Non-merohedral twin crystal of 2,3,9,10-tetra­kis(triisopropyl­silyl­ethynyl)-6,13-bis­(trimethyl­silyl­ethynyl)­penta­cene

Jiang, J.; Kaafarani, B.R.; Kirschbaum, K.; Hu, Y.; Neckers, D.C.

doi:10.1107/S1600536807038664

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Non-merohedral twin crystal of 2,3,9,10-tetrakis(triisopropylsilylethynyl)-6,13-bis(trimethylsilylethynyl)pentacene

J. Jiang, B. R. Kaafarani, K. Kirschbaum, Y. Hu and D. C. Neckers

All investigated crystals of the title pentacene derivative, C₇₆H₁₁₀Si₆, obtained from benzene solution and examined at 120 K, were identified as non-merohedral twins. The crystal examined in this study had an approximate 2:1 domain ratio. The molecules have crystallographic inversion symmetry and approximate C_2h symmetry, with a planar conjugated central core, including the peripheral C [triple bond]

C triple bonds. The molecules pack in layers perpendicular to the a axis, with a dihedral angle between individual molecules in adjacent layers of 5.25 (2)°; π–π stacking is prevented by the bulky substituents. One methyl group is disordered over two positions with occupancies of 0.6 and 0.4.

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Supporting information

	Crystallographic Information File (CIF) https://doi.org/10.1107/S1600536807038664/cf2122sup1.cif Contains datablocks I, global
	Structure factor file (CIF format) https://doi.org/10.1107/S1600536807038664/cf2122Isup2.hkl Contains datablock I

CCDC reference: 660252

checkCIF report

Key indicators

Single-crystal X-ray study
T = 120 K
Mean (C-C) = 0.010 Å
Disorder in main residue
R factor = 0.053
wR factor = 0.154
Data-to-parameter ratio = 20.2

checkCIF/PLATON results

No syntax errors found



Alert level A
DIFF020_ALERT_1_A  _diffrn_standards_interval_count and
            _diffrn_standards_interval_time are missing. Number of measurements
            between standards or time (min) between standards.
DIFF022_ALERT_1_A  _diffrn_standards_decay_% is missing
            Percentage decrease in standards intensity.
PLAT220_ALERT_2_A Large Non-Solvent    C     Ueq(max)/Ueq(min) ...       4.80 Ratio

Author Response: see Experimental Section

PLAT222_ALERT_3_A Large Non-Solvent    H     Ueq(max)/Ueq(min) ...       5.57 Ratio

Author Response: see above


Alert level B
ABSTM02_ALERT_3_B  The ratio of expected to reported Tmax/Tmin(RR') is < 0.75
            Tmin and Tmax reported:      0.718     1.000
            Tmin(prime) and Tmax expected:      0.961     0.964
            RR(prime) =      0.720
            Please check that your absorption correction is appropriate.
PLAT061_ALERT_3_B Tmax/Tmin Range Test RR' too Large .............       0.72
PLAT201_ALERT_2_B Isotropic non-H Atoms in Main Residue(s) .......          1

Alert level C
CRYSC01_ALERT_1_C The word below has not been recognised as a standard
            identifier.
            very
CRYSC01_ALERT_1_C No recognised colour has been given for crystal colour.
PLAT062_ALERT_4_C Rescale T(min) & T(max) by .....................       0.96
PLAT125_ALERT_4_C No _symmetry_space_group_name_Hall Given .......          ?
PLAT242_ALERT_2_C Check Low       Ueq as Compared to Neighbors for        C25
PLAT301_ALERT_3_C Main Residue  Disorder .........................       2.00 Perc.
PLAT340_ALERT_3_C Low Bond Precision on C-C Bonds (x 1000) Ang ...         10
PLAT371_ALERT_2_C Long   C(sp2)-C(sp1) Bond  C1     -   C12    ...       1.42 Ang.
PLAT371_ALERT_2_C Long   C(sp2)-C(sp1) Bond  C6     -   C17    ...       1.43 Ang.
PLAT371_ALERT_2_C Long   C(sp2)-C(sp1) Bond  C7     -   C28    ...       1.43 Ang.
PLAT779_ALERT_2_C Suspect or Irrelevant (Bond) Angle in CIF ......      20.20 Deg.
              C15A -SI1  -C15B    1.555   1.555   1.555

Alert level G
ABSTM02_ALERT_3_G  When printed, the submitted absorption T values will be
            replaced by the scaled T values. Since the ratio of scaled T's
            is identical to the ratio of reported T values, the scaling
            does not imply a change to the absorption corrections used in
            the study.
            Ratio of Tmax expected/reported      0.964
            Tmax scaled      0.964 Tmin scaled      0.692

