1,4-Bis[4-(tert-butyl­diphenyl­silyl)buta-1,3-diyn­yl]benzene

Thevenet, D.; Neier, R.; Stoeckli-Evans, H.

doi:10.1107/S160053681000351X

organic compounds

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ISSN: 2056-9890

Volume 66| Part 4| April 2010| Pages o839-o840

doi:10.1107/S160053681000351X

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1,4-Bis[4-(tert-butyldiphenylsilyl)buta-1,3-diynyl]benzene

Damien Thevenet,^a Reinhard Neier ^a ^* and Helen Stoeckli-Evans ^b

^aInstitute of Chemistry, University of Neuchâtel, rue Emile-Argand 11, 2009 Neuchâtel, Switzerland, and ^bInstitute of Physics, University of Neuchâtel, rue Emile-Argand 11, 2009 Neuchâtel, Switzerland
^*Correspondence e-mail: reinhard.neier@unine.ch

(Received 20 January 2010; accepted 28 January 2010; online 13 March 2010)

The title centrosymmetric molecule, C₄₆H₄₂Si₂, is composed of a central benzene ring with buta-1,3-diynyl chains at positions 1 and 4. These chains are terminated by tert-butyldiphenylsilyl groups, hence the molecule is dumbbell in shape. The molecules are connected via C—H⋯π interactions in the structure, so forming an undulating two-dimensional network in the bc plane. There is also a weak π–π interaction involving centrosymmetrically related phenyl rings with a centroid–centroid distance of 3.8359 (11) Å.

Related literature

For polyynes and acetylenic arrays, see: Ginsburg et al. (1995 ); Siemsen et al. (2000 ); Brandsma (1988 ). For uses and other properties of conjugated carbon–carbon triple bonds, see: Swager (2005 ); Tobe & Wakabayashi (2005 ); Höger (2005 ); Zhou et al. (1994 ); Maruyama & Kawabata (1990 ); Lee et al. (2000 ). For information on the `one-pot' tandem synthesis – Corey–Fuchs reaction/Negishi coupling, see: Corey & Fuchs (1972 ); Desai & McKelvie (1962 ); King et al. (1977 ). For the crystal structure of the trimethylsilyl analogue, see: Shi Shun et al. (2003 ). For the synthesis and crystal structure of related compounds, see: Chalifoux et al. (2009 ); Kim (2009 ); West et al. (2008 ). For a description of the Cambridge Structural Database, see: Allen et al. (1987 ).

Experimental

Crystal data

C₄₆H₄₂Si₂
M_r = 650.98
Monoclinic, P 2₁ /c
a = 8.535 (1) Å
b = 17.2060 (14) Å
c = 13.4923 (14) Å
β = 104.064 (9)°
V = 1922.0 (3) Å³
Z = 2
Mo Kα radiation
μ = 0.12 mm⁻¹
T = 173 K
0.45 × 0.38 × 0.30 mm

Data collection

Stoe IPDS-2 diffractometer
Absorption correction: multi-scan (MULscanABS in PLATON; Spek, 2009 ) T_min = 0.919, T_max = 1.184
19707 measured reflections
4403 independent reflections
3260 reflections with I > 2σ(I)
R_int = 0.098

Refinement

R[F² > 2σ(F²)] = 0.044
wR(F²) = 0.104
S = 0.96
4403 reflections
220 parameters
H-atom parameters constrained
Δρ_max = 0.35 e Å⁻³
Δρ_min = −0.29 e Å⁻³

Table 1
C—H⋯π interactions (Å, °)

Cg1 and Cg2 are the centroids of the C8–C13 and C14–C19 rings, respectively.

D	H	Centroid	C—H	H⋯Cg	D⋯Cg	D—H⋯Cg
C6	H6	Cg2ⁱ	0.95	2.85	3.7703 (17)	164
C7	H7	Cg1ⁱⁱ	0.95	2.95	3.8516 (18)	160
Symmetry codes: (i) -x, -y+1, -z+1; (ii) $[x, -y+{\script{1\over 2}}, z+{\script{1\over 2}}]$ .

Data collection: X-AREA (Stoe & Cie, 2009 ); cell refinement: X-AREA; data reduction: X-RED32 (Stoe & Cie, 2009); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: Mercury (Macrae et al., 2006 ); software used to prepare material for publication: SHELXL97 and PLATON (Spek, 2009).

