Abstracts Chemistry

New and improved syntheses of heteroatom substituted boranes

by L Qin

The Thesis is based upon the development of novel synthetic strategies towards heteroatom substituted boranes. The strategies that have been developed and their application towards the synthesis of new species and their characterisation are discussed. The first chapter contains the introduction and explains the basic concepts of boron cluster chemistry and a brief summary of their applications. A discussion of existing strategies toward the synthesis of heteroatom substituted boranes follows together with a description of those complexes already synthesised and characterised. The second chapter describes the development of high yield syntheses ofnido- [7-PBioHi2]~ and c/o5o-l,2-P2Bi0Hio; important phosphaborane starting materials that had previously only been made in low yield. The third chapter concerns the exploration of the chemistry of the two clusters whose synthesis is described in chapter 2. This includes alkyl substitution ofnido- [7,8-P2B9Hio]~ and the synthesis of several new mixed heteroatom species including closo-l,23-EP2B9R9 (E = Ge, Sn and Pb), c/o50-[l,2-SnPBi0Hi 0]" and c/ojo-l-R-1,2- SiPBioHio (R = Me or H). A study of the multiple alkylation of mWo-[7-PBi0Hi 0]3~ is also described in this chapter. The fourth chapter contains a summary of phosphacarborane chemistry, a description of modifications to the existing synthesis of closo-l,2-PCB\oH\i to allow isolation of larger quantities and some unsuccessful synthetic attempts to synthesize c/<wo-l,2-PCBioHn based on mW0-[7-PBi0Hi2]~. The final chapter briefly describes the development of a new synthesis of «/Jo-7,9,10-NC2BgH 11 in a much improved yield over existing methods together with description of a strategy for the purification of carboranes.