1,1,3,3-Tetra-tert-butyl-2,2-diisopropyl-4,4-diphenyl­cyclo­tetra­silane

Kuribara, T.; Kyushin, S.

doi:10.1107/S160053681205074X

organic compounds

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ISSN: 2056-9890

Volume 69| Part 1| January 2013| Page o149

https://doi.org/10.1107/S160053681205074X

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1,1,3,3-Tetra-tert-butyl-2,2-diisopropyl-4,4-diphenylcyclotetrasilane

Takayoshi Kuribara ^a and Soichiro Kyushin ^a ^*

^aDepartment of Chemistry and Chemical Biology, Graduate School of Engineering, Gunma University, Kiryu, Gunma 376-8515, Japan
^*Correspondence e-mail: kyushin@gunma-u.ac.jp

(Received 22 November 2012; accepted 13 December 2012; online 22 December 2012)

The molecule in the structure of the title compound, C₃₄H₆₀Si₄, lies on a twofold rotation axis that passes through the two Si atoms, resulting in a planar cyclotetrasilane ring. The dihedral angle between the cyclotetrasilane ring and the phenyl ring is 68.20 (5)°. The Si—Si bonds [2.4404 (8) and 2.4576 (8) Å] are longer than a standard Si—Si bond (2.34 Å) and the C—Si—C bond angle [97.07 (14)°] of the phenyl-substituted Si atom is smaller than the tetrahedral bond angle (109.5°). These long bonds and small bond angle are favorable for reducing the steric hindrance among the bulky substituents.

Related literature

For background to and applications of phenyl-substituted oligosilanes, see: Hinch & Krc (1957 ); Matsumoto & Tanaka (2008 ). For a related structure of a cyclotetrasilane without phenyl groups, see: Kyushin et al. (1995 ).

Experimental

Crystal data

C₃₄H₆₀Si₄
M_r = 581.18
Monoclinic, C 2/c
a = 11.9477 (9) Å
b = 17.6585 (12) Å
c = 17.0422 (13) Å
β = 104.9394 (8)°
V = 3474.0 (4) Å³
Z = 4
Mo Kα radiation
μ = 0.19 mm⁻¹
T = 173 K
0.50 × 0.40 × 0.20 mm

Data collection

Rigaku R-AXIS IV imaging plate diffractometer
Absorption correction: multi-scan (REQAB; Jacobson, 1998 ) T_min = 0.910, T_max = 0.963
8534 measured reflections
2917 independent reflections
2899 reflections with I > 2σ(I)
R_int = 0.025

Refinement

R[F² > 2σ(F²)] = 0.048
wR(F²) = 0.095
S = 1.24
2917 reflections
181 parameters
H-atom parameters constrained
Δρ_max = 0.24 e Å⁻³
Δρ_min = −0.20 e Å⁻³

Data collection: CrystalClear (Rigaku, 2003 ); cell refinement: CrystalClear; data reduction: CrystalClear; program(s) used to solve structure: SIR2004 (Burla et al., 2005 ); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ); molecular graphics: ORTEP-3 (Farrugia, 2012 ); software used to prepare material for publication: SHELXL97 and Yadokari-XG 2009 (Kabuto et al., 2009 ).

Supporting information

Crystal structure: contains datablocks global, I. DOI: https://doi.org/10.1107/S160053681205074X/is5224sup1.cif

Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S160053681205074X/is5224Isup2.hkl

Supporting information file. DOI: https://doi.org/10.1107/S160053681205074X/is5224Isup3.cml

checkCIF report

Comment top

Birefringent materials have a wide range of optical applications. Single crystals of calcium carbonate and barium borate have been well known as inorganic birefringent materials. Organic single crystals such as urea have also been known to show birefringence. Since birefringence is related to crystal structures, studies on molecular structures and packing in a crystal are important. In 1957, birefringence of tetrakis(4-phenylphenyl)silane was reported (Hinch & Krc, 1957). Recently, birefringence of single crystals of phenyl-substituted linear oligosilanes and their application to polarizers have been reported (Matsumoto & Tanaka, 2008). From these results, crystals of phenyl-substituted silicon compounds seem interesting as potential optical materials. We report herein the synthesis and X-ray crystal analysis of a phenyl-substituted cyclotetrasilane.