Supporting information

Crystal structure: contains datablocks I, global. DOI: 10.1107/S160053681000351X/fb2180sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S160053681000351X/fb2180Isup2.hkl

checkCIF report

Comment top

The unique properties of polyynes and acetylenic arrays continue to be of great interest (Ginsburg et al., 1995; Siemsen et al., 2000; Brandsma, 1988). Compounds containing conjugated carbon-carbon triple bonds are important building blocks because they can function as carbon-rich scaffolds when incorporated into organic materials (Swager, 2005; Tobe & Wakabayashi, 2005; Höger, 2005; Zhou et al., 1994). Consequently, research into the synthesis of well-defined polyynes continues to expand. The efficiency of the energy and electron transfer processes in polyyne-bridged porphyrin systems (Maruyama & Kawabata, 1990) and bis(benzocrown ether)s (Lee et al., 2000) have been examined for their potential use as molecular wires and chemosensors.

The title compound was designed as a spacer-unit in linked materials for the creation of structured, discotic mesophases. It was synthesized from tert-Butyl(4,4-dibromobut-3-en-1-ynyl)diphenylsilane using a "one-pot" tandem synthesis, consisting of a Corey-Fuchs reaction (Corey & Fuchs, 1972; Desai & McKelvie, 1962) and a Negishi coupling reaction (King et al., 1977). The synthesis and crystal structure of the trimethylsilyl analogue has been described by (Shi Shun et al., 2003), and for some other related compounds by Chalifoux et al., 2009; Kim, 2009; West et al. (2008).

The title molecule is shown in Fig. 1. The bond lengths are normal (Allen et al., 1987) and the geometrical parameters are similar to those in the centrosymmetric trimethylsilyl analogue mentioned above (Shi Shun et al., 2003). The title molecule consists of a central benzene ring to which are attached buta-1,3-diynyl chains in positions 1 and 4. These chains are terminated with tert-butyldiphenylsilyl groups. The molecule is essentially linear and shaped like a dumbbell. The centers of the benzene rings are situated on crystallographic centers of symmetry, therefore the molecule has symmetry 1.

In the crystal of the title compound symmetry related molecules are connected via C—H···π interactions, involving the H-atoms of the central aromatic ring and the silyl phenyl rings, giving rise to the formation of an undulating two-dimensional network in the bc plane (Tab. 1 and Fig. 2). Centrosymmetrically related phenyl rings (C14 - C19), are involved in a weak π–π interaction with a centroid-to-centroid distance [Cg1···Cg1ⁱ, symmetry code: (i) = 1-x, 1-y, 1-z] of 3.836 (1) Å.

Related literature top

For polyynes and acetylenic arrays, see: Ginsburg et al. (1995); Siemsen et al. (2000); Brandsma (1988). For uses and other properties of conjugated carbon–carbon triple bonds, see: Swager (2005); Tobe & Wakabayashi (2005); Höger (2005); Zhou et al. (1994); Maruyama & Kawabata (1990); Lee et al. (2000). For information on the `one-pot' tandem synthesis – Corey–Fuchs reaction/Negishi coupling, see: Corey & Fuchs (1972); Desai & McKelvie (1962); King et al. (1977). For the crystal structure of the trimethylsilyl analogue, see: Shi Shun et al. (2003). For the synthesis and crystal structure of related compounds, see: Chalifoux et al. (2009); Kim (2009); West et al. (2008). For a description of the Cambridge Structural Database, see: Allen et al. (1987).

Experimental top

The synthesis of the title compound was carried out under a nitrogen atmosphere. To a solution of tert-butyl(4,4-dibromobut-3-en-1-ynyl)diphenylsilane (2.64 mmol in 5.0 ml of dry tetrahydrofuran) was added N-butyl lithium (3.63 ml of 1.6 M in hexane; 5.81 mmol) at 193 K. The mixture was stirred at 193 K to 233 K for 2 h. Anhydrous ZnCl₂ (5.28 mmol dissolved in 5.0 ml of tetrahydrofuran) was then added and the mixture was stirred at 233 K to 293 K for 1 h. Subsequently 1,4-diiodobenzene (0.88 mmol dissolved in 5 ml of dimethylformamide) and Pd(dppf)Cl₂ [dppf = 1,1'-bis(diphenylphosphino)ferrocene] (0.17 mmol dissolved in 5 ml of CH₂Cl₂) were added and the mixture stirred at 353 K for 24 h. The reaction mixture was then filtered over Celite (a diatomaceous earth, which is a naturally occurring, soft, siliceous sedimentray rock, used for filtration purposes) and concentrated. The crude product was purified by column chromatography (silica gel, petroleum ether:CH₂Cl₂ (9:1)). Colourless rod-like crystals (average size 0.8 × 0.4 × 0.3 mm) of the title compound were grown by slow evaporation of a concentrated solution in hexane at 277 K.

