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Solvent-free single crystals of 1,3,5,7,9,11,13,15-octa­phenyl­penta­cyclo­[9.5.1.13,9.15,15.17,13]octa­siloxane (abbreviated as octa­phenyl-POSS), C48H40O12Si8, were obtained by dehydration/condensation of the tetrol Si4O4(Ph)4(OH)4. The powder pattern generated from the single-crystal data matches well with the experimentally measured powder pattern of commercial octa­phenyl-POSS. The geometry of the centrosymmetric molecule in the crystal was compared with that in the gas phase, and had shorter Si—O bond lengths and a broader range of Si—O—Si bond angles. The average Si—O bond length [1.621 (3) Å], and Si—O—Si and O—Si—O bond angles [149 (5) and 109 (1)°, respectively] were within the same range measured previously for octa­phenyl-POSS solvates.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S2053229614019834/fn3178sup1.cif
Contains datablock I

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S2053229614019834/fn3178Isup2.hkl
Contains datablock I

CCDC reference: 1022585

Introduction top

Fully condensed polyo­cta­hedral silsesquioxanes (POSS) are used in a variety of materials applications that include reinforcement of composites, and as nanoscale building blocks for the assembly of two- and three-dimensional structures (Laine, 2005). The importance of POSS has generated numerous reviews of their synthesis (Voronkov & Lavrentyev, 1982), characterization (Baney et al., 1995; Lickiss & Rataboul, 2008; Cordes et al., 2010), and incorporation into polymers, copolymers and nano-composites (Bourbigot et al., 2006). Hydro­phobic T8[alkyl]8 are used as alternatives to silica nanoparticles in organic polymer matrices to provide increased thermal stability, reduced flammability, higher glass transition temperatures (Tgs), and improved mechanical properties (Lichtenhan, 1995; Provatas & Matisons, 1997; Pittman et al., 2003; Phillips et al., 2004; Joshi & Butola, 2004). The aryl­silsesquioxanes, of which the most common is o­cta­phenyl-POSS, are characterized by their high thermal stability, and have been reviewed separately (Laine & Roll, 2011). Octa­phenyl-POSS has poor solubility in common solvents, with slight solubility in pyridine and CH2Cl2 (Pakjamsai & Kawakami, 2005), but can be used in nanocomposites by melt blending with polycarbonate (Zhao & Schiraldi, 2005) and ep­oxy (Dodiuk et al., 2005) resins to improve tensile and dynamic mechanical moduli, strength and toughness.

Footnote: A polyhedral `T' unit is often used to denote an Si atom with three bridging siloxane O atoms (the core structure), and when there are phenyl units attached at the silicon vertices, can be labelled as T8Ph8, also referred to as phenyl-T8, o­cta­(phenyl­silasesquioxane), or o­cta­(phenyl polyhedral oligosilsesquioxanes), i.e. o­cta­phenyl-POSS (Registered trademark #2, 048 of Hybrid Plastics Inc. https://www.hybridplastics.com/) with the stoichiometry (RSiO3/2)8. The CAS number is [5256-79-1].

Single-crystal structures of several fully condensed symmetric T-8 cages (R8Si8O12), with eight Si atoms arranged at the corners of a cube, 12 O atoms bridging the edges of the Si8 cube forming an inter­stitial cubo­cta­hedron, and eight R groups at the corners of the tetra­hedral Si atoms, have been obtained. These include o­cta­(methyl­silsesquioxane) (R = CH3; Larsson, 1960a), o­cta­silsesquioxane (R = H; Larsson, 1960c), o­cta­(vinyl­silsesquioxane) (R = C2H3; Baidina et al., 1979), o­cta­(meth­oxy­silsesquioxane) (R = OCH3; Day et al., 1985), o­cta­(allyl­silsesquioxanes) [R = OSi(CH3)3; Podberezskaya et al., 1981], and o­cta­(tolyl­silsesquioxane) (R = tolyl; Zakharov et al., 2010). In the case of the o­cta­phenyl­silsesquioxane (C6H5SiO1.5)8(C6H5), there are older structure reports, with solvates of pyridine (Larsson, 1960b) and o-di­chloro­benzene (Shklover et al., 1978), hydrates of acetone (Hossain et al., 1979) or water (Liu et al., 2004), and for [Si8O12Ph8F]- in the salt [NBu4][Si8O12Ph8F] (Bassindale et al., 2003). The equilibrium molecular structure in the gas phase has also been determined by electron diffraction (Zakharov et al., 2010). The crystal structure of dodeca(phenyl­silasesquioxanes) have also been reported (Clegg et al., 1980). We report here the crystal structure of unsolvated o­cta­phenyl-POSS.

