.63912 (12)	−0.19488 (5)	0.0348
C8	−0.4883 (2)	0.61167 (12)	−0.14374 (5)	0.0383
C9	−0.3502 (2)	0.55329 (13)	−0.11215 (5)	0.0392
C10	−0.1630 (2)	0.51991 (12)	−0.13049 (5)	0.0380
C11	−0.1186 (2)	0.54662 (13)	−0.18163 (5)	0.0425
C12	−0.2573 (2)	0.60554 (13)	−0.21262 (5)	0.0411
C13	−0.0158 (2)	0.46191 (13)	−0.09803 (5)	0.0403
C14	0.1134 (2)	0.41480 (13)	−0.07189 (5)	0.0400
C15	0.2629 (2)	0.36037 (13)	−0.04304 (5)	0.0402
C16	0.3953 (2)	0.31275 (13)	−0.01812 (5)	0.0399
C17	0.8892 (2)	0.24459 (13)	0.04483 (5)	0.0378
C18	0.7385 (2)	0.30587 (13)	0.01827 (5)	0.0388
C19	0.5507 (2)	0.25203 (13)	0.01075 (5)	0.0364
C20	0.5180 (2)	0.13698 (13)	0.03093 (5)	0.0396
C21	0.6690 (2)	0.07580 (13)	0.05649 (5)	0.0386
C22	0.8591 (2)	0.12755 (12)	0.06373 (5)	0.0341
C23	1.02184 (19)	0.05969 (12)	0.09049 (5)	0.0344
C24	1.1465 (2)	0.11595 (13)	0.12693 (5)	0.0395
C25	1.2975 (2)	0.05167 (14)	0.15205 (6)	0.0449
C26	1.3293 (2)	−0.06874 (14)	0.14039 (6)	0.0469
C27	1.2081 (2)	−0.12579 (14)	0.10409 (6)	0.0475
C28	1.0551 (2)	−0.06251 (13)	0.07936 (5)	0.0418
H11	−0.4944	0.6259	−0.2972	0.0483*
H21	−0.7229	0.7300	−0.3525	0.0530*
H31	−0.9601	0.8674	−0.3182	0.0563*
H41	−0.9674	0.8999	−0.2277	0.0561*
H51	−0.7379	0.7976	−0.1719	0.0500*
H81	−0.6214	0.6349	−0.1298	0.0458*
H91	−0.3846	0.5346	−0.0758	0.0470*
H111	0.0141	0.5229	−0.1957	0.0508*
H121	−0.2224	0.6248	−0.2489	0.0492*
H171	1.0221	0.2848	0.0506	0.0453*
H181	0.7641	0.3889	0.0044	0.0465*
H201	0.3829	0.0985	0.0268	0.0473*
H211	0.6428	−0.0072	0.0702	0.0463*
H241	1.1268	0.2037	0.1350	0.0473*
H251	1.3838	0.0926	0.1787	0.0535*
H261	1.4399	−0.1146	0.1582	0.0560*
H271	1.2309	−0.2131	0.0957	0.0571*
H281	0.9675	−0.1046	0.0533	0.0500*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
C1	0.0450 (8)	0.0379 (8)	0.0385 (8)	−0.0012 (7)	0.0038 (7)	0.0022 (7)
C2	0.0514 (9)	0.0410 (8)	0.0404 (8)	−0.0040 (8)	−0.0010 (7)	0.0055 (7)
C3	0.0480 (9)	0.0390 (8)	0.0545 (10)	−0.0006 (7)	−0.0062 (8)	0.0082 (8)
C4	0.0441 (9)	0.0401 (8)	0.0565 (10)	0.0040 (7)	0.0017 (8)	−0.0011 (8)
C5	0.0429 (9)	0.0405 (8)	0.0419 (8)	−0.0009 (7)	0.0044 (7)	−0.0037 (7)
