Tridentate Ligands With Platinum Group Metals

In this thesis, a series of symmetrical and unsymmetrical pincer ligands are synthesised and explored as supports for platinum group metals, such as palladium, platinum and ruthenium. In Chapters 2 and 3, the synthesis and characterisation of novel pyridine-based dianionic aryl-containing [C,NPy,O] and phenol-containing [O,NPy,O] pincer pro-ligands and their reactivity towards palladium(II) and ruthenium(II) metal precursors is described. [C,NPy,O]-type pincer pro-ligands have been shown to promote sp2 C-H activations upon reaction with palladium(II) and ruthenium(II) metal salts. Phenol-containing [O,NPy,O] pincer pro-ligands demonstrated deprotonation of the phenolic oxygen, resulting in a tridentate coordination upon binding to palladium(II) and ruthenium(III) metal centres. In Chapter 4, six novel paramagnetic ruthenium(III) pincer complexes developed from aryl-containing [C,NPy,O] and phenol-containing [O,NPy,O] pincer pro-ligands, have been employed as efficient catalysts for the transfer hydrogenation of ketones. Chapter 5 describes the synthesis of mono(imino)pyridyl [N,NPy,O] pincer pro-ligands incorporating an ethyl ester group at 6-position and their ability to undergo hydrolysis to a carboxylic acid upon coordination to palladium. Use of platinum(II) metal precursor, on the contrary, did not promote hydrolysis resulting in a bidentate coordination mode in the corresponding complexes. Chapter 6 explores the reactivity of two dien [N,N,N] pincer pro-ligands towards palladium(II) salts. Preliminary investigations demonstrated the ability of the amine-NH donor moieties to promote NH···A (acceptor) hydrogen bond interactions with the acceptor atoms on their corresponding anions in the solid state.