Theoretical Interpretation of 31P NMR Chemical Shifts. II. Unsymmetrical Molecules

Abstract

An ASP LCAO MO quantum‐mechanical calculation of the 31P chemical shifts has been made for molecules of the form PZ2T and MPZ2T, where M is an electron‐pair‐acceptor atom or group, P is phosphorus, and Z and T are different substituents. The deviations from linearity of the chemical shifts of these mixed species from that predicted by linear interpolation from the shifts of PZ3 and PT3 or of MPZ3 and MPT3 is calculated and used to elucidate molecular parameters such as the extent of π interactions and bond‐angle changes in the mixed as compared to the unmixed molecules.