organic compounds\(\def\hfill{\hskip 5em}\def\hfil{\hskip 3em}\def\eqno#1{\hfil {#1}}\)

Journal logoCRYSTALLOGRAPHIC
COMMUNICATIONS
ISSN: 2056-9890
Volume 65| Part 9| September 2009| Pages o2182-o2183

2,2,6,6-Tetra­kis(bi­phenyl-2-yl)-4,4,8,8-tetra­methyl­cyclo­tetra­siloxane

aDepartment of Chemistry and Pharmaceutical Sciences, Faculty of Sciences, VU University Amsterdam, De Boelelaan 1083, 1081 HV Amsterdam, The Netherlands, and bBijvoet Center for Biomolecular Research, Crystal and Structural Chemistry, Faculty of Science, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands
*Correspondence e-mail: a.l.spek@uu.nl

(Received 3 August 2009; accepted 12 August 2009; online 19 August 2009)

The title compound, [–Si(C12H9)2OSi(CH3)2O–]2, was obtained unintentionally as the product of an attempted crystallization of caesium bis­(biphenyl-2,2′-di­yl)fluoro­silicate from dimethyl­formamide. In the crystal, the mol­ecule is located on an inversion center and the siloxane ring adopts a twist-chair conformation with the two dimethyl-substituted Si atoms lying 0.7081 (5) Å out of the plane defined by the two bis­(biphenyl-2-yl)-substituted Si atoms and the four O atoms. In each Si(C12H9)2 unit, the orientation of one terminal phenyl ring relative to the phenyl­ene ring of the other biphenyl moiety suggests a parallel displaced ππ stacking inter­action [centroid distance = 4.2377 (11) Å and dihedral angle = 15.40 (9)°].

Related literature

For general background to stable compounds of penta­valent, anionic silicon bearing five organic substituents, see: Couzijn et al. (2004[Couzijn, E. P. A., Schakel, M., de Kanter, F. J. J., Ehlers, A. W., Lutz, M., Spek, A. L. & Lammertsma, K. (2004). Angew. Chem. Int. Ed. 43, 3440-3442.], 2006[Couzijn, E. P. A., Ehlers, A. W., Schakel, M. & Lammertsma, K. (2006). J. Am. Chem. Soc. 128, 13634-13639.], 2009[Couzijn, E. P. A., Slootweg, J. C., Ehlers, A. W. & Lammertsma, K. (2009). J. Am. Chem. Soc. 131, 3741-3751.]); Deerenberg et al. (2002[Deerenberg, S., Schakel, M., de Keijzer, A. H. J. F., Kranenburg, M., Lutz, M., Spek, A. L. & Lammertsma, K. (2002). Chem. Commun. pp. 348-349.]); de Keijzer et al. (1997[Keijzer, A. H. J. F. de, de Kanter, F. J. J., Schakel, M., Osinga, V. P. & Klumpp, G. W. (1997). J. Organomet. Chem. 548, 29-32.]). For related structures, see: Malinovskii et al. (2007[Malinovskii, S. T., Tesuro Vallina, A. & Stoeckli-Evans, H. (2007). J. Struct. Chem. 48, 128-136.]); Steinfink et al. (1955[Steinfink, H., Post, B. & Fankuchen, I. (1955). Acta Cryst. 8, 420-424.]); Hensen et al. (1997[Hensen, K., Gebhardt, F., Kettner, M., Pickel, P. & Bolte, M. (1997). Acta Cryst. C53, 1867-1869.]). For puckering analysis,, see: Evans & Boeyens (1989[Evans, D. G. & Boeyens, J. C. A. (1989). Acta Cryst. B45, 581-590.]). Bis(biphenyl-2,2′-di­yl)silane was synthesized using a slight modification of a literature procedure (Gilman & Gorsich, 1958[Gilman, H. & Gorsich, R. D. (1958). J. Am. Chem. Soc. 80, 1883-1884.]).