Experimental top

Si4O4(Ph)4(OH)4 was obtained as a gift from Hybrid Plastics Inc. The theoretical powder pattern of o­cta­phenyl–POSS was calculated using Mercury (Macrae et al., 2008).

Synthesis and crystallization top

Single crystals of o­cta­phenyl-POSS were obtained by the self-condensation of the tetrol Si4O4(Ph)4(OH)4 (15 mg) in an inner vial of methanol (1 ml), with an outer vial (3 ml) of ether. After 2 d at room temperature, crystals were observed. The tetrol is soluble in methanol and insoluble in ether, and o­cta­phenyl-POSS is insoluble in both methanol and ether. We were expecting crystals of tetrol, but instead obtained solvent-free crystals of o­cta­phenyl-POSS resulting from the dehydrative coupling of two molecules of the tetrol (see Scheme).

Octa­phenyl-POSS is more typically synthesized by hydrolysis of either PhSiCl3 or PhSi(OEt)3, first prepared in low yield (Olsson, 1958), but subsequently with improved yields (Voronkov & Lavrentyev, 1982; Lickiss & Rataboul, 2008). However, another route to the synthesis of R8T8 cages is through the condensation of R4T4-tetrols under pressurized hydrogen (Feher & Budzichowski, 1989) or using ammonium salts (Tateyama et al., 2010; Liu et al., 2004), where the R = phenyl-POSS was obtained (Kawakami et al., 2011).

Refinement top

Crystal data, data collection and structure refinement details are summarized in Table 1.

Results and discussion top

The structure of o­cta­phenyl-POSS (Fig. 1) may be described as an approximately cuboidal arrangement of Si atoms with an inter­stitial approximate cubo­cta­hedron of bridging O atoms. The Si—O contacts are in the range 1.6166 (11)–1.6258 (11) Å. The Si atoms have nearly ideal tetra­hedral bond angles ranging from 108.04 (6) to 111.58 (6)°, but the Si—O—Si bond angles are strained by the cuboidal geometry imposed by the Si atoms, and are widened to between 142.28 (7) and 153.22 (8)°, significantly distorted from the ideal oxygen bond angle of 104°. Si—C bonds are in the range 1.8382 (16)–1.8429 (15) Å.

The title compound packs into a c-centered monoclinic arrangement with molecules occupying the corners of the unit cell, as well as the c-face. Additional symmetry-generated molecules appear on the c-edges and in the center of the unit cell (Fig. 2). The inter­molecular inter­actions between neighboring molecules are van der Waals inter­actions described best by inter­calation of phenyl rings rather than π-stacking inter­actions (Fig. 3).

There have been several reported crystal structures for o­cta­phenyl-POSS. Preliminary powder XRD suggested rhombahedral crystals (Larsson, 1960b; Brown et al., 1964). The powder patterns of o­cta­phenyl-POSS could be indexed on the basis of a rhombahedral cell where a = 11.0 Å and α = 95°, with major d-spacings of 10.9 (vs), 8.1, 7.3, 4.76, 4.63 and 3.59 Å. A higher temperature form had d-spacings of 12.0, 10.6 (vs), 10.1, 9.4, 8.4, 7.7 and 3.88 Å. However, single-crystal data (crystallized from pyridine) showed two polymorphs, a triclinic form with one molecule in the unit cell and a monoclinic form with two molecules in the unit cell (Larsson, 1960b).

The monoclinic solvate from pyridine (Larsson, 1960b), the triclinic form from pyridine (Larsson, 1960b), and the triclinic form from pyridine and o-di­chloro­benzene (Mr = 732.8, Si8O12C48H40; Shklover et al., 1978) were reported previously; see Table 2 for the crystal data. The triclinic form undergoes a phase transition at 443 K, decomposes without melting at 723 K and has higher density than the monoclinic form (Larsson, 1960b). In the triclinic form, the solvent molecules were disordered in the large volume of the solvent cavity (150 Å3; Shklover et al., 1978). Single-crystal solvates have also been obtained with acetone (Table 2), or with water (Liu et al., 2004). In all of these structures, the Si—O core framework remains the same, with Si—O bond lengths of 1.61–1.62 Å. A comparison of the geometric data from previously reported polymorphs with the data for solvent-free crystal structure reported here is presented in Table 2.

