Density functional theory calculations were carried out on the transition m
etal phosphorus monoxide complexes (NH2)(3)MoPO, [eta (5)-C5H5Mo(CO)(2)](3)
PO, [eta (5)-C5H5W(CO)(2)](3)PO, [Ru-4(CO)(12)PO](-) [OS4(CO)(12)PO](-). an
d [Ru-5(CO)(15)PO](-.) The results indicate that pi -bonding dominates the
interaction of PO with transition metal clusters and that electrostatic eff
ects as well as orbital interactions, have a significant influence on the P
O bond strength and can lead to IR frequencies above that of free PO.