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The title mol­ecule, C16H16Br2O8, lies on a crystallographic twofold axis. Weak intra­molecular C—H...O hydrogen bonds may, in part, control the conformation of the mol­ecule. In the crystal structure, mol­ecules are connected into a two-dimensional network via weak inter­molecular C—H...O hydrogen bonds.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S1600536807063581/lh2578sup1.cif
Contains datablocks I, global

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S1600536807063581/lh2578Isup2.hkl
Contains datablock I

CCDC reference: 676159

Key indicators

  • Single-crystal X-ray study
  • T = 298 K
  • Mean [sigma](C-C) = 0.009 Å
  • R factor = 0.067
  • wR factor = 0.130
  • Data-to-parameter ratio = 17.5

checkCIF/PLATON results

No syntax errors found



Alert level C PLAT026_ALERT_3_C Ratio Observed / Unique Reflections too Low .... 43 Perc. PLAT062_ALERT_4_C Rescale T(min) & T(max) by ..................... 0.88 PLAT213_ALERT_2_C Atom C2 has ADP max/min Ratio ............. 3.30 oblat PLAT230_ALERT_2_C Hirshfeld Test Diff for O4 - C8 .. 5.40 su PLAT242_ALERT_2_C Check Low Ueq as Compared to Neighbors for C6 PLAT341_ALERT_3_C Low Bond Precision on C-C Bonds (x 1000) Ang ... 9
Alert level G ABSTM02_ALERT_3_G When printed, the submitted absorption T values will be replaced by the scaled T values. Since the ratio of scaled T's is identical to the ratio of reported T values, the scaling does not imply a change to the absorption corrections used in the study. Ratio of Tmax expected/reported 0.882 Tmax scaled 0.423 Tmin scaled 0.245 PLAT860_ALERT_3_G Note: Number of Least-Squares Restraints ....... 29
0 ALERT level A = In general: serious problem 0 ALERT level B = Potentially serious problem 6 ALERT level C = Check and explain 2 ALERT level G = General alerts; check 0 ALERT type 1 CIF construction/syntax error, inconsistent or missing data 3 ALERT type 2 Indicator that the structure model may be wrong or deficient 4 ALERT type 3 Indicator that the structure quality may be low 1 ALERT type 4 Improvement, methodology, query or suggestion 0 ALERT type 5 Informative message, check

Comment top

The molecular structure of the title compound is shown in Fig. 1. The bond lengths and angles are within normal ranges (Allen et al., 1987).

The asymmetric unit contains one half-molecule; the full molecule being generated by a crystallographic twofold rotation axis. Weak intramolecular C—H···O hydrogen bonds may, in part, control the conformation of the molecule. In the crystal structure, molecules are connected into a two-dimensional network via weak intermolecular C—H···O hydrogen bonds. (Fig. 2).

Related literature top

For related literature, see: Allen et al. (1987); Mitchell et al. (1995).

Experimental top

The title compound was prepared by a previously reported method (Mitchell et al., 1995).

The crystals of the title compound, were obtained by dissolving (I) (2.00 g, 4.03 mmol) into acetone (50 ml), and evaporating the solvent slowly at room temperature for about 3 d.

Refinement top

H atoms were positioned geometrically, with C—H = 0.93 - 0.98Å and constrained to ride on their parent atoms, with Uiso(H) = xUeq(C), where x = 1.5 for methyl H and x = 1.2 for all other H atoms.

Structure description top

The molecular structure of the title compound is shown in Fig. 1. The bond lengths and angles are within normal ranges (Allen et al., 1987).

The asymmetric unit contains one half-molecule; the full molecule being generated by a crystallographic twofold rotation axis. Weak intramolecular C—H···O hydrogen bonds may, in part, control the conformation of the molecule. In the crystal structure, molecules are connected into a two-dimensional network via weak intermolecular C—H···O hydrogen bonds. (Fig. 2).

For related literature, see: Allen et al. (1987); Mitchell et al. (1995).

Computing details top

Data collection: CAD-4 Software (Enraf–Nonius, 1985); cell refinement: CAD-4 Software (Enraf–Nonius, 1985); data reduction: XCAD4 (Harms & Wocadlo, 1995); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: SHELXTL (Bruker, 2000); software used to prepare material for publication: SHELXTL (Bruker, 2000).