   4 ALERT level A = In general: serious problem
   3 ALERT level B = Potentially serious problem
  11 ALERT level C = Check and explain
   1 ALERT level G = General alerts; check

   4 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   7 ALERT type 2 Indicator that the structure model may be wrong or deficient
   6 ALERT type 3 Indicator that the structure quality may be low
   2 ALERT type 4 Improvement, methodology, query or suggestion
   0 ALERT type 5 Informative message, check

Comment top

The practical uses of pentacene, the most promising polyacene in the area of organic field-effect transistors (Dimitrakopoulos et al., 1998; Klauk et al., 2000; Nelson et al., 1998; Wurthner, 2001), are limited by its sensitivity to oxygen, poor solubility in organic solvents and herringbone packing in the solid state (Holmes et al., 1999). To overcome these disadvantages, we reported new ethynylated pentacenes (Jiang et al., 2006). In this paper, we present the crystal structure of the title compound (I)·The molecular structure of (I) is shown in Figure 1. The X-ray crystal structure of (I) confirms its chemical structure (C₇₆H₁₁₀Si₆). The five fused benzene rings and the six carbon-carbon triple bonds are coplanar within ±0.14 (1) Å. In the pentacene core of (I), the bond lengths and their alternation are very similar to those in pentacene itself (Campbell et al., 1962; Mattheus et al., 2001). The cross-ring aromatic bonds are consistently longer than the peripheral aromatic bonds. The former average 1.445 (8) Å in length, and the latter 1.401 (8) Å, suggesting that the peripheral bonds form two parallel, delocalized polyacetylenic ribbons as previously reported (Houk et al., 2001; Fokin et al., 1998). The 'single' bonds between 'triple' bonds and the pentacene ring, for example, C1—C12 (1.425 (8) Å), C6—C17 (1.433 (8) Å) and C7—C28 (1.433 (8) Å), are significantly shorter than typical carbon-carbon single bonds, indicating the extended conjugation. The triple bond lengths average 1.20 Å.

The bond angles C17—C18—Si2 and C28—C29—Si3 are 173.4 (6)° and 176.7 (7)°, respectively, indicating that the steric crowding of terminal triisopropylsilyl (TIPS) moieties is released by bending. The two TIPS at the same end also contribute to this release by assuming different conformations. As required by the crystallographic inversion center in the middle of the molecule, the two trimethylsilyl groups at C13 and C13' (= 2 - x,-y,2 - z) assume a staggered conformation.

The molecules of (I) pack in layers perpendicular to the a axis (Figure 2). The dihedral angle between adjacent layers is 5.25 (2)° and alternate layers are parallel to each other as required by the translational symmetry. In contrast to the packing of pentacene, no herringbone packing exists (Holmes et al., 1999; Desiraju et al., 1989). The bulky substituents prevent π–π stacking.

Related literature top

For related literature, see: Dimitrakopoulos et al. (1998); Klauk et al. (2000); Nelson et al. (1998); Wurthner (2001); Holmes et al. (1999); Jiang et al. (2006); Desiraju & Gavezzotti (1989). For related structures, see: Campbell et al. (1962); Mattheus et al. (2001); Houk et al. (2001); Fokin et al. (1998). For twinning analyis tools, see: Bruker (1998, 2000).

Experimental top

The synthesis is described by Jiang et al. (2006).

Structure description top

Computing details top

Data collection: SMART (Bruker, 2003); cell refinement: SAINT (Bruker, 2003); data reduction: SAINT; program(s) used to solve structure: SHELXTL (Bruker, 2005); program(s) used to refine structure: SHELXTL; molecular graphics: DIAMOND (Brandenburg & Putz, 2005); software used to prepare material for publication: SHELXTL.

Figures top

	Fig. 1. The molecular structure of (I) at 120 K, showing the atomic labeling and 50% probability ellipsoids.
	Fig. 2. A packing diagram of (I) viewed down the c axis. Hydrogen atoms are omitted for clarity.

2,3,9,10-Tetrakis(triisopropylsilylethynyl)- 6,13-bis(trimethylsilylethynyl)pentacene top

Crystal data top

C₇₆H₁₁₀Si₆	F(000) = 1300
M_r = 1192.18	D_x = 1.039 Mg m⁻³
Monoclinic, P2₁/n	Mo Kα radiation, λ = 0.71073 Å
a = 10.6492 (12) Å	Cell parameters from 1328 reflections
b = 19.1865 (18) Å	θ = 2.2–30.1°
c = 18.6632 (14) Å	µ = 0.15 mm⁻¹
β = 91.236 (4)°	T = 120 K
V = 3812.4 (6) Å³	Cuboid, very dark turquoise
Z = 2	0.26 × 0.25 × 0.25 mm

