Investigation of the 31 P NMR chemical shift dependence of phosphoryl compounds on the inductive and resonance effects of substituents

Linear dual‐parameter equations relating the 31 P NMR chemical shifts in a series of phosphoryl compounds XYZP = O (X, Y, Z = various organic substituents or halogens) with the sums of inductive (σ I ) and resonance (σ ) constants of the substituents have been obtained. The direction of the influence of the inductive and resonance components of the electron demand of substituents, and their relative contributions to the δ 31P values, have been evaluated. The nature of the resonance contribution is discussed on the basis of the dependence between δ 31P values and the charge characteristics of the phosphorus atom (x‐ray P Kα shifts).