¹H NMR, 400 MHz (CDCl₃) δ 7.80 (m, 8H, H_a,a'), 7.51 (s, 4H, H_2,3,5,6), 7.46-7.38 (m, 12H, H_b,b',c), 1.14 (s, 18H, C(CH₃)₃)) ; ¹³C NMR, 100 MHz (CDCl₃) δ 135.7 (C_a,a'), 132.9 (C_2,3,5,6), 132.5 (C_ar-Si), 129.9 (C_c), 128.0 (C_b,b'), 122.5 (C_1,4), (91.3, 80.0, 77.3) (C₁²,₁³,₁⁴, ₄²,₄³,₄⁴), 76.34 (C₁¹,₄¹), 27.2 (C(CH₃)₃), 19.1 (C(CH₃)₃); HRMS (ESI, +): [M+Na]⁺ = 673.27201. The numbering scheme for the interpretation of the NMR spectra is given in Fig. 3.

Computing details top

Data collection: X-AREA (Stoe & Cie, 2009); cell refinement: X-AREA (Stoe & Cie, 2009); data reduction: X-RED32 (Stoe & Cie, 2009); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: Mercury (Macrae et al., 2006); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008) and PLATON (Spek, 2009).

Figures top

	Fig. 1. The title molecule with the displacement ellipoids drawn at the 50% probability level [symmetry code: (i) = -x, -y+1, -z+2].
	Fig. 2. A view along the a-axis of the crystal packing of the title compound. The C—H···π interactions are represented by the H···C contacts shown as dotted cyan lines (see Tab. 1 for details).
	Fig. 3. The numbering scheme of the title compound for the interpretation of the NMR spectra.

1,4-Bis[4-(tert--butyldiphenylsilyl)buta-1,3-diynyl]benzene top

Crystal data top

C₄₆H₄₂Si₂	F(000) = 692
M_r = 650.98	D_x = 1.125 Mg m⁻³
Monoclinic, P2₁/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybc	Cell parameters from 13367 reflections
a = 8.535 (1) Å	θ = 2.0–29.6°
b = 17.2060 (14) Å	µ = 0.12 mm⁻¹
c = 13.4923 (14) Å	T = 173 K
β = 104.064 (9)°	Block, colourless
V = 1922.0 (3) Å³	0.45 × 0.38 × 0.30 mm
Z = 2

Data collection top

Stoe IPDS-2 diffractometer	4403 independent reflections
Radiation source: fine-focus sealed tube	3260 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.098
ϕ and ω scans	θ_max = 27.5°, θ_min = 2.0°
Absorption correction: multi-scan (MULscanABS in PLATON; Spek, 2009)	h = −11→11
T_min = 0.919, T_max = 1.184	k = −22→22
19707 measured reflections	l = −16→17

Refinement top

Refinement on F²	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F² > 2σ(F²)] = 0.044	Hydrogen site location: difference Fourier map
wR(F²) = 0.104	H-atom parameters constrained
S = 0.96	w = 1/[σ²(F_o²) + (0.0586P)²] where P = (F_o² + 2F_c²)/3
4403 reflections	(Δ/σ)_max = 0.001
220 parameters	Δρ_max = 0.35 e Å⁻³
0 restraints	Δρ_min = −0.29 e Å⁻³
81 constraints

Crystal data top

C₄₆H₄₂Si₂	V = 1922.0 (3) Å³
M_r = 650.98	Z = 2
Monoclinic, P2₁/c	Mo Kα radiation
a = 8.535 (1) Å	µ = 0.12 mm⁻¹
b = 17.2060 (14) Å	T = 173 K
c = 13.4923 (14) Å	0.45 × 0.38 × 0.30 mm
β = 104.064 (9)°