[Scheme 1]

Experimental

Crystal data
  • C52H48O4Si4

  • Mr = 849.26

  • Orthorhombic, P b c a

  • a = 17.3418 (2) Å

  • b = 14.6488 (2) Å

  • c = 17.9584 (2) Å

  • V = 4562.09 (10) Å3

  • Z = 4

  • Mo Kα radiation

  • μ = 0.18 mm−1

  • T = 110 K

  • 0.30 × 0.12 × 0.03 mm

Data collection
  • Nonius KappaCCD diffractometer

  • Absorption correction: none

  • 68467 measured reflections

  • 4317 independent reflections

  • 3247 reflections with I > 2σ(I)

  • Rint = 0.081

Refinement
  • R[F2 > 2σ(F2)] = 0.036

  • wR(F2) = 0.097

  • S = 1.07

  • 4317 reflections

  • 273 parameters

  • H-atom parameters constrained

  • Δρmax = 0.26 e Å−3

  • Δρmin = −0.33 e Å−3

Table 1
Selected geometric parameters (Å, °)

Si1—O1 1.6287 (12)
Si1—O2 1.6290 (13)
Si1—C12 1.8684 (19)
Si1—C11 1.8746 (17)
Si2—O2i 1.6342 (13)
Si2—O1 1.6347 (12)
Si2—C2 1.8452 (19)
Si2—C1 1.8494 (19)
O1—Si1—O2 109.98 (7)
O2i—Si2—O1 107.88 (7)
Si1—O1—Si2 141.85 (8)
Si1—O2—Si2i 142.12 (8)
O1—Si2—O2i—Si1i −74.36 (14)
O2—Si1—O1—Si2 −52.51 (15)
O2i—Si2—O1—Si1 84.84 (14)
O1—Si1—O2—Si2i −37.42 (15)
C11—C61—C71—C81 81.5 (2)
C12—C62—C72—C82 56.1 (3)
Symmetry code: (i) -x+1, -y+1, -z+1.

Data collection: COLLECT (Nonius, 1999[Nonius (1999). COLLECT. Nonius BV, Delft, The Netherlands.]); cell refinement: HKL-2000 (Otwinowski & Minor, 1997[Otwinowski, Z. & Minor, W. (1997). Methods in Enzymology, Vol. 276, Macromolecular Crystallography, Part A, edited by C. W. Carter Jr & R. M. Sweet, pp. 307-326. New York: Academic Press.]); data reduction: HKL-2000 and SORTAV (Blessing, 1997[Blessing, R. H. (1997). J. Appl. Cryst. 30, 421-426.]); program(s) used to solve structure: SIR97 (Altomare et al., 1999[Altomare, A., Burla, M. C., Camalli, M., Cascarano, G. L., Giacovazzo, C., Guagliardi, A., Moliterni, A. G. G., Polidori, G. & Spagna, R. (1999). J. Appl. Cryst. 32, 115-119.]); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]); molecular graphics: PLATON (Spek, 2009[Spek, A. L. (2009). Acta Cryst. D65, 148-155.]); software used to prepare material for publication: manual editing of SHELXL output.

Supporting information


Comment top

Our research is focused on stable compounds of pentavalent, anionic silicon bearing five organic substituents (Couzijn et al., 2009; Couzijn et al., 2006; Couzijn et al., 2004). Such pentaorganosilicates are commonly proposed as intermediates for nucleophilic substitution reactions on silanes, but were only recently characterized in the condensed phase (e.g., de Keijzer et al., 1997; Deerenberg et al., 2002). In solution, these five-coordinate species undergo intramolecular substituent interchange via Berry pseudorotation and related processes. For a better understanding of the influence of the substituents on the stereomutational barrier, we synthesized bis(biphenyl-2,2'-diyl)fluorosilicate as the caesium and tetramethylammonium salts (Couzijn et al., 2009). While attempting to crystallize these salts, we obtained crystals of the title compound, [–Si(C12H9)2OSi(CH3)2O–]2, instead. This siloxane was most probably formed by reaction with silicone grease and adventitious water.

