Selective reduction in ring size of silsesquioxane oligomers mediated by potassium metal

The trisilanol (c-C₅H₉)₇Si₇O₉(OH)₃, generated from the hydrolytic condensation of cyclo­pentyl­tri­chloro­silane, is converted in excellent yield to a new siloxane 3-endo-tert-butyl­di­methylsiloxy-1,3,5,7,9,11,14-hepta­cyclo­pentyl­tetracyclo­[7.3.3.1^3,14.1^5,11]­­heptasiloxane [(c-C₅H₉)₇Si₇O₉(O)(OSiMe₂Bu^t) or C₄₁H₇₈O₁₁Si₈] in two high-yield steps. It is highly unusual for a polyhedral oligosilsesquioxane to give such well diffracting crystals, and even more so for it to crystallize virtually without disorder. Molecules of this siloxane occur in the crystal as isolated units, free from the silanol hydrogen-bonding interactions that dominate the structural characteristics and associated reaction chemistry of the parent polysilanols.

Key indicators

• Single-crystal X-ray study
• T = 150 K
• Mean [sigma](C-C) = 0.006 Å
• H-atom completeness 95%
• Disorder in main residue
• R factor = 0.060
• wR factor = 0.163
• Data-to-parameter ratio = 17.8

checkCIF results

No syntax errors found

ADDSYM reports no extra symmetry


 Alert Level C:



ABSMU_01  Alert C The ratio of given/expected absorption coefficient lies
          outside the range 0.99 <> 1.01
          Calculated value of mu =     0.264
          Value of mu given      =     0.260

PLAT_301  Alert C Main residue disorder ........................       2.00 Perc.

General Notes



FORMU_01  There is a discrepancy between the atom counts in the
          _chemical_formula_sum and the formula from the _atom_site* data.
          Atom count from _chemical_formula_sum:C41 H78 O11 Si8
          Atom count from the _atom_site data:  C41 H74 O11 Si8

CELLZ_01
         From the CIF: _cell_formula_units_Z    2
         From the CIF: _chemical_formula_sum  C41 H78 O11 Si8
         TEST: Compare cell contents of formula and atom_site data

         atom    Z*formula  cif sites diff
         C         82.00     82.00    0.00
         H        156.00    148.00    8.00
         O         22.00     22.00    0.00
         Si        16.00     16.00    0.00
          Difference between formula and atom_site contents detected.
          WARNING: H atoms missing from atom site list. Is this intentional?


 0 Alert Level A = Potentially serious problem

 0 Alert Level B = Potential problem

 2 Alert Level C = Please check

---

S1. Comment

Over the past year, a number of groups have found that under certain conditions lithiation of the siloxane triol (c-C₅H₉)₇Si₇O₉(OH)₃ proceeds smoothly, without the cage destruction which had been reported to arise during reactions to generate a sodium salt (Annand et al., 1999; Feher et al., 1992). The TBDMS (TBDMS is tert-butyldimethylsilyl) functionalization has provided us with a highly soluble tractable disilanol, (c-C₅H₉)₇Si₇O₉(OH)₂(OSiMe₂Bu^t), (I), which we were able to convert quantitatively to a dilithio salt using tert-butyl lithium (Arnold et al., 2001). Treatment of a pentane or toluene solution of (I) with two equivalents of potassium metal results in dissolution of the metal over a few hours (the reaction is accelerated by sonication). This colourless solution contains the siloxane, (c-C₅H₉)₇Si₇O₉(O)(OSiMe₂Bu^t), (II), arising from the condensation of adjacent silanols to form a new six-membered siloxane ring in the complex. It is widely agreed that these classes of siloxanes crystallize readily but form poorly diffracting crystals that rarely yield satisfactory structural information (Herrmann et al., 1994; Abbenhuis, 2000). This held true for (II), with further complications arising from crystals that cracked upon cooling in the cold nitrogen stream on the diffractometer. A range of morphologies of crystals was obtained from different solvents and solvent mixtures, but the only crystals that diffracted reasonably were large colourless blocks grown by ethanol diffusion into an ether solution of (II); this too was mounted at room temperature to eliminate the problem of disintegration. Distances and angles for the compound are as anticipated; whilst the TBDMS anchoring vertex Si7 bends away from the cube, the tert-butyl group is folded back towards the siloxane oxygen O1, possibly facilitating the surprisingly highly ordered packing of the molecules.

