Structure determination of benzil in its two phases

More, M.; Odou, G.; Jacques, Laurent

doi:10.1107/s0108768187097660

Cited by 57 publications

(53 citation statements)

References 9 publications

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“…In solution, however, the NMR spectra indicate that R/S interconversion is fast at room temperature, so that crystallization in P2~2121 represents a case of spontaneous resolution, or 'conglomerate crystallization' [Fe(C5H5) , 1985;Bernal, Cetrullo, Cai & Massoud, 1995). The intramolecular bond lengths and angles are unexceptional; the central C--C distance, 1.529 (5)~,, is very similar to the lengths found in butane-2,3-dione [gas-phase 1.524(3)A (Danielson & Hedberg, 1979), solid state 1.540 (6)A (Eriks et al, 1983)] and in benzil [trigonal high-temperature phase 1.523 (6) .~, monoclinic low-temperature phase 1.526 (13)-1.549 (16) ,~,, mean 1.536 A (More et al, 1987)]. …”

Section: Commentsupporting

confidence: 80%

“…Benzil, Ph-CO-CO-Ph, exhibits a similar value, 111.6 °, for this torsion angle in the solid state (Brown & Sadanaga, 1965;More, Odou & Lefebvre, 1987), and similar torsion angles have been found for a range of 4,4'-disubstituted benzils (XCrH4CO)2 (Kimura, McCluney & Watson, 1979;Crowley, Balanson & Mayerie, 1983). However, butane-2,3-dione, CH3---CO--CO-CH3 (Eriks, Hayden, Yang &Chan, 1983) and its 1,4-bis-diazo derivative (Hope & Black, 1972) are both centrosymmetric molecules in the solid state (P21/n, Z = 2) and hence adopt the trans-planar C2h conformation; similarly, this conformer was the sole rotamer found in the gas phase even at 798 K (Danielson & Hedberg, 1979).…”

Section: Commentmentioning

confidence: 53%

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1-Ferrocenyl-2-phenylethanedione

Glidewell¹,

Gottfried²,

Trotter³

et al. 1996

Acta Crystallogr C

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Section: Commentsupporting

confidence: 80%

Section: Commentmentioning

confidence: 53%

1-Ferrocenyl-2-phenylethanedione

Glidewell¹,

Gottfried²,

Trotter³

et al. 1996

Acta Crystallogr C

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“…83 K) presenting particularly interesting structural, electrical, and mechanical properties. 20,[48][49][50][51][52][53][54][55][56][57][58] However, to the best of our knowledge, no vibrational spectroscopic studies have been performed on gaseous benzil or for the compound isolated in a low-temperature inert matrix.…”

Section: Introductionmentioning

confidence: 99%

Matrix-Isolation FTIR Spectroscopy of Benzil: Probing the Flexibility of the C−C Torsional Coordinate

et al. 2004

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The infrared spectrum and conformational flexibility of benzil, (C 6 H 5 CO) 2 , are studied by matrix-isolation FTIR spectroscopy, supported by DFT calculations. It is shown that the low-frequency (ca. 25 cm -1 ), largeamplitude torsion around the C-C central bond strongly affects the structural and spectroscopic properties exhibited by the compound. The equilibrium conformational distribution of molecules with different OdC-CdO dihedral angles, existing at room temperature in the gas phase, and trapped in a low-temperature (T ) 9 K) inert matrix can be changed either by in situ irradiation with UV light (λ > 235 nm) or by annealing the matrix to higher temperatures (T ≈ 34 K). In the first case, the increase of the average OdC-CdO angle results from conformational relaxation in the excited electronic states (S 1 and T 1 ), whose lowest-energy conformations correspond, for both S 1 and T 1 states, to a nearly planar configuration with the OdC-CdO dihedral angle equal to 180°. In the second case, the decrease of the average value of the OdC-CdO dihedral angle is a consequence of the change in the S o C-C torsional potential, resulting from interactions with the matrix media, which favors the stability of the more polar structures with smaller OdC-CdO dihedral angles.

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“…The corresponding value in 1-ferrocenyl-2-phenylethanedione is -20.0 (4) ° and both values are essentially midway between the value for complete eclipsing of the rings (0 °) and the value for perfect staggering (-36°). The O1--C1--C2--O2 torsion angle is -120.0 (5) °, which is significantly larger than the values found for both 1-ferrocenyl-2-phenylethanedione [ 109.1 (5) ° ] and benzil (PhCOCOPh) [111.6°; Brown & Sadanaga, 1965;More, Odou & Lefebvre, 1987], although much less than the value of 180.0 ° found in the centrosymmetric molecules of butane-2,3-dione (MeCOCOMe) (Eriks, Hayden, Yang & Chan, 1983). The conformation found for (I) has (?2 symmetry, so that in the solid state the mop ecules are chiral.…”

mentioning

confidence: 65%