The title compound crystallizes with Ci point group symmetry, adopting a twist-chair conformation of the eight-membered siloxane ring (Fig. 1, Table 1). A ring puckering analysis (Evans & Boeyens, 1989) shows that the out-of-plane displacements in the ring can be described as a linear combination of the E3g (sin form) and E3g (cos form) normal modes, respectively, in a ratio of 0.891:0.109. The two bis(biphenyl)-substituted silicon atoms and the four oxygen atoms lie in a plane (RMS deviation 0.025 Å), whereas the two dimethyl-substituted silicon atoms are situated at 0.7081 (5)Å above and below this plane, respectively. Similar arrangements have been reported for octamethyl- (Steinfink et al., 1955) and 2,2,6,6-tetraphenyl-4,4,8,8-tetramethyltetrasiloxane (Malinovskii et al., 2007). Each Si(C12H9)2 unit features a parallel displaced π-π stacking interaction between one terminal phenyl ring and the phenylene ring of the other biphenyl moiety. The ring centroids are 4.2377 (11)Å apart and their vector makes an angle of 38.65° with the phenylene plane, while the ring planes make a dihedral angle of 15.40 (9)°.

Related literature top

For general background to stable compounds of pentavalent, anionic silicon bearing five organic substituents, see: Couzijn et al. (2004, 2006, 2009); Deerenberg et al. (2002); de Keijzer et al. (1997). For related structures, see: Malinovskii et al. (2007); Steinfink et al. (1955); Hensen et al. (1997). For puckering analysis,, see: Evans & Boeyens (1989). Bis(biphenyl-2,2'-diyl)silane was synthesized using a slight modification of a literature procedure (Gilman & Gorsich, 1958).

Experimental top

General procedures: dimethylformamide (DMF) was distilled from phenylzinc iodide and stored in a glovebox on 3Å molecular sieves. Commercial caesium fluoride was dried in vacuo at > 373 K. Bis(biphenyl-2,2'-diyl)silane was synthesized from 1,1'-dibromobiphenyl and tetrachlorosilane using a slight modification of a literature procedure (Gilman & Gorsich, 1958).

The title compound was obtained as follows. In the purified nitrogen atmosphere of a glovebox, a flame-dried Schlenk tube was charged with caesium fluoride (71.45 mg, 470 µmol) and bis(biphenyl-2,2'-diyl)silane (73.95 mg, 222 µmol). Anhydrous DMF (3 ml) was added and the mixture was stirred in the glovebox for 2 days. 19F and 1H NMR indicated almost quantitative conversion to the desired caesium bis(biphenyl-2,2'-diyl)fluorosilicate (Couzijn et al., 2009). The clear colorless supernate was filtered through glass wool in the glovebox and evaporated on a Schlenk line to afford the crude fluorosilicate as a white solid. Recrystallization of the fluorosilicate from DMF was initially performed by cooling the Schlenk tube in a freezer outside the glovebox. After repeated attempts, colorless blocks were obtained that were shown by X-ray analysis to be the title compound. Recrystallizations of the fluorosilicate using Young-type glassware (closed with a greaseless Teflon tap) in the freezer of a glovebox invariably afforded an amorphous solid.

Refinement top

All H atoms were located in difference Fourier maps and refined using a riding model (including free rotation of the methyl substituents), with C—H = 0.95–0.99 Å and with Uiso(H) = 1.2 (1.5 for methyl groups) times Ueq(C).

Computing details top

Data collection: COLLECT (Nonius, 1999); cell refinement: HKL-2000 (Otwinowski & Minor, 1997); data reduction: HKL-2000 (Otwinowski & Minor, 1997) and SORTAV (Blessing, 1997); program(s) used to solve structure: SIR97 (Altomare et al., 1999); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: PLATON (Spek, 2009); software used to prepare material for publication: manual editing of SHELXL output.