S2. Experimental

A toluene solution of (I) (317 mg, 0.32 mmol, 10 ml) was added to high purity K lumps (25.0 mg, 0.64 mmol) and either sonicated or stirred vigorously for 4 h, or until no K was visible. Removal of volatiles under reduced pressure afforded a colourless solid. Extraction with pentane, followed by concentration and cooling to 243 K afforded colourless highly crystalline (II) (yield 231 mg, 74%). Crystals selected for data collection were grown at room temperature by ethanol diffusion into a diethyl ether solution of (II).

S3. Refinement

Although the crystal has a unit cell which is metrically close to monoclinic, merging of the data under 2/m symmetry gave a very high merging R of 0.584; we accordingly adopted the lower triclinic system where the corresponding value was 0.070. For its class, compound (II) displays a surprisingly low level of disorder in the peripheral groups. Positional disorder of one cyclopentyl group was modelled and refined satisfactorily upon application of geometric similarity restraints: the major and minor components comprise 0.76 (2) and 0.24 (2), respectively. H atoms were refined riding on their parent atoms with U_iso(H) = xU_eq(C), where x = 1.5 for methyl H atoms and 1.2 for all others; C—H distances were restrained to 0.98, 0.99 and 1.00 Å for methyl, methylene and methine H atoms, respectively.

Computing details

Data collection: DENZO (Otwinowski & Minor, 1997) and COLLECT (Nonius, 1999); cell refinement: DENZO and COLLECT; data reduction: DENZO and COLLECT; program(s) used to solve structure: SHELXS97 (Sheldrick, 1990); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: SHELXTL (Bruker, 1997); software used to prepare material for publication: SHELXL97 and PLATON (Spek, 2000).

Figures

Fig. 1. A view of the structure of (II) showing atom-numbering scheme. Displacement ellipsoids are drawn at the 25% probability level. Atoms C52 and C56 are disorder components of the same atom, with occupancies of 0.76 (2) and 0.24 (2), respectively.

(I)

Crystal data

C41H78O11Si8	Z = 2
Mr = 971.75	F(000) = 1048
Triclinic, P1	Dx = 1.267 Mg m^−3
a = 11.9992 (8) Å	Mo Kα radiation, λ = 0.71073 Å
b = 14.6230 (9) Å	Cell parameters from 26509 reflections
c = 15.0146 (13) Å	θ = 2.9–27.5°
α = 75.182 (3)°	µ = 0.26 mm^−1
β = 89.959 (3)°	T = 150 K
γ = 89.793 (2)°	Block, colourless
V = 2546.9 (3) Å^3	0.25 × 0.10 × 0.08 mm

Data collection

Nonius kappaCCD area-detector diffractometer	9603 independent reflections
Radiation source: Nonius FR591 rotating anode	5603 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.070
Detector resolution: 9.091 pixels/mm pixels mm^-1	θmax = 26.0°, θmin = 3.3°
ϕ and ω scans	h = −15→15
Absorption correction: multi-scan (SORTAV; Blessing, 1995)	k = −18→18
Tmin = 0.87, Tmax = 0.99	l = −16→19
195409 measured reflections

Refinement

Refinement on F^2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.060	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.163	H-atom parameters constrained
S = 1.00	w = 1/[σ^2(Fo^2) + (0.0617P)^2] where P = (Fo^2 + 2Fc^2)/3
9603 reflections	(Δ/σ)max = 0.001
541 parameters	Δρmax = 0.47 e Å^−3
2 restraints	Δρmin = −0.38 e Å^−3

Special details

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 (Ų)

