Publication

About the structure of phosphorus ylides: electron distribution and geometry

Manfred Schlosser
1990
Journal Articles

Abstract

Using 13C-chem. shifts as a probe for the electronic environment of carbon centers, triphenylphosphoniomethanide, the model case of a reactive phosphorus ylide, have much more zwitterion than PC double bond character. Triphenylphosphoniopropenide (triphenylphosphonium-allyide), a moderated ylide, accumulates electron excess mainly at the a-carbon atom, whereas triphenylphosphonioethenoate (formyl-methylenetriphenylphosphorane) and other stabilized ylides carry roughly equal fractions of neg. charge at the a-carbon and the oxygen atom. The one-bond C,H coupling const. of triphenylphosphoniomethanide argues against a perfectly planar ylide center. The three-bond P,C coupling consts. permit the assignment of endo- or exo-configurations to ylides having an allyl-type side-chain. [on SciFinder (R)]

Official source

https://infoscience.epfl.ch/entities/publication/861645f9-f7f6-403c-a50b-b8ecb69bb0d5

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Manfred Schlosser
1990
Journal Articles

Abstract

Official source

https://infoscience.epfl.ch/entities/publication/861645f9-f7f6-403c-a50b-b8ecb69bb0d5

About this result

Related concepts (32)

Carbon

Carbon () is a chemical element with the symbol C and atomic number 6. It is nonmetallic and tetravalent—its atom making four electrons available to form covalent chemical bonds. It belongs to group 14 of the periodic table. Carbon makes up about 0.025 percent of Earth's crust. Three isotopes occur naturally, ^12C and ^13C being stable, while ^14C is a radionuclide, decaying with a half-life of about 5,730 years. Carbon is one of the few elements known since antiquity.

Covalent bond

A covalent bond is a chemical bond that involves the sharing of electrons to form electron pairs between atoms. These electron pairs are known as shared pairs or bonding pairs. The stable balance of attractive and repulsive forces between atoms, when they share electrons, is known as covalent bonding. For many molecules, the sharing of electrons allows each atom to attain the equivalent of a full valence shell, corresponding to a stable electronic configuration. In organic chemistry, covalent bonding is much more common than ionic bonding.

Chemical bond

A chemical bond is a lasting attraction between atoms or ions that enables the formation of molecules, crystals, and other structures. The bond may result from the electrostatic force between oppositely charged ions as in ionic bonds, or through the sharing of electrons as in covalent bonds. The strength of chemical bonds varies considerably; there are "strong bonds" or "primary bonds" such as covalent, ionic and metallic bonds, and "weak bonds" or "secondary bonds" such as dipole–dipole interactions, the London dispersion force, and hydrogen bonding.