Figures top
[Figure 1] Fig. 1. The molecular structure, with the atom-numbering scheme. Displacement ellipsoids are drawn at the 40% probability level. Hydrogen bonds are shown by dashed lines. [Symmetry code: (A) -x + 1, y, -z + 1/2.]
[Figure 2] Fig. 2. The packing of the title compound with C—H···O hydrogen bonds are shown by dashed lines.
(4,6-Dibromo-m-phenylenedimethylidyne) tetraacetate top
Crystal data top
C16H16Br2O8F(000) = 984
Mr = 496.09Dx = 1.731 Mg m3
Orthorhombic, PbcnMo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2n 2abCell parameters from 25 reflections
a = 20.639 (4) Åθ = 10–14°
b = 10.150 (2) ŵ = 4.30 mm1
c = 9.0880 (18) ÅT = 298 K
V = 1903.8 (6) Å3Plate, colourless
Z = 40.40 × 0.30 × 0.20 mm
Data collection top
Enraf–Nonius CAD-4
diffractometer
805 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tubeRint = 0.054
Graphite monochromatorθmax = 26.0°, θmin = 2.0°
ω/2θ scansh = 025
Absorption correction: ψ scan
(North et al., 1968)
k = 012
Tmin = 0.278, Tmax = 0.480l = 011
3687 measured reflections3 standard reflections every 200 reflections
1877 independent reflections intensity decay: none
Refinement top
Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.067Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.130H-atom parameters constrained
S = 0.96 w = 1/[σ2(Fo2) + (0.02P)2 + 0.0P]
where P = (Fo2 + 2Fc2)/3
1877 reflections(Δ/σ)max = 0.001
107 parametersΔρmax = 0.58 e Å3
29 restraintsΔρmin = 0.49 e Å3
Crystal data top
C16H16Br2O8V = 1903.8 (6) Å3
Mr = 496.09Z = 4
Orthorhombic, PbcnMo Kα radiation
a = 20.639 (4) ŵ = 4.30 mm1
b = 10.150 (2) ÅT = 298 K
c = 9.0880 (18) Å0.40 × 0.30 × 0.20 mm
Data collection top
Enraf–Nonius CAD-4
diffractometer
805 reflections with I > 2σ(I)
Absorption correction: ψ scan
(North et al., 1968)
Rint = 0.054
Tmin = 0.278, Tmax = 0.4803 standard reflections every 200 reflections
3687 measured reflections intensity decay: none
1877 independent reflections
Refinement top
R[F2 > 2σ(F2)] = 0.06729 restraints
wR(F2) = 0.130H-atom parameters constrained
S = 0.96Δρmax = 0.58 e Å3
1877 reflectionsΔρmin = 0.49 e Å3
107 parameters
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
xyzUiso*/Ueq
Br0.61944 (4)0.39329 (6)0.10603 (9)0.0671 (3)
O10.6622 (2)0.6733 (4)0.2433 (6)0.0456 (11)
O20.7386 (3)0.6717 (7)0.0680 (7)0.0852 (19)
O30.6065 (2)0.8406 (5)0.1438 (5)0.049
O40.5702 (3)0.8387 (5)0.0882 (6)0.0750 (17)
C10.50000.4229 (8)0.25000.042 (2)
H1A0.50000.33130.25000.051*
C20.5520 (3)0.4888 (6)0.1917 (7)0.0390 (16)
C30.5535 (3)0.6316 (6)0.1962 (7)0.0414 (17)
C40.50000.6958 (9)0.25000.037 (2)
H4A0.50000.78740.25000.044*
C50.6135 (3)0.6973 (7)0.1474 (7)0.041
H5A0.62560.66520.04940.049*
C60.7244 (4)0.6543 (8)0.1961 (9)0.052 (2)
C70.7671 (4)0.6004 (9)0.3066 (9)0.084 (3)
H7A0.80980.59060.26610.126*
H7B0.75130.51590.33750.126*
H7C0.76880.65880.38960.126*
C80.5877 (3)0.8970 (7)0.0164 (10)0.063 (2)
C90.5899 (4)1.0491 (6)0.0331 (9)0.060 (2)
H9A0.57611.08960.05710.090*
H9B0.63341.07620.05520.090*
H9C0.56161.07570.11160.090*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Br0.0785 (5)0.0252 (4)0.0977 (6)0.0028 (4)0.0283 (5)0.0106 (5)
O10.055 (3)0.033 (2)0.049 (3)0.001 (2)0.007 (2)0.009 (3)
O20.064 (4)0.107 (5)0.084 (4)0.006 (4)0.024 (3)0.001 (4)
O30.0490.0490.0490.0000.0000.000
O40.095 (4)0.051 (3)0.080 (4)0.008 (3)0.023 (3)0.005 (4)
C10.058 (5)0.019 (4)0.049 (5)0.0000.010 (5)0.000
C20.051 (3)0.013 (3)0.053 (4)0.004 (3)0.011 (3)0.016 (3)
C30.058 (4)0.022 (3)0.045 (4)0.005 (3)0.008 (3)0.010 (3)
C40.051 (5)0.021 (4)0.040 (5)0.0000.005 (4)0.000
C50.0410.0410.0410.0000.0000.000
C60.058 (5)0.052 (5)0.046 (5)0.010 (4)0.010 (4)0.018 (4)
C70.067 (5)0.095 (8)0.090 (7)0.020 (6)0.000 (5)0.012 (6)
C80.037 (3)0.059 (5)0.094 (6)0.009 (4)0.011 (4)0.055 (6)
C90.077 (5)0.018 (3)0.084 (5)0.005 (4)0.004 (5)0.001 (5)
Geometric parameters (Å, º) top
Br—C21.866 (6)C3—C51.476 (9)
O1—C51.353 (7)C4—C3i1.372 (8)
O1—C61.366 (8)C4—H4A0.9300
O2—C61.213 (9)C5—H5A0.9800
O3—C81.349 (9)C6—C71.445 (10)
O3—C51.461 (9)C7—H7A0.9600
O4—C81.177 (8)C7—H7B0.9600
C1—C21.371 (7)C7—H7C0.9600
C1—C2i1.371 (7)C8—C91.552 (8)
C1—H1A0.9300C9—H9A0.9600
C2—C31.450 (8)C9—H9B0.9600
C3—C41.372 (8)C9—H9C0.9600
C5—O1—C6121.4 (6)C3—C5—H5A109.6
C8—O3—C5118.0 (5)O2—C6—O1120.5 (7)
C2—C1—C2i121.6 (8)O2—C6—C7125.0 (7)
C2—C1—H1A119.2O1—C6—C7114.1 (6)
C2i—C1—H1A119.2C6—C7—H7A109.5
C1—C2—C3119.6 (6)C6—C7—H7B109.5
C1—C2—Br119.4 (4)H7A—C7—H7B109.5
C3—C2—Br121.0 (5)C6—C7—H7C109.5
C4—C3—C2117.9 (6)H7A—C7—H7C109.5
C4—C3—C5124.6 (6)H7B—C7—H7C109.5
C2—C3—C5117.5 (6)O4—C8—O3124.6 (7)
C3i—C4—C3123.3 (8)O4—C8—C9126.0 (8)
C3i—C4—H4A118.4O3—C8—C9109.3 (6)
C3—C4—H4A118.4C8—C9—H9A109.5
O1—C5—O3105.5 (5)C8—C9—H9B109.5
O1—C5—C3110.4 (5)H9A—C9—H9B109.5
O3—C5—C3112.0 (5)C8—C9—H9C109.5
O1—C5—H5A109.6H9A—C9—H9C109.5
O3—C5—H5A109.6H9B—C9—H9C109.5
C2i—C1—C2—C32.3 (4)C8—O3—C5—O1147.6 (5)
C2i—C1—C2—Br177.1 (5)C8—O3—C5—C392.3 (7)
C1—C2—C3—C44.6 (9)C4—C3—C5—O1109.4 (6)
Br—C2—C3—C4174.8 (3)C2—C3—C5—O168.3 (8)
C1—C2—C3—C5173.3 (5)C4—C3—C5—O37.8 (8)
Br—C2—C3—C57.3 (9)C2—C3—C5—O3174.5 (6)
C2—C3—C4—C3i2.2 (4)C5—O1—C6—O27.5 (12)
C5—C3—C4—C3i175.5 (7)C5—O1—C6—C7166.4 (6)
C6—O1—C5—O396.1 (7)C5—O3—C8—O47.9 (10)
C6—O1—C5—C3142.8 (6)C5—O3—C8—C9174.6 (6)
Symmetry code: (i) x+1, y, z+1/2.
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
C4—H4A···O30.932.462.815 (7)103
C5—H5A···O20.982.342.693 (9)100
C7—H7C···O2ii0.962.373.318 (11)170
Symmetry code: (ii) x+3/2, y+3/2, z+1/2.