	x	y	z	Uiso*/Ueq	Occ. (<1)
Si1	0.01225 (8)	0.15604 (8)	0.23254 (7)	0.0282 (3)
Si2	0.02615 (8)	0.36359 (8)	0.15802 (7)	0.0274 (3)
Si3	0.11064 (8)	0.23690 (8)	0.04756 (7)	0.0279 (3)
Si4	0.33701 (8)	0.23705 (8)	0.13452 (7)	0.0264 (3)
Si5	0.24491 (8)	0.10733 (8)	0.32140 (7)	0.0266 (3)
Si6	0.26589 (8)	0.39705 (8)	0.22323 (7)	0.0263 (3)
Si7	0.32435 (8)	0.25818 (8)	0.41658 (7)	0.0269 (3)
Si10	0.18038 (9)	0.31176 (8)	0.57353 (8)	0.0332 (3)
O1	−0.02061 (18)	0.26566 (18)	0.22658 (17)	0.0279 (6)
O2	0.06786 (19)	0.33729 (18)	0.06449 (16)	0.0284 (6)
O3	0.05739 (19)	0.15370 (18)	0.13060 (17)	0.0288 (6)
O4	0.24523 (18)	0.23285 (18)	0.05573 (16)	0.0292 (6)
O5	0.11174 (19)	0.12290 (19)	0.30599 (17)	0.0329 (7)
O6	0.13216 (18)	0.39934 (18)	0.20622 (17)	0.0308 (6)
O7	0.2649 (2)	0.27108 (19)	0.50728 (17)	0.0355 (7)
O8	0.30923 (19)	0.15483 (18)	0.22653 (17)	0.0312 (6)
O9	0.32770 (19)	0.33883 (18)	0.15847 (17)	0.0306 (6)
O10	0.28286 (19)	0.15907 (18)	0.39911 (17)	0.0309 (6)
O11	0.28854 (19)	0.34463 (18)	0.32965 (16)	0.0286 (6)
C10	−0.1060 (3)	0.0764 (3)	0.2662 (3)	0.0303 (9)
H10A	−0.0812	0.0125	0.2614	0.036*
C11	−0.2121 (3)	0.1014 (3)	0.2078 (3)	0.0410 (11)
H11A	−0.2029	0.0871	0.1473	0.049*
H11B	−0.2311	0.1693	0.1978	0.049*
C12	−0.3022 (3)	0.0385 (3)	0.2655 (3)	0.0448 (12)
H12A	−0.3106	−0.0206	0.2456	0.054*
H12B	−0.3748	0.0720	0.2580	0.054*
C13	−0.2639 (3)	0.0162 (3)	0.3666 (3)	0.0425 (11)
H13A	−0.2569	−0.0529	0.3928	0.051*
H13B	−0.3177	0.0417	0.4042	0.051*
C14	−0.1498 (3)	0.0647 (3)	0.3644 (3)	0.0362 (10)
H14A	−0.1580	0.1270	0.3783	0.043*
H14B	−0.0984	0.0250	0.4099	0.043*
C20	−0.0823 (3)	0.4545 (3)	0.1294 (3)	0.0310 (9)
H20A	−0.0487	0.5112	0.0860	0.037*
C21	−0.1334 (3)	0.4873 (3)	0.2095 (3)	0.0392 (11)
H21A	−0.0851	0.5346	0.2270	0.047*
H21B	−0.1442	0.4332	0.2639	0.047*
C22	−0.2459 (3)	0.5314 (3)	0.1722 (3)	0.0495 (12)
H22A	−0.3020	0.5207	0.2221	0.059*
H22B	−0.2380	0.6004	0.1456	0.059*
C23	−0.2802 (4)	0.4845 (5)	0.1004 (4)	0.081 (2)
H23A	−0.3013	0.5327	0.0436	0.097*
H23B	−0.3456	0.4439	0.1218	0.097*
C24	−0.1840 (3)	0.4250 (3)	0.0804 (3)	0.0469 (12)
H24A	−0.1708	0.4379	0.0132	0.056*
H24B	−0.1998	0.3568	0.1049	0.056*
C30	0.0645 (3)	0.2222 (3)	−0.0637 (3)	0.0328 (10)
H30A	0.1028	0.2704	−0.1136	0.039*
C31	0.0889 (3)	0.1233 (3)	−0.0775 (3)	0.0427 (11)
H31A	0.1588	0.1235	−0.1126	0.051*
H31B	0.0957	0.0760	−0.0174	0.051*
C32	−0.0104 (3)	0.1018 (3)	−0.1312 (3)	0.0471 (12)
H32A	−0.0023	0.1318	−0.1979	0.057*
H32B	−0.0200	0.0328	−0.1218	0.057*
