| Summary: | The work contained in this thesis focuses on the synthesis, electrochemistry and reactivity of {2Fe2S}-chemical models of the "H-cluster" found in [FeFe]-hydrogenase enzymes. This active subsite is comprised of a diiron organometallic subsite ligated by dithiolate, CO and CN groups, and is linked to an {Fe4S4}-cubane via a cysteinyl bridge which acts as an electron transfer relay. The [FeFe]-hydrogenase enzymes are able to catalyse the reversible reduction of protons to H2. Chapter 1 Gives a general overview of the biology and chemistry of iron-sulphur proteins of the three classes of the hydrogenase enzyme, with particular emphasis on the [FeFe]-hydrogenase class, and the chemistry of modelling this enzyme. Chapter 2 Reports the synthesis and structures of one disulphide and two dithiolate ligands for the construction of new {2Fe2S}-subsite model complexes with the potential for further functionalisation. This is complimented with X-ray crystallographic structures of many novel organic compounds. Chapter 3 Describes the synthesis, structure, spectroscopic features and electrochemistry of two {2Fe2S}-subsite model complexes bearing pendant hydroxy groups. Chapter 4 Reports the synthesis, structure and spectroscopic features of a series of novel {2Fe2S}-subsites ligated by CO, PMe3 and a bridging K, all coupled to one or two cobaltocenium centres as electron transfer units, analogous to the{Fe4S4}- cubane ofthe "H-cluster". Chapter 5 Describes the electrochemistry, electrocatalysis and preliminary spectroelectrochemical results of the new cobaltocenium coupled {2Fe2S}- subsites, in relation to proton reduction for the evolution of dihydrogen.
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