The equilibrium molecular structure of o­cta­phenyl-POSS in the gas phase and from theoretical calculations can be compared with its structure in the solid state, to assess the effects of inter­molecular inter­actions from the crystalline lattice (Zakharov et al., 2010). In the gas phase, o­cta­phenyl-POSS has d4 point-group symmetry (the o­cta­hedral point group symmetry is broken by the planar phenyl groups), with Si—O bond lengths of 1.634 (15)–1.645 (19) Å, and a narrow range of Si—O—Si angles [148 (5)–150 (2)°]. In the present structural report, o­cta­phenyl-POSS sits on an inversion operation, giving the molecule rigorous Ci symmetry, though the core similarly approximates o­cta­hedral symmetry, with Si—O bond lengths of 1.6166 (11)–1.6258 (11) Å and a narrow range of Si—O—Si bond angles [142.28 (7)– 153.22 (8)°]. The Si8O12 cages of Si8O12(p-tolyl)8 and Si8O12(p-ClCH2C6H4)8 were found to be significantly distorted from the gas-phase geometry, with Si—O—Si angles in the range 144.2 (2)–151.64 (16)° for Si8O12(p-tolyl)8 and 138.8 (2)–164.2 (2)° for Si8O12(p-ClCH2C6H4)8 (Zakharov et al., 2010).

The powder pattern generated from the single-crystal data we obtained matches well with the powder pattern measured from a commercial sample manufactured by Hybrid Plastics, Inc. (Fig. 4). The powder pattern of the starting material, (Si4O4(Ph)4(OH)4, is shown for comparison, and is not a match.

Related literature top

For related literature, see: Baidina et al. (1979); Baney et al. (1995); Bassindale et al. (2003); Bourbigot et al. (2006); Brown et al. (1964); Clegg et al. (1980); Cordes et al. (2010); Day et al. (1985); Dodiuk et al. (2005); Feher & Budzichowski (1989); Hossain et al. (1979); Joshi & Butola (2004); Kawakami et al. (2011); Laine (2005); Laine & Roll (2011); Larsson (1960a, 1960b, 1960c); Lichtenhan (1995); Lickiss & Rataboul (2008); Liu et al. (2004); Macrae et al. (2008); Olsson (1958); Pakjamsai & Kawakami (2005); Phillips et al. (2004); Pittman et al. (2003); Podberezskaya et al. (1981); Provatas & Matisons (1997); Shklover et al. (1978); Tateyama et al. (2010); Voronkov & Lavrentyev (1982); Zakharov et al. (2010); Zhao & Schiraldi (2005).

Computing details top

Data collection: COSMO (Bruker, 2006); cell refinement: SAINT (Bruker, 2006); data reduction: SADABS (Bruker, 2006); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL2013 (Sheldrick, 2013); molecular graphics: XP in SHELXL2013 (Sheldrick, 2013); software used to prepare material for publication: APEX2 Report Generator (Bruker, 2006).

