Synthetic models of [FeFe]-hydrogenase: case studies utilizing azadithiolate and nitrosyl coligands
type: CreativeWork
description: Hydrogenases are enzymes that catalyze the reversible interconversion of protons, electrons, and dihydrogen (2H+ + 2e− <-> H2). Because of the potential utility of H2 as an energy carrier, the detailed understanding of hydrogenases has received considerable attention and funding. In particular, hydrogenases are fascinating because they employ inexpensive first row transition metals, while operating at overpotentials and rates comparable with the industrial standard, Pt metal. Synthetic models of hydrogenase active sites are useful for understanding the chemistry occurring within the active site. Chapter One reviews general background information on hydrogenases as well as their synthetic models. Chapter Two describes the oxidation of dihydrogen by a hydrogenase model. The studies are enabled by the finding that salts of [Fe2(adtR)(CO)3(PMe3)(dppv)]+ are thermally stable when the anion is BArF4-, where adt = (azadithiolate, (SCH2)2NR), R = H and CH2C6H5, BArF4- = tetrakis(bis(3,5-trifluoromethyl)phenyl)borate, and dppv = cis-1,2-bis(diphenylphosphino)ethylene). Solutions of [Fe2(adtR)(CO)3(PMe3)(dppv)]+ react with high pressures of H2 to give the hydride [(mu-H)Fe2(adt)(CO)3(PMe3)(dppv)]BArF4. The oxadithiolate [Fe2(odt)(CO)3(PMe3)(dppv)]+ (odt = 2-oxa-1,3-dithiolate) and propanedithiolate [Fe2(pdt)(CO)3(PMe3)(dppv)]+ are unreactive toward H2, thus implicating a role for the amine. According to the proposed mechanism, H2 binds to the mixed-valence cation to give the dihydrogen adduct whereupon the H2 undergoes intramolecular heterolysis utilizing the amine. Use of D2 in place of H2 gave the deuteride as well as the hydride, implicating the transient formation of free protons that exchange with water. Chapter Three summarizes studies on the redox behavior of synthetic models for the [FeFe]-hydrogenases, consisting of diiron dithiolato carbonyl complexes bearing the amine cofactor and its N-benzyl derivative. Of specific interest are the causes of the low reactivity of…
abstract: Hydrogenases are enzymes that catalyze the reversible interconversion of protons, electrons, and dihydrogen (2H+ + 2e− <-> H2). Because of the potential utility of H2 as an energy carrier, the detailed understanding of hydrogenases has received considerable attention and funding. In particular, hydrogenases are fascinating because they employ inexpensive first row transition metals, while operating at overpotentials and rates comparable with the industrial standard, Pt metal. Synthetic models of hydrogenase active sites are useful for understanding the chemistry occurring within the active site. Chapter One reviews general background information on hydrogenases as well as their synthetic models. Chapter Two describes the oxidation of dihydrogen by a hydrogenase model. The studies are enabled by the finding that salts of [Fe2(adtR)(CO)3(PMe3)(dppv)]+ are thermally stable when the anion is BArF4-, where adt = (azadithiolate, (SCH2)2NR), R = H and CH2C6H5, BArF4- = tetrakis(bis(3,5-trifluoromethyl)phenyl)borate, and dppv = cis-1,2-bis(diphenylphosphino)ethylene). Solutions of [Fe2(adtR)(CO)3(PMe3)(dppv)]+ react with high pressures of H2 to give the hydride [(mu-H)Fe2(adt)(CO)3(PMe3)(dppv)]BArF4. The oxadithiolate [Fe2(odt)(CO)3(PMe3)(dppv)]+ (odt = 2-oxa-1,3-dithiolate) and propanedithiolate [Fe2(pdt)(CO)3(PMe3)(dppv)]+ are unreactive toward H2, thus implicating a role for the amine. According to the proposed mechanism, H2 binds to the mixed-valence cation to give the dihydrogen adduct whereupon the H2 undergoes intramolecular heterolysis utilizing the amine. Use of D2 in place of H2 gave the deuteride as well as the hydride, implicating the transient formation of free protons that exchange with water. Chapter Three summarizes studies on the redox behavior of synthetic models for the [FeFe]-hydrogenases, consisting of diiron dithiolato carbonyl complexes bearing the amine cofactor and its N-benzyl derivative. Of specific interest are the causes of the low reactivity of…
author: Olsen, Matthew T.
language: en
keywords: hydrogenase, diiron, azadithiolate, nitrosyl, hydrogen activation
date published: 2011-05-25T14:53:49Z
date modified: 2026-07-22T22:25:23Z
provider: University of Illinois - Urbana-Champaign
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: University of Illinois at Urbana-Champaign

PropertyValue
property ID: Handle
value: http://hdl.handle.net/2142/24018