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Acta Crystallogr Sect E Struct Rep Online. 2008 August 1; 64(Pt 8): o1615–o1616.
Published online 2008 July 31. doi:  10.1107/S1600536808023386
PMCID: PMC2962226

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

Abstract

In the mol­ecule of the title compound, C16H14O2, a substituted benzil, the dicarbonyl unit has an s-trans conformation. This conformation is substanti­ated by the O—C—C—O torsion angle of 108.16 (15)°. The dihedral angle between the two aromatic rings is 72.00 (6)°. In the crystal structure, neighbouring mol­ecules are linked together by weak inter­molecular C—H(...)O hydrogen bonds and weak inter­molecular C—H(...)π inter­actions. In addition, the crystal structure is further stabilized by inter­molecular π–π inter­actions with centroid–centroid distances in the range 3.6000 (8)–3.8341 (8) Å.

Related literature

For bond-length data, see Allen et al. (1987 [triangle]). For carbonyl–carbonyl interactions, see Allen et al. (1998 [triangle]). For related structures and applications, see, for example: Fun & Kia, (2008 [triangle]); Kaftory & Rubin, (1983 [triangle]); Frey et al. (1995 [triangle]); Crowley et al. (1983 [triangle]); More et al. (1987 [triangle]); Brown et al. (1965 [triangle]); Gabe et al. (1981 [triangle]); Kimura et al. (1979 [triangle]); Stevens & Dubois (1962 [triangle]); Shimizu & Bartlett, (1976 [triangle]); Rubin (1978 [triangle]).

An external file that holds a picture, illustration, etc.
Object name is e-64-o1615-scheme1.jpg

Experimental

Crystal data

  • C16H14O2
  • M r = 238.27
  • Monoclinic, An external file that holds a picture, illustration, etc.
Object name is e-64-o1615-efi1.jpg
  • a = 6.5658 (1) Å
  • b = 7.0916 (1) Å
  • c = 26.5958 (5) Å
  • β = 96.473 (1)°
  • V = 1230.46 (3) Å3
  • Z = 4
  • Mo Kα radiation
  • μ = 0.08 mm−1
  • T = 100.0 (1) K
  • 0.30 × 0.22 × 0.09 mm

Data collection

  • Bruker SMART APEXII CCD area-detector diffractometer
  • Absorption correction: multi-scan (SADABS; Bruker, 2005 [triangle]) T min = 0.975, T max = 0.993
  • 15023 measured reflections
  • 3562 independent reflections
  • 2473 reflections with I > 2σ(I)
  • R int = 0.046

Refinement

  • R[F 2 > 2σ(F 2)] = 0.052
  • wR(F 2) = 0.129
  • S = 1.04
  • 3562 reflections
  • 165 parameters
  • H-atom parameters constrained
  • Δρmax = 0.34 e Å−3
  • Δρmin = −0.23 e Å−3

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

Table 1
Selected distances (Å)
Table 2
Hydrogen-bond geometry (Å, °)

Supplementary Material

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536808023386/at2603sup1.cif

Structure factors: contains datablocks I. DOI: 10.1107/S1600536808023386/at2603Isup2.hkl

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

Acknowledgments

HKF and RK thanks 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.

supplementary crystallographic information

Comment

Investigation of the photophysical properties of the α-dicarbonyls has focused on the intramolecular carbonyl group electronic interaction as a function of their geometrical relationship. As in previous extensive studies of the photochemistry (Stevens & Dubois, 1962; Shimizu & Bartlett, 1976) of these compounds, 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 normally sp2sp2 single bonds, such as in butadiene. This is probably the result of decreasing the unfavourable vicinal dipole-dipole interactions. The dicarbonyl unit has s-trans conformation as can be indicated by the torsion angles of O1–C7–C6–C1, and O2–C8–C9–C10 being 169.55 (13) and 179.45 (14)°, respectively. This conformation is substantiated by the torsion angle of O–C–C–O, being 108.16 (15)°. The overal effect is to maximize the distance between the two electronegative oxygen atoms [O1···O2 = 3.1702 (15) 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 hydrogen bond and weak intermolecular C—H···π interaction. The packing mode (Fig. 2) tend to be dominated by van der Wwaals close packing considerations and the preference for aligning the substituted phenyl rings parallel to each other along the a axis at about 3.6000 (8) – 3.8341 (8) Å.

