organic compounds\(\def\hfill{\hskip 5em}\def\hfil{\hskip 3em}\def\eqno#1{\hfil {#1}}\)

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ISSN: 2056-9890
Volume 64| Part 8| August 2008| Pages o1617-o1618

(E)-1,2-Bis(4-fluoro­phen­yl)ethane-1,2-dione

aX-ray Crystallography Unit, School of Physics, Universiti Sains Malaysia, 11800 USM, Penang, Malaysia
*Correspondence e-mail: hkfun@usm.my

(Received 22 July 2008; accepted 24 July 2008; online 31 July 2008)

The title compound, C14H8F2O2, is a substituted benzil with an s-trans conformation of the dicarbonyl unit. This conformation is also shown by the O—C—C—O torsion angle of −110.65 (12)°. An unusual feature of the structure is the length, 1.536 (2) Å, of the central C—C bond connecting the carbonyl units, which is significantly longer than a normal Csp2—Csp2 single bond. This is probably the result of decreasing the unfavourable vicinal dipole–dipole inter­actions by increasing the distance between the two electronegative O atoms [O⋯O = 3.1867 (12) Å] and allowing orbital overlap of the dione with the π system of the benzene rings. The dihedral angle between the aromatic rings is 64.74 (5)°. In the crystal structure, neighbouring mol­ecules are linked together by weak inter­molecular C—H⋯O (× 2) hydrogen bonds. In addition, the crystal structure is further stabilized by inter­molecular ππ inter­actions with centroid–centroid distances in the range 3.6416 (6)–3.7150 (7) Å.

Related literature

For bond-length data, see Allen et al. (1987[Allen, F. H., Kennard, O., Watson, D. G., Brammer, L., Orpen, A. G. & Taylor, R. (1987). J. Chem. Soc. Perkin Trans. 2, pp. S1-S19.]). For carbonyl–carbonyl interaction, see Allen et al. (1998[Allen, F. H., Baalham, C. A., Lommerse, J. P. M. & Raithby, P. R. (1998). Acta Cryst. B54, 320-329.]). For related structures and applications see, for example: Kaftory & Rubin (1983[Kaftory, M. & Rubin, M. B. (1983). J. Chem. Soc. Perkin Trans. 2, pp. 149-154.]); Frey et al. (1995[Frey, J., Faraggi, E., Rappoport, Z. & Kaftory, M. (1995). J. Chem. Soc. Perkin Trans. 2, pp. 1745-1748.]); Crowley et al. (1983[Crowley, J. I., Balanson, R. D. & Mayerle, J. J. (1983). J. Am. Chem. Soc. 105, 6416-6422.]); More et al. (1987[More, M., Odou, G. & Lefebvre, J. (1987). Acta Cryst. B43, 398-405.]); Brown et al. (1965[Brown, C. J. & Sadanaga, R. (1965). Acta Cryst. 18, 158-164.]); Gabe et al. (1981[Gabe, E. J., Le Page, Y., Lee, F. L. & Barclay, L. R. C. (1981). Acta Cryst. B37, 197-200.]); Kimura et al. (1979[Kimura, M., McCluney, R. E. & Watson, W. H. (1979). Acta Cryst. B35, 483-484.]); Stevens & Dubois (1962[Stevens, B. & Dubois, J. T. (1962). J. Chem. Soc. pp. 2813-2815.]); Shimizu & Bartlett (1976[Shimizu, N. & Bartlett, P. D. (1976). J. Am. Chem. Soc. 98, 4193-4200.]); Rubin (1978[Rubin, M. B. (1978). Chem. Rev. 78, 1121-1164.]).

[Scheme 1]

Experimental

Crystal data
  • C14H8F2O2

  • Mr = 246.20

  • Monoclinic, P 21 /c

  • a = 12.1351 (2) Å

  • b = 7.3500 (1) Å

  • c = 13.1572 (2) Å

  • β = 110.507 (1)°

  • V = 1099.16 (3) Å3

  • Z = 4

  • Mo Kα radiation

  • μ = 0.12 mm−1

  • T = 100.0 (1) K

  • 0.39 × 0.30 × 0.28 mm

Data collection
  • Bruker SMART APEXII CCD area-detector diffractometer

  • Absorption correction: multi-scan (SADABS; Bruker, 2005[Bruker (2005). APEX2, SAINT and SADABS. Bruker AXS Inc., Madison, Wisconsin, USA.]) Tmin = 0.903, Tmax = 0.967

  • 14891 measured reflections

  • 3489 independent reflections

  • 2846 reflections with I > 2σ(I)

