The chemistry of gold with unsaturated organics: coordination, activation and catalysis
The aim was to understand gold‟s reactivity with unsaturated organic bonds. We focused on the role of supporting ligands, activating agents and the organic substrates employed in such reactions. Gold tetrafluorophthalimidates have been isolated, with coordination found to be surprisingly strong; no [N(CO)2C6F4]- displacement with ζ- and π-donors were observed. B(C6F5)3 and norbornene addition to [(Ph3P)Au{N(CO)2C6F4}] leads to a [Au(nbe)3]+ cation paired with a new, non-coordinating phthalimido-diborate anion. Aryl-N substituents of [(Ph3P)Au{nacnac}] influences its differing solid state structures; examples of κ1- and (the first example of) asymmetric κ2-coordination was observed. In solution these complexes show intricate fluxional behaviour. Attempts at oxidation to synthesise a gold(III)-oxo complex were unsuccessful. In situ generated Au+ cations can selectively activate benzylic C-H and C-C bonds of methylarenes and dimesitylmethane under mild conditions. Mechanistic and kinetic studies with hexamethylbenzene have identified a C-H activation step of and the formation of a benzyl cation intermediate. Zwitterionic and heterobimetallic gold(I) complexes containing a (o-sulfophenyl)- diphenylphosphine ligand were formed, with the supporting Cl- and R2S ligands on gold(I) found to be non-labile, resulting in the complexes being catalytically inert. The incorporation of anions to [(C6F5)4Au2Ag2]n clusters gave structural and photoluminescent data, which evidently show that the emission colours of these powders are dependent on the extent of aurophilic bonding between cluster units. Dechlorination of [(C6F5)2AuCl]2 in the presence of olefins were prone to reductive elimination to yield „naked‟ gold(I)-(η2)olefin complexes. Repeating the reaction with benzene, toluene and xylenes appeared to give the unstable and unidentified gold(I)-arene analogues. 1H NMR monitoring of gold(III)-catalysed hydroarylation reactions revealed that silver salts do not act as a simple chloride scavengers, but identification of the gold species in solution was unsuccessful. In addition, a family of highly electrophilic fluorosulfonium and fluorobismuthium compounds were synthesised. These complexes decomposed at room temperature by intermolecular fluorination of the aryl substituents. N.B.: CIF files were attached to this thesis at the time of its submission. Please refer to the author for further details.
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