C6	0.0368 (8)	0.0337 (7)	0.0374 (8)	−0.0059 (6)	0.0019 (6)	−0.0001 (6)
C7	0.0367 (8)	0.0322 (7)	0.0354 (7)	−0.0022 (6)	0.0010 (6)	−0.0033 (6)
C8	0.0382 (8)	0.0397 (8)	0.0370 (8)	−0.0023 (7)	0.0044 (6)	−0.0039 (7)
C9	0.0458 (9)	0.0389 (8)	0.0330 (7)	−0.0021 (7)	0.0018 (6)	−0.0016 (6)
C10	0.0426 (9)	0.0323 (7)	0.0390 (8)	−0.0019 (7)	−0.0044 (7)	−0.0039 (6)
C11	0.0404 (8)	0.0457 (9)	0.0415 (8)	0.0012 (7)	0.0037 (7)	−0.0024 (7)
C12	0.0426 (8)	0.0466 (9)	0.0342 (7)	0.0003 (7)	0.0039 (7)	0.0007 (7)
C13	0.0459 (9)	0.0362 (8)	0.0388 (8)	−0.0053 (7)	−0.0015 (7)	−0.0043 (7)
C14	0.0448 (9)	0.0380 (8)	0.0373 (8)	−0.0038 (7)	−0.0001 (7)	−0.0037 (7)
C15	0.0444 (9)	0.0392 (8)	0.0370 (8)	−0.0051 (7)	0.0005 (7)	−0.0038 (7)
C16	0.0435 (9)	0.0412 (8)	0.0350 (7)	−0.0047 (7)	0.0032 (7)	−0.0053 (7)
C17	0.0391 (8)	0.0361 (8)	0.0383 (8)	−0.0070 (7)	0.0011 (6)	−0.0033 (6)
C18	0.0455 (9)	0.0346 (7)	0.0363 (7)	−0.0039 (7)	0.0003 (6)	−0.0013 (6)
C19	0.0391 (8)	0.0396 (8)	0.0305 (7)	0.0004 (7)	0.0013 (6)	−0.0052 (6)
C20	0.0368 (8)	0.0429 (8)	0.0392 (8)	−0.0062 (7)	0.0017 (6)	−0.0023 (7)
C21	0.0400 (8)	0.0367 (8)	0.0394 (8)	−0.0071 (7)	0.0044 (7)	0.0011 (6)
C22	0.0381 (8)	0.0350 (7)	0.0293 (7)	−0.0026 (6)	0.0033 (6)	−0.0039 (6)
C23	0.0359 (8)	0.0356 (8)	0.0320 (7)	−0.0050 (6)	0.0057 (6)	0.0001 (6)
C24	0.0398 (8)	0.0382 (8)	0.0405 (8)	−0.0048 (7)	0.0034 (7)	−0.0014 (7)
C25	0.0394 (9)	0.0507 (9)	0.0445 (8)	−0.0048 (7)	−0.0015 (7)	0.0042 (7)
C26	0.0408 (9)	0.0504 (9)	0.0496 (9)	0.0051 (8)	0.0083 (7)	0.0118 (8)
C27	0.0552 (10)	0.0397 (8)	0.0480 (9)	0.0057 (8)	0.0113 (8)	0.0024 (7)
C28	0.0472 (9)	0.0387 (8)	0.0397 (8)	−0.0024 (7)	0.0071 (7)	−0.0023 (7)

Geometric parameters (Å, º)

C1—C2	1.3815 (18)	C15—C16	1.2045 (18)
C1—C6	1.3977 (18)	C16—C19	1.433 (2)
C1—H11	1.000	C17—C18	1.3834 (18)
C2—C3	1.379 (2)	C17—C22	1.3977 (19)
C2—H21	1.000	C17—H171	1.000
C3—C4	1.381 (2)	C18—C19	1.3965 (18)
C3—H31	1.000	C18—H181	1.000
C4—C5	1.3834 (19)	C19—C20	1.393 (2)
C4—H41	1.000	C20—C21	1.3722 (18)
C5—C6	1.3979 (18)	C20—H201	1.000