Data collection top

Bruker SMART 6000 diffractometer	7479 independent reflections
Radiation source: fine-focus sealed tube	6159 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.044
ω scans	θ_max = 26.0°, θ_min = 1.5°
Absorption correction: multi-scan (TWINABS; Sheldrick, 1999)	h = −13→13
T_min = 0.718, T_max = 1.000	k = 0→23
26858 measured reflections	l = 0→23

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)] = 0.053	Hydrogen site location: inferred from neighbouring sites
wR(F²) = 0.154	H-atom parameters constrained
S = 1.32	w = 1/[σ²(F_o²) + (0.16P)² + 15.6P] where P = (F_o² + 2F_c²)/3
7479 reflections	(Δ/σ)_max < 0.001
370 parameters	Δρ_max = 0.64 e Å⁻³
0 restraints	Δρ_min = −0.33 e Å⁻³

Crystal data top

C₇₆H₁₁₀Si₆	V = 3812.4 (6) Å³
M_r = 1192.18	Z = 2
Monoclinic, P2₁/n	Mo Kα radiation
a = 10.6492 (12) Å	µ = 0.15 mm⁻¹
b = 19.1865 (18) Å	T = 120 K
c = 18.6632 (14) Å	0.26 × 0.25 × 0.25 mm
β = 91.236 (4)°

Data collection top

Bruker SMART 6000 diffractometer	7479 independent reflections
Absorption correction: multi-scan (TWINABS; Sheldrick, 1999)	6159 reflections with I > 2σ(I)
T_min = 0.718, T_max = 1.000	R_int = 0.044
26858 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.053	0 restraints
wR(F²) = 0.154	H-atom parameters constrained
S = 1.32	w = 1/[σ²(F_o²) + (0.16P)² + 15.6P] where P = (F_o² + 2F_c²)/3
7479 reflections	Δρ_max = 0.64 e Å⁻³
370 parameters	Δρ_min = −0.33 e Å⁻³

Special details top

Experimental. As several crystals before, this crystal was identified as a non-merohedral twin using RLATT. Two orientation matrices were assigned to the two different twin components (GEMINI 1.02). Integration of the data with SAINT 6.45 A using both orientation matrices deconvoluted the data set into overlapped reflections and reflections originated by only one of the twin components. Correction for absorption, decay and inhomogeneity of the X-ray beam were applied using TWINABS. The twinning law is a 180 degree rotation around c*, the ratio of the two twin components was refined to 0.363 (1):0.637 (1).

