NMR investigation of stereochemical nonrigidity of five-coordinate phosphorus fluorides

Abstract

Phenomena associated with stereochemical nonrigidity of five-coordinate phosphorus fluorides (Berry pseudorotation and restricted rotation of different functional groups about the bond with the central phosphorus atom) have been analyzed. The main cause of restricted rotation ispπdπ bonding of unsharedp-electron pairs of substituents with vacantd-orbitals of the phosphorus. Additional stabilization of the molecule occurs when it is possible to form an H...F hydrogen bond between the liquid and an axial fluorine atom in the phosphorane. The relationship between pseudorotation and restricted rotation is considered.