Disorder and pseudo-symmetry in octakis(trivinylsilyl)octasilicate

Octakis(trivinylsilyl)octasilicate was prepared by capping octaspherosilicate cubes, [Si₈O₂₀]^8-, with trivinylsilyl groups in methanol solution. Crystals grown from CCl₄ crystallize in the tetragonal space group I4₁. Systematic absences are consistent with the space group I4₁/amd, although the R_int values clearly indicate 4/m rather than 4/mmm Laue symmetry. Structure solution and refinement show that the pseudo a-glide results from the approximate symmetry of the core (Si₈O₁₂)O unit. The positions of the molecules conform to a {110} d-glide that is broken by the small rotations of all the molecules in the same direction about [001]. Crystals grown from toluene give a diffraction pattern consisting of sharp peaks that can be indexed on the same ca 7200 Å³ unit cell, but with h + k even, and l even only. The l = odd layers contain no Bragg spots, but instead exhibit diffuse sheets of intensity. Within the sheets of diffuse scattering are streaks parallel to r* = <110>* that cross at the h + k odd Bragg positions. This diffuse scattering pattern arises from well ordered rods of molecules parallel to c with frequent faults in the stacking sequence of molecules parallel to <110>, with displacement vectors of [00½].

Computing details

For both compounds, data collection: CrysAlis (Oxford Diffraction); cell refinement: CrysAlis (Oxford Diffraction); data reduction: CrysAlis (Oxford Diffraction). Program(s) used to solve structure: SHELXS97 (Sheldrick, 1990) for cs521. For both compounds, program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: Bruker SHELXTL; software used to prepare material for publication: Bruker SHELXTL.

Figures

(cs521)

Crystal data

C48H72O20Si16	Dx = 1.309 Mg m^−3
Mr = 1418.50	Mo Kα radiation, λ = 0.71073 Å
Tetragonal, I41	Cell parameters from 4937 reflections
Hall symbol: I 4bw	θ = 1.6–28.2°
a = 21.1698 (18) Å	µ = 0.35 mm^−1
c = 16.059 (3) Å	T = 100 K
V = 7197.2 (16) Å^3	Plate, colorless
Z = 4	0.12 × 0.11 × 0.04 mm
F(000) = 2976

Data collection

Oxford Diffraction Xcalibur2 diffractometer	6414 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	Rint = 0.052
Graphite monochromator	θmax = 30.1°, θmin = 2.9°
phi and ω scans	h = −29→29
26352 measured reflections	k = −18→29
10566 independent reflections	l = −22→22

Refinement

Refinement on F^2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F^2 > 2σ(F^2)] = 0.060	H-atom parameters constrained
wR(F^2) = 0.137	w = 1/[σ^2(Fo^2) + (0.0571P)^2] where P = (Fo^2 + 2Fc^2)/3
S = 0.96	(Δ/σ)max = 0.001
10566 reflections	Δρmax = 1.15 e Å^−3
380 parameters	Δρmin = −0.33 e Å^−3
1 restraint	Absolute structure: Flack H D (1983), Acta Cryst. A39, 876-881, 5098 Friedel pairs
Primary atom site location: structure-invariant direct methods	Absolute structure parameter: 0.59 (13)