Data collection top

Stoe IPDS-2 diffractometer	4403 independent reflections
Absorption correction: multi-scan (MULscanABS in PLATON; Spek, 2009)	3260 reflections with I > 2σ(I)
T_min = 0.919, T_max = 1.184	R_int = 0.098
19707 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.044	0 restraints
wR(F²) = 0.104	H-atom parameters constrained
S = 0.96	Δρ_max = 0.35 e Å⁻³
4403 reflections	Δρ_min = −0.29 e Å⁻³
220 parameters

Special details top

Geometry. Bond distances, angles etc. have been calculated using the rounded fractional coordinates. All su's are estimated from the variances of the (full) variance-covariance matrix. The cell esds are taken into account in the estimation of distances, angles and torsion angles

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 (Å²) top

	x	y	z	U_iso*/U_eq
Si1	0.21188 (5)	0.33985 (2)	0.45574 (3)	0.0274 (1)
C1	0.17432 (18)	0.37157 (8)	0.57829 (12)	0.0319 (4)
C2	0.15087 (18)	0.39564 (8)	0.65764 (11)	0.0304 (4)
C3	0.12243 (18)	0.42333 (8)	0.74707 (11)	0.0313 (4)
C4	0.09221 (18)	0.44715 (8)	0.82412 (11)	0.0312 (4)
C5	0.04697 (17)	0.47453 (8)	0.91335 (11)	0.0284 (4)
C6	−0.09906 (19)	0.51441 (9)	0.90339 (11)	0.0330 (4)
C7	0.14561 (19)	0.46019 (9)	1.01075 (11)	0.0331 (5)
C8	0.35951 (17)	0.25716 (8)	0.48565 (11)	0.0305 (4)
C9	0.4176 (2)	0.21781 (10)	0.41082 (14)	0.0442 (5)
C10	0.5271 (2)	0.15713 (11)	0.43600 (17)	0.0545 (6)
C11	0.5821 (2)	0.13405 (11)	0.53583 (19)	0.0556 (7)
C12	0.5256 (2)	0.17083 (11)	0.61040 (16)	0.0559 (7)
C13	0.4161 (2)	0.23146 (10)	0.58596 (13)	0.0397 (5)
C14	0.29838 (17)	0.42645 (8)	0.40325 (11)	0.0304 (4)
C15	0.2355 (2)	0.50019 (9)	0.41244 (14)	0.0423 (5)
C16	0.2954 (2)	0.56598 (10)	0.37522 (15)	0.0478 (6)
C17	0.4212 (2)	0.55952 (10)	0.32833 (14)	0.0458 (6)
C18	0.4861 (2)	0.48762 (11)	0.31796 (16)	0.0504 (6)
C19	0.4256 (2)	0.42169 (10)	0.35525 (14)	0.0420 (5)
C20	0.00954 (18)	0.30897 (9)	0.37155 (13)	0.0346 (4)
C21	−0.0513 (2)	0.23744 (11)	0.41817 (17)	0.0535 (7)
C22	0.0254 (2)	0.28984 (12)	0.26356 (14)	0.0521 (6)
C23	−0.1143 (2)	0.37500 (11)	0.36436 (16)	0.0518 (6)
H6	−0.16650	0.52410	0.83740	0.0400*
H7	0.24460	0.43300	1.01790	0.0400*
H9	0.38100	0.23300	0.34130	0.0530*
H10	0.56440	0.13140	0.38380	0.0650*
H11	0.65830	0.09300	0.55310	0.0670*
H12	0.56190	0.15460	0.67950	0.0670*
H13	0.37870	0.25610	0.63890	0.0480*
