The synthesis of kinetically stabilised heavy group 13 hydride complexes

Abstract

The work presented in this thesis describes the synthesis and stability of a range of hydrido and low oxidation state complexes of the group 13 elements. The underlying theme is the stabilisation of these species. The work upon this subject is divided into eight chapters. Chapter One provides a general introduction to the members of group 13, with particular emphasis on the development of group 13 metal trihydrides and low oxidation group 13 metals. The reasons behind the inherent instability of these species are discussed, and is the development of stabilising ligands. Chapter Two discusses the variability in the stereoelectronic character of stabilising ligands and describes the development of a number of probes to quantify the stereoelectronic character of monoanionic bidentate N,Nʹ-ligands. This Chapter also describes the syntheses of a new super bulky 1,3 bis(2,6 terphenyl)triazene and two C 2,6-terphenyl substituted amidines. Chapter Three introduces the alkali metal chemistry of monoanionic bidentate N,Nʹ ligands. Alkali metal complexes of the aforementioned super bulky ligands (Chapter Two) have been prepared. Chapter Four introduces the +1 oxidation state chemistry of the group 13 metals. The stabilisation of +1 oxidation state group 13 species with triazenide ligands was found to be dependent on the steric character of the ligand employed. Chapter Five introduces the coordination chemistry of trivalent group 13 complexes. The syntheses and crystallographic characterisations of dihalo- and dimethyl group 13 complexes featuring a super bulky triazenide are presented. Chapter Six describes the kinetic stabilisation of group 13 heavy hydrides with monoanionic bidentate N,Nʹ-ligands. The impact of the ligand’s steric character on the thermal stabilities of these complexes is discussed. Chapter Seven introduces the known hydride chemistry of indium and describes the synthesis of a number of NHC adducts of indane (InH3). The decomposition pathways and reactivities of these species were studied. Chapter Eight introduces the stabilisation of low oxidation state main group species by NHCs. A series of dimeric metal dihalide NHC complexes of the form [{MX2(NHC)}2] (M = Ga, In) have been prepared and characterised. Novel bis(NHC) complexes of thallium(I) were also characterised.