The UPS of some compounds containing the heteroatoms phosphorus, nitrogen, and oxygen

Abstract The “lone-pair” regions of the He(I) UPS of 25 compounds containing phosphorus, nitrogen, and oxygen as heteroatoms are presented and discussed. The semiempirical MNDO SCF MO method has been employed to compute the orbital energies of many of the molecules. Although this theoretical treatment seems to predict correct geometries and conformations for the molecules, it does not always reproduce the most logical orbital-ordering sequence. In particular, the phosphorus “lone-pair” orbitals tend to be computed too stable. The controversial interpretation of the UPS of tris -dimethylaminophosphine is reviewed.