Zur Struktur des Enols von Benzoylaceton / On the Structure of the Enol of Benzoylacetone

Winter, Werner; Zeller, Klaus‐Peter; Berger, Stefan

doi:10.1515/znb-1979-1124

Cited by 14 publications

(3 citation statements)

References 6 publications

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“…Winter and Zeller [792] investigated the enolic form of benzoylacetone-2 and demonstrated that the d( 17 O) values are practically solvent and temperature independent. The results were explained by an intramolecular hydrogen bonding model in which the proton tunnels between the two oxygen atoms.…”

Section: Intramolecular Hydrogen Bonding Effectsmentioning

confidence: 99%

Oxygen-17 NMR spectroscopy: Basic principles and applications (part II)

Gerothanassis

2010

Progress in Nuclear Magnetic Resonance Spectroscopy

105

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Section: Intramolecular Hydrogen Bonding Effectsmentioning

confidence: 99%

Oxygen-17 NMR spectroscopy: Basic principles and applications (part II)

Gerothanassis

2010

Progress in Nuclear Magnetic Resonance Spectroscopy

105

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“…Our 160 K U ij values are systematically 20±50% higher than those of Winter et al (1979) at 143 K, although the trends are similar.² The s.u.s of ND coordinates for non-H atoms are about twice as large as those from comparable XRD analyses, while those for hydrogen are about one-third. The atomic displacement parameters (ADPs, U ij ) also agree well.…”

Section: Comparison Of Various Re®nementsmentioning

confidence: 56%

X-ray and neutron diffraction study of benzoylacetone in the temperature range 8–300 K: comparison with other cis-enol molecules

Herbstein

Iversen

Kapon

et al. 1999

Acta Crystallogr Sect B

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The crystal structure of benzoylacetone (1-phenyl-1,3-butanedione, C(10)H(10)O(2); P2(1)/c, Z = 4) has been determined at 300, 160 (both Mo Kalpha X-ray diffraction, XRD), 20 (lambda = 1.012 Å neutron diffraction, ND) and 8 K (Ag Kalpha XRD), to which should be added earlier structure determinations at 300 (Mo Kalpha XRD and ND, lambda = 0.983 Å) and 143 K (Mo Kalpha XRD). Cell dimensions have been measured over the temperature range 8-300 K; a first- or second-order phase change does not occur within this range. The atomic displacement parameters have been analyzed using the thermal motion analysis program THMA11. The most marked change in the molecular structure is in the disposition of the methyl group, which has a librational amplitude of approximately 20 degrees at 20 K and is rotationally disordered at 300 K. The lengths of the two C-O bonds in the cis-enol ring do not differ significantly, nor do those of the two C-C bonds, nor do these lengths change between 8 and 300 K. An ND difference synthesis (20 K) shows a single enol hydrogen trough (rather than two half H atoms), approximately centered between the O atoms; analogous results were obtained by XRD (8 K). It is inferred that the enol hydrogen is in a broad, flat-bottomed single-minimum potential well between the O atoms, with a libration amplitude of approximately 0.30 Å at 8 K. These results suggest that at 8 K the cis-enol ring in benzoylacetone has quasi-aromatic character, in agreement with the results of high-level ab initio calculations made for benzoylacetone [Schiøtt et al. (1998). J. Am. Chem. Soc. 120, 12117-12124]. Application [in a related paper by Madsen et al. (1998). J. Am. Chem. Soc. 120, 10040-10045] of multipolar analysis and topological methods to the charge density obtained from the combined lowest temperature X-ray and neutron data provides evidence for an intramolecular hydrogen bond with partly electrostatic and partly covalent character, and large p-delocalization in the cis-enol ring. This is in good agreement with what is expected from the observed bond lengths. Analysis of the total available (through the Cambridge Structural Database, CSD) population of cis-enol ring geometries confirms earlier reports of correlation between the degree of bond localization in the pairs of C-C and C-O bonds, but does not show the dependence of bond localization on d(O.O) that was reported earlier for a more restricted sample. It is suggested that the only reliable method of determining whether the enol hydrogen is found in a single or double potential well is by low-temperature X-ray or (preferably) neutron diffraction.

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“…(7) 1.0114 (8) Keto-Enol tautomerism of 1,3-diketones such as bzac has been extensively studied [14]. Neutron diffraction and accurate low temperature X-ray diffraction reveals that within the conjugated enol ring of bzac the C-C bond furthest from the phenyl ring is slightly longer than the C-C bond nearest the phenyl ring [15,16]. The relatively longer C(15)-C(16) bond [1.404(4) Å ] and shorter C(14)-C(15) bond [1.388(4) Å ] in the structure agree well with the above conclusion.…”

Section: Crystal Structurementioning

confidence: 99%

Synthesis and Crystal Structure of an Mn(II) Complex with Benzoylacetone

Liu

Xü

2003

Journal of Coordination Chemistry

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The complex (benzoato)benzoylacetonato(bipyridine)Mn(II) has been prepared and its crystal structure determined by X-ray diffraction methods. Benzoic acid, benzoylacetone (bzac) and 2,2 0 -bipyridine all chelate to Mn(II) to form a six coordinate complex. As bond angles around the Mn(II) atom greatly deviate from those expected for an octahedron, the coordination geometry may be described as distorted pyramidal with a bidentate carboxyl group occupying the apex of the pyramid. Although the Mn atom deviates by 0.550 Å from the enol ring plane of bzac, Mn-O distances [2.105(2) and 2.098(2) Å ] are normal. This suggests the existence of electrostatic interactions between Mn(II) and the bzac ligand.

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Zur Struktur des Enols von Benzoylaceton / On the Structure of the Enol of Benzoylacetone

Cited by 14 publications

References 6 publications

Oxygen-17 NMR spectroscopy: Basic principles and applications (part II)

Oxygen-17 NMR spectroscopy: Basic principles and applications (part II)

X-ray and neutron diffraction study of benzoylacetone in the temperature range 8–300 K: comparison with other cis-enol molecules

Synthesis and Crystal Structure of an Mn(II) Complex with Benzoylacetone

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