Figures top
[Figure 1] Fig. 1. Displacement ellipsoid plot of [–Si(C12H9)2OSi(CH3)2O–]2 with ellipsoids drawn at the 50% probability level. The parallel displaced π-π stacking interaction is indicated by a dashed line between the ring centroids. Hydrogen atoms are omitted for clarity. Symmetry operation i: 1 - x, 1 - y, 1 - z.
2,2,6,6-Tetrakis(biphenyl-2-yl)-4,4,8,8-tetramethylcyclotetrasiloxane top
Crystal data top
C52H48O4Si4F(000) = 1792
Mr = 849.26Dx = 1.236 Mg m3
Orthorhombic, PbcaMo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ac 2abCell parameters from 88729 reflections
a = 17.3418 (2) Åθ = 1.0–25.7°
b = 14.6488 (2) ŵ = 0.18 mm1
c = 17.9584 (2) ÅT = 110 K
V = 4562.09 (10) Å3Needle, colourless
Z = 40.30 × 0.12 × 0.03 mm
Data collection top
Nonius KappaCCD
diffractometer
3247 reflections with I > 2σ(I)
Radiation source: rotating anodeRint = 0.081
Graphite monochromatorθmax = 25.7°, θmin = 2.1°
ϕ and ω scansh = 2121
68467 measured reflectionsk = 1717
4317 independent reflectionsl = 2121
Refinement top
Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.036Hydrogen site location: difference Fourier map
wR(F2) = 0.097H-atom parameters constrained
S = 1.07 w = 1/[σ2(Fo2) + (0.0428P)2 + 1.7858P]
where P = (Fo2 + 2Fc2)/3
4317 reflections(Δ/σ)max = 0.001
273 parametersΔρmax = 0.26 e Å3
0 restraintsΔρmin = 0.33 e Å3
Crystal data top
C52H48O4Si4V = 4562.09 (10) Å3
Mr = 849.26Z = 4
Orthorhombic, PbcaMo Kα radiation
a = 17.3418 (2) ŵ = 0.18 mm1
b = 14.6488 (2) ÅT = 110 K
c = 17.9584 (2) Å0.30 × 0.12 × 0.03 mm
Data collection top
Nonius KappaCCD
diffractometer
3247 reflections with I > 2σ(I)
68467 measured reflectionsRint = 0.081
4317 independent reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0360 restraints
wR(F2) = 0.097H-atom parameters constrained
S = 1.07Δρmax = 0.26 e Å3
4317 reflectionsΔρmin = 0.33 e Å3
273 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 > 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
xyzUiso*/Ueq
Si10.42728 (3)0.37257 (3)0.49618 (3)0.02364 (14)
Si20.41400 (3)0.57131 (3)0.44096 (3)0.02422 (14)
O10.42038 (7)0.45998 (8)0.44053 (6)0.0257 (3)
O20.49862 (7)0.38739 (8)0.55394 (6)0.0272 (3)
C10.35711 (12)0.60943 (14)0.52232 (11)0.0382 (5)
H1A0.30640.57980.52150.057*
H1B0.35050.67580.52030.057*
H1C0.38430.59280.56820.057*
C20.37276 (12)0.60687 (14)0.35079 (11)0.0367 (5)
H2A0.40620.58580.31030.055*
H2B0.36890.67360.34920.055*
H2C0.32130.58010.34500.055*
C110.45192 (10)0.27253 (12)0.43560 (9)0.0243 (4)
C210.46918 (11)0.28754 (13)0.36038 (10)0.0298 (4)
H210.46460.34750.34080.036*
C310.49264 (11)0.21768 (13)0.31368 (10)0.0332 (5)
H310.50340.22980.26280.040*
C410.50025 (12)0.13027 (13)0.34161 (11)0.0329 (5)
