Supporting information
Crystallographic Information File (CIF) https://doi.org/10.1107/S1600536807042924/nc2049sup1.cif | |
Structure factor file (CIF format) https://doi.org/10.1107/S1600536807042924/nc2049Isup2.hkl |
CCDC reference: 663706
The title compound was prepared according to a published procedure (Heine, 1971) by reaction of bromine on 1,2-bis(trimethylsilyloxy)-cyclobut-1,2-ene in n-pentane. Crystals were obtained upon warming to room temperature and storage of the reaction batch at ambient temperature under exclusion of light for 72 h.
Spectroscopic data: 1H NMR (399.8 MHz, CDCl3, 24 °C) δ/p.p.m.: 3.07 (s, 4 H, CH2). 13C{1H} NMR (100.5 MHz, CDCl3, 26 °C) δ/p.p.m.: 207.3 (CO), 41.8 (CH2).
All H atoms were located in a difference map and refined as riding on their parent atoms. One common isotropic displacement parameter for all H atoms was refined to Uiso(H) = 0.048 (3) Å2.
Due to the absence of significant anomalous scattering the absolute structure factor (Flack, 1983), which is 2.9 with an estimated standard deviation of 2 for the unmerged data set, is meaningless. Thus, Friedel opposites (351 pairs) have been merged. The absolute structure has been arbitrarily chosen.
The title compound, C4H4O2, was prepared as an intermediate in the synthesis of α-hydroxycyclopropanecarboxylic acid. In the crystal structure the cyclobutane ring is almost planar (Fig. 1).
Details of the synthesis of the title compound were given by Heine (1971). For related literature, see: Flack (1983).
Data collection: Collect (Bruker–Nonius, 2004); cell refinement: HKL SCALEPACK (Otwinowski & Minor, 1997); data reduction: HKL DENZO and SCALEPACK (Otwinowski & Minor, 1997); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEPIII (Burnett & Johnson, 1996); software used to prepare material for publication: SHELXL97 (Sheldrick, 1997).
Fig. 1. The molecular structure of (I), with atom labels and anisotropic displacement ellipsoids (drawn at 50% probability level) for non-H atoms. |
C4H4O2 | F(000) = 176 |
Mr = 84.07 | Dx = 1.394 Mg m−3 |
Orthorhombic, P212121 | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: P 2ac 2ab | Cell parameters from 5161 reflections |
a = 5.3719 (3) Å | θ = 3.1–27.5° |
b = 6.8819 (3) Å | µ = 0.11 mm−1 |
c = 10.8378 (6) Å | T = 200 K |
V = 400.66 (4) Å3 | Block, yellow–orange |
Z = 4 | 0.20 × 0.17 × 0.14 mm |
Nonius KappaCCD diffractometer | 488 reflections with I > 2σ(I) |
Radiation source: rotating anode | Rint = 0.038 |
MONTEL, graded multilayered X-ray optics monochromator | θmax = 27.5°, θmin = 3.5° |
CCD; rotation images; thick slices scans | h = −6→6 |
3074 measured reflections | k = −8→8 |
557 independent reflections | l = −13→14 |
Refinement on F2 | Primary atom site location: structure-invariant direct methods |
Least-squares matrix: full | Secondary atom site location: difference Fourier map |
R[F2 > 2σ(F2)] = 0.031 | Hydrogen site location: difference Fourier map |
wR(F2) = 0.081 | Only H-atom displacement parameters refined |
S = 1.09 | w = 1/[σ2(Fo2) + (0.0567P)2 + 0.294P] where P = (Fo2 + 2Fc2)/3 |
557 reflections | (Δ/σ)max < 0.001 |
56 parameters | Δρmax = 0.12 e Å−3 |
0 restraints | Δρmin = −0.15 e Å−3 |
C4H4O2 | V = 400.66 (4) Å3 |
Mr = 84.07 | Z = 4 |
Orthorhombic, P212121 | Mo Kα radiation |
a = 5.3719 (3) Å | µ = 0.11 mm−1 |
b = 6.8819 (3) Å | T = 200 K |
c = 10.8378 (6) Å | 0.20 × 0.17 × 0.14 mm |
Nonius KappaCCD diffractometer | 488 reflections with I > 2σ(I) |
