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The title compound, C
8H
12O
8Si, previously reported by Kamenar & Bruvo [
Z. Kristallogr. (1975).
141, 97-103], has been rerefined against new intensity data. Geometric parameters agree quite well. However, our results are of significantly higher precision. The Si atom is located on a special position of site symmetry
.
Supporting information
CCDC reference: 193777
Key indicators
- Single-crystal X-ray study
- T = 173 K
- Mean (C-C) = 0.001 Å
- R factor = 0.023
- wR factor = 0.063
- Data-to-parameter ratio = 27.3
checkCIF results
No syntax errors found
ADDSYM reports no extra symmetry
Alert Level A:
DIFF_019 Alert A _diffrn_standards_number is missing
Number of standards used in measurement.
| Author response: The data have been collected on an area detector.
|
DIFF_020 Alert A _diffrn_standards_interval_count and
_diffrn_standards_interval_time are missing. Number of measurements
between standards or time (min) between standards.
| Author response: The data have been collected on an area detector.
|
DIFF_022 Alert A _diffrn_standards_decay_% is missing
Percentage decrease in standards intensity.
| Author response: The data have been collected on an area detector.
|
Alert Level B:
ABSTM_02 Alert B The ratio of expected to reported Tmax/Tmin(RR') is < 0.75
Tmin and Tmax reported: 0.659 0.952
Tmin' and Tmax expected: 0.897 0.952
RR' = 0.735
Please check that your absorption correction is appropriate.
General Notes
REFLT_03
From the CIF: _diffrn_reflns_theta_max 32.74
From the CIF: _reflns_number_total 1091
Count of symmetry unique reflns 650
Completeness (_total/calc) 167.85%
TEST3: Check Friedels for noncentro structure
Estimate of Friedel pairs measured 441
Fraction of Friedel pairs measured 0.678
Are heavy atom types Z>Si present yes
Please check that the estimate of the number of Friedel pairs is
correct. If it is not, please give the correct count in the
_publ_section_exptl_refinement section of the submitted CIF.
3 Alert Level A = Potentially serious problem
1 Alert Level B = Potential problem
0 Alert Level C = Please check
Data collection: X-AREA (Stoe & Cie, 2001); cell refinement: X-AREA; data reduction: X-AREA; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: XP in SHELXTL-Plus (Sheldrick, 1991).
Crystal data top
C8H12O8Si | Dx = 1.463 Mg m−3 |
Mr = 264.27 | Mo Kα radiation, λ = 0.71073 Å |
Tetragonal, P421c | Cell parameters from 10715 reflections |
a = 7.3086 (6) Å | θ = 3.8–32.6° |
c = 11.2295 (12) Å | µ = 0.22 mm−1 |
V = 599.83 (9) Å3 | T = 173 K |
Z = 2 | Block, colourless |
F(000) = 276 | 0.48 × 0.24 × 0.22 mm |
Data collection top
Stoe IPDS II two-circle diffractometer | 1091 independent reflections |
Radiation source: fine-focus sealed tube | 1059 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.040 |
ω scans | θmax = 32.7°, θmin = 3.9° |
