View in EDS

CO Affinity and Bonding Properties of [FeFe] Hydrogenase Active Site Models. A DFT Study.

Saved in:
Bibliographic Details
Title: CO Affinity and Bonding Properties of [FeFe] Hydrogenase Active Site Models. A DFT Study.
Authors: Luca Bertini1, Claudio Greco1, Maurizio Bruschi1, Piercarlo Fantucci1, Luca De Gioia1
Source: Organometallics. May2010, Vol. 29 Issue 9, p2013-2025. 13p.
Subjects: Hydrogenase, Metal bonding, Carbon monoxide, Metal complexes, Iron compounds, Density functionals, Addition reactions, Binding sites
Abstract: In this work a density functional theory study of the CO addition reaction to FeIFeIand FeIFeIImodels of the active site of [FeFe] hydrogenases is presented. A series of model complexes, ranging from simple diiron model complexes of the binuclear [2Fe]Hsubcluster to the full H-cluster, have been investigated. For each system, the thermodynamic parameters for the CO adduct formation, a reaction that mimics the enzyme CO inhibition, were computed. Parallel to the investigation of the CO addition reaction, the structural features of the various FeIFeIand FeIFeIIspecies have been evaluated, with particular attention to the issue of the ligand arrangement as a function of the redox state. CO affinity depends on the redox state of the model and the chemical nature of its ligands. FeIFeIIspecies are more favorable to form the CO adducts than the reduced FeIFeIspecies. According to the computed free energies and enthalpies for the CO adduct formation from Fe2(pdt)(CO)5L models, the CO affinity follows the ligand sequence L = SCH3−> CN−> PPh3> CO (FeIFeI) and L = CO > CN−> PPh3> SCH3−(FeIFeII). As the models become more similar to the H-cluster, the CO affinity increases, although the FeIFeICO -inhibited H-cluster is not stable. The bonding properties of the models considered have been investigated by means of the quantum theory of atoms in molecules approach. Upon CO addiction, the new Fe−C bond is formed to the detriment of the Fe−Fe bonds and, to a lesser extent, the Fe−S bonds. Regarding the FeIFeIIsystems investigated, the spin density is initially localized on the rotated Fe atom, and the formation of the CO adducts results in a delocalization of the spin density. Consequently, the FeIFeIICO-inhibited forms are better described as (Fe.5)2. [ABSTRACT FROM AUTHOR]
Copyright of Organometallics is the property of American Chemical Society and its content may not be copied or emailed to multiple sites without the copyright holder's express written permission. Additionally, content may not be used with any artificial intelligence tools or machine learning technologies. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
Database: Engineering Source
Description
Abstract:In this work a density functional theory study of the CO addition reaction to FeIFeIand FeIFeIImodels of the active site of [FeFe] hydrogenases is presented. A series of model complexes, ranging from simple diiron model complexes of the binuclear [2Fe]Hsubcluster to the full H-cluster, have been investigated. For each system, the thermodynamic parameters for the CO adduct formation, a reaction that mimics the enzyme CO inhibition, were computed. Parallel to the investigation of the CO addition reaction, the structural features of the various FeIFeIand FeIFeIIspecies have been evaluated, with particular attention to the issue of the ligand arrangement as a function of the redox state. CO affinity depends on the redox state of the model and the chemical nature of its ligands. FeIFeIIspecies are more favorable to form the CO adducts than the reduced FeIFeIspecies. According to the computed free energies and enthalpies for the CO adduct formation from Fe2(pdt)(CO)5L models, the CO affinity follows the ligand sequence L = SCH3−> CN−> PPh3> CO (FeIFeI) and L = CO > CN−> PPh3> SCH3−(FeIFeII). As the models become more similar to the H-cluster, the CO affinity increases, although the FeIFeICO -inhibited H-cluster is not stable. The bonding properties of the models considered have been investigated by means of the quantum theory of atoms in molecules approach. Upon CO addiction, the new Fe−C bond is formed to the detriment of the Fe−Fe bonds and, to a lesser extent, the Fe−S bonds. Regarding the FeIFeIIsystems investigated, the spin density is initially localized on the rotated Fe atom, and the formation of the CO adducts results in a delocalization of the spin density. Consequently, the FeIFeIICO-inhibited forms are better described as (Fe.5)2. [ABSTRACT FROM AUTHOR]
ISSN:02767333
DOI:10.1021/om900658b