  • Rint = 0.022

Refinement
  • R[F2 > 2σ(F2)] = 0.042

  • wR(F2) = 0.107

  • S = 1.06

  • 3489 reflections

  • 163 parameters

  • H-atom parameters constrained

  • Δρmax = 0.39 e Å−3

  • Δρmin = −0.21 e Å−3

Table 1
Selected centroid⋯centroid distances (Å)

Cg1⋯Cg1i 3.6416 (6)
Cg2⋯Cg2ii 3.7150 (7)
Symmetry codes: (i) -x+1, -y+2, -z; (ii) -x+2, -y+2, -z+1. Cg1 and Cg2 are the centroids of the C1–C6 and C9–C14 benzene rings, respectively.

Table 2
Hydrogen-bond geometry (Å, °)

D—H⋯A D—H H⋯A DA D—H⋯A
C2—H2A⋯O1iii 0.93 2.40 3.2648 (15) 155
C11—H11A⋯O2iv 0.93 2.51 3.3098 (16) 145
Symmetry codes: (iii) x, y-1, z; (iv) [x, -y+{\script{5\over 2}}, z+{\script{1\over 2}}].

Data collection: APEX2 (Bruker, 2005[Bruker (2005). APEX2, SAINT and SADABS. Bruker AXS Inc., Madison, Wisconsin, USA.]); cell refinement: APEX2; data reduction: SAINT (Bruker, 2005[Bruker (2005). APEX2, SAINT and SADABS. Bruker AXS Inc., Madison, Wisconsin, USA.]); program(s) used to solve structure: SHELXTL (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL and PLATON (Spek, 2003[Spek, A. L. (2003). J. Appl. Cryst. 36, 7-13.]).

Supporting information


Comment top

Investigation of photophysical properties of α-dicarbonyls has focused on the intramolecular carbonyl group electronic interaction as a function of their geometrical relationship. In previous extensive studies of the photochemistry of these compounds (Stevens & Dubois, 1962; Shimizu & Bartlett, 1976), biacetyl and benzil were the exclusive experimental vehicles for photophysical study. The structure of vicinal di- and polycarbonyl compounds have been of interest for many years (Rubin, 1978; Crowley et al., 1983; Kaftory et al., 1983; Frey et al., 1995; Kimura et al., 1979). Only a limited amount of data has been gathered from solid-state configurations such as in single crystals or as inclusion dopants in host crystals.

In the title compound (I, Fig.1), bond lengths, bond angles, and torsion angles of the dicarbonyl unit deviate significantly from normal values (Allen et al., 1987) in order to minimize the repulsive interactions resulting from juxtaposition of dipolar carbonyl groups (Allen et al., 1987). The C7–C8 bond distance connecting the carbonyl units is longer than those in normal sp2sp2 single bonds, such as in butadiene. This is probably the result of decreasing the unfavourable vicinal dipole-dipole interactions. The dicarbonyl unit has an s-trans conformation as indicated by the torsion angle of O1–C7–C6–C5, and O2–C8–C9–C10 being -174.32 (11) and 174.49 (11)°, respectively. This conformation is substantiated by the torsion angle of O–C–C–O, being -110.65 (12)°. The overal effect is to maximize the distance between the two electronegative oxygen atoms [O1···O2 = 3.1867 (12) Å] and to allow orbital overlap of the dione with the π system of the benzene rings. The dihedral angle between two phenyl rings is 64.74 (5)°. In the crystal structure, neighbouring molecules are linked together by weak intermolecular C—H···O (2 ×) hydrogen bonds. The packing mode (Fig. 2) tends to be dominated by van der Waals close packing interactions and the preference for aligning the substituted phenyl rings parallel to each other along the c axis with centroid to centroid distances of the π rings of 3.6416 (6) to 3.7150 (7) Å.

Related literature top

For bond-length data, see Allen et al. (1987, 1998). For related structures and applications see, for example: Kaftory & Rubin, (1983); Frey et al. (1995); Crowley et al. (1983); More et al. (1987); Brown et al. (1965); Gabe et al. (1981); Kimura et al. (1979); Stevens & Dubois (1962); Shimizu & Bartlett (1976); Rubin (1978).

Experimental top

The synthetic method has been described earlier (Frey et al., 1995). Single crystals suitable for X-ray diffraction were obtained by evaporation of a methanol solution at room temperature.

Refinement top

All of the hydrogen atoms were positioned geometrically and refined using a riding model with isotropic thermal parameters 1.2 times that of the parent atom.

