Chapter 1 reviews the literature concerning trimethylenemethane and oxodimethylenemethane metal complexes and their r?le in organic synthesis. The preparation and characterisation of ?4-trimethylenemethane metal complexes of iridium, rhodium, osmium and ruthenium are presented in Chapter 2, together with the molecular structure of three of these complexes which establishes the presence of the ?4-trimethylenemethane ligand. The room temperature 1H n.m.r. spectra show the expected features for a static structure and no sign of rotation of the trimethylenemethane ligand was observed at higher temperatures. Preliminary investigation into the reactivity of these trimethylenemethane complexes is detailed in Chapter 3. A series of cationic ?4-trimethylenemethane complexes are prepared by the reaction of [Ir{?4-C(CH2)3}C1 (CO)(PPh3)] with silver hexafluorophosphate in the presence of a donor ligand such as carbon monoxide or ethene. The reactions of these cationic complexes with neutral and anionic nucleophiles are investigated and show that displacement of other donor ligands or attack on co-ordinated carbonyl and ethene ligands occurs, rather than attack at, or displacement of the trimethylenemethane ligand. Chapter 4 describes the reaction of 3-trimethylsilyl-2-(methyl- sulphonyloxymethyl) prop-l-ene with d10-metal complexes of platinum, palladium and nickel. The isolation of ?3-2-trimethylsilylmethylallyl palladium and platinum complexes are of interest since they are postulated intermediates implicated in the generation of the catalytic species [Pd (?3-trimethylenemethane) (PPh3)2]. The d10 -nickel complex [Ni{P(OEt)3}4] catalyses the cycloaddition of trimethylenemethane to electron-deficient alkenes and imines, the latter reaction affords a high yield synthesis of 4-methylenepyrrolidines. The final Chapter describes the reactions of 3-chloro-l-(trimethyl-silyl)propan-2-one and 3-chloro-2-(trimethylsiloxy)prop-l-ene with low-valent metal complexes to afford oxodimethylenemethane complexes of platinum, iridium, and osmium. The molecular structure of two of these complexes establishes the presence of an ?3-oxodimethylenemethane ligand. The silylenol ether, 3-chloro-2-(trimethylsiloxy)prop-l-ene was readily prepared from 3-chloro-l-(trimethylsilyl)propan-2-one, the isomerisation being catalysed by a number of low-valent metal complexes.

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published_or_final_version / Chemistry / Master / Master of Science

published_or_final_version / abstract / toc / Chemistry / Master / Master of Philosophy

published_or_final_version / Mathematics / Master / Master of Philosophy

The Betic Cordillera of southern Spain is an orogen formed in response to convergence between Africa and Iberia, from the late Mesozoic to the present. The orogen consists of three main tectonic complexes, two of which have been subducted to depth, then exhumed back to the surface over short timescales. Subduction in the structurally higher of these complexes is relatively well constrained to the Eocene, but the timing of high-pressure metamorphism in the structurally lower complex, known as the Nevado-Filabride Complex, has been a topic of debate for several years due to conflicting geochronological data. Several proposed tectonic models for the Nevado-Filabride Complex are based on ages of single mineral phases. For example, models based primarily on 40Ar/ 39Ar dating on white mica in high-pressure schists require that the Nevado-Filabride and the overlying tectonic unit, the Alpujarride Complex, were coevally subjected to high-pressure metamorphism in the Eocene, and subsequently exhumed at different rates. More recent models, based on Lu-Hf dating on prograde garnets in eclogites, separate the timing of high-pressure metamorphism of the Nevado-Filabride Complex from the Alpujarride Complex by at least 10 m.y. We examine the viability of these models using multimineral Rb-Sr dating of blueschist and eclogite facies rocks in the Nevado-Filabride Complex. The multimineral isochron method uses the whole high-pressure mineral assemblage rather than a single phase, which allows testing for isotopic disequilibrium. Statistically valid Rb-Sr ages of two schists and one eclogite from the Nevado-Filabride Complex yield ages of 15.78+/-0.47, 15.8+/-1.1, and 17.6+/-1.1 Ma, respectively. The early Miocene Rb-Sr ages are in agreement with garnet Lu-Hf ages and zircon U-Pb ages for high-pressure conditions in the Nevado-Filabride Complex. The new ages imply that two episodes of subduction, punctuated by a period of extension and exhumation, occurred in the Western Mediterranean. / text

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No description available.