Since at least the 1830's, many research groups have synthesized cyclic chlorophosphazenes [PCl2N]m (m = 3-9) from PCl5 and NH4Cl. The bulk of the work done in this area is centered on the smaller rings where m = 3 or 4. Earlier work in our group focused on separating the [PCl2N]m rings with m= 3-8 and characterizing them by 31P NMR and x-ray crystallography.1 The aim of this work is to further study the linear species that have been proposed to be precursors of the rings, to improve yields of the higher oligomers by the use of reaction conditions and additives and to further characterize both types of species. In particular, ambiguity in the assignment of 31P resonances arise for the heptamer and higher oligomers which show resonance in the same region as what is called "the polymer peak" at about -18 ppm. It is unknown whether the resonances represent a variety of larger rings, or, if there is a limit to ring size, and therefore they represent large linear molecules. This research presents characterization of these higher molecular weight chlorophosphazenes using various analytical methods including DOSY NMR.

Higher molecular weight cyclic chlorophosphazenes

256th National Meeting (2018)

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