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This thesis reports laser spectroscopic studies of gas-phase transition metal dimers using laser ablation/reaction with free jet expansion and laser-induced fluorescence (LIF) spectroscopy technique. Themolecules studied in this work are palladium dimer (Pd2) and vanadium dimer (V2). Many compounds formed from these transition metals are important and functional catalysts in chemical reactions. Therefore, it is of great significance to start from the fundamental level to understand the properties and characteristics of the metal bonding and also the behavior of these metals when reacting with other chemicals. The electronic transitions of Pd2and V2in the visible region were studied. Gas-phase Pd2and V2moleculeswereproduced by laser ablation of palladium and vanadium metal rod, respectively. For the Pd2molecule, eleven vibrational bands were recorded and analyzed, and have been assigned to the 〖[17.1]〗^3 □_g□ X^3 □_u^+ transition system. The bond length and vibrational frequency of the ground X^3 □_u^+ state were determined to be 2.47 Å and 211.38 cm-1, respectively. This is the first experimental investigation of the electronic transitions of Pd2.For the V2molecule,six vibrational bands were observed and assigned to a new 〖[19.6] 〗^3 □_u^□□ X^3 □_g^□ transition system. Molecular constants for the 〖[19.6] 〗^3 □_u^□ excited state were obtained from high-resolution LIF spectra. The electronic structure of the Pd2andV2molecules was discussed in detail using molecular orbital energy level diagrams, which is important for understanding the nature of chemical bonding in these dimers. Comparison of the transition metal dimers studied in this work with other dimers is also presented. / published_or_final_version / Chemistry / Master / Master of Philosophy

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This thesis describes studies directed towards the preparation of bis (imido) complexes of the Group 6 metals containing olefin, phosphine, acetylene, and alkyl ligands with particular emphasis on their relationship with Group 4 bent metallocenes. The polymerisation mechanism of the Phillips catalyst (CrO(_3)/SiO(_2)) is examined using XPS (X-Ray Photoelectron Spectroscopy) and in situ mass spectroscopy. Chapter 1 highlights properties of some of the important ligand classes that are used throughout the remainder of this thesis. Chapter 2 describes a high yield one-pot synthesis of molybdenum bis (imido) complexes of the type Mo(NR')(NR")Cl(_2).DME. In addition a number of attempts to extend this strategy to other metals are described, including a novel synthesis of the chromium complex [Cr(_2)Cl(_9)] [NHEt(_3)](_3). Chapter 3 describes the synthesis, characterisation, and reactivity of the bis (imido) bis (phosphine) complexes Mo(NAr)(_2)(PMe(_3))(_2) and [Mo(N(^t)Bu)(µ-N(^t)Bu)(PMe(_3))](_2). Further studies on bis (imido) olefin complexes of the type Mo(NAr)(_2)(PMe(_3))2(η(^2)-C(_2)H (_2)) and Mo(N(^t)Bu)(_2)(PMe(_3))(η(^2)-C(_2)H(_4)) was undertaken and concentrated on their structural relationship to Group 4 metallocene species. Chapter 4 describes the preparation, structure, and reactivity of some bis (imido) acetylene complexes Mo(NR)(_2)(PMe(_3)) (PhC=CR’) (R= Ar, (^t)Bu; R'= Ph, H). Preparation of bis (imido) alkyls was undertaken in attempts to generate benzyne and alkylidene derivatives. Chapter 5 studies the Phillips polymerisation catalyst using XPS and mass spectroscopy. Model systems were used to probe reactive surface species their use reveals a number of features that are difficult to observe with the actual catalyst. Aspects of molecular chemistry have been examined which are believed to relate directly to the heterogeneous system allowing a possible polymerisation mechanism to be postulated. Chapter 6 gives experimental details for Chapters 2-5. Philip William Dyer (November 1993)

This project was aimed at synthesising, characterising and examining the properties of the novel polyamine ligand 4’-{2’”-(12-Amino-2,6,9-triazadodecyl)-phenyl}-2,2’:6’,2”-terpyridine and its related complexes. The ligand would be based around the 4’-(o-toluyl)-2,2’:6’,2”-terpyridine framework and have potential applications in analytical chemistry. The 4’-(o-toluyl)-2,2’:6’,2”-terpyridine framework would have a tail attached on the functionalised o-toluyl methyl group. The ortho toluyl functionality was chosen so that the donor atom containing tail would be directed back towards the coordination site. This would make it easier for the tail to interact with a central metal ion. There is potential to be able to change the number and type of donor atom in the tail so that the ligand may be metal ion selective. As the tail would contain donor atoms, the denticity of the ligand would be increased making it more applicable for complexometric titrations. The 2,2’:6’,2” terpyridines exhibit strong colours when coordinated to selective metal ions and so would have potential applications in colorimetry also. The ligand was successfully synthesised and characterised. In a multi-step process, the 4’-(o-toluyl)-2,2’:6’,2”-terpyridine underwent radical bromination before the tail was attached. The tail used in this research was N,N'-bis (3-aminopropyl)ethane-1,2-diamine (3,2,3-tet). The secondary amines in this polyamine tail were protected before addition to the brominated 4’-(o-toluyl)-2,2’:6’,2”-terpyridine to ensure terminal addition. After the tail addition, a two step separation process purified a sample of 4’-{2’”-(12-Amino-2,6,9-triazadodecyl)-phenyl}-2,2’:6’,2”-terpyridine for analysis. Due to the late stage in this research where a successful separation technique was found, little work was done on examining the properties of this ligand and its complexes.