H410.51650.08200.31000.039*
C510.48408 (11)0.11334 (13)0.41570 (10)0.0305 (4)
H510.49010.05330.43470.037*
C610.45917 (10)0.18265 (12)0.46293 (10)0.0240 (4)
C710.43948 (10)0.15854 (11)0.54194 (10)0.0252 (4)
C810.36294 (11)0.14336 (12)0.56199 (10)0.0307 (4)
H810.32330.15260.52630.037*
C910.34381 (12)0.11508 (13)0.63306 (11)0.0347 (5)
H910.29140.10450.64570.042*
C1010.40081 (13)0.10219 (13)0.68579 (11)0.0358 (5)
H1010.38770.08270.73460.043*
C1110.47717 (12)0.11785 (13)0.66701 (10)0.0342 (5)
H1110.51650.10960.70320.041*
C1210.49649 (11)0.14550 (12)0.59550 (10)0.0300 (4)
H1210.54900.15560.58300.036*
C120.33957 (11)0.36475 (12)0.55627 (10)0.0264 (4)
C220.35201 (12)0.35934 (12)0.63354 (10)0.0319 (5)
H220.40340.35540.65170.038*
C320.29145 (13)0.35950 (13)0.68412 (11)0.0386 (5)
H320.30150.35610.73600.046*
C420.21658 (13)0.36468 (15)0.65844 (12)0.0433 (5)
H420.17490.36410.69270.052*
C520.20213 (12)0.37074 (14)0.58287 (11)0.0388 (5)
H520.15040.37450.56580.047*
C620.26242 (11)0.37139 (12)0.53110 (10)0.0298 (4)
C720.24184 (11)0.38291 (13)0.45090 (11)0.0299 (4)
C820.26624 (11)0.32206 (13)0.39587 (10)0.0328 (5)
H820.29660.27070.40940.039*
C920.24684 (12)0.33543 (15)0.32168 (11)0.0392 (5)
H920.26430.29360.28500.047*
C1020.20206 (12)0.40966 (15)0.30091 (11)0.0399 (5)
H1020.18910.41900.25010.048*
C1120.17661 (12)0.46966 (15)0.35464 (11)0.0392 (5)
H1120.14570.52050.34090.047*
C1220.19584 (11)0.45615 (14)0.42866 (11)0.0346 (5)
H1220.17730.49770.46510.042*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Si10.0279 (3)0.0196 (3)0.0235 (3)0.0010 (2)0.0023 (2)0.0001 (2)
Si20.0271 (3)0.0214 (3)0.0241 (3)0.0024 (2)0.0005 (2)0.0006 (2)
O10.0306 (7)0.0207 (6)0.0258 (6)0.0004 (5)0.0028 (5)0.0004 (5)
O20.0308 (7)0.0240 (6)0.0266 (7)0.0015 (5)0.0002 (5)0.0014 (5)
C10.0389 (12)0.0349 (11)0.0409 (12)0.0038 (9)0.0085 (9)0.0055 (9)
C20.0380 (12)0.0349 (11)0.0370 (11)0.0011 (9)0.0074 (9)0.0067 (9)
C110.0237 (9)0.0242 (9)0.0251 (9)0.0016 (8)0.0005 (7)0.0011 (7)
C210.0359 (11)0.0253 (10)0.0282 (10)0.0007 (8)0.0037 (8)0.0018 (8)
C310.0392 (12)0.0334 (11)0.0270 (10)0.0006 (9)0.0067 (8)0.0029 (8)
C410.0392 (12)0.0278 (10)0.0317 (10)0.0028 (9)0.0079 (9)0.0063 (8)
C510.0336 (11)0.0220 (9)0.0359 (11)0.0030 (8)0.0039 (9)0.0004 (8)
C610.0214 (9)0.0242 (9)0.0263 (9)0.0010 (7)0.0000 (7)0.0001 (7)
C710.0314 (10)0.0155 (8)0.0286 (10)0.0006 (7)0.0010 (8)0.0017 (7)
C810.0306 (11)0.0295 (10)0.0321 (10)0.0019 (8)0.0002 (8)0.0003 (8)
C910.0358 (12)0.0348 (11)0.0335 (11)0.0058 (9)0.0071 (9)0.0017 (9)
C1010.0553 (14)0.0257 (10)0.0264 (10)0.0006 (9)0.0074 (9)0.0003 (8)
C1110.0422 (12)0.0309 (11)0.0295 (11)0.0062 (9)0.0052 (9)0.0010 (8)
C1210.0299 (10)0.0267 (10)0.0335 (11)0.0039 (8)0.0000 (8)0.0023 (8)
