The Synthesis And Characterisation Of Model Complexes For Hydrogenases

This dissertation comprises mainly two aspects.We design and synthesise a series of multidentate ligands containing pyridinyl group and sulphur atoms. The reactions of these ligands with ferrous sulphate are performed in an appropriate organic solvent to synthesise model complex, [Fe(cis-CO)₂L³] (H₂L³=2-(N,N- bis(2'-ethylthiol)aminomethyl)pyridine), for the cofactor of iron-sulfur-cluster-free hydrogenase, that is, H₂-forming methylene tetrahydromethanopterin dehydrogenase (Hmd). NMR, FTIR and Uv-vis Spectroscopic, X-ray crystallographic and electrochemical techniques are employed when appropriate to characterise the compounds involved in this research. Our results suggest that the iron centre in the cofactor of the iron-sulfur-cluster-free hydrogenase be very likely a low spin Fe (0).Secondly, we also investigate CO substitution and protonation reactions of model complexes of the di-iron sub-unit of iron-only hydrogenase. Possible mechanisms for both the CO substitution and protonation reactions are discussed.