Figures top
[Figure 1] Fig. 1. Displacement ellipsoid plot of octaphenyl-POSS, with ellipsoids at the 50% probability level. H atoms are shown as open circles. Atom labels with the suffix `A' are generated by crystallographic inversion symmetry.
[Figure 2] Fig. 2. The crystal packing of octaphenyl-POSS in the C2/c space group (phenyl groups are not shown for clarity).
[Figure 3] Fig. 3. The intermolecular arrangement of neighboring octaphenyl-POSS molecules. Four phenyl rings are labeled and highlighted with a ball-and-stick representation, showing the absence of direct ππ stacking interactions. The C11B–C16B phenyl ring is arranged parallel to the plane of the page, showing that the C41–C46 phenyl ring does not lie directly above it. This can be seen also with the second symmetry-equivalent pair of phenyl rings, viz. C11–C16 and C41B–C46B.
[Figure 4] Fig. 4. Comparison of the powder X-ray diffraction pattern generated from single-crystal data (Theory) and the measured powder patterns of commercial octaphenyl-POSS (Ph8T8) and the tetrol Si4O4(Ph)4(OH)4 (Ph4T4OH).
1,3,5,7,9,11,13,15-Octaphenylpentacyclo[9.5.1.13,9.15,15.17,13]octasiloxane top
Crystal data top
C48H40O12Si8F(000) = 2144
Mr = 1033.52Dx = 1.400 Mg m3
Monoclinic, C2/cMo Kα radiation, λ = 0.71073 Å
a = 16.406 (2) ÅCell parameters from 9926 reflections
b = 13.8849 (17) Åθ = 2.2–28.0°
c = 21.570 (3) ŵ = 0.28 mm1
β = 93.458 (2)°T = 100 K
V = 4904.7 (10) Å3Plate, white
Z = 40.45 × 0.30 × 0.07 mm
Data collection top
Bruker Kappa APEXII DUO
diffractometer
5707 independent reflections
Radiation source: fine-focused sealed tube5201 reflections with I > 2σ(I)
Detector resolution: 8.333 pixels mm-1Rint = 0.022
ω scansθmax = 28.0°, θmin = 1.9°
Absorption correction: multi-scan
(SADABS; Bruker, 2006)
h = 2121
Tmin = 0.653, Tmax = 0.746k = 1818
16438 measured reflectionsl = 2828
Refinement top
Refinement on F20 restraints
Least-squares matrix: fullHydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.035H-atom parameters constrained
wR(F2) = 0.095 w = 1/[σ2(Fo2) + (0.0485P)2 + 7.6053P]
where P = (Fo2 + 2Fc2)/3
S = 1.05(Δ/σ)max < 0.001
5707 reflectionsΔρmax = 0.63 e Å3
307 parametersΔρmin = 0.38 e Å3
Crystal data top
C48H40O12Si8V = 4904.7 (10) Å3
Mr = 1033.52Z = 4
Monoclinic, C2/cMo Kα radiation
a = 16.406 (2) ŵ = 0.28 mm1
b = 13.8849 (17) ÅT = 100 K
c = 21.570 (3) Å0.45 × 0.30 × 0.07 mm
β = 93.458 (2)°
Data collection top
Bruker Kappa APEXII DUO
diffractometer
5707 independent reflections
Absorption correction: multi-scan
(SADABS; Bruker, 2006)
5201 reflections with I > 2σ(I)
Tmin = 0.653, Tmax = 0.746Rint = 0.022
16438 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0350 restraints
wR(F2) = 0.095H-atom parameters constrained
S = 1.05Δρmax = 0.63 e Å3
5707 reflectionsΔρmin = 0.38 e Å3
307 parameters
Special details top

Experimental. Absorption correction: 16803 Corrected reflections written to file mo_1732_0m.hkl Estimated minimum and maximum transmission: 0.6528 0.7456 The ratio of these values is more reliable than their absolute values! Additional spherical absorption correction applied with mu*r = 0.2000 Lambda/2 correction factor = 0.0015

The crystal was selected and mounted on a MiTeGen loop with Paratone-N oil. during collection the crystal slipped, and so had to be reindexed. The crystal slippage resulted in an incomplete sphere of data (97.5%).

Data were acquired on a Kappa APEX II DUO diffractometer using Mo Kα radiation from a sealed tube, monochromatized with a TRIUMPH monochromator. The crystal was mounted on a MiTeGen loop using paratone-N oil. Data were collected in φ and ω scans, and integrated using SAINT (Bruker, 2006). Multi-scan absorption corrections and scaling were applied using SADABS (Bruker, 2006), and the structure was solved using direct methods, and refined using the SHELXL2013 suite.