C120.0332 (10)0.0194 (9)0.0267 (9)0.0025 (8)0.0051 (8)0.0018 (7)
C220.0390 (12)0.0257 (10)0.0309 (10)0.0029 (9)0.0045 (9)0.0001 (8)
C320.0524 (14)0.0356 (12)0.0278 (10)0.0059 (10)0.0092 (10)0.0010 (9)
C420.0449 (14)0.0489 (13)0.0361 (12)0.0058 (11)0.0183 (10)0.0042 (10)
C520.0325 (12)0.0449 (13)0.0390 (12)0.0043 (9)0.0087 (9)0.0041 (10)
C620.0349 (11)0.0239 (10)0.0304 (10)0.0051 (8)0.0064 (8)0.0041 (8)
C720.0239 (10)0.0297 (10)0.0360 (10)0.0065 (8)0.0053 (8)0.0033 (8)
C820.0298 (11)0.0332 (11)0.0354 (11)0.0032 (9)0.0027 (8)0.0048 (9)
C920.0349 (12)0.0465 (13)0.0361 (11)0.0050 (10)0.0043 (9)0.0096 (10)
C1020.0331 (12)0.0549 (14)0.0318 (11)0.0042 (10)0.0011 (9)0.0018 (10)
C1120.0297 (11)0.0446 (13)0.0432 (12)0.0014 (9)0.0020 (9)0.0052 (10)
C1220.0282 (11)0.0372 (11)0.0386 (11)0.0029 (9)0.0065 (9)0.0047 (9)
Geometric parameters (Å, º) top
Si1—O11.6287 (12)C91—C1011.382 (3)
Si1—O21.6290 (13)C91—H910.9500
Si1—C121.8684 (19)C101—C1111.386 (3)
Si1—C111.8746 (17)C101—H1010.9500
Si2—O2i1.6342 (13)C111—C1211.387 (3)
Si2—O11.6347 (12)C111—H1110.9500
Si2—C21.8452 (19)C121—H1210.9500
Si2—C11.8494 (19)C12—C221.407 (3)
O2—Si2i1.6342 (13)C12—C621.415 (3)
C1—H1A0.9800C22—C321.388 (3)
C1—H1B0.9800C22—H220.9500
C1—H1C0.9800C32—C421.380 (3)
C2—H2A0.9800C32—H320.9500
C2—H2B0.9800C42—C521.383 (3)
C2—H2C0.9800C42—H420.9500
C11—C211.401 (2)C52—C621.399 (3)
C11—C611.411 (2)C52—H520.9500
C21—C311.384 (3)C62—C721.493 (3)
C21—H210.9500C72—C1221.395 (3)
C31—C411.381 (3)C72—C821.396 (3)
C31—H310.9500C82—C921.388 (3)
C41—C511.382 (3)C82—H820.9500
C41—H410.9500C92—C1021.387 (3)
C51—C611.392 (2)C92—H920.9500
C51—H510.9500C102—C1121.378 (3)
C61—C711.501 (2)C102—H1020.9500
C71—C1211.393 (3)C112—C1221.385 (3)
C71—C811.393 (3)C112—H1120.9500
C81—C911.382 (3)C122—H1220.9500
C81—H810.9500
O1—Si1—O2109.98 (7)C71—C81—H81119.5
O1—Si1—C12110.05 (7)C101—C91—C81120.13 (19)
O2—Si1—C12105.00 (8)C101—C91—H91119.9
O1—Si1—C11105.97 (7)C81—C91—H91119.9
O2—Si1—C11107.49 (7)C91—C101—C111119.62 (18)
C12—Si1—C11118.22 (8)C91—C101—H101120.2
O2i—Si2—O1107.88 (7)C111—C101—H101120.2
O2i—Si2—C2107.71 (8)C101—C111—C121120.29 (18)
O1—Si2—C2107.68 (8)C101—C111—H111119.9
O2i—Si2—C1109.78 (8)C121—C111—H111119.9
O1—Si2—C1109.94 (8)C111—C121—C71120.53 (18)
C2—Si2—C1113.66 (10)C111—C121—H121119.7
Si1—O1—Si2141.85 (8)C71—C121—H121119.7
Si1—O2—Si2i142.12 (8)C22—C12—C62117.63 (17)
Si2—C1—H1A109.5C22—C12—Si1116.64 (14)
Si2—C1—H1B109.5C62—C12—Si1125.51 (14)
H1A—C1—H1B109.5C32—C22—C12121.96 (19)
Si2—C1—H1C109.5C32—C22—H22119.0
H1A—C1—H1C109.5C12—C22—H22119.0
H1B—C1—H1C109.5C42—C32—C22119.55 (19)
Si2—C2—H2A109.5C42—C32—H32120.2
Si2—C2—H2B109.5C22—C32—H32120.2
H2A—C2—H2B109.5C32—C42—C52120.13 (19)
Si2—C2—H2C109.5C32—C42—H42119.9