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 (Å²) top

	x	y	z	U_iso*/U_eq	Occ. (<1)
Si1	0.9658 (2)	0.17271 (10)	0.73900 (10)	0.0343 (5)
Si2	0.96038 (17)	−0.31575 (9)	0.55599 (9)	0.0268 (4)
Si3	1.0477 (2)	−0.51484 (9)	0.82961 (11)	0.0353 (5)
C1	0.9887 (5)	0.0421 (3)	0.9372 (3)	0.0187 (11)
C2	0.9908 (5)	−0.0317 (3)	0.9308 (3)	0.0176 (11)
C3	0.9825 (6)	−0.0645 (3)	0.8638 (3)	0.0201 (12)
H3A	0.9735	−0.0367	0.8218	0.024*
C4	0.9872 (5)	−0.1363 (3)	0.8570 (3)	0.0203 (12)
C5	0.9799 (6)	−0.1697 (3)	0.7887 (3)	0.0229 (12)
H5A	0.9706	−0.1420	0.7468	0.027*
C6	0.9859 (6)	−0.2407 (3)	0.7819 (3)	0.0232 (12)
C7	0.9996 (6)	−0.2838 (3)	0.8454 (3)	0.0230 (12)
C8	1.0047 (6)	−0.2527 (3)	0.9114 (3)	0.0222 (12)
H8A	1.0119	−0.2813	0.9528	0.027*
C9	0.9996 (5)	−0.1789 (3)	0.9201 (3)	0.0197 (11)
C10	1.0071 (5)	−0.1474 (3)	0.9866 (3)	0.0189 (12)
H10A	1.0150	−0.1758	1.0282	0.023*
C11	1.0033 (5)	−0.0743 (3)	0.9945 (3)	0.0180 (11)
C12	0.9787 (6)	0.0835 (3)	0.8740 (3)	0.0215 (12)
C13	0.9723 (6)	0.1179 (3)	0.8200 (3)	0.0269 (13)
C14	1.1282 (8)	0.1937 (5)	0.7130 (5)	0.050 (2)
H14A	1.1667	0.2249	0.7487	0.076*
H14B	1.1266	0.2166	0.6660	0.076*
H14C	1.1774	0.1506	0.7104	0.076*
C15A	0.8610 (14)	0.1311 (8)	0.6700 (8)	0.042 (3)*	0.60
H15A	0.7767	0.1513	0.6725	0.063*	0.60
H15B	0.8565	0.0809	0.6790	0.063*	0.60
H15C	0.8947	0.1393	0.6223	0.063*	0.60
C15B	0.913 (2)	0.1141 (11)	0.6637 (11)	0.043 (5)*	0.40
H15D	0.9838	0.0852	0.6488	0.064*	0.40
H15E	0.8832	0.1424	0.6231	0.064*	0.40
H15F	0.8450	0.0840	0.6799	0.064*	0.40
C16	0.8795 (9)	0.2531 (5)	0.7634 (6)	0.064 (3)
H16A	0.9225	0.2758	0.8040	0.096*
H16B	0.7937	0.2409	0.7766	0.096*
H16C	0.8767	0.2849	0.7223	0.096*
C17	0.9778 (6)	−0.2711 (3)	0.7118 (3)	0.0264 (13)
C18	0.9685 (6)	−0.2927 (3)	0.6515 (3)	0.0282 (14)
C19	0.9126 (9)	−0.2335 (5)	0.5079 (4)	0.051 (2)
H19A	0.9156	−0.2428	0.4552	0.062*
C20	1.0012 (11)	−0.1723 (5)	0.5249 (6)	0.070 (3)
H20A	0.9721	−0.1307	0.4989	0.105*
H20B	1.0864	−0.1841	0.5102	0.105*
H20C	1.0016	−0.1629	0.5765	0.105*
C21	0.7793 (10)	−0.2129 (5)	0.5252 (8)	0.085 (4)
H21A	0.7571	−0.1699	0.4996	0.128*
H21B	0.7731	−0.2053	0.5769	0.128*
H21C	0.7216	−0.2502	0.5102	0.128*
C22	1.1217 (7)	−0.3480 (5)	0.5310 (5)	0.050 (2)
H22A	1.1207	−0.3992	0.5410	0.060*
C23	1.2276 (9)	−0.3191 (7)	0.5779 (6)	0.075 (3)
H23A	1.3079	−0.3379	0.5620	0.113*
H23B	1.2146	−0.3325	0.6278	0.113*
H23C	1.2287	−0.2681	0.5741	0.113*
C24	1.1454 (10)	−0.3417 (6)	0.4502 (5)	0.067 (3)
H24A	1.2297	−0.3590	0.4400	0.101*
H24B	1.1388	−0.2927	0.4358	0.101*
H24C	1.0828	−0.3692	0.4234	0.101*
C25	0.8394 (7)	−0.3864 (4)	0.5443 (4)	0.0378 (17)
H25A	0.7568	−0.3660	0.5578	0.045*
C26	0.8649 (9)	−0.4476 (5)	0.5946 (7)	0.064 (3)
H26A	0.8002	−0.4833	0.5869	0.096*
H26B	0.8633	−0.4314	0.6443	0.096*
H26C	0.9476	−0.4675	0.5848	0.096*
C27	0.8254 (8)	−0.4107 (6)	0.4669 (6)	0.070 (3)
H27A	0.7617	−0.4475	0.4635	0.105*
H27B	0.9060	−0.4289	0.4507	0.105*
H27C	0.7996	−0.3713	0.4365	0.105*
C28	1.0113 (6)	−0.3579 (3)	0.8384 (3)	0.0269 (14)
C29	1.0234 (7)	−0.4199 (3)	0.8331 (4)	0.0328 (15)
C30	0.8883 (8)	−0.5580 (4)	0.8309 (5)	0.046 (2)
H30A	0.9024	−0.6095	0.8338	0.055*
C31	0.8160 (9)	−0.5367 (5)	0.8975 (5)	0.053 (2)
H31A	0.7337	−0.5596	0.8967	0.080*
H31B	0.8045	−0.4860	0.8977	0.080*
H31C	0.8634	−0.5508	0.9406	0.080*
C32	0.8074 (10)	−0.5441 (6)	0.7641 (6)	0.066 (3)
H32A	0.7264	−0.5677	0.7685	0.099*
H32B	0.8502	−0.5617	0.7218	0.099*
H32C	0.7935	−0.4938	0.7590	0.099*
C33	1.1273 (10)	−0.5363 (4)	0.7429 (5)	0.054 (2)
