Etude de complexes acide de Lewis–halogénure d'acide. II. Structure cristalline du tétrachlorogallate d'éthyl oxocarbonium et de l'hexachloroantimonate d'isopropyl oxocarbonium

Carpentier, J. M. Le; Weiss, Raymond

doi:10.1107/s0567740872004418

Cited by 13 publications

(1 citation statement)

References 6 publications

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“…The geometry of propionyl cation CH 3 CH 2 CO + ( 4 ) at the B3LYP/6-31G** level is in agreement with previous 18 ab initio calculations at the Hartree−Fock level and with an X-ray structure obtained for the salt CH 3 CH 2 CO + GaCl 4 - . The calculated C−O bond length of 1.126 Å in 4 agrees well with the experimental value of 1.099 Å in CH 3 CH 2 CO + GaCl 4 - .…”

Section: Resultssupporting

confidence: 88%

Protioacyl Dications: Hydrogen/Deuterium Exchange, Rearrangements, and Theoretical Studies¹

et al. 1996

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Hydrogen/deuterium exchange was observed by 2H-NMR spectroscopy at the CH3 groups of the long-lived alkanoyl cations CH3CH2CO+ (4), (CH3)2CHCO+ (8), and (CH3)3CCO+ (13) when treated with excess DF·SbF5 superacid. The intermediacy of the corresponding protio(deuterio)acylium dications is suggested to account for the exchanges. Under similar conditions, no exchange was observed in the acetyl ion CH3CO+ (1) in DF·SbF5, but at the same time its electrophilic reactivity is greatly enhanced in superacids. The acetyl cation in a superacidic medium also abstracts tertiary hydrogens of isoalkanes to give protonated acetaldehyde. Density functional theory calculations at the B3LYP/6-31G** level were carried out to support the suggested exchange mechanism as well as lack of exchange in the acetyl cation. On the basis of the calculated results, two alternative mechanisms are also suggested for the Nenitzescu rearrangement of pivaloyl chloride in isobutane with excess AlCl3.

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Section: Resultssupporting

confidence: 88%

Protioacyl Dications: Hydrogen/Deuterium Exchange, Rearrangements, and Theoretical Studies¹

et al. 1996

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Strukturen der intermediären Komplexe bei der Friedel‐Crafts‐Acylierung

Chevrier¹,

Weiss²

1974

Angewandte Chemie

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Additionsverbindungen aus Lewis-Sauren MX, und Saurehalogeniden R-COX treten intermediar bei der Friedel-Crafts-Acylierung auf. IR-und NMR-Untersuchungen dieser Zwischenprodukte haben die Existenz von Strukturisomeren wahrscheinlich gemacht. Bei der Rontgen-Strukturanalyse lassen sich zwei Formen unterscheiden: die Molekiilform, in der die Verbindungen als Donor-Acceptor-Komplexe R-CXO-t MX, vorliegen, und die Ionenform, in der sie als Oxocarbenium-Salze [R-CO]+[MX,+ I] ~ formuliert werden konnen. Die Verbindungen vom Donor-Acceptor-Typ R-CXO-tMX, zeichnen sich durch die Bildung einer koordinativen Sauerstoff-Metall-Bindung aus; der Elek tronenubergang vom Sauerstoff zum Metall des Acceptors riihrt immer von einer schwachen Donor-AcceptorWechselwirkung her. Die positive Ladung der Aryloxocarbenium-Ionen ist teilweise uber den aromatischen Kern delokalisiert. Im Gegensatz dazu befindet sich die positive Ladung bei den Alkyloxocarbenium-Ionen im wesentlichen auf dem Kohlenstoffatom der Carbonylgruppe, wie Berechnungen der Elektronendichteverteilung bestatigten.

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Structures of the Intermediate Complexes in Friedel‐Crafts Acylations

Chevrier

Weiss

1974

Angew. Chem. Int. Ed. Engl.

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Addition compounds of Lewis acids MX, and acyl halides R-COX occur as intermediates in Friedel-Crafts acylations. IR and NMR studies on these intermediates have indicated the probable existence of structural isomers. In X-ray structural analysis, it is possible to distinguish two forms, i.e. the molecular form, in which the compounds are present as donor-acceptor complexes R-CXO+MX,.and the ionic form, in which they can be formulated as oxocarbenium salts [R-CO]+ [MX, + ,I--. The compounds of the donor-acceptor type R-CXO+MX, are characterized by the formation of a coordinate oxygen-metal bond; the transfer of electrons from the oxygen to the metal of the acceptor is always due to a weak donor-acceptor interaction. The positive charge of the aryloxocarbenium ions is partly delocalized over the aromatic nucleus. The positive charge in alkyloxocarbenium ions, on the other hand, is essentially localized on the carbon atom of the carbonyl group, as is confirmed by electron density distribution calculations.

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Etude de complexes acide de Lewis–halogénure d'acide. II. Structure cristalline du tétrachlorogallate d'éthyl oxocarbonium et de l'hexachloroantimonate d'isopropyl oxocarbonium

Cited by 13 publications

References 6 publications

Protioacyl Dications: Hydrogen/Deuterium Exchange, Rearrangements, and Theoretical Studies¹

Protioacyl Dications: Hydrogen/Deuterium Exchange, Rearrangements, and Theoretical Studies¹

Strukturen der intermediären Komplexe bei der Friedel‐Crafts‐Acylierung

Structures of the Intermediate Complexes in Friedel‐Crafts Acylations

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Etude de complexes acide de Lewis–halogénure d'acide. II. Structure cristalline du tétrachlorogallate d'éthyl oxocarbonium et de l'hexachloroantimonate d'isopropyl oxocarbonium

Cited by 13 publications

References 6 publications

Protioacyl Dications: Hydrogen/Deuterium Exchange, Rearrangements, and Theoretical Studies1

Protioacyl Dications: Hydrogen/Deuterium Exchange, Rearrangements, and Theoretical Studies1

Strukturen der intermediären Komplexe bei der Friedel‐Crafts‐Acylierung

Structures of the Intermediate Complexes in Friedel‐Crafts Acylations

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Protioacyl Dications: Hydrogen/Deuterium Exchange, Rearrangements, and Theoretical Studies¹

Protioacyl Dications: Hydrogen/Deuterium Exchange, Rearrangements, and Theoretical Studies¹