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
Si1	0.58119 (5)	0.56367 (5)	0.40246 (8)	0.0133 (2)
Si2	0.57944 (5)	0.56537 (5)	0.59613 (7)	0.0112 (2)
Si3	0.43610 (5)	0.58080 (5)	0.59636 (7)	0.0122 (2)
Si4	0.43715 (5)	0.58149 (5)	0.40221 (7)	0.0107 (2)
Si5	0.66037 (6)	0.62804 (6)	0.26187 (8)	0.0203 (3)
Si6	0.66849 (5)	0.60475 (5)	0.73889 (9)	0.0163 (2)
Si7	0.39189 (5)	0.66543 (5)	0.73958 (8)	0.0155 (2)
Si8	0.37121 (6)	0.65554 (5)	0.25859 (8)	0.0180 (3)
O1	0.58627 (14)	0.48918 (13)	0.3839 (2)	0.0198 (7)
O2	0.58422 (14)	0.49116 (13)	0.6152 (2)	0.0187 (7)
O3	0.59405 (13)	0.57682 (13)	0.4996 (2)	0.0190 (6)
O4	0.50996 (13)	0.58997 (13)	0.61905 (19)	0.0175 (6)
O5	0.42609 (13)	0.59656 (13)	0.4986 (2)	0.0182 (6)
O6	0.51089 (13)	0.58792 (14)	0.37961 (19)	0.0195 (7)
O7	0.63299 (14)	0.60046 (14)	0.3499 (2)	0.0197 (7)
O8	0.63025 (14)	0.60343 (13)	0.6498 (2)	0.0160 (6)
O9	0.39380 (13)	0.62693 (14)	0.6511 (2)	0.0176 (6)
O10	0.39844 (13)	0.63115 (13)	0.3496 (2)	0.0161 (6)
C1	0.7320 (2)	0.5827 (2)	0.2348 (3)	0.0285 (11)
H1A	0.7569	0.5977	0.1897	0.034*
C2	0.7510 (2)	0.5322 (2)	0.2723 (3)	0.0302 (12)
H2A	0.7274	0.5156	0.3177	0.036*
H2B	0.7884	0.5115	0.2545	0.036*
C3	0.5981 (3)	0.6203 (2)	0.1815 (3)	0.0342 (12)
H3A	0.5608	0.6448	0.1887	0.041*
C4	0.6011 (4)	0.5839 (3)	0.1153 (5)	0.066 (2)
H4A	0.6374	0.5587	0.1057	0.080*
H4B	0.5668	0.5828	0.0770	0.080*
C5	0.6800 (2)	0.7112 (2)	0.2805 (3)	0.0304 (12)
H5A	0.7098	0.7207	0.3229	0.037*
C6	0.6549 (3)	0.7594 (2)	0.2379 (5)	0.0486 (17)
H6A	0.6249	0.7514	0.1951	0.058*
H6B	0.6670	0.8015	0.2505	0.058*
C7	0.6289 (2)	0.5519 (2)	0.8148 (3)	0.0213 (9)
H7A	0.6271	0.5083	0.8010	0.026*
C8	0.6035 (3)	0.5688 (3)	0.8847 (3)	0.0316 (12)
H8A	0.6042	0.6119	0.9012	0.038*
H8B	0.5843	0.5380	0.9196	0.038*
C9	0.6706 (2)	0.68763 (19)	0.7739 (3)	0.0201 (9)
H9A	0.6944	0.6980	0.8222	0.024*
C10	0.6400 (2)	0.7337 (2)	0.7339 (3)	0.0316 (12)
H10A	0.6160	0.7243	0.6855	0.038*
H10B	0.6423	0.7759	0.7539	0.038*
C11	0.7489 (2)	0.5743 (2)	0.7192 (3)	0.0277 (11)
H11A	0.7724	0.5922	0.6747	0.033*
C12	0.7755 (3)	0.5296 (2)	0.7629 (4)	0.0354 (13)
H12A	0.7533	0.5107	0.8079	0.043*
H12B	0.8171	0.5160	0.7497	0.043*
C13	0.4420 (2)	0.6241 (2)	0.8165 (3)	0.0258 (10)
H13A	0.4852	0.6190	0.8020	0.031*
C14	0.4242 (3)	0.6006 (3)	0.8905 (3)	0.0347 (14)
H14A	0.3816	0.6043	0.9082	0.042*
H14B	0.4543	0.5801	0.9251	0.042*
C15	0.42537 (19)	0.7452 (2)	0.7207 (3)	0.0171 (9)
H15A	0.4075	0.7706	0.6780	0.021*
C16	0.4733 (2)	0.7682 (2)	0.7647 (4)	0.0314 (12)
H16A	0.4918	0.7436	0.8077	0.038*
H16B	0.4891	0.8093	0.7531	0.038*
C17	0.3084 (2)	0.6682 (2)	0.7733 (3)	0.0255 (10)
H17A	0.2985	0.6915	0.8221	0.031*
C18	0.2624 (2)	0.6403 (2)	0.7343 (3)	0.0352 (13)
H18A	0.2708	0.6166	0.6852	0.042*
H18B	0.2204	0.6435	0.7548	0.042*
C19	0.2887 (2)	0.6782 (2)	0.2746 (3)	0.0284 (11)
H19A	0.2802	0.7093	0.3158	0.034*
C20	0.2401 (2)	0.6548 (2)	0.2336 (4)	0.0370 (13)
H20A	0.2466	0.6235	0.1920	0.044*
H20B	0.1986	0.6691	0.2457	0.044*
C21	0.3767 (2)	0.5907 (2)	0.1832 (3)	0.0299 (11)
H21A	0.3513	0.5545	0.1928	0.036*
C22	0.4141 (3)	0.5907 (3)	0.1149 (4)	0.0533 (19)
H22A	0.4402	0.6261	0.1031	0.064*
H22B	0.4143	0.5552	0.0786	0.064*
C23	0.4196 (2)	0.7241 (2)	0.2242 (3)	0.0253 (11)