H33A	1.0588	−0.5356	0.7054	0.065*
C34	1.2203 (11)	−0.4849 (5)	0.7188 (6)	0.076 (4)
H34A	1.2562	−0.5006	0.6737	0.113*
H34B	1.2874	−0.4802	0.7553	0.113*
H34C	1.1792	−0.4397	0.7115	0.113*
C35	1.1790 (10)	−0.6106 (4)	0.7422 (6)	0.061 (3)
H35A	1.2196	−0.6194	0.6964	0.092*
H35B	1.1099	−0.6437	0.7481	0.092*
H35C	1.2405	−0.6164	0.7815	0.092*
C36	1.1365 (8)	−0.5365 (4)	0.9154 (5)	0.0458 (19)
H36A	1.0913	−0.5118	0.9543	0.055*
C37	1.2701 (9)	−0.5080 (6)	0.9180 (6)	0.065 (3)
H37A	1.3108	−0.5209	0.9637	0.098*
H37B	1.2678	−0.4572	0.9136	0.098*
H37C	1.3175	−0.5278	0.8784	0.098*
C38	1.1356 (11)	−0.6140 (5)	0.9360 (6)	0.070 (3)
H38A	1.1835	−0.6206	0.9809	0.106*
H38B	1.1740	−0.6414	0.8979	0.106*
H38C	1.0488	−0.6294	0.9422	0.106*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Si1	0.0557 (13)	0.0245 (9)	0.0226 (9)	−0.0043 (8)	−0.0026 (8)	0.0091 (7)
Si2	0.0293 (9)	0.0326 (9)	0.0183 (8)	0.0021 (7)	−0.0003 (7)	−0.0083 (7)
Si3	0.0578 (13)	0.0169 (8)	0.0316 (10)	0.0026 (8)	0.0103 (9)	−0.0032 (7)
C1	0.022 (3)	0.016 (3)	0.018 (3)	0.001 (2)	0.002 (2)	0.000 (2)
C2	0.021 (3)	0.016 (3)	0.017 (3)	0.001 (2)	0.001 (2)	−0.002 (2)
C3	0.027 (3)	0.018 (3)	0.015 (3)	0.000 (2)	0.002 (2)	0.000 (2)
C4	0.024 (3)	0.019 (3)	0.018 (3)	0.000 (2)	−0.001 (2)	−0.003 (2)
C5	0.029 (3)	0.022 (3)	0.017 (3)	0.002 (2)	−0.001 (2)	−0.003 (2)
C6	0.027 (3)	0.023 (3)	0.020 (3)	0.000 (2)	−0.002 (2)	−0.005 (2)
C7	0.028 (3)	0.017 (3)	0.024 (3)	−0.002 (2)	0.000 (2)	−0.004 (2)
C8	0.030 (3)	0.018 (3)	0.019 (3)	0.000 (2)	0.001 (2)	−0.001 (2)
C9	0.023 (3)	0.017 (3)	0.019 (3)	0.001 (2)	0.002 (2)	−0.002 (2)
C10	0.023 (3)	0.017 (3)	0.017 (3)	0.001 (2)	0.000 (2)	0.001 (2)
C11	0.020 (3)	0.017 (3)	0.016 (3)	0.000 (2)	0.001 (2)	−0.001 (2)
C12	0.028 (3)	0.017 (3)	0.020 (3)	0.001 (2)	0.001 (2)	−0.005 (2)
C13	0.042 (4)	0.019 (3)	0.019 (3)	0.001 (3)	0.002 (3)	0.000 (2)
C14	0.066 (6)	0.045 (5)	0.041 (5)	0.009 (4)	0.014 (4)	0.018 (4)
C16	0.061 (6)	0.040 (5)	0.091 (8)	0.014 (4)	0.018 (5)	0.023 (5)
C17	0.033 (4)	0.021 (3)	0.025 (3)	0.000 (3)	0.000 (3)	−0.005 (2)
C18	0.035 (4)	0.025 (3)	0.024 (3)	0.002 (3)	−0.004 (3)	−0.006 (2)
C19	0.076 (6)	0.048 (5)	0.030 (4)	0.008 (4)	−0.013 (4)	0.002 (4)
C20	0.085 (8)	0.048 (5)	0.076 (7)	−0.004 (5)	0.014 (6)	0.020 (5)
C21	0.063 (7)	0.042 (6)	0.149 (12)	0.007 (5)	−0.042 (7)	0.007 (7)
C22	0.036 (4)	0.070 (6)	0.045 (5)	−0.001 (4)	0.010 (3)	−0.021 (4)
C23	0.042 (5)	0.117 (10)	0.067 (7)	0.005 (6)	0.004 (4)	−0.008 (7)
C24	0.063 (6)	0.091 (8)	0.049 (6)	−0.008 (5)	0.027 (5)	−0.025 (5)
C25	0.027 (4)	0.043 (4)	0.044 (4)	−0.001 (3)	0.001 (3)	−0.022 (3)
C26	0.050 (6)	0.037 (5)	0.105 (9)	−0.010 (4)	0.006 (5)	−0.007 (5)
C27	0.035 (5)	0.106 (8)	0.069 (7)	−0.006 (5)	0.002 (4)	−0.066 (6)
C28	0.036 (4)	0.023 (3)	0.022 (3)	−0.001 (3)	0.002 (3)	−0.006 (2)
C29	0.047 (4)	0.023 (3)	0.029 (3)	0.000 (3)	0.007 (3)	−0.006 (3)
C30	0.066 (6)	0.025 (4)	0.047 (5)	−0.006 (3)	−0.003 (4)	−0.002 (3)
C31	0.057 (6)	0.048 (5)	0.056 (6)	−0.011 (4)	0.005 (4)	0.007 (4)
C32	0.075 (7)	0.069 (7)	0.053 (6)	−0.013 (5)	−0.012 (5)	−0.005 (5)
C33	0.086 (7)	0.030 (4)	0.046 (5)	0.003 (4)	0.023 (4)	−0.008 (4)
C34	0.103 (9)	0.048 (6)	0.079 (8)	−0.018 (5)	0.058 (6)	−0.018 (5)
C35	0.087 (7)	0.034 (5)	0.063 (6)	0.013 (4)	0.029 (5)	−0.013 (4)
C36	0.054 (5)	0.039 (5)	0.044 (5)	0.007 (4)	0.005 (4)	0.002 (4)
C37	0.050 (6)	0.076 (7)	0.069 (7)	0.008 (5)	0.002 (4)	−0.003 (6)
C38	0.093 (8)	0.051 (6)	0.067 (7)	0.014 (5)	−0.007 (5)	0.024 (5)