C33	−0.1064 (4)	0.1443 (4)	−0.0908 (4)	0.0643 (16)
H33A	−0.1709	0.1554	−0.1334	0.077*
H33B	−0.1298	0.1018	−0.0313	0.077*
C34	−0.0638 (3)	0.2353 (3)	−0.0773 (3)	0.0520 (13)
H34A	−0.0986	0.2494	−0.0224	0.062*
H34B	−0.0806	0.2880	−0.1318	0.062*
C40	0.4759 (3)	0.2166 (3)	0.0913 (3)	0.0295 (9)
H40A	0.5306	0.2136	0.1422	0.035*
C41	0.4846 (3)	0.1230 (3)	0.0624 (3)	0.0410 (11)
H41A	0.5048	0.0703	0.1160	0.049*
H41B	0.4127	0.1080	0.0372	0.049*
C42	0.5752 (4)	0.1374 (4)	−0.0109 (4)	0.0640 (15)
H42A	0.6377	0.0928	0.0102	0.077*
H42B	0.5450	0.1267	−0.0688	0.077*
C43	0.6146 (4)	0.2385 (3)	−0.0264 (3)	0.0539 (13)
H43A	0.6301	0.2669	−0.0924	0.065*
H43B	0.6829	0.2415	0.0096	0.065*
C44	0.5178 (3)	0.2890 (3)	0.0068 (3)	0.0428 (11)
H44A	0.5434	0.3470	0.0230	0.051*
H44B	0.4590	0.3061	−0.0408	0.051*
C50	0.2806 (3)	−0.0181 (3)	0.3565 (3)	0.0331 (10)
H50A	0.2422	−0.0470	0.4161	0.040*
C51	0.2441 (3)	−0.0732 (3)	0.2838 (3)	0.0458 (12)
C52	0.3317 (5)	−0.1545 (6)	0.3025 (7)	0.059 (3)*	0.76 (2)
H52A	0.3094	−0.2056	0.3565	0.071*	0.76 (2)
H52B	0.3381	−0.1812	0.2484	0.071*	0.76 (2)
C56	0.3515 (12)	−0.111 (2)	0.2521 (15)	0.050 (8)*	0.24 (2)
H56A	0.3391	−0.1756	0.2445	0.059*	0.24 (2)
H56B	0.3748	−0.0699	0.1919	0.059*	0.24 (2)
C53	0.4381 (4)	−0.1136 (4)	0.3201 (4)	0.0656 (15)
C54	0.4080 (3)	−0.0374 (3)	0.3698 (3)	0.0467 (12)
H54A	0.4505	0.0212	0.3434	0.056*
H54B	0.4262	−0.0596	0.4362	0.056*
C60	0.3177 (3)	0.5183 (3)	0.1988 (3)	0.0291 (9)
H60A	0.3015	0.5508	0.1329	0.035*
C61	0.4452 (3)	0.5250 (3)	0.2165 (3)	0.0348 (10)
H61A	0.4753	0.4622	0.2492	0.042*
H61B	0.4857	0.5475	0.1575	0.042*
C62	0.4579 (3)	0.5943 (3)	0.2750 (3)	0.0467 (12)
H62A	0.5238	0.5786	0.3158	0.056*
H62B	0.4656	0.6598	0.2361	0.056*
C63	0.3518 (3)	0.5830 (3)	0.3300 (3)	0.0450 (12)
H63A	0.3385	0.6384	0.3552	0.054*
H63B	0.3543	0.5251	0.3815	0.054*
C64	0.2627 (3)	0.5756 (3)	0.2614 (3)	0.0373 (10)
H64A	0.2397	0.6392	0.2248	0.045*
H64B	0.1965	0.5422	0.2932	0.045*
C70	0.4760 (3)	0.2547 (3)	0.4322 (3)	0.0307 (9)
H70A	0.4922	0.1974	0.4834	0.037*
C71	0.5280 (3)	0.3392 (3)	0.4609 (3)	0.0418 (11)
H71A	0.4863	0.3982	0.4332	0.050*
H71B	0.5272	0.3282	0.5287	0.050*
C72	0.6481 (4)	0.3460 (4)	0.4247 (4)	0.0635 (15)
H72A	0.6617	0.4092	0.3828	0.076*
H72B	0.7016	0.3359	0.4765	0.076*
C73	0.6621 (4)	0.2727 (4)	0.3753 (4)	0.0712 (17)
H73A	0.7008	0.2171	0.4148	0.085*
H73B	0.7070	0.2970	0.3189	0.085*
C74	0.5467 (3)	0.2451 (3)	0.3502 (3)	0.0412 (11)
H74A	0.5460	0.1794	0.3439	0.049*
H74B	0.5201	0.2883	0.2921	0.049*
C100	0.0338 (3)	0.2892 (3)	0.5441 (3)	0.0375 (10)