3074 measured reflections | Rint = 0.038 |
557 independent reflections |
R[F2 > 2σ(F2)] = 0.031 | 0 restraints |
wR(F2) = 0.081 | Only H-atom displacement parameters refined |
S = 1.09 | Δρmax = 0.12 e Å−3 |
557 reflections | Δρmin = −0.15 e Å−3 |
56 parameters |
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. |
x | y | z | Uiso*/Ueq | ||
O1 | 0.0632 (3) | 0.2198 (2) | 0.25237 (14) | 0.0496 (4) | |
O2 | −0.0783 (3) | 0.42078 (19) | 0.51173 (12) | 0.0429 (4) | |
C1 | 0.1626 (4) | 0.3358 (2) | 0.31712 (16) | 0.0327 (4) | |
C2 | 0.0924 (3) | 0.4362 (2) | 0.44147 (14) | 0.0310 (4) | |
C3 | 0.3323 (4) | 0.5531 (3) | 0.43585 (16) | 0.0359 (4) | |
H31 | 0.4477 | 0.5256 | 0.5049 | 0.048 (3)* | |
H32 | 0.3051 | 0.6947 | 0.4267 | 0.048 (3)* | |
C4 | 0.4048 (4) | 0.4512 (3) | 0.31457 (16) | 0.0358 (4) | |
H41 | 0.4181 | 0.5408 | 0.2434 | 0.048 (3)* | |
H42 | 0.5555 | 0.3693 | 0.3216 | 0.048 (3)* |
U11 | U22 | U33 | U12 | U13 | U23 | |
O1 | 0.0511 (9) | 0.0464 (8) | 0.0513 (7) | −0.0045 (8) | −0.0136 (9) | −0.0149 (7) |
O2 | 0.0370 (7) | 0.0500 (8) | 0.0416 (7) | 0.0022 (7) | 0.0056 (7) | 0.0056 (6) |
C1 | 0.0340 (9) | 0.0310 (8) | 0.0331 (8) | 0.0007 (8) | −0.0038 (8) | 0.0012 (7) |
C2 | 0.0303 (9) | 0.0314 (8) | 0.0311 (8) | 0.0020 (8) | −0.0043 (8) | 0.0029 (7) |
C3 | 0.0328 (9) | 0.0337 (9) | 0.0413 (9) | −0.0030 (8) | −0.0033 (8) | −0.0053 (8) |
C4 | 0.0338 (9) | 0.0356 (9) | 0.0380 (8) | −0.0026 (8) | 0.0028 (8) | 0.0031 (8) |
O1—C1 | 1.190 (2) | C3—C4 | 1.540 (2) |
O2—C2 | 1.196 (2) | C3—H31 | 0.9900 |
C1—C4 | 1.524 (3) | C3—H32 | 0.9900 |
C1—C2 | 1.561 (2) | C4—H41 | 0.9900 |
C2—C3 | 1.520 (3) | C4—H42 | 0.9900 |
O1—C1—C4 | 136.23 (18) | C2—C3—H32 | 113.6 |
O1—C1—C2 | 134.26 (18) | C4—C3—H32 | 113.6 |
C4—C1—C2 | 89.50 (13) | H31—C3—H32 | 110.8 |
O2—C2—C3 | 136.21 (16) | C1—C4—C3 | 90.33 (14) |
O2—C2—C1 | 134.07 (17) | C1—C4—H41 | 113.6 |
C3—C2—C1 | 89.70 (13) | C3—C4—H41 | 113.6 |
C2—C3—C4 | 90.44 (13) | C1—C4—H42 | 113.6 |
C2—C3—H31 | 113.6 | C3—C4—H42 | 113.6 |
C4—C3—H31 | 113.6 | H41—C4—H42 | 110.9 |
O1—C1—C2—O2 | 3.7 (4) | C1—C2—C3—C4 | −1.11 (12) |
C4—C1—C2—O2 | −177.2 (2) | O1—C1—C4—C3 | 178.0 (2) |
O1—C1—C2—C3 | −178.0 (2) | C2—C1—C4—C3 | −1.11 (12) |
C4—C1—C2—C3 | 1.12 (12) | C2—C3—C4—C1 | 1.14 (13) |
O2—C2—C3—C4 | 177.2 (2) |
Experimental details
Crystal data | |
Chemical formula | C4H4O2 |
Mr | 84.07 |
Crystal system, space group | Orthorhombic, P212121 |
Temperature (K) | 200 |
a, b, c (Å) | 5.3719 (3), 6.8819 (3), 10.8378 (6) |
V (Å3) | 400.66 (4) |
Z | 4 |
Radiation type | Mo Kα |
µ (mm−1) | 0.11 |
Crystal size (mm) | 0.20 × 0.17 × 0.14 |
Data collection | |
Diffractometer | Nonius KappaCCD |
Absorption correction | – |
No. of measured, independent and observed [I > 2σ(I)] reflections | 3074, 557, 488 |
Rint | 0.038 |
(sin θ/λ)max (Å−1) | 0.649 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.031, 0.081, 1.09 |
No. of reflections | 557 |
No. of parameters | 56 |
H-atom treatment | Only H-atom displacement parameters refined |
Δρmax, Δρmin (e Å−3) | 0.12, −0.15 |
Computer programs: Collect (Bruker–Nonius, 2004), HKL SCALEPACK (Otwinowski & Minor, 1997), HKL DENZO and SCALEPACK (Otwinowski & Minor, 1997), SHELXS97 (Sheldrick, 1997), SHELXL97 (Sheldrick, 1997), ORTEPIII (Burnett & Johnson, 1996).
The title compound, C4H4O2, was prepared as an intermediate in the synthesis of α-hydroxycyclopropanecarboxylic acid. In the crystal structure the cyclobutane ring is almost planar (Fig. 1).