H2A—C2—H2C109.5C52—C42—H42119.9
H2B—C2—H2C109.5C42—C52—C62121.1 (2)
C21—C11—C61117.57 (16)C42—C52—H52119.4
C21—C11—Si1119.05 (13)C62—C52—H52119.4
C61—C11—Si1123.23 (13)C52—C62—C12119.58 (18)
C31—C21—C11122.07 (17)C52—C62—C72117.58 (18)
C31—C21—H21119.0C12—C62—C72122.79 (16)
C11—C21—H21119.0C122—C72—C82117.48 (18)
C41—C31—C21119.56 (17)C122—C72—C62119.97 (17)
C41—C31—H31120.2C82—C72—C62122.54 (17)
C21—C31—H31120.2C92—C82—C72121.05 (19)
C31—C41—C51119.77 (17)C92—C82—H82119.5
C31—C41—H41120.1C72—C82—H82119.5
C51—C41—H41120.1C102—C92—C82120.29 (19)
C41—C51—C61121.25 (17)C102—C92—H92119.9
C41—C51—H51119.4C82—C92—H92119.9
C61—C51—H51119.4C112—C102—C92119.40 (19)
C51—C61—C11119.77 (16)C112—C102—H102120.3
C51—C61—C71118.35 (16)C92—C102—H102120.3
C11—C61—C71121.87 (15)C102—C112—C122120.3 (2)
C121—C71—C81118.42 (17)C102—C112—H112119.9
C121—C71—C61121.58 (16)C122—C112—H112119.9
C81—C71—C61119.90 (16)C112—C122—C72121.49 (19)
C91—C81—C71121.01 (18)C112—C122—H122119.3
C91—C81—H81119.5C72—C122—H122119.3
O1—Si2—O2i—Si1i74.36 (14)C81—C91—C101—C1110.1 (3)
O2—Si1—O1—Si252.51 (15)C91—C101—C111—C1210.6 (3)
C12—Si1—O1—Si262.69 (15)C101—C111—C121—C710.5 (3)
C11—Si1—O1—Si2168.40 (12)C81—C71—C121—C1110.1 (3)
O2i—Si2—O1—Si184.84 (14)C61—C71—C121—C111176.07 (16)
C2—Si2—O1—Si1159.17 (13)O1—Si1—C12—C22127.17 (14)
C1—Si2—O1—Si134.85 (16)O2—Si1—C12—C228.85 (15)
O1—Si1—O2—Si2i37.42 (15)C11—Si1—C12—C22110.94 (14)
C12—Si1—O2—Si2i155.78 (13)O1—Si1—C12—C6247.32 (17)
C11—Si1—O2—Si2i77.52 (14)O2—Si1—C12—C62165.63 (15)
O1—Si1—C11—C217.60 (16)C11—Si1—C12—C6274.57 (17)
O2—Si1—C11—C21109.97 (15)C62—C12—C22—C320.6 (3)
C12—Si1—C11—C21131.54 (15)Si1—C12—C22—C32175.55 (14)
O1—Si1—C11—C61176.83 (14)C12—C22—C32—C420.3 (3)
O2—Si1—C11—C6165.60 (16)C22—C32—C42—C520.8 (3)
C12—Si1—C11—C6152.89 (18)C32—C42—C52—C620.3 (3)
C61—C11—C21—C310.1 (3)C42—C52—C62—C120.7 (3)
Si1—C11—C21—C31175.77 (15)C42—C52—C62—C72176.95 (19)
C11—C21—C31—C410.7 (3)C22—C12—C62—C521.1 (3)
C21—C31—C41—C510.3 (3)Si1—C12—C62—C52175.54 (14)
C31—C41—C51—C610.8 (3)C22—C12—C62—C72176.41 (17)
C41—C51—C61—C111.6 (3)Si1—C12—C62—C722.0 (3)
C41—C51—C61—C71177.46 (18)C52—C62—C72—C12252.9 (2)
C21—C11—C61—C511.1 (3)C12—C62—C72—C122124.6 (2)
Si1—C11—C61—C51174.49 (14)C52—C62—C72—C82126.4 (2)
C21—C11—C61—C71177.85 (16)C12—C62—C72—C8256.1 (3)
Si1—C11—C61—C716.5 (2)C122—C72—C82—C921.5 (3)
C51—C61—C71—C12178.6 (2)C62—C72—C82—C92179.20 (18)
C11—C61—C71—C121102.4 (2)C72—C82—C92—C1020.5 (3)
C51—C61—C71—C8197.5 (2)C82—C92—C102—C1120.4 (3)
C11—C61—C71—C8181.5 (2)C92—C102—C112—C1220.3 (3)
C121—C71—C81—C910.7 (3)C102—C112—C122—C720.8 (3)
C61—C71—C81—C91175.58 (17)C82—C72—C122—C1121.7 (3)
C71—C81—C91—C1010.6 (3)C62—C72—C122—C112179.02 (17)
Symmetry code: (i) x+1, y+1, z+1.

