This chapter deals with the topic phosphazenes which are compounds containing the ‘PN’ motif. Compounds containing such motifs can be acyclic, cyclic or polymeric. Accordingly, the subject matter is dealt under these three sections: (a) Acyclic phosphazenes; (b) Cyclophosphazenes (c) Polyphosphazenes and related polymers. These compounds have various applications ranging from catalysis to materials. These applications, where relevant, are dealt with the individual sections, rather than in a separate section. This chapter reviews the literature published in the calendar year 2018.
The synthesis of the lithium salt [(tBuNPNtBu)Li TMEDA] (TMEDA: tetramethyl ethylene diamine) 1 was accomplished by the thermolysis of [PhP(NHtBu)(NtBu)] Li(TMEDA) in toluene. This leads to a cleavage of the P–C bond and the formation of 1.1 Alternatively, 1 could also be prepared by the 1 : 1 reaction of nBuLi with cis-[(tBuNP)2(tBuNH)2]. The synthetic utility of 1 was demonstrated by the formation of a tin derivative 2.1