Experimental details

Crystal data
Chemical formulaC16H16Br2O8
Mr496.09
Crystal system, space groupOrthorhombic, Pbcn
Temperature (K)298
a, b, c (Å)20.639 (4), 10.150 (2), 9.0880 (18)
V3)1903.8 (6)
Z4
Radiation typeMo Kα
µ (mm1)4.30
Crystal size (mm)0.40 × 0.30 × 0.20
Data collection
DiffractometerEnraf–Nonius CAD-4
Absorption correctionψ scan
(North et al., 1968)
Tmin, Tmax0.278, 0.480
No. of measured, independent and
observed [I > 2σ(I)] reflections
3687, 1877, 805
Rint0.054
(sin θ/λ)max1)0.617
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.067, 0.130, 0.96
No. of reflections1877
No. of parameters107
No. of restraints29
H-atom treatmentH-atom parameters constrained
Δρmax, Δρmin (e Å3)0.58, 0.49

Computer programs: CAD-4 Software (Enraf–Nonius, 1985), XCAD4 (Harms & Wocadlo, 1995), SHELXS97 (Sheldrick, 1997), SHELXL97 (Sheldrick, 1997), SHELXTL (Bruker, 2000).

Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
C4—H4A···O30.93002.46002.815 (7)103.00
C5—H5A···O20.98002.34002.693 (9)100.00
C7—H7C···O2i0.96002.37003.318 (11)170.00
Symmetry code: (i) x+3/2, y+3/2, z+1/2.
 

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