The coupling of 1,3-dibromo-1,1,3,3-tetra-tert-butyl-2,2-diphenyltrisilane and dichlorodiisopropylsilane with lithium in tetrahydrofuran (THF) gave 1,1,3,3-tetra-tert-butyl-2,2-diisopropyl-4,4-diphenylcyclotetrasilane (1) in 21% yield (Fig. 1). The molecular structure of 1 is shown in Fig. 2. Compound 1 has the crystallographic C2 symmetry, and therefore the cyclotetrasilane ring has a completely planar structure. The silicon–silicon bonds [2.4404 (8) and 2.4576 (8) Å] are longer than the standard silicon–silicon bond (2.34 Å). The C1—Si1—C1ⁱ bond angle [97.07 (14)°] is smaller than the tetrahedral bond angle (109.5°), while the C7—Si2—C11 [111.39 (10)°] and C15—Si3—C15ⁱ [106.97 (15)°] bond angles are within normal values. The long silicon–silicon bonds and the small carbon–silicon–carbon bond angle are favorable for reducing the steric hindrance among bulky substituents.

Packing diagram of 1 is shown in Fig. 3. Four molecules are present in a unit cell. All cyclotetrasilane rings are oriented toward the same direction with the line through the Si1 and Si3 atoms parallel to the b axis. There is no intermolecular π–π interaction among phenyl groups.

Related literature top

For background to and applications of phenyl-substituted oligosilanes, see: Hinch & Krc (1957); Matsumoto & Tanaka (2008). For the related structure of a cyclotetrasilane without phenyl groups, see: Kyushin et al. (1995).

Experimental top

A mixture of 1,3-dibromo-1,1,3,3-tetra-tert-butyl-2,2-diphenyltrisilane (5.00 g, 7.98 mmol), dichlorodiisopropylsilane (2.24 g, 12.1 mmol) and lithium (0.28 g, 40 mmol) in THF (50 ml) was stirred at room temperature for 1 day. The solvent was removed under reduced pressure. The residue was dissolved in hexane and passed through a short column of silica gel. After the silica gel was washed with hexane, the eluent was changed to diethyl ether. The diethyl ether eluate was evaporated. Recrystallization of the residue from methanol–THF (ca 1:1) gave 1 (0.956 g, 21%) as colorless crystals. Single crystals were obtained from methanol–THF (ca 1:1) by slow evaporation.

M.p.: 210–211 °C. ¹H NMR (400 MHz, CDCl₃): δ 1.21 (s, 36H), 1.46 (d, 12H, J = 7.4 Hz), 1.94 (sept, 2H, J = 7.4 Hz), 7.14–7.18 (m, 6H), 7.68–7.70 (m, 4H). ¹³C NMR (76 MHz, CDCl₃): δ 17.5, 24.7, 25.4, 32.8, 127.1, 127.4, 138.6, 142.1. ²⁹Si NMR (119 MHz, CDCl₃): δ -6.2, 14.0, 20.4. IR (KBr): 3050, 2950, 2920, 2850, 1470, 1420, 1390, 1360, 810, 730, 700 cm^-1. MS (EI, 70 eV): m/z 580 (M⁺, 17), 360 (100).

Structure description top

Computing details top

Data collection: CrystalClear (Rigaku, 2003); cell refinement: CrystalClear (Rigaku, 2003); data reduction: CrystalClear (Rigaku, 2003); program(s) used to solve structure: SIR2004 (Burla et al., 2005); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 (Farrugia, 2012); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008) and Yadokari-XG 2009 (Kabuto et al., 2009).

Figures top

	Fig. 1. Synthesis of 1.
	Fig. 2. The molecular structure of 1, showing 50% probability displacement ellipsoids. [Symmetry code: (i) –x, y, –z + 3/2.]
	Fig. 3. Packing diagram of 1, showing 50% probability displacement ellipsoids.

