31P and 15NNMR spectra of 11 cyclic and non‐cyclic phosphoramidates were measured. Comparison of the closely related structures demonstrated correlation between the bond angles at nitrogen and the 15NNMRchemicalshifts and the 1J(P,N) couplingconstants. 15NNMR parameters allowed the exo‐ and endocyclic nitrogens to be distinguished and could be related to the hydrolytic stability of the P—N bonds