Experimental details

Crystal data
Chemical formulaC52H48O4Si4
Mr849.26
Crystal system, space groupOrthorhombic, Pbca
Temperature (K)110
a, b, c (Å)17.3418 (2), 14.6488 (2), 17.9584 (2)
V3)4562.09 (10)
Z4
Radiation typeMo Kα
µ (mm1)0.18
Crystal size (mm)0.30 × 0.12 × 0.03
Data collection
DiffractometerNonius KappaCCD
diffractometer
Absorption correction
No. of measured, independent and
observed [I > 2σ(I)] reflections
68467, 4317, 3247
Rint0.081
(sin θ/λ)max1)0.610
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.036, 0.097, 1.07
No. of reflections4317
No. of parameters273
H-atom treatmentH-atom parameters constrained
Δρmax, Δρmin (e Å3)0.26, 0.33

Computer programs: COLLECT (Nonius, 1999), HKL-2000 (Otwinowski & Minor, 1997) and SORTAV (Blessing, 1997), SIR97 (Altomare et al., 1999), SHELXL97 (Sheldrick, 2008), PLATON (Spek, 2009), manual editing of SHELXL output.

Selected geometric parameters (Å, º) top
Si1—O11.6287 (12)Si2—O2i1.6342 (13)
Si1—O21.6290 (13)Si2—O11.6347 (12)
Si1—C121.8684 (19)Si2—C21.8452 (19)
Si1—C111.8746 (17)Si2—C11.8494 (19)
O1—Si1—O2109.98 (7)Si1—O1—Si2141.85 (8)
O2i—Si2—O1107.88 (7)Si1—O2—Si2i142.12 (8)
O1—Si2—O2i—Si1i74.36 (14)O1—Si1—O2—Si2i37.42 (15)
O2—Si1—O1—Si252.51 (15)C11—C61—C71—C8181.5 (2)
O2i—Si2—O1—Si184.84 (14)C12—C62—C72—C8256.1 (3)
Symmetry code: (i) x+1, y+1, z+1.
 

Acknowledgements

Financial assistance for this project was provided by the Dutch Organization for Scientific Research, Chemical Sciences (NWO-CW).

References

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Volume 65| Part 9| September 2009| Pages o2182-o2183
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