H23A	0.4080	0.7450	0.1742	0.030*
C24	0.4692 (2)	0.7452 (3)	0.2654 (4)	0.0374 (13)
H24A	0.4818	0.7251	0.3157	0.045*
H24B	0.4922	0.7804	0.2450	0.045*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Si1	0.0136 (6)	0.0125 (6)	0.0137 (6)	−0.0002 (5)	0.0003 (4)	0.0007 (4)
Si2	0.0100 (6)	0.0106 (6)	0.0129 (6)	−0.0003 (5)	−0.0015 (4)	−0.0005 (4)
Si3	0.0125 (6)	0.0103 (6)	0.0137 (6)	0.0007 (5)	0.0007 (4)	−0.0012 (4)
Si4	0.0115 (6)	0.0097 (6)	0.0107 (6)	0.0013 (5)	−0.0008 (4)	0.0013 (4)
Si5	0.0201 (6)	0.0247 (7)	0.0161 (7)	−0.0022 (6)	0.0035 (5)	0.0074 (5)
Si6	0.0148 (6)	0.0143 (6)	0.0197 (6)	−0.0024 (5)	−0.0026 (5)	0.0018 (5)
Si7	0.0210 (6)	0.0133 (5)	0.0122 (6)	0.0047 (5)	−0.0006 (5)	−0.0052 (5)
Si8	0.0205 (6)	0.0145 (6)	0.0191 (7)	0.0014 (5)	−0.0081 (5)	0.0020 (5)
O1	0.0198 (16)	0.0153 (15)	0.0243 (19)	−0.0014 (12)	0.0048 (13)	−0.0002 (12)
O2	0.0233 (16)	0.0105 (14)	0.0223 (18)	0.0007 (12)	−0.0038 (13)	0.0005 (12)
O3	0.0197 (14)	0.0244 (15)	0.0129 (16)	−0.0024 (11)	0.0013 (12)	−0.0024 (13)
O4	0.0117 (14)	0.0188 (15)	0.0220 (17)	0.0017 (11)	−0.0026 (12)	−0.0015 (12)
O5	0.0226 (15)	0.0183 (14)	0.0138 (16)	0.0044 (11)	−0.0010 (12)	0.0024 (12)
O6	0.0161 (15)	0.0253 (16)	0.0171 (17)	0.0039 (13)	−0.0009 (12)	0.0023 (13)
O7	0.0165 (15)	0.0215 (16)	0.0212 (18)	−0.0027 (12)	0.0035 (13)	0.0039 (13)
O8	0.0167 (15)	0.0125 (14)	0.0189 (17)	−0.0060 (12)	−0.0060 (12)	0.0018 (12)
O9	0.0140 (15)	0.0206 (15)	0.0182 (17)	0.0040 (12)	0.0013 (12)	−0.0057 (13)
O10	0.0170 (15)	0.0122 (14)	0.0192 (17)	0.0007 (11)	−0.0024 (12)	0.0056 (12)
C1	0.025 (2)	0.038 (3)	0.022 (3)	0.002 (2)	0.011 (2)	−0.005 (2)
C2	0.021 (2)	0.036 (3)	0.033 (3)	0.010 (2)	0.001 (2)	−0.005 (2)
C3	0.039 (3)	0.031 (3)	0.033 (3)	0.008 (2)	−0.015 (2)	0.003 (2)
C4	0.083 (5)	0.065 (5)	0.051 (5)	0.054 (4)	0.033 (4)	0.025 (4)
C5	0.025 (3)	0.031 (3)	0.035 (3)	−0.007 (2)	0.010 (2)	0.012 (2)
C6	0.050 (3)	0.023 (3)	0.073 (5)	0.004 (2)	0.016 (3)	0.014 (3)
C7	0.025 (2)	0.017 (2)	0.022 (2)	−0.0027 (18)	0.0005 (18)	0.0001 (17)
C8	0.040 (3)	0.023 (3)	0.031 (3)	0.000 (2)	−0.001 (2)	−0.005 (2)
C9	0.027 (2)	0.014 (2)	0.020 (2)	0.0011 (17)	−0.0045 (17)	−0.0012 (16)
C10	0.042 (3)	0.021 (2)	0.032 (3)	−0.002 (2)	0.001 (2)	−0.002 (2)
C11	0.020 (2)	0.030 (3)	0.033 (3)	−0.001 (2)	−0.015 (2)	0.001 (2)
C12	0.042 (3)	0.034 (3)	0.030 (3)	0.012 (2)	−0.005 (2)	0.000 (2)
C13	0.038 (3)	0.016 (2)	0.024 (2)	0.0018 (19)	−0.010 (2)	0.0030 (18)
C14	0.040 (3)	0.051 (4)	0.013 (2)	−0.032 (3)	0.006 (2)	−0.014 (2)
C15	0.017 (2)	0.020 (2)	0.015 (2)	0.0033 (16)	0.0045 (16)	0.0061 (16)
C16	0.036 (3)	0.022 (2)	0.036 (3)	−0.008 (2)	−0.001 (2)	0.003 (2)
C17	0.033 (3)	0.022 (2)	0.021 (2)	0.004 (2)	0.010 (2)	−0.0070 (18)
C18	0.025 (2)	0.048 (3)	0.033 (3)	−0.007 (2)	0.011 (2)	−0.013 (2)
C19	0.025 (2)	0.030 (3)	0.030 (3)	0.000 (2)	−0.006 (2)	0.011 (2)
C20	0.032 (3)	0.039 (3)	0.040 (3)	−0.005 (2)	−0.012 (2)	0.007 (2)
C21	0.037 (3)	0.029 (3)	0.023 (2)	−0.007 (2)	0.003 (2)	0.000 (2)
C22	0.090 (5)	0.040 (4)	0.030 (3)	−0.030 (3)	−0.015 (3)	0.004 (3)
C23	0.021 (2)	0.031 (3)	0.025 (2)	0.0040 (19)	−0.0021 (18)	−0.0007 (19)
C24	0.041 (3)	0.040 (3)	0.031 (3)	−0.009 (2)	0.010 (2)	0.001 (2)