Computing details top

Data collection: APEX2 (Bruker, 2005); cell refinement: APEX2 (Bruker, 2005); data reduction: SAINT (Bruker, 2005); program(s) used to solve structure: SHELXTL (Sheldrick, 2008); program(s) used to refine structure: SHELXTL (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL (Sheldrick, 2008) and PLATON (Spek, 2003).

Figures top
[Figure 1] Fig. 1. The molecular structure of (I) with atom labels and 50% probability ellipsoids for non-H atoms.
[Figure 2] Fig. 2. The crystal packing, showing parallel aligning of the benzene rings along the c axis. Intermolecular C—H···O interactions are shown as dashed lines.
(E)-1,2-Bis(4-fluorophenyl)ethane-1,2-dione top
Crystal data top
C14H8F2O2F(000) = 504
Mr = 246.20Dx = 1.488 Mg m3
Monoclinic, P21/cMo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybcCell parameters from 6651 reflections
a = 12.1351 (2) Åθ = 3.2–30.8°
b = 7.3500 (1) ŵ = 0.12 mm1
c = 13.1572 (2) ÅT = 100 K
β = 110.507 (1)°Block, pale-yellow
V = 1099.16 (3) Å30.39 × 0.30 × 0.28 mm
Z = 4
Data collection top
Bruker SMART APEXII CCD area-detector
diffractometer
3489 independent reflections
Radiation source: fine-focus sealed tube2846 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.022
ϕ and ω scansθmax = 31.0°, θmin = 3.2°
Absorption correction: multi-scan
(SADABS; Bruker, 2005)
h = 1517
Tmin = 0.903, Tmax = 0.967k = 810
14891 measured reflectionsl = 1818
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)] = 0.042Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.107H-atom parameters constrained
S = 1.06 w = 1/[σ2(Fo2) + (0.0458P)2 + 0.3386P]
where P = (Fo2 + 2Fc2)/3
3489 reflections(Δ/σ)max = 0.001
163 parametersΔρmax = 0.39 e Å3
0 restraintsΔρmin = 0.21 e Å3
Crystal data top
C14H8F2O2V = 1099.16 (3) Å3
Mr = 246.20Z = 4
Monoclinic, P21/cMo Kα radiation
a = 12.1351 (2) ŵ = 0.12 mm1
b = 7.3500 (1) ÅT = 100 K
c = 13.1572 (2) Å0.39 × 0.30 × 0.28 mm
β = 110.507 (1)°
Data collection top
Bruker SMART APEXII CCD area-detector
diffractometer
3489 independent reflections
Absorption correction: multi-scan
(SADABS; Bruker, 2005)
2846 reflections with I > 2σ(I)
Tmin = 0.903, Tmax = 0.967Rint = 0.022
14891 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0420 restraints
wR(F2) = 0.107H-atom parameters constrained
S = 1.06Δρmax = 0.39 e Å3
3489 reflectionsΔρmin = 0.21 e Å3
163 parameters
Special details top

Experimental. The low-temperature data was collected with the Oxford Cyrosystem Cobra low-temperature attachment.