H15	0.14930	0.50540	0.44510	0.0510*
H16	0.24970	0.61550	0.38200	0.0570*
H17	0.46320	0.60460	0.30320	0.0550*
H18	0.57240	0.48300	0.28520	0.0610*
H19	0.47180	0.37240	0.34790	0.0500*
H21A	−0.06650	0.25060	0.48590	0.0800*
H21B	0.02800	0.19540	0.42450	0.0800*
H21C	−0.15440	0.22050	0.37400	0.0800*
H22A	0.06540	0.33560	0.23410	0.0780*
H22B	−0.08040	0.27500	0.22090	0.0780*
H22C	0.10140	0.24670	0.26660	0.0780*
H23A	−0.12390	0.38880	0.43310	0.0780*
H23B	−0.21950	0.35780	0.32320	0.0780*
H23C	−0.07830	0.42050	0.33220	0.0780*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Si1	0.0368 (2)	0.0266 (2)	0.0211 (2)	0.0044 (2)	0.0119 (2)	−0.0017 (2)
C1	0.0410 (8)	0.0295 (7)	0.0284 (8)	0.0031 (6)	0.0144 (6)	−0.0001 (6)
C2	0.0400 (8)	0.0268 (7)	0.0270 (8)	0.0025 (6)	0.0131 (6)	0.0007 (5)
C3	0.0434 (8)	0.0276 (7)	0.0251 (7)	0.0022 (6)	0.0128 (6)	0.0007 (5)
C4	0.0443 (8)	0.0256 (7)	0.0258 (8)	0.0017 (6)	0.0126 (6)	0.0002 (5)
C5	0.0414 (8)	0.0238 (6)	0.0222 (7)	−0.0018 (5)	0.0123 (6)	−0.0034 (5)
C6	0.0428 (8)	0.0344 (8)	0.0205 (7)	0.0048 (6)	0.0053 (6)	−0.0006 (5)
C7	0.0385 (8)	0.0343 (8)	0.0274 (8)	0.0069 (6)	0.0099 (6)	−0.0016 (6)
C8	0.0347 (7)	0.0297 (7)	0.0286 (8)	0.0012 (6)	0.0106 (6)	−0.0017 (6)
C9	0.0543 (10)	0.0447 (9)	0.0381 (9)	0.0140 (8)	0.0200 (8)	−0.0009 (7)
C10	0.0552 (10)	0.0494 (10)	0.0658 (13)	0.0164 (9)	0.0279 (10)	−0.0062 (9)
C11	0.0427 (9)	0.0473 (10)	0.0738 (15)	0.0183 (8)	0.0083 (9)	0.0025 (9)
C12	0.0556 (11)	0.0562 (12)	0.0482 (11)	0.0151 (9)	−0.0023 (9)	0.0086 (9)
C13	0.0449 (8)	0.0413 (9)	0.0309 (8)	0.0075 (7)	0.0052 (7)	0.0000 (7)
C14	0.0377 (8)	0.0326 (7)	0.0206 (7)	0.0008 (6)	0.0065 (6)	−0.0013 (5)
C15	0.0587 (10)	0.0329 (8)	0.0408 (10)	0.0019 (7)	0.0230 (8)	−0.0018 (7)
C16	0.0661 (11)	0.0312 (8)	0.0468 (11)	−0.0019 (8)	0.0151 (9)	−0.0006 (7)
C17	0.0515 (10)	0.0422 (9)	0.0400 (10)	−0.0132 (8)	0.0040 (8)	0.0058 (7)
C18	0.0444 (9)	0.0535 (11)	0.0583 (12)	−0.0030 (8)	0.0219 (9)	0.0091 (9)
C19	0.0415 (8)	0.0396 (9)	0.0494 (11)	0.0023 (7)	0.0195 (8)	0.0043 (7)
C20	0.0388 (8)	0.0296 (7)	0.0348 (8)	0.0038 (6)	0.0079 (6)	−0.0041 (6)
C21	0.0524 (10)	0.0420 (10)	0.0671 (14)	−0.0065 (8)	0.0165 (10)	0.0016 (9)
C22	0.0584 (11)	0.0587 (11)	0.0357 (10)	−0.0017 (9)	0.0049 (8)	−0.0165 (8)
C23	0.0429 (9)	0.0461 (10)	0.0598 (13)	0.0130 (8)	−0.0001 (9)	−0.0124 (9)

