Chemistry related to the [Fe]-Hydrogenases
Abstract
The work in this thesis is focused on the synthesis, reactivity and electrochemistry of chemical models of the active site structures found in [Fe]-hydrogenase, an enzyme that catalyses the reversible reduction of protons to dihydrogen. This enzyme possesses an unusual active site, the “H-cluster”, which is comprised of an {Fe4S4}-cubane linked by a cysteinyl bridge to a di-iron organometallic subsite which is ligated by dithiolate, CO and CN groups.
Chapter I gives a general overview of the biology and chemistry of iron-sulfur proteins and chemical models of their prosthetic groups, with emphasis on the [Fe]-hydrogenase.
Chapter II describes the synthesis, structures and spectroscopic features of 6 new {2Fe3S}-subsite model complexes with a range of functional groups together with X-ray crystallographic structures for all of these.
Chapter III reports and discusses the electrochemical properties of the new {2Fe3S}-complexes. Studies on electrocatalytic hydrogen evolution by these systems are also described.
Chapter IV reports the first synthesis of a free-standing “H-cluster” model complex in which an {Fe4S4}-cubane cluster is coupled to an {2Fe3S}-subsite as in [Fe]-hydrogenase. Spectroscopic, electrochemical and DFT calculations provide an insight into the electronic properties of the synthetic assembly and this is placed in the context of the natural system.
Chapter V describes some early results on the incorporation of synthetic di-iron subsites into electropolymers to provide solid-state electrocatalysts together with the prospects for future work in the area.
Chapter I gives a general overview of the biology and chemistry of iron-sulfur proteins and chemical models of their prosthetic groups, with emphasis on the [Fe]-hydrogenase.
Chapter II describes the synthesis, structures and spectroscopic features of 6 new {2Fe3S}-subsite model complexes with a range of functional groups together with X-ray crystallographic structures for all of these.
Chapter III reports and discusses the electrochemical properties of the new {2Fe3S}-complexes. Studies on electrocatalytic hydrogen evolution by these systems are also described.
Chapter IV reports the first synthesis of a free-standing “H-cluster” model complex in which an {Fe4S4}-cubane cluster is coupled to an {2Fe3S}-subsite as in [Fe]-hydrogenase. Spectroscopic, electrochemical and DFT calculations provide an insight into the electronic properties of the synthetic assembly and this is placed in the context of the natural system.
Chapter V describes some early results on the incorporation of synthetic di-iron subsites into electropolymers to provide solid-state electrocatalysts together with the prospects for future work in the area.
La synthèse de modèles du site actif de l'hydrogénase à fer, responsable de la catalyse réversible de la réduction des protons en dihydrogène, est un enjeu crucial dans l'optique d'une meilleure compréhension du fonctionnement du système enzymatique et du développement de nouveaux types de catalyseurs à base de clusters fer-soufre. Durant cette thèse ont été abordés les aspects synthétiques (ligands soufrés et complexes fer-carbonyle) aussi bien que les études spectroscopiques et électrochimiques.
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