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
F10.35237 (6)0.66325 (10)0.08245 (6)0.03021 (18)
F21.21050 (6)1.20663 (11)0.59266 (6)0.03299 (19)
O10.69635 (7)1.33900 (11)0.19570 (7)0.0273 (2)
O20.85192 (7)1.05531 (12)0.12153 (7)0.02583 (19)
C10.64396 (10)0.85311 (15)0.16653 (9)0.0200 (2)
H1A0.72180.81520.18690.024*
C20.55476 (10)0.72510 (16)0.14036 (9)0.0217 (2)
H2A0.57120.60120.14340.026*
C30.44035 (10)0.78766 (16)0.10962 (9)0.0215 (2)
C40.41085 (10)0.96950 (17)0.10511 (9)0.0223 (2)
H4A0.33271.00600.08440.027*
C50.50092 (10)1.09585 (16)0.13226 (8)0.0202 (2)
H5A0.48361.21930.13040.024*
C60.61811 (9)1.03855 (15)0.16255 (8)0.0183 (2)
C70.71259 (9)1.17601 (15)0.18983 (9)0.0201 (2)
C80.83778 (9)1.11508 (14)0.20254 (9)0.0195 (2)
C90.93465 (9)1.14174 (14)0.30709 (9)0.0186 (2)
C100.91694 (10)1.22467 (15)0.39561 (9)0.0206 (2)
H10A0.84221.26440.38960.025*
C111.01017 (11)1.24806 (15)0.49231 (10)0.0231 (2)
H11A0.99951.30470.55140.028*
C121.11907 (10)1.18496 (16)0.49832 (9)0.0230 (2)
C131.14030 (10)1.09925 (16)0.41347 (10)0.0228 (2)
H13A1.21491.05630.42120.027*
C141.04700 (9)1.07948 (15)0.31680 (9)0.0204 (2)
H14A1.05891.02450.25780.025*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
F10.0221 (3)0.0307 (4)0.0367 (4)0.0068 (3)0.0089 (3)0.0029 (3)
F20.0255 (4)0.0401 (5)0.0272 (4)0.0061 (3)0.0014 (3)0.0002 (3)
O10.0255 (4)0.0194 (4)0.0371 (5)0.0035 (3)0.0110 (4)0.0006 (3)
O20.0237 (4)0.0296 (4)0.0263 (4)0.0006 (3)0.0114 (3)0.0042 (3)
C10.0174 (5)0.0227 (5)0.0199 (5)0.0039 (4)0.0064 (4)0.0032 (4)
C20.0225 (5)0.0202 (5)0.0227 (5)0.0026 (4)0.0082 (4)0.0026 (4)
C30.0189 (5)0.0256 (6)0.0200 (5)0.0022 (4)0.0068 (4)0.0002 (4)
C40.0169 (5)0.0291 (6)0.0207 (5)0.0041 (4)0.0062 (4)0.0011 (4)
C50.0199 (5)0.0220 (5)0.0190 (5)0.0051 (4)0.0070 (4)0.0014 (4)
C60.0179 (5)0.0207 (5)0.0166 (4)0.0024 (4)0.0065 (4)0.0016 (4)
C70.0192 (5)0.0216 (5)0.0200 (5)0.0023 (4)0.0075 (4)0.0014 (4)
C80.0189 (5)0.0162 (5)0.0251 (5)0.0003 (4)0.0097 (4)0.0009 (4)
C90.0184 (5)0.0148 (5)0.0238 (5)0.0002 (4)0.0089 (4)0.0014 (4)
C100.0199 (5)0.0183 (5)0.0264 (5)0.0001 (4)0.0118 (4)0.0011 (4)
C110.0272 (6)0.0203 (5)0.0243 (5)0.0031 (4)0.0121 (4)0.0010 (4)
C120.0215 (5)0.0212 (5)0.0240 (5)0.0046 (4)0.0050 (4)0.0033 (4)
C130.0177 (5)0.0213 (5)0.0302 (6)0.0005 (4)0.0093 (4)0.0045 (4)
C140.0207 (5)0.0172 (5)0.0263 (5)0.0013 (4)0.0118 (4)0.0020 (4)
Geometric parameters (Å, º) top
F1—C31.3551 (13)C6—C71.4751 (15)
F2—C121.3536 (14)C7—C81.5358 (15)
O1—C71.2209 (14)C8—C91.4764 (15)
O2—C81.2193 (13)C9—C101.3962 (15)
C1—C21.3836 (16)C9—C141.4009 (14)
C1—C61.3955 (15)C10—C111.3854 (17)
C1—H1A0.9300C10—H10A0.9300
C2—C31.3818 (15)C11—C121.3764 (17)
C2—H2A0.9300C11—H11A0.9300
C3—C41.3795 (17)C12—C131.3824 (17)
C4—C51.3825 (16)C13—C141.3826 (16)
C4—H4A0.9300C13—H13A0.9300
C5—C61.4005 (14)C14—H14A0.9300
C5—H5A0.9300
Cg1···Cg1i3.6416 (6)Cg2···Cg2ii3.7150 (7)
C2—C1—C6120.58 (10)O2—C8—C9123.53 (10)
C2—C1—H1A119.7O2—C8—C7116.53 (10)
C6—C1—H1A119.7C9—C8—C7119.81 (9)
C3—C2—C1117.70 (11)C10—C9—C14119.72 (10)
C3—C2—H2A121.1C10—C9—C8122.02 (9)
C1—C2—H2A121.1C14—C9—C8118.26 (9)
F1—C3—C4118.28 (10)C11—C10—C9120.35 (10)
F1—C3—C2118.08 (10)C11—C10—H10A119.8
C4—C3—C2123.64 (11)C9—C10—H10A119.8
C3—C4—C5118.03 (10)C12—C11—C10118.01 (10)
C3—C4—H4A121.0C12—C11—H11A121.0
C5—C4—H4A121.0C10—C11—H11A121.0
C4—C5—C6120.24 (10)F2—C12—C11118.37 (11)
C4—C5—H5A119.9F2—C12—C13118.00 (10)
C6—C5—H5A119.9C11—C12—C13123.63 (11)
C1—C6—C5119.80 (10)C12—C13—C14117.81 (10)
C1—C6—C7120.96 (10)C12—C13—H13A121.1
C5—C6—C7119.24 (10)C14—C13—H13A121.1
O1—C7—C6123.95 (10)C13—C14—C9120.44 (10)
O1—C7—C8117.05 (10)C13—C14—H14A119.8
C6—C7—C8118.80 (9)C9—C14—H14A119.8
C6—C1—C2—C30.53 (16)O1—C7—C8—C965.39 (14)
C1—C2—C3—F1179.13 (9)C6—C7—C8—C9119.59 (11)
C1—C2—C3—C40.89 (17)O2—C8—C9—C10174.49 (11)
F1—C3—C4—C5179.60 (9)C7—C8—C9—C101.26 (15)
C2—C3—C4—C50.41 (17)O2—C8—C9—C146.17 (16)
C3—C4—C5—C60.42 (15)C7—C8—C9—C14178.08 (9)
C2—C1—C6—C50.26 (16)C14—C9—C10—C110.97 (16)
C2—C1—C6—C7179.72 (10)C8—C9—C10—C11179.71 (10)
C4—C5—C6—C10.75 (15)C9—C10—C11—C120.93 (16)
C4—C5—C6—C7179.23 (10)C10—C11—C12—F2179.73 (10)
C1—C6—C7—O1174.32 (10)C10—C11—C12—C130.22 (17)
C5—C6—C7—O15.70 (16)F2—C12—C13—C14179.18 (10)
C1—C6—C7—C811.03 (15)C11—C12—C13—C141.31 (17)
C5—C6—C7—C8168.95 (9)C12—C13—C14—C91.24 (16)
O1—C7—C8—O2110.65 (12)C10—C9—C14—C130.15 (16)
C6—C7—C8—O264.37 (13)C8—C9—C14—C13179.20 (10)
Symmetry codes: (i) x+1, y+2, z; (ii) x+2, y+2, z+1.
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
C2—H2A···O1iii0.932.403.2648 (15)155
C11—H11A···O2iv0.932.513.3098 (16)145
Symmetry codes: (iii) x, y1, z; (iv) x, y+5/2, z+1/2.