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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
C110.13847 (9)0.02387 (11)0.18861 (7)0.0146 (3)
C120.19925 (10)0.09321 (12)0.20040 (8)0.0203 (3)
H120.21410.13460.16780.024*
C130.23838 (11)0.10246 (14)0.25940 (9)0.0265 (4)
H130.27930.15020.26680.032*
C140.21785 (11)0.04245 (15)0.30699 (8)0.0292 (4)
H140.24500.04850.34700.035*
C150.15775 (11)0.02668 (16)0.29648 (8)0.0300 (4)
H150.14350.06780.32930.036*
C160.11809 (10)0.03590 (14)0.23763 (8)0.0225 (3)
H160.07680.08330.23080.027*
C210.26280 (8)0.07409 (11)0.03537 (7)0.0132 (3)
C220.28411 (9)0.16287 (12)0.06074 (8)0.0181 (3)
H220.24400.21190.06670.022*
C230.36386 (10)0.18003 (13)0.07737 (8)0.0222 (3)
H230.37790.24070.09410.027*
C240.42256 (10)0.10848 (13)0.06950 (8)0.0234 (4)
H240.47670.12030.08080.028*
C250.40245 (9)0.01969 (13)0.04509 (8)0.0208 (3)
H250.44260.02940.04010.025*
C260.32329 (9)0.00284 (12)0.02794 (7)0.0170 (3)
H260.31000.05790.01090.020*
C310.01312 (9)0.28363 (11)0.10470 (7)0.0138 (3)
C320.04954 (10)0.31391 (13)0.14748 (8)0.0218 (3)
H320.09640.27450.15500.026*
C330.04391 (11)0.40056 (14)0.17899 (9)0.0275 (4)
H330.08700.42020.20760.033*
C340.02451 (11)0.45875 (13)0.16882 (8)0.0238 (4)
H340.02820.51810.19040.029*
C350.08740 (10)0.43004 (12)0.12702 (8)0.0204 (3)
H350.13440.46950.12020.025*
C360.08174 (9)0.34350 (12)0.09507 (7)0.0174 (3)
H360.12490.32460.06630.021*
C410.11248 (9)0.22708 (11)0.11826 (7)0.0130 (3)
C420.07873 (9)0.24465 (12)0.17834 (7)0.0169 (3)
H420.02990.21250.19240.020*
C430.11561 (10)0.30857 (12)0.21785 (8)0.0207 (3)
H430.09170.32000.25840.025*
C440.18726 (10)0.35550 (12)0.19800 (8)0.0228 (3)
H440.21250.39910.22490.027*
C450.22184 (11)0.33838 (14)0.13870 (9)0.0272 (4)
H450.27100.37010.12510.033*
C460.18486 (10)0.27519 (12)0.09920 (8)0.0216 (3)
H460.20890.26440.05860.026*
O10.01096 (6)0.08997 (8)0.10406 (5)0.0174 (2)
O20.03730 (7)0.19140 (8)0.00462 (5)0.0161 (2)
O30.09575 (6)0.12755 (8)0.04478 (5)0.0172 (2)
O40.14973 (6)0.03997 (8)0.05878 (5)0.0163 (2)
O50.05027 (7)0.09389 (8)0.10045 (5)0.0167 (2)
O60.13307 (6)0.05788 (8)0.04539 (5)0.0165 (2)
Si10.08573 (2)0.01414 (3)0.11101 (2)0.01078 (10)
Si20.15755 (2)0.04615 (3)0.01590 (2)0.01073 (10)
Si30.00515 (2)0.17142 (3)0.06025 (2)0.01109 (10)
Si40.06665 (2)0.13942 (3)0.06676 (2)0.01047 (10)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
C110.0101 (6)0.0197 (8)0.0136 (7)0.0047 (5)0.0026 (5)0.0033 (5)
C120.0178 (7)0.0192 (8)0.0225 (8)0.0031 (6)0.0084 (6)0.0033 (6)
C130.0216 (8)0.0270 (9)0.0289 (9)0.0062 (7)0.0140 (7)0.0122 (7)
C140.0245 (9)0.0470 (12)0.0150 (8)0.0153 (8)0.0092 (7)0.0109 (7)
C150.0231 (8)0.0541 (13)0.0126 (8)0.0081 (8)0.0001 (7)0.0039 (7)
C160.0145 (7)0.0363 (10)0.0165 (8)0.0005 (7)0.0008 (6)0.0024 (7)
C210.0083 (6)0.0173 (7)0.0135 (7)0.0018 (5)0.0020 (5)0.0023 (5)
C220.0128 (7)0.0191 (8)0.0223 (8)0.0001 (6)0.0007 (6)0.0002 (6)
C230.0171 (7)0.0213 (8)0.0286 (9)0.0059 (6)0.0030 (6)0.0014 (7)