C5—H51	1.000	C21—C22	1.3999 (18)
C6—C7	1.4806 (18)	C21—H211	1.000
C7—C8	1.3994 (18)	C22—C23	1.4799 (18)
C7—C12	1.3995 (19)	C23—C24	1.3929 (17)
C8—C9	1.3803 (18)	C23—C28	1.3975 (19)
C8—H81	1.000	C24—C25	1.3838 (18)
C9—C10	1.3968 (19)	C24—H241	1.000
C9—H91	1.000	C25—C26	1.380 (2)
C10—C11	1.4006 (19)	C25—H251	1.000
C10—C13	1.431 (2)	C26—C27	1.381 (2)
C11—C12	1.3767 (18)	C26—H261	1.000
C11—H111	1.000	C27—C28	1.3835 (19)
C12—H121	1.000	C27—H271	1.000
C13—C14	1.2041 (18)	C28—H281	1.000
C14—C15	1.373 (2)
C2—C1—C6	121.20 (14)	C14—C15—C16	179.36 (15)
C2—C1—H11	119.4	C15—C16—C19	177.96 (15)
C6—C1—H11	119.4	C18—C17—C22	121.24 (12)
C1—C2—C3	120.43 (14)	C18—C17—H171	119.4
C1—C2—H21	119.8	C22—C17—H171	119.4
C3—C2—H21	119.8	C17—C18—C19	120.12 (13)
C2—C3—C4	119.41 (14)	C17—C18—H181	119.9
C2—C3—H31	120.3	C19—C18—H181	119.9
C4—C3—H31	120.3	C16—C19—C18	120.75 (13)
C3—C4—C5	120.44 (14)	C16—C19—C20	120.37 (13)
C3—C4—H41	119.8	C18—C19—C20	118.87 (13)
C5—C4—H41	119.8	C19—C20—C21	120.73 (13)
C4—C5—C6	121.03 (13)	C19—C20—H201	119.6
C4—C5—H51	119.5	C21—C20—H201	119.6
C6—C5—H51	119.5	C20—C21—C22	121.20 (13)
C5—C6—C1	117.48 (12)	C20—C21—H211	119.4
C5—C6—C7	121.64 (12)	C22—C21—H211	119.4
C1—C6—C7	120.87 (12)	C21—C22—C17	117.79 (12)
C6—C7—C8	121.81 (12)	C21—C22—C23	120.67 (12)
C6—C7—C12	120.88 (12)	C17—C22—C23	121.54 (12)
C8—C7—C12	117.31 (12)	C22—C23—C24	121.02 (12)
C7—C8—C9	121.34 (13)	C22—C23—C28	120.58 (12)
C7—C8—H81	119.3	C24—C23—C28	118.40 (13)
C9—C8—H81	119.3	C23—C24—C25	120.68 (14)
C8—C9—C10	120.66 (13)	C23—C24—H241	119.7
C8—C9—H91	119.7	C25—C24—H241	119.7
C10—C9—H91	119.7	C24—C25—C26	120.23 (14)
C9—C10—C11	118.60 (12)	C24—C25—H251	119.9
C9—C10—C13	121.56 (13)	C26—C25—H251	119.9
C11—C10—C13	119.83 (13)	C25—C26—C27	119.88 (14)
C10—C11—C12	120.12 (13)	C25—C26—H261	120.1
C10—C11—H111	120.0	C27—C26—H261	120.0
C12—C11—H111	119.9	C26—C27—C28	120.17 (14)
C7—C12—C11	121.96 (13)	C26—C27—H271	119.9
C7—C12—H121	119.0	C28—C27—H271	119.9
C11—C12—H121	119.0	C23—C28—C27	120.62 (13)
C10—C13—C14	177.56 (15)	C23—C28—H281	119.7
C13—C14—C15	178.75 (15)	C27—C28—H281	119.7