Experimental

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

Refinement

All of the hydrogen atoms were positioned geometrically and refined using a riding model with isotropic thermal parameters 1.2 or 1.5 times that of the parent atom.

Figures

Fig. 1.
The molecular structure of (I) with atom labels and 50% probability ellipsoids for non-H atoms.
Fig. 2.
The crystal packing, showing parallel aligning of the benzene rings along the a-axis, and stacking of the molecules down the b-axis. Intermolecular interactions are shown as dashed lines.

Crystal data

C16H14O2F000 = 504
Mr = 238.27Dx = 1.286 Mg m3
Monoclinic, P21/nMo Kα radiation λ = 0.71073 Å
Hall symbol: -P 2ynCell parameters from 2861 reflections
a = 6.5658 (1) Åθ = 3.0–29.0º
b = 7.0916 (1) ŵ = 0.08 mm1
c = 26.5958 (5) ÅT = 100.0 (1) K
β = 96.473 (1)ºBlock, colourless
V = 1230.46 (3) Å30.30 × 0.22 × 0.09 mm
Z = 4

Data collection

Bruker SMART APEXII CCD area-detector diffractometer3562 independent reflections
Radiation source: fine-focus sealed tube2473 reflections with I > 2σ(I)
Monochromator: graphiteRint = 0.046
T = 100.0(1) Kθmax = 30.0º
[var phi] and ω scansθmin = 3.0º
Absorption correction: multi-scan(SADABS; Bruker, 2005)h = −9→9
Tmin = 0.975, Tmax = 0.993k = −9→9
15023 measured reflectionsl = −37→37

Refinement

Refinement on F2Secondary atom site location: difference Fourier map
Least-squares matrix: fullHydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.053H-atom parameters constrained
wR(F2) = 0.129  w = 1/[σ2(Fo2) + (0.0539P)2 + 0.2688P] where P = (Fo2 + 2Fc2)/3
S = 1.05(Δ/σ)max < 0.001
3562 reflectionsΔρmax = 0.34 e Å3
165 parametersΔρmin = −0.23 e Å3
Primary atom site location: structure-invariant direct methodsExtinction correction: none

Special details

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)

xyzUiso*/Ueq
O10.78303 (16)0.85817 (16)0.10574 (4)0.0265 (3)
O20.52337 (16)0.56364 (16)0.16163 (4)0.0284 (3)
C10.7563 (2)0.3603 (2)0.07576 (5)0.0216 (3)
H1A0.75850.31420.10860.026*
C20.7544 (2)0.2362 (2)0.03573 (5)0.0228 (3)
H2A0.75720.10710.04190.027*
C30.7484 (2)0.3022 (2)−0.01380 (5)0.0211 (3)
C40.7468 (2)0.4963 (2)−0.02211 (5)0.0206 (3)
H4A0.74220.5422−0.05500.025*
C50.7519 (2)0.6211 (2)0.01774 (5)0.0202 (3)
H5A0.75330.75020.01170.024*
C60.7550 (2)0.5541 (2)0.06734 (5)0.0193 (3)
C70.7559 (2)0.6884 (2)0.10961 (5)0.0200 (3)
C80.7002 (2)0.6162 (2)0.16073 (5)0.0210 (3)
C90.8525 (2)0.6278 (2)0.20558 (5)0.0197 (3)
C101.0524 (2)0.6905 (2)0.20242 (5)0.0216 (3)
H10A1.09340.72070.17100.026*
C111.1896 (2)0.7079 (2)0.24546 (5)0.0234 (3)
H11A1.32230.74950.24280.028*
C121.1314 (2)0.6638 (2)0.29296 (5)0.0233 (3)
C130.9340 (2)0.5956 (2)0.29583 (5)0.0237 (3)
H13A0.89490.56140.32710.028*
C140.7955 (2)0.5781 (2)0.25295 (5)0.0219 (3)
H14A0.66410.53310.25560.026*
C150.7434 (2)0.1652 (2)−0.05715 (6)0.0273 (4)
H15A0.70750.2309−0.08850.041*
H15B0.64360.0690−0.05330.041*
H15C0.87610.1084−0.05730.041*
C161.2805 (3)0.6890 (3)0.33977 (6)0.0316 (4)
H16A1.21280.66290.36920.047*
H16B1.33020.81640.34130.047*
H16C1.39350.60380.33870.047*