C240.0107 (7)0.0309 (9)0.0288 (9)0.0045 (6)0.0032 (6)0.0027 (7)
C250.0105 (7)0.0244 (9)0.0274 (9)0.0020 (6)0.0014 (6)0.0029 (7)
C260.0112 (7)0.0194 (8)0.0200 (7)0.0004 (6)0.0022 (6)0.0003 (6)
C310.0129 (6)0.0151 (7)0.0133 (7)0.0006 (5)0.0005 (5)0.0010 (5)
C320.0153 (7)0.0251 (9)0.0242 (8)0.0044 (6)0.0052 (6)0.0077 (7)
C330.0221 (8)0.0313 (10)0.0280 (9)0.0008 (7)0.0066 (7)0.0137 (7)
C340.0273 (9)0.0200 (8)0.0241 (8)0.0022 (7)0.0012 (7)0.0087 (7)
C350.0194 (7)0.0191 (8)0.0228 (8)0.0055 (6)0.0008 (6)0.0004 (6)
C360.0143 (7)0.0182 (8)0.0193 (7)0.0012 (6)0.0025 (6)0.0009 (6)
C410.0109 (6)0.0129 (7)0.0151 (7)0.0003 (5)0.0008 (5)0.0000 (5)
C420.0131 (7)0.0187 (8)0.0186 (7)0.0003 (6)0.0022 (6)0.0031 (6)
C430.0229 (8)0.0202 (8)0.0189 (8)0.0025 (6)0.0001 (6)0.0059 (6)
C440.0232 (8)0.0188 (8)0.0270 (9)0.0029 (6)0.0065 (7)0.0061 (6)
C450.0226 (8)0.0286 (10)0.0300 (9)0.0130 (7)0.0014 (7)0.0031 (7)
C460.0198 (8)0.0239 (9)0.0203 (8)0.0077 (6)0.0048 (6)0.0022 (6)
O10.0129 (5)0.0211 (6)0.0174 (5)0.0056 (4)0.0047 (4)0.0021 (4)
O20.0167 (5)0.0161 (5)0.0157 (5)0.0009 (4)0.0028 (4)0.0007 (4)
O30.0097 (5)0.0198 (6)0.0219 (6)0.0023 (4)0.0018 (4)0.0047 (4)
O40.0104 (5)0.0254 (6)0.0128 (5)0.0022 (4)0.0019 (4)0.0009 (4)
O50.0177 (5)0.0149 (5)0.0166 (5)0.0031 (4)0.0061 (4)0.0003 (4)
O60.0115 (5)0.0167 (6)0.0213 (6)0.0036 (4)0.0004 (4)0.0049 (4)
Si10.00722 (17)0.0140 (2)0.01069 (19)0.00050 (14)0.00308 (14)0.00083 (14)
Si20.00633 (17)0.0136 (2)0.01194 (19)0.00056 (14)0.00195 (14)0.00075 (14)
Si30.00833 (18)0.0125 (2)0.01214 (19)0.00006 (14)0.00200 (14)0.00085 (14)
Si40.00713 (17)0.0120 (2)0.01195 (19)0.00032 (14)0.00178 (14)0.00098 (14)
Geometric parameters (Å, º) top
C11—C121.398 (2)C41—C421.400 (2)
C11—C161.400 (2)C41—C461.402 (2)
C11—Si11.8423 (15)C41—Si41.8390 (15)
C12—C131.396 (2)C42—C431.394 (2)
C13—C141.380 (3)C43—C441.389 (2)
C14—C151.385 (3)C44—C451.388 (3)
C15—C161.397 (2)C45—C461.388 (2)
C21—C221.402 (2)O1—Si11.6166 (11)
C21—C261.404 (2)O1—Si41.6175 (11)
C21—Si21.8429 (15)O2—Si41.6209 (11)
C22—C231.398 (2)O2—Si31.6241 (11)
C23—C241.387 (2)O3—Si21.6177 (11)
C24—C251.388 (3)O3—Si31.6223 (11)
C25—C261.391 (2)O4—Si11.6258 (11)
C31—C321.404 (2)O4—Si21.6258 (11)
C31—C361.405 (2)O5—Si11.6200 (12)
C31—Si31.8382 (16)O5—Si3i1.6255 (11)
C32—C331.388 (2)O6—Si4i1.6189 (11)
C33—C341.390 (2)O6—Si21.6192 (11)
C34—C351.387 (2)Si3—O5i1.6255 (11)
C35—C361.391 (2)Si4—O6i1.6189 (11)
C12—C11—C16118.09 (14)C45—C46—C41120.99 (15)
C12—C11—Si1120.42 (12)Si1—O1—Si4153.22 (8)
C16—C11—Si1121.47 (12)Si4—O2—Si3143.19 (8)
C13—C12—C11120.84 (17)Si2—O3—Si3152.45 (8)
C14—C13—C12120.21 (17)Si1—O4—Si2142.28 (7)
C13—C14—C15120.01 (16)Si1—O5—Si3i150.78 (8)
C14—C15—C16120.01 (18)Si4i—O6—Si2151.94 (8)
C15—C16—C11120.82 (17)O1—Si1—O5109.03 (6)
C22—C21—C26118.24 (14)O1—Si1—O4108.07 (6)
C22—C21—Si2122.23 (11)O5—Si1—O4110.38 (6)
C26—C21—Si2119.43 (12)O1—Si1—C11110.41 (6)
C23—C22—C21120.63 (15)O5—Si1—C11109.91 (7)