1,1,3,3-Tetra-tert-butyl-2,2-diisopropyl-4,4-diphenylcyclotetrasilane top

Crystal data top

C₃₄H₆₀Si₄	F(000) = 1280
M_r = 581.18	D_x = 1.111 Mg m⁻³
Monoclinic, C2/c	Melting point = 483–484 K
Hall symbol: -C 2yc	Mo Kα radiation, λ = 0.71073 Å
a = 11.9477 (9) Å	Cell parameters from 7676 reflections
b = 17.6585 (12) Å	θ = 1.2–28.3°
c = 17.0422 (13) Å	µ = 0.19 mm⁻¹
β = 104.9394 (8)°	T = 173 K
V = 3474.0 (4) Å³	Prism, colourless
Z = 4	0.50 × 0.40 × 0.20 mm

Data collection top

Rigaku R-AXISIV imaging plate diffractometer	2917 independent reflections
Radiation source: rotating anode	2899 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.025
Detector resolution: 10.00 pixels mm^-1	θ_max = 25.0°, θ_min = 2.1°
ω scans	h = −14→14
Absorption correction: multi-scan (REQAB; Jacobson, 1998)	k = −18→20
T_min = 0.910, T_max = 0.963	l = −20→20
8534 measured reflections

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)] = 0.048	Hydrogen site location: inferred from neighbouring sites
wR(F²) = 0.095	H-atom parameters constrained
S = 1.24	w = 1/[σ²(F_o²) + (0.0127P)² + 7.2943P] where P = (F_o² + 2F_c²)/3
2917 reflections	(Δ/σ)_max = 0.001
181 parameters	Δρ_max = 0.24 e Å⁻³
0 restraints	Δρ_min = −0.20 e Å⁻³

Crystal data top

C₃₄H₆₀Si₄	V = 3474.0 (4) Å³
M_r = 581.18	Z = 4
Monoclinic, C2/c	Mo Kα radiation
a = 11.9477 (9) Å	µ = 0.19 mm⁻¹
b = 17.6585 (12) Å	T = 173 K
c = 17.0422 (13) Å	0.50 × 0.40 × 0.20 mm
β = 104.9394 (8)°

Data collection top

Rigaku R-AXISIV imaging plate diffractometer	2917 independent reflections
Absorption correction: multi-scan (REQAB; Jacobson, 1998)	2899 reflections with I > 2σ(I)
T_min = 0.910, T_max = 0.963	R_int = 0.025
8534 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.048	0 restraints
wR(F²) = 0.095	H-atom parameters constrained
S = 1.24	Δρ_max = 0.24 e Å⁻³
2917 reflections	Δρ_min = −0.20 e Å⁻³
181 parameters