Absorption correction: empirical (using intensity measurements) (MULABS; Spek, 1990; Blessing, 1995) | h = −11→10 |
Tmin = 0.659, Tmax = 0.952 | k = −11→11 |
7495 measured reflections | l = −17→17 |
Refinement top
Refinement on F2 | Hydrogen site location: inferred from neighbouring sites |
Least-squares matrix: full | H-atom parameters constrained |
R[F2 > 2σ(F2)] = 0.023 | w = 1/[σ2(Fo2) + (0.0407P)2 + 0.0161P] where P = (Fo2 + 2Fc2)/3 |
wR(F2) = 0.063 | (Δ/σ)max < 0.001 |
S = 1.10 | Δρmax = 0.15 e Å−3 |
1091 reflections | Δρmin = −0.20 e Å−3 |
40 parameters | Extinction correction: SHELXL97, Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4 |
0 restraints | Extinction coefficient: 0.084 (16) |
Primary atom site location: structure-invariant direct methods | Absolute structure: Flack (1983), 441 Friedel pairs |
Secondary atom site location: difference Fourier map | Absolute structure parameter: 0.07 (13) |
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 | x | y | z | Uiso*/Ueq | |
Si1 | 1.0000 | 1.0000 | 0.0000 | 0.02785 (10) | |
O1 | 0.85017 (9) | 0.91606 (9) | 0.09372 (5) | 0.03344 (14) | |
C1 | 0.69252 (11) | 0.82883 (11) | 0.06204 (6) | 0.03103 (15) | |
C2 | 0.59766 (13) | 0.74777 (15) | 0.16648 (7) | 0.0424 (2) | |
H2A | 0.4718 | 0.7160 | 0.1445 | 0.064* | |
H2B | 0.5959 | 0.8366 | 0.2319 | 0.064* | |
H2C | 0.6627 | 0.6372 | 0.1920 | 0.064* | |
O2 | 0.64357 (11) | 0.82040 (12) | −0.03984 (6) | 0.0483 (2) | |
Atomic displacement parameters (Å2) top | U11 | U22 | U33 | U12 | U13 | U23 |
Si1 | 0.03295 (13) | 0.03295 (13) | 0.01765 (14) | 0.000 | 0.000 | 0.000 |
O1 | 0.0347 (3) | 0.0431 (3) | 0.0226 (2) | −0.0052 (2) | 0.00045 (19) | 0.0004 (2) |
C1 | 0.0364 (3) | 0.0315 (3) | 0.0252 (3) | −0.0015 (2) | −0.0015 (2) | −0.0009 (2) |
C2 | 0.0445 (4) | 0.0523 (5) | 0.0304 (3) | −0.0148 (4) | −0.0008 (3) | 0.0057 (3) |
O2 | 0.0596 (4) | 0.0586 (4) | 0.0267 (2) | −0.0143 (3) | −0.0091 (3) | 0.0015 (3) |
Geometric parameters (Å, º) top
Si1—O1i | 1.6380 (6) | C1—O2 | 1.2002 (8) |
Si1—O1 | 1.6380 (6) | C1—C2 | 1.4857 (11) |
Si1—O1ii | 1.6380 (6) | C2—H2A | 0.9800 |
Si1—O1iii | 1.6381 (6) | C2—H2B | 0.9800 |
O1—C1 | 1.3640 (10) | C2—H2C | 0.9800 |
| | | |
O1i—Si1—O1 | 100.04 (4) | O2—C1—C2 | 126.36 (8) |
O1i—Si1—O1ii | 114.38 (2) | O1—C1—C2 | 112.00 (6) |
O1—Si1—O1ii | 114.38 (2) | C1—C2—H2A | 109.5 |
O1i—Si1—O1iii | 114.38 (2) | C1—C2—H2B | 109.5 |
O1—Si1—O1iii | 114.38 (2) | H2A—C2—H2B | 109.5 |
O1ii—Si1—O1iii | 100.04 (4) | C1—C2—H2C | 109.5 |
C1—O1—Si1 | 124.90 (5) | H2A—C2—H2C | 109.5 |
O2—C1—O1 | 121.63 (7) | H2B—C2—H2C | 109.5 |
| | | |
O1i—Si1—O1—C1 | 179.65 (9) | Si1—O1—C1—O2 | −6.42 (13) |
O1ii—Si1—O1—C1 | 56.92 (9) | Si1—O1—C1—C2 | 172.66 (6) |
O1iii—Si1—O1—C1 | −57.63 (9) | | |
Symmetry codes: (i) −x+2, −y+2, z; (ii) y, −x+2, −z; (iii) −y+2, x, −z. |
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