Geometric parameters (Å, º)

Si1—O7	1.588 (3)	C4—H4B	0.9500
Si1—O3	1.608 (3)	C5—C6	1.337 (7)
Si1—O1	1.609 (3)	C5—H5A	0.9500
Si1—O6	1.616 (3)	C6—H6A	0.9500
Si2—O8	1.597 (3)	C6—H6B	0.9500
Si2—O3	1.599 (3)	C7—C8	1.296 (7)
Si2—O4	1.603 (3)	C7—H7A	0.9500
Si2—O2	1.604 (3)	C8—H8A	0.9500
Si3—O9	1.590 (3)	C8—H8B	0.9500
Si3—O2^i	1.612 (3)	C9—C10	1.335 (6)
Si3—O4	1.617 (3)	C9—H9A	0.9500
Si3—O5	1.619 (3)	C10—H10A	0.9500
Si4—O10	1.578 (3)	C10—H10B	0.9500
Si4—O5	1.597 (3)	C11—C12	1.305 (7)
Si4—O1^i	1.603 (3)	C11—H11A	0.9500
Si4—O6	1.609 (3)	C12—H12A	0.9500
Si5—O7	1.635 (3)	C12—H12B	0.9500
Si5—C5	1.834 (5)	C13—C14	1.343 (7)
Si5—C1	1.847 (5)	C13—H13A	0.9500
Si5—C3	1.853 (5)	C14—H14A	0.9500
Si6—O8	1.644 (3)	C14—H14B	0.9500
Si6—C9	1.843 (4)	C15—C16	1.328 (6)
Si6—C11	1.848 (5)	C15—H15A	0.9500
Si6—C7	1.854 (5)	C16—H16A	0.9500
Si7—O9	1.639 (3)	C16—H16B	0.9500
Si7—C13	1.848 (5)	C17—C18	1.300 (7)
Si7—C17	1.850 (5)	C17—H17A	0.9500
Si7—C15	1.856 (4)	C18—H18A	0.9500
Si8—O10	1.654 (3)	C18—H18B	0.9500
Si8—C19	1.829 (5)	C19—C20	1.318 (6)
Si8—C21	1.833 (5)	C19—H19A	0.9500
Si8—C23	1.860 (5)	C20—H20A	0.9500
O1—Si4^i	1.603 (3)	C20—H20B	0.9500
O2—Si3^i	1.612 (3)	C21—C22	1.354 (8)
C1—C2	1.291 (7)	C21—H21A	0.9500
C1—H1A	0.9500	C22—H22A	0.9500
C2—H2A	0.9500	C22—H22B	0.9500
C2—H2B	0.9500	C23—C24	1.318 (7)
C3—C4	1.315 (9)	C23—H23A	0.9500
C3—H3A	0.9500	C24—H24A	0.9500
C4—H4A	0.9500	C24—H24B	0.9500
O7—Si1—O3	108.32 (17)	C4—C3—H3A	117.2
O7—Si1—O1	109.62 (17)	Si5—C3—H3A	117.2
O3—Si1—O1	109.78 (17)	C3—C4—H4A	120.0
O7—Si1—O6	111.05 (17)	C3—C4—H4B	120.0
O3—Si1—O6	108.74 (16)	H4A—C4—H4B	120.0
O1—Si1—O6	109.31 (16)	C6—C5—Si5	124.0 (5)
O8—Si2—O3	108.47 (17)	C6—C5—H5A	118.0
O8—Si2—O4	109.28 (17)	Si5—C5—H5A	118.0
O3—Si2—O4	110.54 (17)	C5—C6—H6A	120.0
O8—Si2—O2	110.41 (16)	C5—C6—H6B	120.0
O3—Si2—O2	108.73 (16)	H6A—C6—H6B	120.0
O4—Si2—O2	109.41 (16)	C8—C7—Si6	126.3 (4)
O9—Si3—O2^i	109.07 (17)	C8—C7—H7A	116.9
O9—Si3—O4	110.27 (17)	Si6—C7—H7A	116.9
O2^i—Si3—O4	109.22 (16)	C7—C8—H8A	120.0
O9—Si3—O5	109.61 (16)	C7—C8—H8B	120.0
O2^i—Si3—O5	109.98 (17)	H8A—C8—H8B	120.0
O4—Si3—O5	108.68 (16)	C10—C9—Si6	122.5 (4)
O10—Si4—O5	108.01 (16)	C10—C9—H9A	118.7
O10—Si4—O1^i	111.28 (16)	Si6—C9—H9A	118.7
O5—Si4—O1^i	108.60 (17)	C9—C10—H10A	120.0
O10—Si4—O6	109.08 (16)	C9—C10—H10B	120.0
O5—Si4—O6	110.11 (16)	H10A—C10—H10B	120.0
O1^i—Si4—O6	109.73 (16)	C12—C11—Si6	124.0 (4)
O7—Si5—C5	106.4 (2)	C12—C11—H11A	118.0
O7—Si5—C1	108.0 (2)	Si6—C11—H11A	118.0
C5—Si5—C1	110.6 (2)	C11—C12—H12A	120.0
O7—Si5—C3	108.6 (2)	C11—C12—H12B	120.0
C5—Si5—C3	111.1 (2)	H12A—C12—H12B	120.0
C1—Si5—C3	112.0 (3)	C14—C13—Si7	127.3 (5)
O8—Si6—C9	107.05 (18)	C14—C13—H13A	116.3
O8—Si6—C11	107.4 (2)	Si7—C13—H13A	116.3
C9—Si6—C11	111.2 (2)	C13—C14—H14A	120.0
O8—Si6—C7	109.83 (18)	C13—C14—H14B	120.0
C9—Si6—C7	112.6 (2)	H14A—C14—H14B	120.0
C11—Si6—C7	108.5 (2)	C16—C15—Si7	122.6 (4)
O9—Si7—C13	109.27 (19)	C16—C15—H15A	118.7
O9—Si7—C17	107.04 (18)	Si7—C15—H15A	118.7
C13—Si7—C17	111.6 (2)	C15—C16—H16A	120.0
O9—Si7—C15	107.55 (19)	C15—C16—H16B	120.0
C13—Si7—C15	108.7 (2)	H16A—C16—H16B	120.0
C17—Si7—C15	112.56 (19)	C18—C17—Si7	124.1 (4)
O10—Si8—C19	106.9 (2)	C18—C17—H17A	118.0