Special details top

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 > 2σ(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	0.0000	0.32355 (5)	0.7500	0.01350 (19)
Si2	0.09403 (5)	0.22594 (3)	0.68813 (3)	0.01324 (15)
Si3	0.0000	0.12695 (5)	0.7500	0.01475 (19)
C1	−0.07934 (19)	0.39557 (13)	0.67052 (13)	0.0179 (5)
C2	−0.0078 (2)	0.45046 (14)	0.64962 (15)	0.0269 (6)
H1	0.0725	0.4498	0.6763	0.032*
C3	−0.0487 (2)	0.50564 (15)	0.59179 (17)	0.0330 (6)
H2	0.0031	0.5416	0.5791	0.040*
C4	−0.1657 (2)	0.50818 (15)	0.55245 (15)	0.0307 (6)
H3	−0.1947	0.5455	0.5122	0.037*
C5	−0.2392 (2)	0.45599 (15)	0.57252 (16)	0.0313 (6)
H4	−0.3196	0.4576	0.5462	0.038*
C6	−0.1968 (2)	0.40088 (14)	0.63102 (15)	0.0262 (5)
H5	−0.2494	0.3659	0.6444	0.031*
C7	0.03683 (19)	0.22973 (13)	0.56985 (13)	0.0191 (5)
C8	−0.0961 (2)	0.23931 (15)	0.54491 (14)	0.0259 (5)
H6	−0.1243	0.2356	0.4857	0.039*
H7	−0.1165	0.2890	0.5629	0.039*
H8	−0.1318	0.1994	0.5703	0.039*
C9	0.0639 (2)	0.15671 (16)	0.52878 (15)	0.0331 (6)
H9	0.0373	0.1622	0.4697	0.050*
H10	0.0240	0.1139	0.5462	0.050*
H11	0.1476	0.1476	0.5444	0.050*
C10	0.0887 (2)	0.29704 (15)	0.53389 (15)	0.0307 (6)
H12	0.1716	0.2884	0.5404	0.046*
H13	0.0779	0.3436	0.5623	0.046*
H14	0.0497	0.3020	0.4760	0.046*
C11	0.26218 (18)	0.23095 (14)	0.72206 (14)	0.0204 (5)
C12	0.3017 (2)	0.21501 (14)	0.81400 (14)	0.0253 (5)
H15	0.2866	0.1618	0.8242	0.038*
H16	0.2587	0.2477	0.8425	0.038*
H17	0.3848	0.2254	0.8338	0.038*
C13	0.3052 (2)	0.31047 (16)	0.70706 (17)	0.0347 (6)
H18	0.3880	0.3148	0.7340	0.052*
H19	0.2621	0.3486	0.7291	0.052*
H20	0.2929	0.3186	0.6486	0.052*
C14	0.3208 (2)	0.17278 (18)	0.67839 (17)	0.0379 (7)
H21	0.3064	0.1865	0.6209	0.057*
H22	0.2889	0.1223	0.6830	0.057*
H23	0.4044	0.1724	0.7034	0.057*
C15	0.0992 (2)	0.06194 (13)	0.82929 (15)	0.0241 (5)
H24	0.1364	0.0948	0.8766	0.029*
C16	0.0306 (3)	0.00034 (16)	0.86183 (17)	0.0387 (7)
H25	0.0068	−0.0395	0.8209	0.058*
H26	−0.0382	0.0231	0.8734	0.058*
H27	0.0798	−0.0215	0.9118	0.058*
C17	0.1985 (2)	0.02186 (16)	0.80303 (19)	0.0387 (7)
H28	0.2509	−0.0020	0.8504	0.058*
H29	0.2414	0.0591	0.7796	0.058*
H30	0.1662	−0.0170	0.7624	0.058*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Si1	0.0139 (4)	0.0121 (4)	0.0151 (4)	0.000	0.0047 (3)	0.000
Si2	0.0127 (3)	0.0149 (3)	0.0133 (3)	−0.0005 (2)	0.0055 (2)	−0.0008 (2)
Si3	0.0165 (4)	0.0118 (4)	0.0169 (4)	0.000	0.0061 (4)	0.000
C1	0.0219 (11)	0.0167 (12)	0.0162 (11)	0.0022 (9)	0.0072 (10)	−0.0007 (9)
C2	0.0260 (12)	0.0273 (14)	0.0279 (14)	0.0013 (10)	0.0081 (11)	0.0074 (10)
C3	0.0415 (15)	0.0258 (14)	0.0367 (15)	−0.0008 (11)	0.0189 (13)	0.0106 (11)
C4	0.0465 (16)	0.0230 (14)	0.0230 (13)	0.0109 (11)	0.0101 (12)	0.0100 (10)
C5	0.0273 (13)	0.0336 (15)	0.0298 (14)	0.0095 (11)	0.0012 (12)	0.0062 (11)
C6	0.0227 (12)	0.0271 (14)	0.0276 (13)	0.0002 (10)	0.0044 (11)	0.0060 (10)
C7	0.0236 (12)	0.0209 (12)	0.0143 (11)	0.0012 (9)	0.0078 (10)	−0.0023 (9)
C8	0.0242 (12)	0.0346 (15)	0.0179 (12)	0.0005 (10)	0.0033 (10)	0.0002 (10)
C9	0.0410 (15)	0.0343 (16)	0.0232 (13)	0.0076 (12)	0.0070 (12)	−0.0095 (11)
C10	0.0375 (14)	0.0359 (16)	0.0219 (13)	−0.0041 (11)	0.0135 (12)	0.0068 (11)
C11	0.0144 (10)	0.0271 (13)	0.0210 (12)	−0.0006 (9)	0.0068 (10)	−0.0040 (9)
C12	0.0192 (11)	0.0299 (14)	0.0240 (13)	0.0013 (10)	0.0005 (10)	−0.0042 (10)
C13	0.0288 (13)	0.0431 (17)	0.0327 (15)	−0.0176 (12)	0.0086 (12)	0.0011 (12)
C14	0.0210 (13)	0.058 (2)	0.0355 (16)	0.0079 (12)	0.0092 (12)	−0.0157 (14)
C15	0.0289 (12)	0.0170 (12)	0.0243 (13)	0.0059 (10)	0.0029 (11)	0.0024 (9)
C16	0.0570 (18)	0.0254 (15)	0.0335 (15)	−0.0005 (13)	0.0113 (14)	0.0090 (12)
C17	0.0319 (14)	0.0246 (15)	0.058 (2)	0.0119 (11)	0.0084 (14)	0.0004 (13)