Atomic displacement parameters (Å2)

U11U22U33U12U13U23
O10.0327 (6)0.0224 (6)0.0251 (5)−0.0009 (5)0.0062 (4)0.0025 (5)
O20.0246 (5)0.0343 (7)0.0271 (6)−0.0046 (5)0.0065 (4)0.0017 (5)
C10.0216 (7)0.0247 (8)0.0185 (6)0.0009 (6)0.0020 (5)0.0042 (6)
C20.0222 (7)0.0208 (8)0.0254 (7)0.0003 (6)0.0027 (6)0.0019 (6)
C30.0152 (6)0.0268 (8)0.0213 (7)0.0002 (6)0.0028 (5)−0.0007 (6)
C40.0160 (6)0.0282 (8)0.0178 (6)0.0001 (6)0.0020 (5)0.0043 (6)
C50.0171 (6)0.0221 (8)0.0215 (7)0.0012 (6)0.0028 (5)0.0054 (6)
C60.0157 (6)0.0233 (8)0.0189 (6)0.0003 (6)0.0027 (5)0.0021 (6)
C70.0171 (6)0.0230 (8)0.0202 (7)0.0010 (6)0.0030 (5)0.0031 (6)
C80.0245 (7)0.0186 (8)0.0205 (6)−0.0001 (6)0.0060 (6)−0.0002 (6)
C90.0245 (7)0.0154 (7)0.0199 (6)0.0012 (6)0.0059 (5)0.0001 (6)
C100.0257 (7)0.0211 (8)0.0192 (6)0.0011 (6)0.0073 (6)0.0022 (6)
C110.0218 (7)0.0216 (8)0.0272 (7)−0.0003 (6)0.0041 (6)0.0024 (6)
C120.0308 (8)0.0161 (7)0.0226 (7)0.0027 (6)0.0007 (6)0.0013 (6)
C130.0339 (8)0.0189 (8)0.0195 (7)0.0026 (7)0.0081 (6)0.0017 (6)
C140.0242 (7)0.0191 (8)0.0237 (7)−0.0004 (6)0.0087 (6)0.0005 (6)
C150.0258 (8)0.0311 (9)0.0251 (7)−0.0013 (7)0.0037 (6)−0.0040 (7)
C160.0381 (9)0.0292 (9)0.0261 (8)−0.0001 (8)−0.0032 (7)0.0022 (7)

Geometric parameters (Å, °)

