AbstractThis thesis describes new catalytic and stoichiometric routes towards polyphosphinoboranes
and explores the carbene initiated depolymerisation of polyaminoboranes.
Chapter 1 gives a general introduction to the synthesis and properties of polyaminoboranes and polyphosphinoboranes, along with the properties and applications of nitrogen
heterocyclic carbenes and cyclic (alkyl)(amino)carbenes.
Chapter 2 describes the metal-free dehydropolymerisation of phosphine-boranes using cyclic(alkyl)(amino)carbenes as hydrogen acceptors. The synthesis of both P-mono and P-disubstituted polyphosphinoboranes are described along with a discussion of the dehydrogenation mechanism supported by DFT studies.
Chapter 3 describes the use of Ni(COD)2 as a precatalyst for the dehydropolymerisation of PPhH2·BH3. The optimisation of polymerisation conditions is described along with investigations into the substate scope. Preliminary investigations into the polymerisation mechanism are discussed.
Chapter 4 describes a detailed study into the carbene-mediated depolymerisation of
poly(N-methylaminoborane) [MeHN–BH2]n. The reactivity of selected N-heterocyclic
carbenes and cyclic (alkyl)(amino)carbenes towards [MeHN–BH2]n, [MeHN–BH2]3 and
MeNH2·BH3 is discussed and depolymerisation mechanisms proposed.
Chapter 5 is split into two sections. The first focusses on expanding the substrate scope of the cyclic (alkyl)(amino)carbene mediated dehydropolymerisation of phosphine-boranes described in Chapter 2 and the second explores the reactivity of the adduct IDipp–BH2NMeH, both thermally and upon the addition of Lewis acids.
Chapter 6 describes ongoing and potential future work based upon the results presented in Chapters 2–5.
|Date of Award||12 May 2020|
|Sponsors||Engineering and Physical Sciences Research Council|
|Supervisor||Duncan Wass (Supervisor) & Ian Manners (Supervisor)|