Capsules, secondary interactions and unusual multi-metallic complexes
Hart, John Stewart
Research into inorganic supramolecular chemistry is burgeoning, in particular that which focuses on the formation of capsular molecules and the effects that these unique environments have on catalytic reactions. With the aim of producing new ligand designs that could not only support reactive metals, but also partake in supramolecular aggregation to provide a capsular microenvironment, new tripodal ligands and wide span imines and amines have been synthesised. Furthermore, the exploitation of hydrogen-bonding motifs formed through pyrrole-imine tautomerisation upon metallation of these ligands has been explored, with the aim of enhancing reactivity and stabilising reactive intermediates. In Chapter one, the concept of covalent and non-covalent capsules is introduced, and includes the different aspects affecting the encapsulation of molecules and their use as nanoreactors. The use of secondary interactions, e.g. hydrogen-bonding in metal complexes of tetrapodal and tripodal ligands is discussed. Chapter two describes the synthesis of a tripodal pyrrole-imine ligand and the formation of its multi-metallic complexes of Group one metals, transition metal and the f-block elements. The complete and partial tautomerisation of this ligand upon metal complexation is also examined. In Chapter three, the formation of hangman complexes of the tripodal pyrrole-imine ligand is described and is extrapolated to the chemistry of a new pyrrole-amide ligand. The synthesis of this latter ligand and its properties with regards to anion binding are also explored. Chapter four describes the formation of wide span diamine and diimine ligands and their propensity to form adducts with cobalt and zinc chlorometallates and unusual multimetallic palladium complexes. The final conclusions of the work presented in this thesis are drawn in Chapter five. Chapter six presents experimental details and characterising data for all of the new compounds presented in this thesis.