The Nuclear Magnetic Resonance Spectroscopy of 15N-Labelled Cyclophosphazenes

The ³¹P NMR spectra of ¹⁵N-labelled cyclophosphazenes contain additional information compared with the unlabelled compounds, namely, apart from the spin–spin coupling constant J_PN, it is also possible to obtain information, in the case of homosubstituted compounds, about the spin–spin coupling constants J_PP and J_NN. The ¹⁵N NMR spectra of these compounds yield the same information and in addition the chemical shift of the ¹⁵N signal. All these NMR parameters are sensitive to changes in the electronic structure of the cyclic P–N systems, which depend on the type and number of substituents and also on the ring size. Studies on labelled halides, amino-derivatives, ethers, thioethers, and alkyl-substituted derivatives of cyclic phosphazenes containing between three and six P–N structural units are examined. The NMR data are interpreted on the basis of empirical relations and also with the aid of semiempirical quantum-chemical methods.
The bibliography includes 109 references.