Acceleration of the pseudorotation rates in pentacoordinated phosphorus compounds. Conformational transmission versus hexacoordinated zwitterionic intermediates

Abstract

A variable-temperature 13C NMR study, accompanied by a high-resolution 1H NMR conformational analysis study, on a series of monocyclic oxyphosphoranes is reported. The selected compounds enabled us to study the acceleration of the rates of intramolecular ligand reorganization on pentacoordinated phosphorus. It allowed us to determine whether the enhancement of the reorganization rates was brought about by accelerated pseudorotation due to the conformational transmission effect or by the involvement of hexacoordinated zwitterionic phosphorus intermediates. The results of the study further substantiate the findings that the involvement of such hexacoordinated intermediates is of no importance in the type of oxyphosphoranes studied.