Dibismuthines: synthesis, metal complexes and evaluation as precursors for Bi alloy films

Organophosphorus ligands (phosphines) play a central role in much transition metal coordination and organometallic chemistry. Their complexes present discrete molecular forms of the transition metal, soluble in organic solvents, which is key to their spectroscopic study and to applications in organometallic synthesis. The properties of the metal centre can be tuned by systematic changes in the phosphine substituents. The heavier analogues of phosphines have received less attention, and this is particularly true of the heaviest member of the group, bismuthines.This proposal sets out to develop the chemistry of dibismuthines (organobismuth compounds containing two bismuth centres linked by an organic group and each carrying two further organic terminal groups). We propose to synthesise a range of such compounds, explore their properties and their complexes with a carefully chosen series of transition metal species. The new complexes will be fully characterised spectroscopically and structurally, and this work will open up a hitherto unexplored area of coordination chemistry. We will also explore some ligands containing bismuth in combination with phosphorus or arsenic donor groups, where the P or As atom will act as a stronger tether to the metal acceptor, enabling a wider range of metals to be complexed to the bismuth.In the final part of the project we will carry out exploratory studies to assess whether the bismuthine complexes can function as precursors for the synthesis of bismuth alloys by chemical vapour deposition methods. Such techniques are widely used to make thin films etc for the electronics industries but have not been developed for bismuth. Environmental legislation requires the replacement of lead from many (electronics) applications and bismuth is the most likely choice to achieve this. The project will establish if some key bismuth-alloys can be produced as films by CVD methods from metal bismuthine complexes. Formation of Bi alloy nanoparticles will also be investigated.