Structure of acetylacetone by electron diffraction

Lowrey, Alfred H.; George, C.; D’Antonio, Peter; Karle, J.

doi:10.1021/ja00753a011

Cited by 183 publications

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“…Information on this latter parameter could also be brought through the d OO distance, the O-H stretching, height, frequency, or the energy difference between nonchelated and CCC forms. 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.…”

Section: Introductionmentioning

confidence: 99%

“…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%

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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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Section: Introductionmentioning

confidence: 99%

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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“…Both in solution and in the vapour phase (Lowrey, George, D'Antonio & Karle, 1971), 1,3-diketones R'COCH2COR" generally exist as equilibrium mixtures of keto and enol tautomers where the enol tautomer contains a six-membered hydrogen-bonded ring.…”

Section: Commentmentioning

confidence: 99%

4-(Ferrocenylmethyl)-2,2,6,6-tetramethyl-3,5-heptanedione, a non-enolized 1,3-diketone

Ferguson¹,

Glidewell²,

Zakaria³

1994

Acta Crystallogr C

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Program(s) used to solve structure: SHELXTL-Plus (Sheldrick, 1991). Program(s) used to refine structure: SHELXL93 (Sheldrick, 1993 AbstractThe analysis of the title compound, (r/5-cyclopentadien -shows that it exists in the solid state in the diketo form; there is no evidence at all for any keto-enol tautomeric contribution to the ground-state structure. CommentBoth in solution and in the vapour phase (Lowrey, George, D'Antonio & Karle, 1971), 1,3-diketones R'COCH2COR" generally exist as equilibrium mixtures of keto and enol tautomers where the enol tautomer contains a six-membered hydrogen-bonded ring.In the solid state, however, only a single form is generally observed. This is most frequently the enol form in which the hydrogen-bonded ring is virtually planar with the two C---O bonds necessarily cis (T~nnesen, Karlsen & Mostad, 1982;TCnnesen, Karlsen, Mostad, Pedersen, Rasmussen & Lawesson, 1983;Etter, Jahn & Urbanczyk-Lipkowska, 1987;Baxter, Blake, Heath & Stephenson, 1990 (Gyepes, Glowiak, Toma & Sold~inov~i, 1984) the ring containing the 1,3-diketone fragment is twisted severely as a result of the ring strain in the [3]ferrocenophane skeleton, so that enolization is again prevented. However, in the acyclic diketone 2-ethyl-1,3-diphenyl-l,3-propanedione, (PhCO)2CHC2H5 (MuUica, Karban & Grossie, 1987), the solid-state structure again indicates a complete lack of enolization associated with a markedly non-planar O==C~C---C==O fragment, although 1,3-diphenyl-1,3-propanedione itself is wholly in the enol form in both crystalline modifications (Jones, 1976a;Etter, Jahn & Urbanczyk-Lipkowska, 1987). In a study of the 1-ferrocenyldiketone [(CsHs)Fe-{(CsH4)COCH2COCH3}], it was found (Bell, Crayston, Glidewell, Mazid & Hursthouse, 1992) that in chloroform solution the enol:keto ratio was ca 17:1, but in the solid state both XSC CP-MAS (cross-polarization magic angle spinning) NMR and X-ray diffraction revealed only the enol form, 1-ferrocenyl-3-hydroxybut-2-en-l-one. In contrast, the 4-ferrocenylmethyl derivative [(CsHs)Fe{(CsHn)CH2CH(COCMe3)2}] (I) exhibits an enol:keto ratio in chloroform solution of 1:3 (Zakaria, Morrison, McAndrew, Bell & Glidewell, 1994), suggesting that, like (PhCO)2CHC2Hs, it might exist in the solid state solely in the diketo form. Here we report a single-crystal X-ray study of this compound which confirms that in the solid state it is indeed a non-enolizedCompound (I) crystallizes in the triclinic system (space group Pi) with one molecule in the asymmetric unit. The structure comprises isolated molecules with no short intermolecular contacts. In the --CH2CH(COCMe3)2 substituent, the C2---C3 and C2--C5 bond lengths (Table 2, Fig. 1) are typical of those in unenolized 1,3-diketones (range 1.507-1.537 ,~; Gyepes, Glowiak, Toma & Sold~inov~i, 1984;Gyepes, Glowiak & Toma, 1986;Mullica, Karban & Grossie, 1987), whereas in enolized 1,3-diketones the corresponding C---C distances lie in the range 1.34-1.43/~ (Bell, Crayston, Glidewell, Mazid & Hursthouse, 1992).The C3---O1 and C5----O2 distance...

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“…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%

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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Structure of acetylacetone by electron diffraction

Cited by 183 publications

References 0 publications

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

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

4-(Ferrocenylmethyl)-2,2,6,6-tetramethyl-3,5-heptanedione, a non-enolized 1,3-diketone

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

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