Synthesis of multicomponent heavy alkali metal amide systems and extensions to zirconium chemistry

Due to the nature of the work undertaken during the course of this PhD, the results of this thesis will be broken down into three sections. The first section comprises Chapter 1 and includes an introduction on reported homometallic lithium, sodium and potassium salts of the bulky utility amines [HMDS(H), TMP(H) and DA(H)]. The second section, Chapter 2−Chapter 5, includes the achieved results obtained during the course of this PhD work based on the homometallic alkali metal building block amides. The third section involves an introduction on zirconium species and their applications in specific reactions, along with the solid and solution state studies of zirconocene species combined with alkali metal and alkali earth metal amides obtained during this work.Chapter 2 includes a deep discussion in the solid state of NaHMDS systems capturing Na halide units in the presence of a multidentate Lewis base donor ligand, taking on different structural guises depending on the denticity of the ligand of choice. This topic is currently a hot topic in organometallic chemistry, being lithium amide congeners have already been characterised. This study allows a deep examination of these structures and confirms the AM-amide/AM-halide interaction to exist in sodium chemistry as well.Chapter 3 unveils the structural chemistry of the utility base, potassium hexamethyldisilazide (KHMDS), which is explored through the incorporation of different dentate ligands into its structure. This study containing the solid state characterisation of homometallic potasium amides being a necessary preface to the bimetallic work. Having investigated the solid state structure of homometallic potasium systems, it was also deemed important to study heavier alkali metal building blocks. Thus, Chapter 4 includes the structural characterisation of specific amine adducts of the heavy alkali metal amide CsHMDS, which is recently being used in important organic transformations. Having investigated homometallic systems of heavy bulky amides, it was also deemed important to synthesise and characterise heterobimetallic species containing early and heavy alkali metal species adding to the solvent-coordination free heterobimetallic alkali metal building blocks. Due to the usage that sodium hexamethyldisilazide (NaHMDS) is gaining as a proton abstractor reagent in organic synthesis, akin to its homometallic lithium congener LiHMDS, Chapter 5 includes the synthesis and structural characterisation of three novel adducts of NaHMDS by using the chiral amine N,N,Nʹ,Nʹ-(1R,2R)-tetramethylcyclohexane-1,2-diamine [(R,R)-TMCDA] and the synthetically important tridentate ligand PMDETA allowing the development of a homologues series of [(R,R)-TMCDA]- and PMDETA-solvated NaHMDS complexes. Having successfully synthesised solvated homo- and hetero-bimetallic alkali metal salts of HMDS, the attention turned to the possibility of incorporating the tetravalent transition metal zirconium into these systems to afford homo- and hetero-bimetallic HMDS-containing zirconocene species (Chapter 6).Due to the nature of the work undertaken during the course of this PhD, the results of this thesis will be broken down into three sections. The first section comprises Chapter 1 and includes an introduction on reported homometallic lithium, sodium and potassium salts of the bulky utility amines [HMDS(H), TMP(H) and DA(H)]. The second section, Chapter 2−Chapter 5, includes the achieved results obtained during the course of this PhD work based on the homometallic alkali metal building block amides. The third section involves an introduction on zirconium species and their applications in specific reactions, along with the solid and solution state studies of zirconocene species combined with alkali metal and alkali earth metal amides obtained during this work.Chapter 2 includes a deep discussion in the solid state of NaHMDS systems capturing Na halide units in the presence of a multidentate Lewis base donor ligand, taking on different structural guises depending on the denticity of the ligand of choice. This topic is currently a hot topic in organometallic chemistry, being lithium amide congeners have already been characterised. This study allows a deep examination of these structures and confirms the AM-amide/AM-halide interaction to exist in sodium chemistry as well.Chapter 3 unveils the structural chemistry of the utility base, potassium hexamethyldisilazide (KHMDS), which is explored through the incorporation of different dentate ligands into its structure. This study containing the solid state characterisation of homometallic potasium amides being a necessary preface to the bimetallic work. Having investigated the solid state structure of homometallic potasium systems, it was also deemed important to study heavier alkali metal building blocks. Thus, Chapter 4 includes the structural characterisation of specific amine adducts of the heavy alkali metal amide CsHMDS, which is recently being used in important organic transformations. Having investigated homometallic systems of heavy bulky amides, it was also deemed important to synthesise and characterise heterobimetallic species containing early and heavy alkali metal species adding to the solvent-coordination free heterobimetallic alkali metal building blocks. Due to the usage that sodium hexamethyldisilazide (NaHMDS) is gaining as a proton abstractor reagent in organic synthesis, akin to its homometallic lithium congener LiHMDS, Chapter 5 includes the synthesis and structural characterisation of three novel adducts of NaHMDS by using the chiral amine N,N,Nʹ,Nʹ-(1R,2R)-tetramethylcyclohexane-1,2-diamine [(R,R)-TMCDA] and the synthetically important tridentate ligand PMDETA allowing the development of a homologues series of [(R,R)-TMCDA]- and PMDETA-solvated NaHMDS complexes. Having successfully synthesised solvated homo- and hetero-bimetallic alkali metal salts of HMDS, the attention turned to the possibility of incorporating the tetravalent transition metal zirconium into these systems to afford homo- and hetero-bimetallic HMDS-containing zirconocene species (Chapter 6)