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Title: Phosphoranimines : investigations of their phosphite-initiated polymerisation and novel reactivity
Author: Bendle, Martin
ISNI:       0000 0004 2720 2569
Awarding Body: University of Bristol
Current Institution: University of Bristol
Date of Award: 2011
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This thesis describes investigations into the phosphite-initiated polymerisation of the phosphoranimines, their reactivity with phosphine oxides and dehalogenation reactions. Chapter 1 introduces a number of inorganic polymers, and then focuses on the synthetic routes to the poly(phosphazene)s and the broad range of properties and applications of these materials. This chapter also provides a general introduction to the chemistry of compounds containing phosphorus-nitrogen bonds, particularly the phosphazenes. The phosphoranimines are then discussed, and their synthesis, properties and reactions described in detail. In Chapter 2, the reactions between phosphine oxides, R3P=O (R = Me, tBU, Et, iPr and Ph) and bromophosphoranimines, BrPR'R"P=NSiMe3 (R' = R" = Me; R' = Me, R" = Ph; R' = R" = OCH2CF3) are described. These reactions were shown to initially give the phosphine oxide-donor stabilised phosphoranimine cations, [R3P=O•PR"R'=NSiMe3t. However, it was also demonstrated that these cations rearranged to generate species of the form [R3P=N=PR'R"O-SiMe3t. The reactions between the phosphine oxides and phosphoranimines were also monitored by 31p{ IH} NMR to gain insight into the mechanism of the rearrangement process. Chapter 3 discusses studies into the polymerisation of the bromophosphoranimine BrMePhP=NSiMe3 initiated by the phosphite (MeO)3P, and provides evidence that the phosphite is not the active initiator. It was subsequently found that the initiation requires the presence of impurities in samples of either the phosphoranimine or phosphite. An investigation into these impurities and related compounds led to the identification of a new, highly-active combination of co- initiators, as well as giving insight into the mechanism of the initiation process. Chapter 4 initially describes the reductive dehalogenation of the phosphoranimine ChP=NSiPh3 and identifies the product of this reaction to be the cyclodiphosphazane (CIPNSiPh3)2. The thermal decompositions of this and another compound, (CIPNSiMe3h are then discussed, along with the reaction of (CIPNSiPh3h with the halide-abstracting reagent, GaCh. Chapter 5 provides supplementary information to Chapter 2.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available