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Nuclear Magnetic Resonance of Cyclophosphazenes

1987; Elsevier BV; Linguagem: Inglês

10.1016/s0066-4103(08)60247-1

2163-6052

Setharampattu S. Krishnamurthy, Michael Woods,

Synthesis and Reactivity of Sulfur-Containing Compounds

Cyclophosphazenes is considered an important class of inorganic heterocyclic compounds. These compounds occur in varied ring sizes and shapes, and thus offer some examples of multispin systems that are studied by NMR techniques. The bulk of NMR studies in cyclophosphazenes chemistry concerns the 6-membered cyclotriphosphazene system. Phosphorus NMR spectroscopy has proved to be an invaluable structural tool for cyclophosphazenes. Phosphorus NMR measurements can also be employed to monitor the course of reactions and to identify unstable intermediates or products that cannot be easily separated from reaction mixtures. This chapter presents a comprehensive survey of the extensive 31P NMR data accumulated for cyclophosphazenes. The chapter also summarizes major findings involving other familiar nuclei (1H, I3C, 15N, 19F) and assesses the significant trends. For all the NMR data presented in the chapter, shifts to low frequency of the reference standard, 85% aqueous phosphoric acid, are assigned a negative sign in accordance with the convention of IUPAC. Structural elucidation and empirical correlations are largely emphasized. Moreover, the NMR data permit conclusions to be drawn regarding the nature of the electronic interactions within the phosphazene ring as well as of the interaction between the ring and an exocyclic substituent.