Geometric parameters (Å, º) top

Si1—C1	1.921 (2)	C9—H11	0.9800
Si1—Si2	2.4404 (8)	C10—H12	0.9800
Si2—C11	1.944 (2)	C10—H13	0.9800
Si2—C7	1.956 (2)	C10—H14	0.9800
Si2—Si3	2.4576 (8)	C11—C14	1.539 (3)
Si3—C15	1.929 (2)	C11—C13	1.539 (3)
C1—C6	1.394 (3)	C11—C12	1.541 (3)
C1—C2	1.398 (3)	C12—H15	0.9800
C2—C3	1.382 (3)	C12—H16	0.9800
C2—H1	0.9500	C12—H17	0.9800
C3—C4	1.386 (4)	C13—H18	0.9800
C3—H2	0.9500	C13—H19	0.9800
C4—C5	1.376 (4)	C13—H20	0.9800
C4—H3	0.9500	C14—H21	0.9800
C5—C6	1.392 (3)	C14—H22	0.9800
C5—H4	0.9500	C14—H23	0.9800
C6—H5	0.9500	C15—C17	1.543 (3)
C7—C10	1.539 (3)	C15—C16	1.548 (3)
C7—C9	1.541 (3)	C15—H24	1.0000
C7—C8	1.544 (3)	C16—H25	0.9800
C8—H6	0.9800	C16—H26	0.9800
C8—H7	0.9800	C16—H27	0.9800
C8—H8	0.9800	C17—H28	0.9800
C9—H9	0.9800	C17—H29	0.9800
C9—H10	0.9800	C17—H30	0.9800

