The structures of acetylacetone, trifluoroacetyl-acetone and trifluoroacetone

Andreassen, A. L.; Bauer, S. H.

doi:10.1016/0022-2860(72)87047-9

Cited by 115 publications

(56 citation statements)

References 29 publications

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“…The present MINDO/3 calculations gave a value of 1.35 Ä for the C -F bond length, in satisfactory agree ment with the observed value of 1.34 Ä reported [3,4] for other fluorinated acyclic /?-diketones, but over estimate the C -H bond lengths, which is known to be a systematic error of the MINDO/3 method [30].…”

Section: Geometries and Enthalpies Of Formationsupporting

confidence: 74%

“…Gas phase electron diffraction measurements on acetylacetone [2], trifluoroacetylacetone [3], and hexafluoroacetylacetone [4] gave short O ... O nonbonded distances (2.38-2.55 Ä), which has been taken as evidence for a symmetric enol form with linear hydrogen bond whereas x-ray diffraction studies on benzoylacetone [5] and dibenzoylmethane [6] suggest an asymmetric enol form with non-linear hydrogen bond. Egan and coworkers [10] have carried out 13C and 2H spin-relaxation time and deuterium quadru pole coupling constant measurements and concluded that the intramolecular hydrogen bond in acetyl acetone is asymmetrical and that the potential energy function is of double minimum type.…”

Section: Introductionmentioning

confidence: 98%

“…Although numerous experimental investigations [1][2][3][4][5][6][7][8][9][10][11][12][13][14] and molecular orbit calculations [15][16][17][18][19][20][21][22] of varying sophistication have been reported on the structure of the intramolecularly hydrogen bonded eis enol form of acetylacetone and related molecules, they disagree on the nature of the potential energy function and the symmetry of the intramolecular hydrogen bond. Gas phase electron diffraction measurements on acetylacetone [2], trifluoroacetylacetone [3], and hexafluoroacetylacetone [4] gave short O ... O nonbonded distances (2.38-2.55 Ä), which has been taken as evidence for a symmetric enol form with linear hydrogen bond whereas x-ray diffraction studies on benzoylacetone [5] and dibenzoylmethane [6] suggest an asymmetric enol form with non-linear hydrogen bond.…”

Section: Introductionmentioning

confidence: 99%

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MINDO/3 Investigation of the Structure of the Intramolecularly Hydrogen Bonded Enol Forms of 2 -Trifluoroacetylcycloalkanones

Ebraheem¹,

Hamdi

Al-Derzi³

1989

Zeitschrift Für Naturforschung A

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MINDO/3 SCF-MO calculations with full geometry optimization were performed to determine the structure of the intramolecularly hydrogen bonded enol forms of 2-trifluoroacetylcycloalkanones. The presence of two stable exocyclic and endocyclic enol forms with a non-planar unsymmetric hydrogen bonded chelate ring is established. It is found that the intramolecular hydrogen bond is weaker in the exocyclic enol of 2-trifluoroacetylcyclopentanone, which showed greater deviation from planarity by ~23.8°. The geometrical features predicted by the MINDO/3 method and the calculated charge distribution are discussed and found to agree with the available experimental data on these systems. The merits and limitations of the MINDO/3 method are discussed.

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Section: Geometries and Enthalpies Of Formationsupporting

confidence: 74%

Section: Introductionmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

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MINDO/3 Investigation of the Structure of the Intramolecularly Hydrogen Bonded Enol Forms of 2 -Trifluoroacetylcycloalkanones

Ebraheem¹,

Hamdi

Al-Derzi³

1989

Zeitschrift Für Naturforschung A

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“…Consequently, a significant improvement upon the STO-3G results for the two series is not expected as a result of reoptimization at the '4-3 IG' level. This is further justified by the poor agreement between the theoretical '4-3 1G' geometries of CF,COCH, and CF3COCF, with the experimental results of Adreassen and Bauer (23) and Bauer and co-workers (24), respectively. This paper reports the first extensive theoretical study on the structures of the fluoroacetones and their conjugate acids.…”

Section: Equilibrium Structuresmentioning

confidence: 86%

Equilibrium structures, proton affinities, and ionization potentials of the fluoroacetones

Choi¹,

Boyd²

1985

Can. J. Chem.

