Transition metal complexes of bis(carboranes) and their potential as catalyst precursors

Abstract

Chapter 1 provides a short overview of heteroborane chemistry with particular attention on the areas of metallacarborane catalysts and bis(o-carborane). It also includes a more detailed scope of the thesis. Chapter 2 reports the first examples of heterometalated bis(carboranes) using cobalt and ruthenium, specifically their preparation and characterisation. Tangential to this is the isolation of a novel 13-vertex/12-vertex species, the former of which possesses the first crystallographically-determined 4,5,1,12-M2C2B9 architecture (where M = CoCp*). Chapter 3 expands the range of heterometalated bis(carboranes) to include those with the catalytically-active rhodium fragment {Rh(PPh3)2H}. Additionally, the first example of a crystallographically-characterised rhodacarborane/carborane species is reported. Chapter 4 discusses the catalytic activity of the rhodacarborane compounds in alkene isomerisation and ketone hydrosilylation. The results of preliminary DFT calculations into the possible mechanisms of these catalytic reactions are also included. Chapter 5 contains the experimental procedures and spectroscopic details for all novel compounds discussed. Appendix A explores the use of phosphites as ligands in rhodacarboranes and Appendix B details the preliminary results in the deboronation/metalation of bis(m-carborane). Appendix C summarises the crystallographic tables of all compounds studied by XRD in this thesis.