O10—Si8—C21	109.2 (2)	Si7—C17—H17A	118.0
C19—Si8—C21	110.4 (2)	C17—C18—H18A	120.0
O10—Si8—C23	108.29 (19)	C17—C18—H18B	120.0
C19—Si8—C23	111.3 (2)	H18A—C18—H18B	120.0
C21—Si8—C23	110.7 (2)	C20—C19—Si8	125.2 (5)
Si4^i—O1—Si1	149.3 (2)	C20—C19—H19A	117.4
Si2—O2—Si3^i	150.9 (2)	Si8—C19—H19A	117.4
Si2—O3—Si1	151.8 (2)	C19—C20—H20A	120.0
Si2—O4—Si3	142.8 (2)	C19—C20—H20B	120.0
Si4—O5—Si3	151.55 (19)	H20A—C20—H20B	120.0
Si4—O6—Si1	144.6 (2)	C22—C21—Si8	125.0 (4)
Si1—O7—Si5	151.6 (2)	C22—C21—H21A	117.5
Si2—O8—Si6	144.1 (2)	Si8—C21—H21A	117.5
Si3—O9—Si7	143.0 (2)	C21—C22—H22A	120.0
Si4—O10—Si8	149.5 (2)	C21—C22—H22B	120.0
C2—C1—Si5	125.2 (4)	H22A—C22—H22B	120.0
C2—C1—H1A	117.4	C24—C23—Si8	123.6 (4)
Si5—C1—H1A	117.4	C24—C23—H23A	118.2
C1—C2—H2A	120.0	Si8—C23—H23A	118.2
C1—C2—H2B	120.0	C23—C24—H24A	120.0
H2A—C2—H2B	120.0	C23—C24—H24B	120.0
C4—C3—Si5	125.5 (5)	H24A—C24—H24B	120.0
O7—Si1—O1—Si4^i	176.7 (4)	C13—Si7—O9—Si3	−26.5 (4)
O3—Si1—O1—Si4^i	57.9 (5)	C17—Si7—O9—Si3	−147.5 (3)
O6—Si1—O1—Si4^i	−61.3 (5)	C15—Si7—O9—Si3	91.3 (4)
O8—Si2—O2—Si3^i	−173.4 (4)	O5—Si4—O10—Si8	−171.0 (4)
O3—Si2—O2—Si3^i	−54.5 (5)	O1^i—Si4—O10—Si8	−51.9 (4)
O4—Si2—O2—Si3^i	66.3 (5)	O6—Si4—O10—Si8	69.3 (4)
O8—Si2—O3—Si1	175.0 (4)	C19—Si8—O10—Si4	135.3 (4)
O4—Si2—O3—Si1	−65.2 (5)	C21—Si8—O10—Si4	15.9 (5)
O2—Si2—O3—Si1	55.0 (5)	C23—Si8—O10—Si4	−104.7 (4)
O7—Si1—O3—Si2	−174.8 (4)	O7—Si5—C1—C2	9.6 (5)
O1—Si1—O3—Si2	−55.1 (5)	C5—Si5—C1—C2	125.7 (5)
O6—Si1—O3—Si2	64.4 (5)	C3—Si5—C1—C2	−109.9 (5)
O8—Si2—O4—Si3	178.2 (3)	O7—Si5—C3—C4	−114.6 (6)
O3—Si2—O4—Si3	58.9 (4)	C5—Si5—C3—C4	128.8 (6)
O2—Si2—O4—Si3	−60.8 (4)	C1—Si5—C3—C4	4.6 (6)
O9—Si3—O4—Si2	−179.7 (3)	O7—Si5—C5—C6	−121.4 (5)
O2^i—Si3—O4—Si2	60.5 (4)	C1—Si5—C5—C6	121.5 (5)
O5—Si3—O4—Si2	−59.5 (4)	C3—Si5—C5—C6	−3.5 (6)
O10—Si4—O5—Si3	176.6 (4)	O8—Si6—C7—C8	−117.9 (5)
O1^i—Si4—O5—Si3	55.8 (5)	C9—Si6—C7—C8	1.4 (5)
O6—Si4—O5—Si3	−64.4 (4)	C11—Si6—C7—C8	125.0 (5)
O9—Si3—O5—Si4	−173.1 (4)	O8—Si6—C9—C10	5.7 (5)
O2^i—Si3—O5—Si4	−53.2 (5)	C11—Si6—C9—C10	122.7 (4)
O4—Si3—O5—Si4	66.3 (4)	C7—Si6—C9—C10	−115.1 (4)
O10—Si4—O6—Si1	174.6 (3)	O8—Si6—C11—C12	−129.2 (4)
O5—Si4—O6—Si1	56.2 (4)	C9—Si6—C11—C12	113.9 (4)
O1^i—Si4—O6—Si1	−63.2 (4)	C7—Si6—C11—C12	−10.5 (5)
O7—Si1—O6—Si4	−175.7 (3)	O9—Si7—C13—C14	−121.3 (4)
O3—Si1—O6—Si4	−56.6 (4)	C17—Si7—C13—C14	−3.1 (5)
O1—Si1—O6—Si4	63.2 (4)	C15—Si7—C13—C14	121.6 (4)
O3—Si1—O7—Si5	−167.0 (4)	O9—Si7—C15—C16	−125.1 (4)
O1—Si1—O7—Si5	73.2 (5)	C13—Si7—C15—C16	−6.9 (5)
O6—Si1—O7—Si5	−47.7 (5)	C17—Si7—C15—C16	117.2 (4)
C5—Si5—O7—Si1	129.8 (4)	O9—Si7—C17—C18	4.1 (5)
C1—Si5—O7—Si1	−111.4 (5)	C13—Si7—C17—C18	−115.4 (5)
C3—Si5—O7—Si1	10.2 (5)	C15—Si7—C17—C18	122.1 (5)
O3—Si2—O8—Si6	−151.6 (3)	O10—Si8—C19—C20	−123.3 (4)
O4—Si2—O8—Si6	87.8 (4)	C21—Si8—C19—C20	−4.6 (5)
O2—Si2—O8—Si6	−32.5 (4)	C23—Si8—C19—C20	118.7 (4)
C9—Si6—O8—Si2	−139.1 (3)	O10—Si8—C21—C22	−114.7 (5)
C11—Si6—O8—Si2	101.3 (4)	C19—Si8—C21—C22	128.0 (5)
C7—Si6—O8—Si2	−16.5 (4)	C23—Si8—C21—C22	4.3 (6)
O2^i—Si3—O9—Si7	94.0 (4)	O10—Si8—C23—C24	3.8 (5)
O4—Si3—O9—Si7	−25.9 (4)	C19—Si8—C23—C24	120.9 (5)
O5—Si3—O9—Si7	−145.5 (3)	C21—Si8—C23—C24	−115.8 (5)