Geometric parameters (Å, º) top

Si1—C1	1.8418 (16)	C20—C22	1.532 (2)
Si1—C8	1.8782 (15)	C20—C23	1.539 (2)
Si1—C14	1.8764 (15)	C6—H6	0.9500
Si1—C20	1.8978 (17)	C7—H7	0.9500
C1—C2	1.209 (2)	C9—H9	0.9500
C2—C3	1.373 (2)	C10—H10	0.9500
C3—C4	1.202 (2)	C11—H11	0.9500
C4—C5	1.431 (2)	C12—H12	0.9500
C5—C6	1.400 (2)	C13—H13	0.9500
C5—C7	1.400 (2)	C15—H15	0.9500
C6—C7ⁱ	1.384 (2)	C16—H16	0.9500
C8—C9	1.402 (2)	C17—H17	0.9500
C8—C13	1.394 (2)	C18—H18	0.9500
C9—C10	1.387 (3)	C19—H19	0.9500
C10—C11	1.373 (3)	C21—H21A	0.9800
C11—C12	1.372 (3)	C21—H21B	0.9800
C12—C13	1.386 (3)	C21—H21C	0.9800
C14—C15	1.395 (2)	C22—H22A	0.9800
C14—C19	1.395 (2)	C22—H22B	0.9800
C15—C16	1.386 (2)	C22—H22C	0.9800
C16—C17	1.377 (3)	C23—H23A	0.9800
C17—C18	1.376 (3)	C23—H23B	0.9800
C18—C19	1.390 (3)	C23—H23C	0.9800
C20—C21	1.529 (3)

C1—Si1—C8	106.60 (7)	C6ⁱ—C7—H7	120.00
C1—Si1—C14	105.89 (6)	C8—C9—H9	119.00
C1—Si1—C20	106.78 (7)	C10—C9—H9	119.00
C8—Si1—C14	112.19 (7)	C9—C10—H10	120.00
C8—Si1—C20	112.45 (7)	C11—C10—H10	120.00
C14—Si1—C20	112.38 (7)	C10—C11—H11	120.00
Si1—C1—C2	177.19 (13)	C12—C11—H11	120.00
C1—C2—C3	179.29 (17)	C11—C12—H12	120.00
C2—C3—C4	177.85 (17)	C13—C12—H12	120.00
C3—C4—C5	176.80 (17)	C8—C13—H13	119.00
C4—C5—C6	119.77 (13)	C12—C13—H13	119.00
C4—C5—C7	120.55 (14)	C14—C15—H15	119.00
C6—C5—C7	119.65 (14)	C16—C15—H15	119.00
C5—C6—C7ⁱ	120.29 (14)	C15—C16—H16	120.00
C5—C7—C6ⁱ	120.06 (15)	C17—C16—H16	120.00
Si1—C8—C9	123.17 (12)	C16—C17—H17	120.00
Si1—C8—C13	120.33 (12)	C18—C17—H17	120.00
C9—C8—C13	116.50 (14)	C17—C18—H18	120.00
C8—C9—C10	121.47 (17)	C19—C18—H18	120.00
C9—C10—C11	120.49 (18)	C14—C19—H19	119.00
C10—C11—C12	119.27 (18)	C18—C19—H19	119.00
C11—C12—C13	120.65 (19)	C20—C21—H21A	109.00
C8—C13—C12	121.63 (16)	C20—C21—H21B	109.00
Si1—C14—C15	119.58 (12)	C20—C21—H21C	110.00
Si1—C14—C19	123.40 (11)	H21A—C21—H21B	110.00
C15—C14—C19	117.02 (14)	H21A—C21—H21C	109.00
C14—C15—C16	121.81 (16)	H21B—C21—H21C	109.00
C15—C16—C17	119.88 (16)	C20—C22—H22A	109.00
C16—C17—C18	119.82 (16)	C20—C22—H22B	109.00
C17—C18—C19	120.17 (17)	C20—C22—H22C	109.00
C14—C19—C18	121.29 (16)	H22A—C22—H22B	109.00
Si1—C20—C21	109.25 (12)	H22A—C22—H22C	109.00
Si1—C20—C22	110.59 (11)	H22B—C22—H22C	109.00
Si1—C20—C23	110.02 (11)	C20—C23—H23A	109.00
C21—C20—C22	109.62 (15)	C20—C23—H23B	109.00
C21—C20—C23	108.87 (14)	C20—C23—H23C	109.00
C22—C20—C23	108.48 (15)	H23A—C23—H23B	109.00
C5—C6—H6	120.00	H23A—C23—H23C	109.00
C7ⁱ—C6—H6	120.00	H23B—C23—H23C	109.00
C5—C7—H7	120.00

