Phosphorus(III) oxide: The reaction of tetraphosphorus hexaoxide with group VIB metal carbonyls

The monosubstituted Group VIB metal carbonyl derivatives of phosphorus(III) oxide, P₄O₆, have been prepared and characterized by mass spectrometry, and IR and ³¹P NMR spectroscopy. The ³¹P NMR chemical shift of the uncoordinated phosphorus(III) atoms in the P₄O₆ cage is found to be a measure of the extent of interaction between the coordinated phosphorus atom and the Lewis acid metal carbonyl site. The P₄O₆ cage appears to be a strong π acceptor ligand.