C1ⁱ—Si1—C1	97.07 (14)	H10—C9—H11	109.5
C1ⁱ—Si1—Si2	125.03 (7)	C7—C10—H12	109.5
C1—Si1—Si2	111.19 (6)	C7—C10—H13	109.5
Si2ⁱ—Si1—Si2	90.13 (4)	H12—C10—H13	109.5
C11—Si2—C7	111.39 (10)	C7—C10—H14	109.5
C11—Si2—Si1	113.26 (7)	H12—C10—H14	109.5
C7—Si2—Si1	110.10 (7)	H13—C10—H14	109.5
C11—Si2—Si3	117.16 (8)	C14—C11—C13	108.4 (2)
C7—Si2—Si3	112.93 (7)	C14—C11—C12	108.2 (2)
Si1—Si2—Si3	90.27 (3)	C13—C11—C12	107.92 (19)
C15ⁱ—Si3—C15	106.97 (15)	C14—C11—Si2	112.95 (16)
C15ⁱ—Si3—Si2	112.89 (7)	C13—C11—Si2	110.84 (17)
C15—Si3—Si2	117.23 (7)	C12—C11—Si2	108.42 (14)
Si2ⁱ—Si3—Si2	89.33 (4)	C11—C12—H15	109.5
C6—C1—C2	115.8 (2)	C11—C12—H16	109.5
C6—C1—Si1	129.59 (18)	H15—C12—H16	109.5
C2—C1—Si1	114.57 (17)	C11—C12—H17	109.5
C3—C2—C1	122.9 (2)	H15—C12—H17	109.5
C3—C2—H1	118.6	H16—C12—H17	109.5
C1—C2—H1	118.6	C11—C13—H18	109.5
C2—C3—C4	119.7 (2)	C11—C13—H19	109.5
C2—C3—H2	120.2	H18—C13—H19	109.5
C4—C3—H2	120.2	C11—C13—H20	109.5
C5—C4—C3	119.1 (2)	H18—C13—H20	109.5
C5—C4—H3	120.4	H19—C13—H20	109.5
C3—C4—H3	120.4	C11—C14—H21	109.5
C4—C5—C6	120.6 (2)	C11—C14—H22	109.5
C4—C5—H4	119.7	H21—C14—H22	109.5
C6—C5—H4	119.7	C11—C14—H23	109.5
C5—C6—C1	121.9 (2)	H21—C14—H23	109.5
C5—C6—H5	119.1	H22—C14—H23	109.5
C1—C6—H5	119.1	C17—C15—C16	107.4 (2)
C10—C7—C9	108.18 (19)	C17—C15—Si3	116.68 (18)
C10—C7—C8	107.3 (2)	C16—C15—Si3	112.50 (17)
C9—C7—C8	106.7 (2)	C17—C15—H24	106.6
C10—C7—Si2	111.55 (16)	C16—C15—H24	106.6
C9—C7—Si2	112.41 (16)	Si3—C15—H24	106.6
C8—C7—Si2	110.42 (14)	C15—C16—H25	109.5
C7—C8—H6	109.5	C15—C16—H26	109.5
C7—C8—H7	109.5	H25—C16—H26	109.5
H6—C8—H7	109.5	C15—C16—H27	109.5
C7—C8—H8	109.5	H25—C16—H27	109.5
H6—C8—H8	109.5	H26—C16—H27	109.5
H7—C8—H8	109.5	C15—C17—H28	109.5
C7—C9—H9	109.5	C15—C17—H29	109.5
C7—C9—H10	109.5	H28—C17—H29	109.5
H9—C9—H10	109.5	C15—C17—H30	109.5
C7—C9—H11	109.5	H28—C17—H30	109.5
H9—C9—H11	109.5	H29—C17—H30	109.5

C1ⁱ—Si1—Si2—C11	−3.63 (12)	C3—C4—C5—C6	−0.6 (4)
C1—Si1—Si2—C11	112.02 (11)	C4—C5—C6—C1	−0.9 (4)
Si2ⁱ—Si1—Si2—C11	−119.92 (8)	C2—C1—C6—C5	2.0 (4)
C1ⁱ—Si1—Si2—C7	−129.08 (11)	Si1—C1—C6—C5	−177.9 (2)
C1—Si1—Si2—C7	−13.43 (11)	C11—Si2—C7—C10	−51.24 (19)
Si2ⁱ—Si1—Si2—C7	114.63 (8)	Si1—Si2—C7—C10	75.27 (16)
C1ⁱ—Si1—Si2—Si3	116.29 (8)	Si3—Si2—C7—C10	174.50 (14)
C1—Si1—Si2—Si3	−128.06 (7)	C11—Si2—C7—C9	70.49 (19)
Si2ⁱ—Si1—Si2—Si3	0.0	Si1—Si2—C7—C9	−163.01 (15)
C11—Si2—Si3—C15ⁱ	−124.05 (11)	Si3—Si2—C7—C9	−63.78 (18)
C7—Si2—Si3—C15ⁱ	7.41 (11)	C11—Si2—C7—C8	−170.44 (16)
Si1—Si2—Si3—C15ⁱ	119.45 (8)	Si1—Si2—C7—C8	−43.93 (18)
C11—Si2—Si3—C15	0.95 (12)	Si3—Si2—C7—C8	55.30 (18)
C7—Si2—Si3—C15	132.41 (11)	C7—Si2—C11—C14	−51.3 (2)
Si1—Si2—Si3—C15	−115.55 (9)	Si1—Si2—C11—C14	−176.05 (16)
C11—Si2—Si3—Si2ⁱ	116.50 (8)	Si3—Si2—C11—C14	80.87 (19)
C7—Si2—Si3—Si2ⁱ	−112.04 (8)	C7—Si2—C11—C13	70.59 (18)
Si1—Si2—Si3—Si2ⁱ	0.0	Si1—Si2—C11—C13	−54.17 (17)
C1ⁱ—Si1—C1—C6	−127.9 (2)	Si3—Si2—C11—C13	−157.25 (14)
Si2ⁱ—Si1—C1—C6	−5.8 (3)	C7—Si2—C11—C12	−171.14 (15)
Si2—Si1—C1—C6	100.2 (2)	Si1—Si2—C11—C12	64.11 (17)
C1ⁱ—Si1—C1—C2	52.17 (16)	Si3—Si2—C11—C12	−38.97 (18)
Si2ⁱ—Si1—C1—C2	174.29 (14)	C15ⁱ—Si3—C15—C17	74.54 (19)
Si2—Si1—C1—C2	−79.77 (18)	Si2ⁱ—Si3—C15—C17	−155.06 (17)
C6—C1—C2—C3	−1.9 (4)	Si2—Si3—C15—C17	−53.4 (2)
Si1—C1—C2—C3	178.1 (2)	C15ⁱ—Si3—C15—C16	−50.24 (16)
C1—C2—C3—C4	0.5 (4)	Si2ⁱ—Si3—C15—C16	80.16 (18)
C2—C3—C4—C5	0.7 (4)	Si2—Si3—C15—C16	−178.14 (15)

