About the structure of phosphorus ylides: electron distribution and geometry
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)]
Keywords: Nuclear magnetic resonance (of phosphorus ylides ; multinuclear ; electron distribution and geometry in relation to); Ylides Role: PRP (Properties) (phosphorus ; NMR of ; electron distribution and geometry in relation to) ; phosphorus ylide carbon NMR; electron distribution geometry phosphorus ylide
Organometallic and Organometalloidal Compounds
Inst. Chim. Org.,Univ. Lausanne,Lausanne,Switz.
written in English.
7723-14-0 Role: RCT (Reactant), RACT (Reactant or reagent) (nuclear magnetic resonance, of phosphorus ylides, multinuclear, electron distribution and geometry in relation to)
Record created on 2006-03-03, modified on 2016-08-08