O1—C71.2231 (18)C9—C141.3992 (18)
O2—C81.2221 (17)C10—C111.380 (2)
C1—C21.380 (2)C10—H10A0.9300
C1—C61.393 (2)C11—C121.3960 (19)
C1—H1A0.9300C11—H11A0.9300
C2—C31.394 (2)C12—C131.393 (2)
C2—H2A0.9300C12—C161.505 (2)
C3—C41.394 (2)C13—C141.382 (2)
C3—C151.505 (2)C13—H13A0.9300
C4—C51.378 (2)C14—H14A0.9300
C4—H4A0.9300C15—H15A0.9600
C5—C61.3999 (18)C15—H15B0.9600
C5—H5A0.9300C15—H15C0.9600
C6—C71.473 (2)C16—H16A0.9600
C7—C81.5350 (19)C16—H16B0.9600
C8—C91.470 (2)C16—H16C0.9600
C9—C101.398 (2)
O1···O23.1702 (15)Cg1···Cg1ii3.8341 (8)
Cg1···Cg1i3.6000 (8)
C2—C1—C6120.39 (13)C11—C10—C9120.56 (13)
C2—C1—H1A119.8C11—C10—H10A119.7
C6—C1—H1A119.8C9—C10—H10A119.7
C1—C2—C3120.77 (15)C10—C11—C12120.72 (14)
C1—C2—H2A119.6C10—C11—H11A119.6
C3—C2—H2A119.6C12—C11—H11A119.6
C4—C3—C2118.69 (13)C13—C12—C11118.59 (13)
C4—C3—C15121.12 (13)C13—C12—C16121.20 (13)
C2—C3—C15120.19 (14)C11—C12—C16120.21 (14)
C5—C4—C3120.87 (13)C14—C13—C12121.06 (13)
C5—C4—H4A119.6C14—C13—H13A119.5
C3—C4—H4A119.6C12—C13—H13A119.5
C4—C5—C6120.22 (14)C13—C14—C9120.15 (13)
C4—C5—H5A119.9C13—C14—H14A119.9
C6—C5—H5A119.9C9—C14—H14A119.9
C1—C6—C5119.05 (13)C3—C15—H15A109.5
C1—C6—C7121.06 (12)C3—C15—H15B109.5
C5—C6—C7119.89 (13)H15A—C15—H15B109.5
O1—C7—C6124.07 (12)C3—C15—H15C109.5
O1—C7—C8117.04 (13)H15A—C15—H15C109.5
C6—C7—C8118.65 (13)H15B—C15—H15C109.5
O2—C8—C9124.19 (12)C12—C16—H16A109.5
O2—C8—C7116.15 (12)C12—C16—H16B109.5
C9—C8—C7119.47 (12)H16A—C16—H16B109.5
C10—C9—C14118.86 (13)C12—C16—H16C109.5
C10—C9—C8121.78 (12)H16A—C16—H16C109.5
C14—C9—C8119.35 (13)H16B—C16—H16C109.5
C6—C1—C2—C3−0.9 (2)O1—C7—C8—C9−67.01 (18)
C1—C2—C3—C40.8 (2)C6—C7—C8—C9118.41 (15)
C1—C2—C3—C15−179.15 (13)O2—C8—C9—C10−179.46 (15)
C2—C3—C4—C50.3 (2)C7—C8—C9—C10−4.7 (2)
C15—C3—C4—C5−179.83 (13)O2—C8—C9—C14−0.6 (2)
C3—C4—C5—C6−1.2 (2)C7—C8—C9—C14174.18 (13)
C2—C1—C6—C50.0 (2)C14—C9—C10—C11−1.8 (2)
C2—C1—C6—C7179.66 (13)C8—C9—C10—C11177.11 (14)
C4—C5—C6—C11.0 (2)C9—C10—C11—C12−0.1 (2)
C4—C5—C6—C7−178.64 (12)C10—C11—C12—C132.2 (2)
C1—C6—C7—O1169.54 (14)C10—C11—C12—C16−178.16 (14)
C5—C6—C7—O1−10.8 (2)C11—C12—C13—C14−2.3 (2)
C1—C6—C7—C8−16.28 (19)C16—C12—C13—C14178.02 (14)
C5—C6—C7—C8163.39 (12)C12—C13—C14—C90.4 (2)
O1—C7—C8—O2108.17 (16)C10—C9—C14—C131.6 (2)
C6—C7—C8—O2−66.42 (18)C8—C9—C14—C13−177.28 (13)

Symmetry codes: (i) −x+1, −y+1, −z; (ii) −x+2, −y+1, −z.

Hydrogen-bond geometry (Å, °)

D—H···AD—HH···AD···AD—H···A
C2—H2A···O1iii0.932.443.2573 (18)146
C14—H14A···Cg2iv0.932.943.6105 (15)130

Symmetry codes: (iii) x, y−1, z; (iv) −x+3/2, y−1/2, −z+1/2.

Footnotes

Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: AT2603).

References

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