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. Can. J . Chem. 63, 836 (1985). Theoretical calculations on the fluoroacetones and their conjugate acids exhibit an inverse dependence of the proton affinity on the number of fluorine substituents. The good correlation between increasing proton affinity and decreasing ionization potential is attributed to the observation that the ionization of a nonbonding electron is essentially localized at a single atom which is also the site of protonation. The best quantitative agreement between the theoretical and experimental proton affinities is obtained at the 6-31G* level, while the STO-3G basis set leads to a satisfactory account of the additivity of fluorine substituents. The calculations corroborate the experimental interpretation of the preferred conformations of p-fluoroacetone molecules in terms of the presence of an intramolecular hydrogen bond between the carbonyl proton and the F on the adjacent carbon. Only one type of equilibrium conformation is predicted for the fluorinated acetones, whereas two types of equilibrium conformations are predicted for the conjugate bases. [Traduit par le journal] Introduction One of the major challenges of chemistry is to predict the effect of substituents on the properties of molecules and to develop models and theories which facilitate a better understanding of substituent effects. Most systematic studies of substituent effects have been carried out in solution, where the observed properties are often more a reflection of the effects of solvation than of the intrinsic properties of the species of interest. Recent advances in physical chemistry have provided several powerful methods for studying the reactions and structures of ions in the gas phase. Complementary information on the intrinsic properties of molecules and ions is provided, however, by ab inirio molecular orbital theory.Ion cyclotron resonance studies (1) of the gas-phase basicities of six fluorinated acetones have revealed a very regular decrease in proton affinity of 6.1 t 0.4 kcal/mol for each successive fluorine substituent. This result has been interpreted in terms of a substituent effect which is almost purely inductive and correlates well with the group electronegativity of the methyl substituents. Furthermore, the linear dependence of the observed proton affinities on the number of fluorine substituents reveals a small stabilizing interaction of 2-3 kcal/mol in the protonated fluoroacetones, which is attributed to the formation of an intramolecular hydrogen bond. The additivity of fluorine substituent effects in the gas-phase basicities of fluorinated acetones stands in contrast to the less regular changes in acidities and basicities which are often associated, both in solution and in the gas phase, with multiple substitution in organic molecules (2, 3).The Drummond and McMahon study of the fluorinated acetones is a remarkable application of one of the three tech-

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“…Microwave experiments have determined a C s structure for MA with a d OO distance measured at 255 pm [1] whereas for AA, photon electron spectroscopy [2,3] and x-ray diffraction [4,5] have predicted a C 2v structure. Nevertheless, electron diffraction results are contradictory [2,6,7], predicting a C s or a C 2v structure. A recent ultra fast electron diffraction study of Zewail et al [8] has demonstrated that, at least at the short timescale (~100 ps), the AA structure is asymmetrical with a d OO distance of 259 pm, 8 pm larger than the previous estimation [6].…”

Section: Introductionmentioning

confidence: 99%

Comparative study of structure and photo-induced reactivity of malonaldehyde and acetylacetone isolated in nitrogen matrices

Trivella¹,

Coussan²,

Chiavassa³

et al. 2006

Low Temperature Physics

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Structure and reactivity of the eight enolic forms (one chelated and seven non-chelated) of malonaldehyde and acetylacetone are compared through theoretical and experimental data. Ground-state geometries, energies, and vibrational frequencies are calculated with the B3LYP/6-311++G(2d,2p) model chemistry. The electronic delocalisation as well as the cis/trans rotamer properties are analysed. The hydrogen bond strength of the chelated forms can be estimated by the energy difference between chelated and non-chelated forms, and its enhancement due to methyl-induced electron release is estimated at 1.7 kcal·mol -1 . UV-and IR-induced reactivity of molecules isolated in nitrogen matrices is studied by means of FT-IR spectrometry. Interconversion between rotamers is the main process observed for both molecules, only some among the seven non-chelated forms being created.PACS: 36.20.Ng, 31.15.Ar

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The structures of acetylacetone, trifluoroacetyl-acetone and trifluoroacetone

Cited by 115 publications

References 29 publications

MINDO/3 Investigation of the Structure of the Intramolecularly Hydrogen Bonded Enol Forms of 2 -Trifluoroacetylcycloalkanones

MINDO/3 Investigation of the Structure of the Intramolecularly Hydrogen Bonded Enol Forms of 2 -Trifluoroacetylcycloalkanones

Equilibrium structures, proton affinities, and ionization potentials of the fluoroacetones

Comparative study of structure and photo-induced reactivity of malonaldehyde and acetylacetone isolated in nitrogen matrices

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