Experimental details

Crystal data
Chemical formulaC14H8F2O2
Mr246.20
Crystal system, space groupMonoclinic, P21/c
Temperature (K)100
a, b, c (Å)12.1351 (2), 7.3500 (1), 13.1572 (2)
β (°) 110.507 (1)
V3)1099.16 (3)
Z4
Radiation typeMo Kα
µ (mm1)0.12
Crystal size (mm)0.39 × 0.30 × 0.28
Data collection
DiffractometerBruker SMART APEXII CCD area-detector
diffractometer
Absorption correctionMulti-scan
(SADABS; Bruker, 2005)
Tmin, Tmax0.903, 0.967
No. of measured, independent and
observed [I > 2σ(I)] reflections
14891, 3489, 2846
Rint0.022
(sin θ/λ)max1)0.724
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.042, 0.107, 1.06
No. of reflections3489
No. of parameters163
H-atom treatmentH-atom parameters constrained
Δρmax, Δρmin (e Å3)0.39, 0.21

Computer programs: APEX2 (Bruker, 2005), SAINT (Bruker, 2005), SHELXTL (Sheldrick, 2008) and PLATON (Spek, 2003).

Selected interatomic distances (Å) top
Cg1···Cg1i3.6416 (6)Cg2···Cg2ii3.7150 (7)
Symmetry codes: (i) x+1, y+2, z; (ii) x+2, y+2, z+1.
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
C2—H2A···O1iii0.93002.40003.2648 (15)155.00
C11—H11A···O2iv0.93002.51003.3098 (16)145.00
Symmetry codes: (iii) x, y1, z; (iv) x, y+5/2, z+1/2.
 

Footnotes

Additional correspondance author, e-mail: zsrkk@yahoo.com.

Acknowledgements

HKF and RK thank the Malaysian Government and Universiti Sains Malaysia for the Science Fund grant No. 305/PFIZIK/613312. RK thanks Universiti Sains Malaysia for the award of a post-doctoral research fellowship.

References

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Volume 64| Part 8| August 2008| Pages o1617-o1618
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