C101	0.2153 (4)	0.2508 (4)	0.6935 (3)	0.0506 (12)
H10B	0.2000	0.1830	0.7042	0.076*
H10C	0.1700	0.2769	0.7355	0.076*
H10D	0.2944	0.2599	0.7047	0.076*
C102	0.2078 (4)	0.4397 (3)	0.5548 (3)	0.0528 (13)
H10E	0.2852	0.4490	0.5712	0.079*
H10F	0.1575	0.4660	0.5934	0.079*
H10G	0.1952	0.4719	0.4899	0.079*
C103	0.0074 (4)	0.3438 (4)	0.4439 (3)	0.0577 (14)
H10H	−0.0697	0.3313	0.4291	0.087*
H10I	0.0582	0.3228	0.4018	0.087*
H10J	0.0171	0.4117	0.4371	0.087*
C104	−0.0482 (3)	0.3221 (4)	0.6087 (3)	0.0538 (13)
H10K	−0.1248	0.3100	0.5923	0.081*
H10L	−0.0386	0.3900	0.6024	0.081*
H10M	−0.0334	0.2873	0.6726	0.081*
C105	0.0162 (4)	0.1835 (3)	0.5531 (3)	0.0553 (13)
H10N	−0.0610	0.1728	0.5372	0.083*
H10O	0.0313	0.1479	0.6167	0.083*
H10P	0.0670	0.1623	0.5113	0.083*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Si1	0.0259 (6)	0.0304 (7)	0.0288 (7)	−0.0001 (4)	0.0011 (4)	−0.0085 (5)
Si2	0.0244 (6)	0.0306 (7)	0.0288 (7)	0.0012 (4)	−0.0004 (4)	−0.0104 (5)
Si3	0.0278 (6)	0.0318 (7)	0.0255 (6)	0.0004 (5)	0.0001 (4)	−0.0099 (5)
Si4	0.0253 (6)	0.0292 (7)	0.0260 (6)	0.0008 (4)	0.0019 (4)	−0.0096 (5)
Si5	0.0263 (6)	0.0271 (7)	0.0265 (6)	0.0000 (4)	−0.0003 (4)	−0.0071 (5)
Si6	0.0249 (6)	0.0262 (7)	0.0289 (6)	0.0011 (4)	−0.0008 (4)	−0.0092 (5)
Si7	0.0288 (6)	0.0282 (7)	0.0255 (6)	0.0018 (5)	−0.0003 (4)	−0.0100 (5)
Si10	0.0381 (6)	0.0339 (7)	0.0299 (7)	0.0019 (5)	0.0054 (5)	−0.0121 (6)
O1	0.0259 (13)	0.0297 (16)	0.0299 (16)	−0.0011 (11)	0.0040 (11)	−0.0109 (13)
O2	0.0314 (14)	0.0292 (16)	0.0251 (15)	0.0019 (11)	0.0029 (11)	−0.0077 (13)
O3	0.0302 (14)	0.0290 (16)	0.0285 (16)	−0.0020 (11)	0.0030 (11)	−0.0099 (13)
O4	0.0277 (14)	0.0351 (17)	0.0269 (16)	0.0020 (11)	−0.0014 (10)	−0.0117 (13)
O5	0.0243 (14)	0.0428 (18)	0.0299 (16)	0.0016 (12)	−0.0017 (11)	−0.0063 (14)
O6	0.0254 (14)	0.0349 (17)	0.0355 (16)	0.0021 (11)	−0.0028 (11)	−0.0156 (14)
O7	0.0386 (16)	0.0414 (19)	0.0284 (16)	0.0042 (13)	0.0012 (12)	−0.0126 (14)
O8	0.0301 (14)	0.0330 (17)	0.0291 (16)	−0.0004 (11)	0.0045 (11)	−0.0053 (13)
O9	0.0286 (14)	0.0298 (17)	0.0369 (17)	0.0027 (11)	0.0014 (11)	−0.0150 (13)
O10	0.0396 (15)	0.0263 (16)	0.0289 (16)	−0.0031 (12)	−0.0009 (11)	−0.0109 (13)
O11	0.0341 (14)	0.0269 (16)	0.0234 (15)	0.0040 (11)	−0.0039 (11)	−0.0038 (12)
C10	0.029 (2)	0.028 (2)	0.034 (2)	−0.0025 (17)	0.0022 (17)	−0.009 (2)
C11	0.034 (2)	0.051 (3)	0.038 (3)	−0.007 (2)	−0.0035 (18)	−0.010 (2)
C12	0.032 (2)	0.050 (3)	0.053 (3)	−0.008 (2)	0.003 (2)	−0.014 (2)