C1—Si1—C8—C9	−179.84 (13)	C4—C5—C6—C7ⁱ	178.71 (14)
C1—Si1—C8—C13	0.69 (15)	C7—C5—C6—C7ⁱ	0.2 (2)
C14—Si1—C8—C9	−64.36 (15)	C4—C5—C7—C6ⁱ	−178.70 (14)
C14—Si1—C8—C13	116.16 (13)	C6—C5—C7—C6ⁱ	−0.2 (2)
C20—Si1—C8—C9	63.47 (15)	C5—C6—C7ⁱ—C5ⁱ	−0.2 (2)
C20—Si1—C8—C13	−116.00 (13)	Si1—C8—C9—C10	179.77 (13)
C1—Si1—C14—C15	−40.17 (15)	C13—C8—C9—C10	−0.7 (2)
C1—Si1—C14—C19	139.24 (14)	Si1—C8—C13—C12	−179.70 (13)
C8—Si1—C14—C15	−156.07 (13)	C9—C8—C13—C12	0.8 (2)
C8—Si1—C14—C19	23.34 (16)	C8—C9—C10—C11	−0.2 (3)
C20—Si1—C14—C15	76.05 (14)	C9—C10—C11—C12	1.1 (3)
C20—Si1—C14—C19	−104.54 (14)	C10—C11—C12—C13	−1.0 (3)
C1—Si1—C20—C21	−65.38 (13)	C11—C12—C13—C8	0.1 (3)
C1—Si1—C20—C22	173.89 (12)	Si1—C14—C15—C16	179.82 (14)
C1—Si1—C20—C23	54.08 (13)	C19—C14—C15—C16	0.4 (3)
C8—Si1—C20—C21	51.20 (13)	Si1—C14—C19—C18	−179.71 (14)
C8—Si1—C20—C22	−69.54 (13)	C15—C14—C19—C18	−0.3 (3)
C8—Si1—C20—C23	170.66 (11)	C14—C15—C16—C17	−0.5 (3)
C14—Si1—C20—C21	178.93 (11)	C15—C16—C17—C18	0.5 (3)
C14—Si1—C20—C22	58.20 (13)	C16—C17—C18—C19	−0.4 (3)
C14—Si1—C20—C23	−61.61 (14)	C17—C18—C19—C14	0.3 (3)

Symmetry code: (i) −x, −y+1, −z+2.

Experimental details

Crystal data
Chemical formula	C₄₆H₄₂Si₂
M_r	650.98
Crystal system, space group	Monoclinic, P2₁/c
Temperature (K)	173
a, b, c (Å)	8.535 (1), 17.2060 (14), 13.4923 (14)
β (°)	104.064 (9)
V (Å³)	1922.0 (3)
Z	2
Radiation type	Mo Kα
µ (mm⁻¹)	0.12
Crystal size (mm)	0.45 × 0.38 × 0.30

Data collection
Diffractometer	Stoe IPDS2 diffractometer
Absorption correction	Multi-scan (MULscanABS in PLATON; Spek, 2009)
T_min, T_max	0.919, 1.184
No. of measured, independent and observed [I > 2σ(I)] reflections	19707, 4403, 3260
R_int	0.098
(sin θ/λ)_max (Å⁻¹)	0.650

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.044, 0.104, 0.96
No. of reflections	4403
No. of parameters	220
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.35, −0.29

Computer programs: X-AREA (Stoe & Cie, 2009), X-RED32 (Stoe & Cie, 2009), SHELXS97 (Sheldrick, 2008), Mercury (Macrae et al., 2006), SHELXL97 (Sheldrick, 2008) and PLATON (Spek, 2009).

C—H···π interactions (Å, °) top

Cg1 and Cg2 are the centroids of the C8–C13 and C14–C19 rings, respectively.

D	H	Centroid	C—H	H···Cg	D···Cg	D—H···Cg
C6	H6	Cg2ⁱ	0.95	2.85	3.7703 (17)	164
C7	H7	Cg1ⁱⁱ	0.95	2.95	3.8516 (18)	160

Symmetry codes (i) = -x, -y+1, -z+1; (ii) x, -y+1/2, z+1/2.

Acknowledgements

HSE is grateful to the XRD Application LAB, Microsystems Technology Division, Swiss Center for Electronics and Microtechnology, Neuchâtel, for access to the X-ray diffraction equipment.

References

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