C24—C23—C22120.02 (16)O4—Si1—C11109.02 (6)
C23—C24—C25120.23 (15)O3—Si2—O6109.70 (6)
C24—C25—C26119.81 (15)O3—Si2—O4109.47 (6)
C25—C26—C21121.06 (15)O6—Si2—O4108.04 (6)
C32—C31—C36117.93 (14)O3—Si2—C21109.83 (7)
C32—C31—Si3121.63 (12)O6—Si2—C21108.17 (6)
C36—C31—Si3120.40 (11)O4—Si2—C21111.58 (6)
C33—C32—C31120.92 (15)O3—Si3—O2108.79 (6)
C32—C33—C34120.25 (15)O3—Si3—O5i109.71 (6)
C35—C34—C33119.84 (15)O2—Si3—O5i108.51 (6)
C34—C35—C36120.06 (15)O3—Si3—C31109.42 (6)
C35—C36—C31120.99 (14)O2—Si3—C31110.62 (6)
C42—C41—C46117.98 (14)O5i—Si3—C31109.77 (6)
C42—C41—Si4121.42 (11)O1—Si4—O6i109.93 (6)
C46—C41—Si4120.53 (12)O1—Si4—O2109.64 (6)
C43—C42—C41121.00 (14)O6i—Si4—O2107.72 (6)
C44—C43—C42120.06 (15)O1—Si4—C41108.59 (6)
C45—C44—C43119.67 (15)O6i—Si4—C41110.01 (6)
C46—C45—C44120.30 (16)O2—Si4—C41110.95 (6)
C16—C11—C12—C130.0 (2)C12—C11—Si1—O5155.32 (12)
Si1—C11—C12—C13178.66 (13)C16—C11—Si1—O526.04 (15)
C11—C12—C13—C140.5 (3)C12—C11—Si1—O434.21 (14)
C12—C13—C14—C150.6 (3)C16—C11—Si1—O4147.15 (13)
C13—C14—C15—C160.2 (3)Si3—O3—Si2—O655.39 (19)
C14—C15—C16—C110.2 (3)Si3—O3—Si2—O463.00 (19)
C12—C11—C16—C150.3 (2)Si3—O3—Si2—C21174.16 (16)
Si1—C11—C16—C15179.01 (14)Si4i—O6—Si2—O344.86 (18)
C26—C21—C22—C230.8 (2)Si4i—O6—Si2—O474.42 (18)
Si2—C21—C22—C23177.28 (13)Si4i—O6—Si2—C21164.65 (16)
C21—C22—C23—C240.8 (3)Si1—O4—Si2—O363.36 (14)
C22—C23—C24—C250.0 (3)Si1—O4—Si2—O656.06 (14)
C23—C24—C25—C260.6 (3)Si1—O4—Si2—C21174.85 (12)
C24—C25—C26—C210.5 (3)C22—C21—Si2—O311.23 (15)
C22—C21—C26—C250.2 (2)C26—C21—Si2—O3165.18 (12)
Si2—C21—C26—C25176.74 (12)C22—C21—Si2—O6130.94 (13)
C36—C31—C32—C330.3 (3)C26—C21—Si2—O645.47 (14)
Si3—C31—C32—C33177.60 (14)C22—C21—Si2—O4110.35 (13)
C31—C32—C33—C340.4 (3)C26—C21—Si2—O473.24 (13)
C32—C33—C34—C350.0 (3)Si2—O3—Si3—O261.84 (19)
C33—C34—C35—C360.4 (3)Si2—O3—Si3—O5i56.72 (19)
C34—C35—C36—C310.4 (3)Si2—O3—Si3—C31177.20 (16)
C32—C31—C36—C350.1 (2)Si4—O2—Si3—O360.29 (13)
Si3—C31—C36—C35178.03 (13)Si4—O2—Si3—O5i59.02 (13)
C46—C41—C42—C430.5 (2)Si4—O2—Si3—C31179.49 (11)
Si4—C41—C42—C43177.59 (12)C32—C31—Si3—O3150.49 (13)
C41—C42—C43—C440.4 (2)C36—C31—Si3—O331.63 (15)
C42—C43—C44—C450.0 (3)C32—C31—Si3—O289.67 (14)
C43—C44—C45—C460.4 (3)C36—C31—Si3—O288.22 (13)
C44—C45—C46—C410.4 (3)C32—C31—Si3—O5i30.05 (15)
C42—C41—C46—C450.1 (3)C36—C31—Si3—O5i152.07 (12)
Si4—C41—C46—C45177.21 (14)Si1—O1—Si4—O6i55.59 (19)
Si4—O1—Si1—O556.83 (19)Si1—O1—Si4—O262.65 (19)
Si4—O1—Si1—O463.17 (19)Si1—O1—Si4—C41175.99 (17)
Si4—O1—Si1—C11177.68 (17)Si3—O2—Si4—O160.39 (14)
Si3i—O5—Si1—O149.51 (18)Si3—O2—Si4—O6i59.21 (13)
Si3i—O5—Si1—O469.06 (17)Si3—O2—Si4—C41179.67 (11)
Si3i—O5—Si1—C11170.66 (15)C42—C41—Si4—O12.00 (15)
Si2—O4—Si1—O162.68 (14)C46—C41—Si4—O1175.04 (13)
Si2—O4—Si1—O556.47 (14)C42—C41—Si4—O6i122.34 (13)
Si2—O4—Si1—C11177.29 (12)C46—C41—Si4—O6i54.70 (15)
C12—C11—Si1—O184.37 (13)C42—C41—Si4—O2118.57 (13)
C16—C11—Si1—O194.27 (14)C46—C41—Si4—O264.39 (14)
Symmetry code: (i) x, y, z.