Symmetry code: (i) −x+1, −y+1, z.

(cs511)

Crystal data

C48H72O20Si16	Dx = 1.311 Mg m^−3
Mr = 1418.50	Mo Kα radiation, λ = 0.71073 Å
Tetragonal, I4	Cell parameters from 5539 reflections
Hall symbol: I 4	θ = 1.8–22.6°
a = 15.0040 (6) Å	µ = 0.35 mm^−1
c = 7.9872 (5) Å	T = 100 K
V = 1798.08 (15) Å^3	Plate, colorless
Z = 1	0.16 × 0.16 × 0.06 mm
F(000) = 744

Data collection

Oxford Diffraction Xcalibur2 diffractometer	1394 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	Rint = 0.056
Graphite monochromator	θmax = 30.1°, θmin = 3.8°
phi and ω scans	h = −21→21
10423 measured reflections	k = −21→21
1399 independent reflections	l = −11→11

Refinement

Refinement on F^2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F^2 > 2σ(F^2)] = 0.061	H-atom parameters constrained
wR(F^2) = 0.152	w = 1/[σ^2(Fo^2) + (0.0665P)^2 + 1.9447P] where P = (Fo^2 + 2Fc^2)/3
S = 1.23	(Δ/σ)max < 0.001
1399 reflections	Δρmax = 0.34 e Å^−3
190 parameters	Δρmin = −0.29 e Å^−3
1 restraint	Absolute structure: Flack H D (1983), Acta Cryst. A39, 876-881
Primary atom site location: structure-invariant direct methods

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	0.64436 (17)	0.48231 (16)	0.3039 (3)	0.0211 (5)	0.50
Si2	0.64485 (14)	0.48432 (16)	0.6932 (3)	0.0210 (4)	0.50
Si3	0.78503 (18)	0.47145 (16)	0.0190 (4)	0.0316 (6)	0.50
Si4	0.77362 (15)	0.44007 (16)	0.9790 (3)	0.0258 (5)	0.50
O1	0.6716 (3)	0.4807 (3)	0.4998 (8)	0.0289 (9)	0.50
O2	0.5778 (3)	0.4030 (4)	0.7351 (7)	0.0276 (11)	0.50
O3	0.5965 (4)	0.5757 (4)	0.2647 (8)	0.0313 (12)	0.50
O4	0.7330 (4)	0.4690 (4)	0.1977 (8)	0.0292 (11)	0.50
O5	0.7332 (4)	0.4759 (4)	0.8023 (8)	0.0267 (11)	0.50
C1	0.8089 (14)	0.3546 (12)	−0.034 (3)	0.058 (5)	0.50
H1A	0.8486	0.3458	−0.1255	0.069*	0.50
C2	0.7796 (13)	0.2850 (10)	0.033 (3)	0.058 (4)	0.50
H2A	0.7395	0.2891	0.1250	0.069*	0.50
H2B	0.7975	0.2283	−0.0073	0.069*	0.50
C3	0.7138 (8)	0.5249 (7)	−0.1375 (13)	0.049 (2)	0.50
H3A	0.7004	0.5858	−0.1168	0.058*	0.50
C4	0.6803 (16)	0.4933 (11)	−0.267 (2)	0.082 (6)	0.50
H4A	0.6908	0.4328	−0.2963	0.098*	0.50
H4B	0.6443	0.5297	−0.3372	0.098*	0.50
C5	0.8895 (8)	0.5329 (13)	0.053 (3)	0.053 (4)	0.50
H5A	0.9293	0.5098	0.1344	0.064*	0.50
C6	0.9144 (9)	0.6055 (8)	−0.026 (3)	0.062 (4)	0.50
H6A	0.8770	0.6311	−0.1086	0.074*	0.50
H6B	0.9700	0.6325	0.0006	0.074*	0.50
C7	0.6827 (6)	0.4305 (7)	1.1340 (11)	0.0418 (19)	0.50
H7A	0.6350	0.3913	1.1079	0.050*	0.50
C8	0.6785 (11)	0.4721 (9)	1.2725 (19)	0.050 (3)	0.50
H8A	0.7248	0.5120	1.3036	0.060*	0.50
H8B	0.6291	0.4632	1.3450	0.060*	0.50
C9	0.8596 (8)	0.5206 (10)	1.0454 (15)	0.035 (2)	0.50
H9A	0.8922	0.5080	1.1446	0.042*	0.50
C10	0.8786 (8)	0.5944 (8)	0.9636 (17)	0.050 (3)	0.50
H10A	0.8471	0.6088	0.8640	0.060*	0.50
H10B	0.9237	0.6332	1.0043	0.060*	0.50
C11	0.8199 (10)	0.3297 (10)	0.9389 (19)	0.037 (2)	0.50
H11A	0.8612	0.3227	0.8495	0.044*	0.50
C12	0.7982 (12)	0.2584 (10)	1.030 (2)	0.050 (3)	0.50
H12A	0.7571	0.2641	1.1200	0.060*	0.50
H12B	0.8238	0.2020	1.0052	0.060*	0.50