C13	0.037 (2)	0.042 (3)	0.045 (3)	−0.005 (2)	0.0106 (19)	−0.005 (2)
C14	0.036 (2)	0.037 (3)	0.034 (3)	0.0024 (18)	0.0003 (18)	−0.005 (2)
C20	0.028 (2)	0.032 (2)	0.033 (2)	0.0010 (17)	−0.0020 (16)	−0.008 (2)
C21	0.032 (2)	0.044 (3)	0.046 (3)	0.0079 (19)	−0.0016 (18)	−0.020 (2)
C22	0.038 (3)	0.050 (3)	0.064 (3)	0.010 (2)	0.001 (2)	−0.021 (3)
C23	0.040 (3)	0.125 (6)	0.103 (5)	0.037 (3)	−0.031 (3)	−0.076 (4)
C24	0.035 (2)	0.060 (3)	0.052 (3)	0.012 (2)	−0.013 (2)	−0.027 (3)
C30	0.036 (2)	0.031 (3)	0.032 (2)	0.0031 (18)	−0.0028 (17)	−0.010 (2)
C31	0.059 (3)	0.044 (3)	0.028 (3)	0.002 (2)	−0.001 (2)	−0.015 (2)
C32	0.053 (3)	0.050 (3)	0.047 (3)	−0.012 (2)	0.004 (2)	−0.027 (3)
C33	0.045 (3)	0.082 (4)	0.081 (4)	−0.016 (3)	0.013 (3)	−0.048 (3)
C34	0.049 (3)	0.060 (4)	0.055 (3)	0.012 (2)	−0.023 (2)	−0.029 (3)
C40	0.029 (2)	0.032 (3)	0.029 (2)	0.0026 (17)	0.0023 (16)	−0.010 (2)
C41	0.037 (2)	0.039 (3)	0.049 (3)	0.0053 (19)	0.0091 (19)	−0.014 (2)
C42	0.069 (3)	0.066 (4)	0.065 (4)	−0.004 (3)	0.027 (3)	−0.032 (3)
C43	0.051 (3)	0.056 (4)	0.053 (3)	0.000 (2)	0.023 (2)	−0.012 (3)
C44	0.041 (2)	0.040 (3)	0.044 (3)	−0.001 (2)	0.010 (2)	−0.005 (2)
C50	0.039 (2)	0.026 (2)	0.032 (2)	−0.0014 (18)	−0.0006 (17)	−0.004 (2)
C51	0.051 (3)	0.035 (3)	0.061 (3)	0.003 (2)	−0.003 (2)	−0.029 (3)
C53	0.067 (3)	0.063 (4)	0.078 (4)	0.028 (3)	−0.015 (3)	−0.040 (3)
C54	0.044 (3)	0.037 (3)	0.059 (3)	0.011 (2)	−0.014 (2)	−0.011 (2)
C60	0.031 (2)	0.026 (2)	0.029 (2)	0.0005 (17)	0.0007 (16)	−0.0046 (19)
C61	0.029 (2)	0.033 (3)	0.042 (3)	−0.0007 (17)	0.0024 (17)	−0.009 (2)
C62	0.037 (3)	0.047 (3)	0.059 (3)	−0.001 (2)	−0.010 (2)	−0.020 (3)
C63	0.049 (3)	0.045 (3)	0.048 (3)	0.007 (2)	−0.009 (2)	−0.023 (2)
C64	0.034 (2)	0.034 (3)	0.046 (3)	0.0008 (18)	0.0008 (18)	−0.012 (2)
C70	0.034 (2)	0.027 (2)	0.030 (2)	0.0042 (17)	−0.0042 (17)	−0.0064 (19)
C71	0.041 (2)	0.040 (3)	0.049 (3)	−0.002 (2)	−0.005 (2)	−0.019 (2)
C72	0.043 (3)	0.081 (4)	0.076 (4)	−0.019 (3)	0.007 (2)	−0.038 (3)
C73	0.031 (3)	0.080 (4)	0.118 (5)	−0.004 (2)	0.010 (3)	−0.054 (4)
C74	0.036 (2)	0.037 (3)	0.055 (3)	−0.0025 (19)	0.005 (2)	−0.020 (2)
C100	0.037 (2)	0.038 (3)	0.036 (3)	0.0032 (19)	0.0054 (18)	−0.008 (2)
C101	0.057 (3)	0.063 (4)	0.033 (3)	0.004 (2)	0.003 (2)	−0.015 (2)
C102	0.057 (3)	0.046 (3)	0.061 (3)	−0.004 (2)	0.009 (2)	−0.025 (3)
C103	0.046 (3)	0.076 (4)	0.046 (3)	0.001 (2)	0.000 (2)	−0.006 (3)
C104	0.047 (3)	0.057 (3)	0.058 (3)	0.010 (2)	0.014 (2)	−0.015 (3)
C105	0.049 (3)	0.058 (4)	0.064 (4)	−0.009 (2)	0.007 (2)	−0.026 (3)