Experimental details

Crystal data
Chemical formulaC48H40O12Si8
Mr1033.52
Crystal system, space groupMonoclinic, C2/c
Temperature (K)100
a, b, c (Å)16.406 (2), 13.8849 (17), 21.570 (3)
β (°) 93.458 (2)
V3)4904.7 (10)
Z4
Radiation typeMo Kα
µ (mm1)0.28
Crystal size (mm)0.45 × 0.30 × 0.07
Data collection
DiffractometerBruker Kappa APEXII DUO
diffractometer
Absorption correctionMulti-scan
(SADABS; Bruker, 2006)
Tmin, Tmax0.653, 0.746
No. of measured, independent and
observed [I > 2σ(I)] reflections
16438, 5707, 5201
Rint0.022
(sin θ/λ)max1)0.660
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.035, 0.095, 1.05
No. of reflections5707
No. of parameters307
H-atom treatmentH-atom parameters constrained
Δρmax, Δρmin (e Å3)0.63, 0.38

Computer programs: COSMO (Bruker, 2006), SAINT (Bruker, 2006), SADABS (Bruker, 2006), SHELXS97 (Sheldrick, 2008), XP in SHELXL2013 (Sheldrick, 2013), APEX2 Report Generator (Bruker, 2006).

Comparison of crystal data for various solvates. top
Pyridine solvatePyridine solvatePyridine and o-dichlorobenzene solvateAcetone solvate
(monoclinic)(triclinic)(triclinic)(tetragonal)
a (Å)13.612.610.844 (1)14.608 (4)
b (Å)12.810.812.858 (1)14.608 (4)
c (Å)20.410.710.740 (1)12.918 (4)
α (°)907070.87 (1)90
β (°)1317698.70 (1)90
γ (°)907998.89 (1)90
V3)1389.7 (3)2759.5
dcalc (g cm-3)1.271.291.241.31
dmeas (g cm-3)1.301.341.301.30
Z2112
Space groupP2/m or PmP1 or P1P1 or P1P4/n
ReferenceLarsson (1960b)Larsson (1960b)Shklover et al. (1978)Hossain et al. (1979)
Selected bond metrics for the reported structure and previous reports. top
Si—O (Å)Si—O—Si (°)O—Si—O (°)
RangeMeanRangeMeanRangeMean
Acetone solvate1.606 (3)–1.6183 (3)1.6121.44.7 (2)–151.6 (2)149.2108.3 (2)–111.7 (2)109.9
Pyridine/dichlorobenzene solvate1.606 (5)–1.621 (5)1.614143.9 (3)–156.6 (4)141.2
Gas Phase1.634 (15)–1.645 (19)1.640147.5 (45)–149.8 (24)149.0
Calculated1.603–1.6141.609145.4–152.8149.5108.1–111.8110.1
[NBu4][T8Ph8F]1.6198 (15)–1.6295 (15)1.6248138.56 (10)–143.88 (10)141.18103.86 (9)–107.00 (9)105.86
This work1.6166 (11)–1.6258 (11)1.621142.28 (7)–153.22 (8)149107.72 (6)–110.38 (6)109.1
 

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