Symmetry code: (i) −x, y, −z+3/2.

Experimental details

Crystal data
Chemical formula	C₃₄H₆₀Si₄
M_r	581.18
Crystal system, space group	Monoclinic, C2/c
Temperature (K)	173
a, b, c (Å)	11.9477 (9), 17.6585 (12), 17.0422 (13)
β (°)	104.9394 (8)
V (Å³)	3474.0 (4)
Z	4
Radiation type	Mo Kα
µ (mm⁻¹)	0.19
Crystal size (mm)	0.50 × 0.40 × 0.20

Data collection
Diffractometer	Rigaku R-AXISIV imaging plate
Absorption correction	Multi-scan (REQAB; Jacobson, 1998)
T_min, T_max	0.910, 0.963
No. of measured, independent and observed [I > 2σ(I)] reflections	8534, 2917, 2899
R_int	0.025
(sin θ/λ)_max (Å⁻¹)	0.595

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.048, 0.095, 1.24
No. of reflections	2917
No. of parameters	181
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.24, −0.20

Computer programs: CrystalClear (Rigaku, 2003), SIR2004 (Burla et al., 2005), ORTEP-3 (Farrugia, 2012), SHELXL97 (Sheldrick, 2008) and Yadokari-XG 2009 (Kabuto et al., 2009).

Acknowledgements

This work was supported in part by Grants-in-Aid for Scientific Research from the Ministry of Education, Culture, Sports, Science and Technology, Japan, and the Japan Society for the Promotion of Science. This work was also supported by the Element Innovation Project of Gunma University.

References

Burla, M. C., Caliandro, R., Camalli, M., Carrozzini, B., Cascarano, G. L., De Caro, L., Giacovazzo, C., Polidori, G. & Spagna, R. (2005). J. Appl. Cryst. 38, 381–388. Web of Science CrossRef CAS IUCr Journals Google Scholar
Farrugia, L. J. (2012). J. Appl. Cryst. 45, 849–854. Web of Science CrossRef CAS IUCr Journals Google Scholar
Hinch, R. J. & Krc, J. Jr (1957). Anal. Chem. 29, 1550–1551. CSD CrossRef CAS Web of Science Google Scholar
Jacobson, R. (1998). REQAB. Private communication to the Rigaku Corporation, Tokyo, Japan. Google Scholar
Kabuto, C., Akine, S., Nemoto, T. & Kwon, E. (2009). J. Crystallogr. Soc. Jpn, 51, 218–224. CrossRef Google Scholar
Kyushin, S., Sakurai, H. & Matsumoto, H. (1995). J. Organomet. Chem. 499, 235–240. CSD CrossRef CAS Web of Science Google Scholar
Matsumoto, H. & Tanaka, R. (2008). Jpn Kokai Tokkyo Koho JP4132933. Google Scholar
Rigaku (2003). CrystalClear. Rigaku Corporation, Tokyo, Japan. Google Scholar
Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. Web of Science CrossRef CAS IUCr Journals Google Scholar