Geometric parameters (Å, º)

Si1—O1	1.629 (3)	C13—C14	1.540 (5)
Si1—O3	1.632 (3)	C20—C21	1.531 (5)
Si1—O5	1.613 (3)	C20—C24	1.544 (5)
Si1—C10	1.826 (4)	C21—C22	1.537 (5)
Si2—O1	1.636 (3)	C22—C23	1.476 (6)
Si2—O2	1.626 (3)	C23—C24	1.518 (6)
Si2—O6	1.617 (2)	C30—C31	1.540 (6)
Si2—C20	1.828 (4)	C30—C34	1.558 (5)
Si3—O2	1.634 (3)	C31—C32	1.518 (5)
Si3—O3	1.635 (3)	C32—C33	1.506 (6)
Si3—O4	1.619 (2)	C33—C34	1.489 (6)
Si3—C30	1.825 (4)	C40—C44	1.516 (5)
Si4—O4	1.630 (2)	C40—C41	1.541 (5)
Si4—O8	1.618 (3)	C41—C42	1.523 (6)
Si4—O9	1.621 (3)	C42—C43	1.514 (7)
Si4—C40	1.839 (4)	C43—C44	1.525 (6)
Si5—O5	1.622 (2)	C50—C54	1.558 (5)
Si5—O8	1.613 (3)	C50—C51	1.575 (5)
Si5—O10	1.611 (3)	C51—C56	1.526 (14)
Si5—C50	1.823 (4)	C51—C52	1.555 (7)
Si6—O6	1.624 (2)	C52—C53	1.465 (7)
Si6—O9	1.624 (3)	C56—C53	1.451 (14)
Si6—O11	1.609 (3)	C53—C54	1.534 (6)
Si6—C60	1.828 (4)	C60—C64	1.556 (5)
Si7—O7	1.590 (3)	C60—C61	1.562 (5)
Si7—O10	1.618 (3)	C61—C62	1.510 (5)
Si7—O11	1.625 (3)	C62—C63	1.504 (6)
Si7—C70	1.833 (4)	C63—C64	1.508 (5)
Si10—O7	1.634 (3)	C70—C74	1.531 (5)
Si10—C101	1.842 (4)	C70—C71	1.542 (5)
Si10—C102	1.851 (5)	C71—C72	1.536 (6)
Si10—C100	1.865 (4)	C72—C73	1.460 (6)
C10—C14	1.533 (5)	C73—C74	1.517 (6)
C10—C11	1.535 (5)	C100—C105	1.531 (6)
C11—C12	1.538 (5)	C100—C104	1.541 (6)
C12—C13	1.539 (6)	C100—C103	1.545 (6)
O1—Si1—O3	106.48 (14)	C14—C10—C11	102.5 (3)
O1—Si1—O5	109.47 (14)	C14—C10—Si1	116.1 (3)
O3—Si1—O5	108.77 (13)	C11—C10—Si1	116.5 (3)
O5—Si1—C10	109.18 (16)	C10—C11—C12	104.0 (3)
O1—Si1—C10	112.20 (16)	C11—C12—C13	106.9 (3)
O3—Si1—C10	110.65 (16)	C12—C13—C14	105.3 (3)
O1—Si2—O2	106.68 (14)	C10—C14—C13	105.3 (3)
O1—Si2—O6	108.78 (14)	C21—C20—C24	103.9 (3)
O2—Si2—O6	108.67 (13)	C21—C20—Si2	116.9 (3)
O6—Si2—C20	111.45 (16)	C24—C20—Si2	113.5 (3)
O2—Si2—C20	109.41 (16)	C20—C21—C22	104.5 (3)
O1—Si2—C20	111.70 (16)	C23—C22—C21	106.4 (4)
O2—Si3—O3	106.40 (13)	C22—C23—C24	109.2 (4)
O2—Si3—O4	108.37 (13)	C23—C24—C20	105.1 (4)
O3—Si3—O4	109.18 (14)	C31—C30—C34	104.8 (3)