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Si1	0.0176 (11)	0.0203 (10)	0.0254 (10)	0.0001 (8)	0.0030 (9)	−0.0008 (8)
Si2	0.0169 (9)	0.0200 (10)	0.0260 (11)	0.0001 (7)	−0.0027 (7)	−0.0018 (8)
Si3	0.0310 (12)	0.0274 (12)	0.0365 (15)	−0.0006 (10)	0.0094 (10)	−0.0009 (10)
Si4	0.0207 (9)	0.0278 (12)	0.0289 (12)	−0.0005 (9)	−0.0016 (8)	0.0013 (10)
O1	0.0251 (18)	0.036 (2)	0.026 (2)	0.0018 (16)	0.005 (2)	0.001 (2)
O2	0.019 (2)	0.032 (3)	0.032 (3)	−0.011 (2)	−0.0019 (19)	0.002 (2)
O3	0.025 (3)	0.028 (3)	0.042 (3)	0.001 (2)	0.009 (2)	0.003 (2)
O4	0.019 (3)	0.040 (3)	0.028 (3)	0.000 (2)	0.008 (2)	−0.005 (2)
O5	0.019 (2)	0.025 (3)	0.036 (3)	0.001 (2)	−0.010 (2)	0.004 (2)
C1	0.052 (7)	0.054 (9)	0.066 (10)	−0.002 (6)	0.023 (6)	−0.026 (7)
C2	0.062 (8)	0.037 (7)	0.074 (9)	0.014 (5)	0.002 (7)	0.001 (8)
C3	0.068 (6)	0.039 (5)	0.039 (5)	0.008 (4)	−0.002 (4)	0.010 (4)
C4	0.133 (17)	0.046 (8)	0.067 (10)	−0.011 (10)	−0.026 (12)	0.000 (6)
C5	0.029 (6)	0.058 (7)	0.072 (9)	−0.001 (6)	0.022 (7)	0.003 (6)
C6	0.057 (7)	0.037 (5)	0.091 (11)	−0.021 (5)	0.004 (9)	−0.001 (6)
C7	0.033 (4)	0.057 (5)	0.035 (4)	0.006 (4)	0.006 (3)	0.006 (4)
C8	0.048 (8)	0.052 (7)	0.050 (7)	0.009 (6)	0.004 (6)	0.005 (5)
C9	0.037 (6)	0.046 (6)	0.023 (3)	0.005 (5)	−0.003 (5)	0.004 (3)
C10	0.050 (6)	0.043 (5)	0.057 (7)	−0.020 (5)	−0.023 (6)	−0.001 (4)
C11	0.030 (5)	0.047 (8)	0.035 (5)	−0.006 (5)	0.004 (4)	−0.003 (5)
C12	0.061 (9)	0.044 (8)	0.045 (6)	−0.001 (5)	−0.003 (6)	0.002 (7)

Geometric parameters (Å, º)