Geometric parameters (Å, º) top

Si1—C13	1.841 (6)	C20—H20B	0.980
Si1—C14	1.851 (9)	C20—H20C	0.980
Si1—C16	1.856 (9)	C21—H21A	0.980
Si1—C15A	1.865 (14)	C21—H21B	0.980
Si1—C15B	1.88 (2)	C21—H21C	0.980
Si2—C18	1.837 (6)	C22—C23	1.518 (13)
Si2—C25	1.880 (7)	C22—C24	1.540 (12)
Si2—C19	1.880 (9)	C22—H22A	1.00
Si2—C22	1.893 (8)	C23—H23A	0.980
Si3—C29	1.841 (7)	C23—H23B	0.980
Si3—C33	1.888 (8)	C23—H23C	0.980
Si3—C36	1.887 (9)	C24—H24A	0.980
Si3—C30	1.890 (9)	C24—H24B	0.980
C1—C11ⁱ	1.417 (8)	C24—H24C	0.980
C1—C2	1.420 (8)	C25—C27	1.522 (11)
C1—C12	1.425 (8)	C25—C26	1.524 (13)
C2—C3	1.402 (7)	C25—H25A	1.00
C2—C11	1.447 (8)	C26—H26A	0.980
C3—C4	1.384 (8)	C26—H26B	0.980
C3—H3A	0.950	C26—H26C	0.980
C4—C5	1.426 (8)	C27—H27A	0.980
C4—C9	1.438 (8)	C27—H27B	0.980
C5—C6	1.369 (8)	C27—H27C	0.980
C5—H5A	0.950	C28—C29	1.202 (9)
C6—C17	1.433 (8)	C30—C32	1.524 (13)
C6—C7	1.450 (8)	C30—C31	1.531 (13)
C7—C8	1.368 (8)	C30—H30A	1.00
C7—C28	1.433 (8)	C31—H31A	0.980
C8—C9	1.426 (8)	C31—H31B	0.980
C8—H8A	0.950	C31—H31C	0.980
C9—C10	1.381 (8)	C32—H32A	0.980
C10—C11	1.412 (8)	C32—H32B	0.980
C10—H10A	0.950	C32—H32C	0.980
C11—C1ⁱ	1.417 (8)	C33—C34	1.474 (13)
C12—C13	1.206 (8)	C33—C35	1.529 (12)
C14—H14A	0.980	C33—H33A	1.00
C14—H14B	0.980	C34—H34A	0.980
C14—H14C	0.980	C34—H34B	0.980
C15A—H15A	0.980	C34—H34C	0.980
C15A—H15B	0.980	C35—H35A	0.980
C15A—H15C	0.980	C35—H35B	0.980
C15B—H15D	0.980	C35—H35C	0.980
C15B—H15E	0.980	C36—C37	1.523 (13)
C15B—H15F	0.980	C36—C38	1.537 (12)
C16—H16A	0.980	C36—H36A	1.00
C16—H16B	0.980	C37—H37A	0.980
C16—H16C	0.980	C37—H37B	0.980
C17—C18	1.202 (9)	C37—H37C	0.980
C19—C21	1.514 (15)	C38—H38A	0.980
C19—C20	1.537 (14)	C38—H38B	0.980
C19—H19A	1.00	C38—H38C	0.980
C20—H20A	0.980

