Stéréochimie en pentacoordination. Apport des réactifs inducteurs de déplacement chimique à l'etude de spirophosphoranes à liaison P?H

The NMR spectra of eight spirophosphoranes bearing a P? H bond have been recorded in the presence of europium NMR shift reagent. The spectra are simplified by addition of the europium chelate. The observed displacements in the proton NMR lines allow the assignment of the endo and exo signals in some cases. By addition of the NMR shift reagent, one observes a displacement in the phosphite-spirophosphorane equilibrium in some cases.