Si1—O4	1.590 (6)	C3—C4	1.25 (2)
Si1—O3^i	1.599 (6)	C3—H3A	0.9500
Si1—O3	1.605 (6)	C4—H4A	0.9500
Si1—O1	1.617 (7)	C4—H4B	0.9500
Si2—O5	1.591 (6)	C5—C6	1.31 (2)
Si2—O1	1.597 (7)	C5—H5A	0.9500
Si2—O2^ii	1.612 (5)	C6—H6A	0.9500
Si2—O2	1.616 (6)	C6—H6B	0.9500
Si3—O4	1.627 (6)	C7—C8	1.271 (17)
Si3—C3	1.830 (10)	C7—H7A	0.9500
Si3—C5	1.839 (13)	C8—H8A	0.9500
Si3—C1	1.839 (15)	C8—H8B	0.9500
Si4—O5	1.628 (6)	C9—C10	1.317 (19)
Si4—C11	1.824 (15)	C9—H9A	0.9500
Si4—C9	1.845 (13)	C10—H10A	0.9500
Si4—C7	1.848 (9)	C10—H10B	0.9500
C1—C2	1.26 (3)	C11—C12	1.33 (2)
C1—H1A	0.9500	C11—H11A	0.9500
C2—H2A	0.9500	C12—H12A	0.9500
C2—H2B	0.9500	C12—H12B	0.9500
O4—Si1—O3^i	109.9 (3)	C1—C2—H2B	120.0
O4—Si1—O3	112.3 (3)	H2A—C2—H2B	120.0
O3^i—Si1—O3	108.7 (5)	C4—C3—Si3	129.6 (12)
O4—Si1—O1	107.6 (3)	C4—C3—H3A	115.2
O3^i—Si1—O1	109.9 (3)	Si3—C3—H3A	115.2
O3—Si1—O1	108.3 (3)	C3—C4—H4A	120.0
O5—Si2—O1	108.5 (3)	C3—C4—H4B	120.0
O5—Si2—O2^ii	109.1 (3)	H4A—C4—H4B	120.0
O1—Si2—O2^ii	110.1 (3)	C6—C5—Si3	126.2 (15)
O5—Si2—O2	110.2 (3)	C6—C5—H5A	116.9
O1—Si2—O2	109.3 (3)	Si3—C5—H5A	116.9
O2^ii—Si2—O2	109.7 (5)	C5—C6—H6A	120.0
O4—Si3—C3	109.2 (4)	C5—C6—H6B	120.0
O4—Si3—C5	107.0 (7)	H6A—C6—H6B	120.0
C3—Si3—C5	112.2 (7)	C8—C7—Si4	125.6 (10)
O4—Si3—C1	106.0 (8)	C8—C7—H7A	117.2
C3—Si3—C1	111.9 (8)	Si4—C7—H7A	117.2
C5—Si3—C1	110.2 (9)	C7—C8—H8A	120.0
O5—Si4—C11	106.8 (5)	C7—C8—H8B	120.0
O5—Si4—C9	107.1 (4)	H8A—C8—H8B	120.0
C11—Si4—C9	112.2 (6)	C10—C9—Si4	124.0 (8)
O5—Si4—C7	109.3 (4)	C10—C9—H9A	118.0
C11—Si4—C7	109.2 (6)	Si4—C9—H9A	118.0
C9—Si4—C7	112.0 (5)	C9—C10—H10A	120.0
Si2—O1—Si1	150.7 (3)	C9—C10—H10B	120.0
Si2^i—O2—Si2	146.6 (4)	H10A—C10—H10B	120.0
Si1^ii—O3—Si1	148.7 (4)	C12—C11—Si4	122.5 (11)
Si1—O4—Si3	150.1 (4)	C12—C11—H11A	118.7
Si2—O5—Si4	144.3 (4)	Si4—C11—H11A	118.7
C2—C1—Si3	128.7 (15)	C11—C12—H12A	120.0
C2—C1—H1A	115.7	C11—C12—H12B	120.0
Si3—C1—H1A	115.7	H12A—C12—H12B	120.0
C1—C2—H2A	120.0
O5—Si2—O1—Si1	179.8 (6)	O2^ii—Si2—O5—Si4	90.9 (8)
O2^ii—Si2—O1—Si1	−60.9 (7)	O2—Si2—O5—Si4	−29.5 (9)
O2—Si2—O1—Si1	59.6 (7)	C11—Si4—O5—Si2	96.0 (9)
O4—Si1—O1—Si2	−177.7 (6)	C9—Si4—O5—Si2	−143.6 (8)
O3^i—Si1—O1—Si2	−57.9 (7)	C7—Si4—O5—Si2	−22.1 (9)
O3—Si1—O1—Si2	60.7 (7)	O4—Si3—C1—C2	11 (2)
O5—Si2—O2—Si2^i	−177.3 (7)	C3—Si3—C1—C2	−108 (2)
O1—Si2—O2—Si2^i	−58.1 (8)	C5—Si3—C1—C2	127 (2)
O2^ii—Si2—O2—Si2^i	62.7 (9)	O4—Si3—C3—C4	−115.9 (17)
O5—Si2—O2—C4^iii	−158 (3)	C5—Si3—C3—C4	125.6 (18)
O1—Si2—O2—C4^iii	−39 (3)	C1—Si3—C3—C4	1.1 (19)
O2^ii—Si2—O2—C4^iii	82 (3)	Si3—C3—C4—O2^iv	157.6 (10)
O4—Si1—O3—Si1^ii	−176.7 (8)	O4—Si3—C5—C6	−121.3 (16)
O3^i—Si1—O3—Si1^ii	61.5 (11)	C3—Si3—C5—C6	−1.5 (19)
O1—Si1—O3—Si1^ii	−58.0 (10)	C1—Si3—C5—C6	123.8 (18)
O4—Si1—O3—C8^iv	−159 (2)	O5—Si4—C7—C8	−119.8 (10)
O3^i—Si1—O3—C8^iv	79 (2)	C11—Si4—C7—C8	123.6 (11)
O1—Si1—O3—C8^iv	−40 (2)	C9—Si4—C7—C8	−1.3 (12)
O3^i—Si1—O4—Si3	72.5 (9)	Si4—C7—C8—O3^iii	179.8 (8)
O3—Si1—O4—Si3	−48.6 (9)	O5—Si4—C9—C10	3.0 (14)
O1—Si1—O4—Si3	−167.8 (8)	C11—Si4—C9—C10	119.9 (13)
C3—Si3—O4—Si1	10.2 (10)	C7—Si4—C9—C10	−116.9 (12)
C5—Si3—O4—Si1	131.9 (10)	O5—Si4—C11—C12	−127.5 (13)
C1—Si3—O4—Si1	−110.5 (11)	C9—Si4—C11—C12	115.4 (14)
O1—Si2—O5—Si4	−149.2 (7)	C7—Si4—C11—C12	−9.4 (15)

Symmetry codes: (i) y, −x+1, z; (ii) −y+1, x, z; (iii) y, −x+1, z+1; (iv) −y+1, x, z−1.