O4—Si3—C30	111.26 (16)	C31—C30—Si3	113.6 (3)
O2—Si3—C30	111.62 (16)	C34—C30—Si3	112.4 (3)
O3—Si3—C30	109.87 (17)	C32—C31—C30	104.7 (3)
O4—Si4—O8	108.75 (13)	C33—C32—C31	102.9 (4)
O4—Si4—O9	108.90 (14)	C34—C33—C32	105.4 (4)
O8—Si4—O9	108.71 (14)	C33—C34—C30	106.0 (4)
O8—Si4—C40	109.71 (16)	C44—C40—C41	102.9 (3)
O9—Si4—C40	112.27 (15)	C44—C40—Si4	117.1 (3)
O4—Si4—C40	108.44 (15)	C41—C40—Si4	113.2 (2)
O5—Si5—O8	109.46 (14)	C42—C41—C40	106.3 (3)
O5—Si5—O10	108.01 (14)	C43—C42—C41	106.6 (4)
O8—Si5—O10	109.08 (14)	C42—C43—C44	104.2 (4)
O10—Si5—C50	110.42 (16)	C40—C44—C43	103.5 (4)
O8—Si5—C50	108.56 (17)	C54—C50—C51	104.9 (3)
O5—Si5—C50	111.29 (16)	C54—C50—Si5	113.5 (3)
O6—Si6—O9	110.35 (13)	C51—C50—Si5	113.0 (3)
O6—Si6—O11	107.92 (13)	C56—C51—C50	105.7 (7)
O9—Si6—O11	109.20 (14)	C52—C51—C50	100.9 (4)
O11—Si6—C60	109.47 (16)	C53—C52—C51	107.0 (5)
O6—Si6—C60	109.12 (16)	C53—C56—C51	109.3 (10)
O9—Si6—C60	110.73 (16)	C56—C53—C54	106.6 (8)
O7—Si7—O10	107.89 (15)	C52—C53—C54	105.4 (4)
O7—Si7—O11	109.41 (15)	C53—C54—C50	107.2 (3)
O10—Si7—O11	109.48 (14)	C64—C60—C61	104.1 (3)
O7—Si7—C70	109.87 (16)	C64—C60—Si6	112.3 (3)
O10—Si7—C70	109.43 (16)	C61—C60—Si6	113.7 (3)
O11—Si7—C70	110.72 (16)	C62—C61—C60	106.4 (3)
O7—Si10—C101	107.15 (18)	C63—C62—C61	103.6 (3)
O7—Si10—C102	107.87 (18)	C62—C63—C64	104.0 (3)
C101—Si10—C102	109.0 (2)	C63—C64—C60	104.9 (3)
O7—Si10—C100	109.04 (17)	C74—C70—C71	104.1 (3)
C101—Si10—C100	112.0 (2)	C74—C70—Si7	116.9 (3)
C102—Si10—C100	111.6 (2)	C71—C70—Si7	116.2 (3)
Si1—O1—Si2	129.99 (16)	C72—C71—C70	105.5 (4)
Si1—O3—Si3	130.97 (17)	C73—C72—C71	107.2 (4)
Si1—O5—Si5	146.39 (17)	C72—C73—C74	107.5 (4)
Si2—O2—Si3	130.55 (17)	C73—C74—C70	102.8 (3)
Si2—O6—Si6	148.56 (18)	C105—C100—C104	109.0 (4)
Si3—O4—Si4	136.23 (16)	C105—C100—C103	108.4 (4)
Si7—O7—Si10	160.06 (19)	C104—C100—C103	108.5 (4)
Si4—O8—Si5	155.73 (18)	C105—C100—Si10	110.4 (3)
Si4—O9—Si6	144.47 (17)	C104—C100—Si10	110.5 (3)
Si5—O10—Si7	144.31 (18)	C103—C100—Si10	110.1 (3)
Si6—O11—Si7	156.54 (18)