C13—Si1—C14	108.7 (3)	H21A—C21—H21B	109.5
C13—Si1—C16	106.5 (4)	C19—C21—H21C	109.5
C14—Si1—C16	110.7 (4)	H21A—C21—H21C	109.5
C13—Si1—C15A	109.5 (5)	H21B—C21—H21C	109.5
C14—Si1—C15A	117.4 (6)	C23—C22—C24	113.6 (8)
C16—Si1—C15A	103.4 (6)	C23—C22—Si2	113.9 (6)
C13—Si1—C15B	106.1 (7)	C24—C22—Si2	112.6 (7)
C14—Si1—C15B	101.5 (8)	C23—C22—H22A	105.2
C16—Si1—C15B	122.7 (8)	C24—C22—H22A	105.2
C15A—Si1—C15B	20.2 (7)	Si2—C22—H22A	105.2
C18—Si2—C25	107.7 (3)	C22—C23—H23A	109.5
C18—Si2—C19	105.6 (3)	C22—C23—H23B	109.5
C25—Si2—C19	111.8 (4)	H23A—C23—H23B	109.5
C18—Si2—C22	107.0 (3)	C22—C23—H23C	109.5
C25—Si2—C22	111.0 (4)	H23A—C23—H23C	109.5
C19—Si2—C22	113.2 (5)	H23B—C23—H23C	109.5
C29—Si3—C33	108.2 (3)	C22—C24—H24A	109.5
C29—Si3—C36	104.8 (4)	C22—C24—H24B	109.5
C33—Si3—C36	116.9 (4)	H24A—C24—H24B	109.5
C29—Si3—C30	107.8 (4)	C22—C24—H24C	109.5
C33—Si3—C30	109.6 (4)	H24A—C24—H24C	109.5
C36—Si3—C30	109.1 (4)	H24B—C24—H24C	109.5
C11ⁱ—C1—C2	120.6 (5)	C27—C25—C26	111.2 (8)
C11ⁱ—C1—C12	120.2 (5)	C27—C25—Si2	112.6 (6)
C2—C1—C12	119.2 (5)	C26—C25—Si2	111.8 (5)
C3—C2—C1	121.4 (5)	C27—C25—H25A	107.0
C3—C2—C11	118.9 (5)	C26—C25—H25A	107.0
C1—C2—C11	119.7 (5)	Si2—C25—H25A	107.0
C4—C3—C2	121.8 (5)	C25—C26—H26A	109.5
C4—C3—H3A	119.1	C25—C26—H26B	109.5
C2—C3—H3A	119.1	H26A—C26—H26B	109.5
C3—C4—C5	121.9 (5)	C25—C26—H26C	109.5
C3—C4—C9	119.5 (5)	H26A—C26—H26C	109.5
C5—C4—C9	118.6 (5)	H26B—C26—H26C	109.5
C6—C5—C4	121.9 (5)	C25—C27—H27A	109.5
C6—C5—H5A	119.0	C25—C27—H27B	109.5
C4—C5—H5A	119.0	H27A—C27—H27B	109.5
C5—C6—C17	119.2 (6)	C25—C27—H27C	109.5
C5—C6—C7	119.6 (5)	H27A—C27—H27C	109.5
C17—C6—C7	121.1 (5)	H27B—C27—H27C	109.5
C8—C7—C28	120.8 (6)	C29—C28—C7	178.8 (8)
C8—C7—C6	119.2 (5)	C28—C29—Si3	176.7 (7)
C28—C7—C6	119.9 (5)	C32—C30—C31	109.4 (8)
C7—C8—C9	122.3 (5)	C32—C30—Si3	113.9 (7)
C7—C8—H8A	118.8	C31—C30—Si3	111.2 (6)
C9—C8—H8A	118.8	C32—C30—H30A	107.4
C10—C9—C8	122.4 (5)	C31—C30—H30A	107.4
C10—C9—C4	119.4 (5)	Si3—C30—H30A	107.4
C8—C9—C4	118.2 (5)	C30—C31—H31A	109.5
C9—C10—C11	121.9 (5)	C30—C31—H31B	109.5
C9—C10—H10A	119.1	H31A—C31—H31B	109.5
C11—C10—H10A	119.1	C30—C31—H31C	109.5
C10—C11—C1ⁱ	121.8 (5)	H31A—C31—H31C	109.5
C10—C11—C2	118.5 (5)	H31B—C31—H31C	109.5
C1ⁱ—C11—C2	119.7 (5)	C30—C32—H32A	109.5
C13—C12—C1	178.7 (7)	C30—C32—H32B	109.5
C12—C13—Si1	178.0 (6)	H32A—C32—H32B	109.5
Si1—C14—H14A	109.5	C30—C32—H32C	109.5
Si1—C14—H14B	109.5	H32A—C32—H32C	109.5
H14A—C14—H14B	109.5	H32B—C32—H32C	109.5
Si1—C14—H14C	109.5	C34—C33—C35	112.2 (9)
H14A—C14—H14C	109.5	C34—C33—Si3	115.6 (6)
H14B—C14—H14C	109.5	C35—C33—Si3	112.3 (6)
Si1—C15A—H15A	109.5	C34—C33—H33A	105.2
Si1—C15A—H15B	109.5	C35—C33—H33A	105.2
H15A—C15A—H15B	109.5	Si3—C33—H33A	105.2
Si1—C15A—H15C	109.5	C33—C34—H34A	109.5
H15A—C15A—H15C	109.5	C33—C34—H34B	109.5
H15B—C15A—H15C	109.5	H34A—C34—H34B	109.5
Si1—C15B—H15D	109.5	C33—C34—H34C	109.5
Si1—C15B—H15E	109.5	H34A—C34—H34C	109.5
H15D—C15B—H15E	109.5	H34B—C34—H34C	109.5
Si1—C15B—H15F	109.5	C33—C35—H35A	109.5
H15D—C15B—H15F	109.5	C33—C35—H35B	109.5
H15E—C15B—H15F	109.5	H35A—C35—H35B	109.5
Si1—C16—H16A	109.5	C33—C35—H35C	109.5
Si1—C16—H16B	109.5	H35A—C35—H35C	109.5
H16A—C16—H16B	109.5	H35B—C35—H35C	109.5
Si1—C16—H16C	109.5	C37—C36—C38	110.5 (8)
H16A—C16—H16C	109.5	C37—C36—Si3	113.5 (6)
H16B—C16—H16C	109.5	C38—C36—Si3	114.8 (7)
C18—C17—C6	176.0 (7)	C37—C36—H36A	105.7
C17—C18—Si2	173.4 (6)	C38—C36—H36A	105.7
C21—C19—C20	109.3 (8)	Si3—C36—H36A	105.7
C21—C19—Si2	111.2 (7)	C36—C37—H37A	109.5
C20—C19—Si2	112.6 (6)	C36—C37—H37B	109.5
C21—C19—H19A	107.8	H37A—C37—H37B	109.5
C20—C19—H19A	107.8	C36—C37—H37C	109.5
Si2—C19—H19A	107.8	H37A—C37—H37C	109.5
C19—C20—H20A	109.5	H37B—C37—H37C	109.5
C19—C20—H20B	109.5	C36—C38—H38A	109.5
H20A—C20—H20B	109.5	C36—C38—H38B	109.5
C19—C20—H20C	109.5	H38A—C38—H38B	109.5
H20A—C20—H20C	109.5	C36—C38—H38C	109.5
H20B—C20—H20C	109.5	H38A—C38—H38C	109.5
C19—C21—H21A	109.5	H38B—C38—H38C	109.5
C19—C21—H21B	109.5

