CYCLIC OXYPHOSPHORANES - P-31 CHEMICAL-SHIFT CORRELATIONS

Recent X-ray structures and solution NMR behavior of cyclic oxyphosphoranes are reviewed followed by a presentation of P-31 NMR chemical shift data for monocyclic and bicyclic oxyphosphoranes with rings varying from six- to eight-membered. Effects caused by the presence of the number of rings, the ring size, the variation in ring hetero atoms, and the electronegativity of attached nonring substituents, are correlated with structural and bonding features, particularly with changes in P-O pi bonding. The formation of hexacoordinated phosphorus brought about by the introduction of sulfur into ring arrangements is deemed to be a potentially important consideration for enzyme-phosphate action at active sites where sulfur residues may be present.