Symmetry code: (i) −x+2, −y, −z+2.

Experimental details

Crystal data
Chemical formula	C₇₆H₁₁₀Si₆
M_r	1192.18
Crystal system, space group	Monoclinic, P2₁/n
Temperature (K)	120
a, b, c (Å)	10.6492 (12), 19.1865 (18), 18.6632 (14)
β (°)	91.236 (4)
V (Å³)	3812.4 (6)
Z	2
Radiation type	Mo Kα
µ (mm⁻¹)	0.15
Crystal size (mm)	0.26 × 0.25 × 0.25

Data collection
Diffractometer	Bruker SMART 6000
Absorption correction	Multi-scan (TWINABS; Sheldrick, 1999)
T_min, T_max	0.718, 1.000
No. of measured, independent and observed [I > 2σ(I)] reflections	26858, 7479, 6159
R_int	0.044
(sin θ/λ)_max (Å⁻¹)	0.617

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.053, 0.154, 1.32
No. of reflections	7479
No. of parameters	370
H-atom treatment	H-atom parameters constrained
	w = 1/[σ²(F_o²) + (0.16P)² + 15.6P] where P = (F_o² + 2F_c²)/3
Δρ_max, Δρ_min (e Å⁻³)	0.64, −0.33

Computer programs: SMART (Bruker, 2003), SAINT (Bruker, 2003), SAINT, SHELXTL (Bruker, 2005), SHELXTL, DIAMOND (Brandenburg & Putz, 2005).

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