Browse by author
Lookup NU author(s): Adrain John Dunford, Professor Richard Henderson
Full text for this publication is not currently held within this repository. Alternative links are provided below where available.
Kinetic studies on the substitution reaction between [Fe4S4Cl4]2- and ButNC or Et2NCS2- are reported. The binding of small molecules and ions to Fe-S clusters is a fundamental step in substitution reactions but can be difficult to follow directly because these reactions are rapid and often associated with small spectroscopic changes. A novel kinetic method is reported which allows the time course of molecule and ion binding to Fe-S clusters to be followed by monitoring the lability of the cluster. Using a stopped-flow, sequential-mix apparatus, [Fe4S4Cl4]2- and L (L = Et2NCS2- or ButNC) are rapidly mixed, and after a known time (δ) the resulting solution is mixed with a solution of PhS-. The thiolate substitutes for the chloro ligands on the cluster, in a reaction which is easy to follow because of the large change in the visible absorption spectrum. The rate of this substitution is extremely sensitive to whether L is bound to the cluster or not. By correlation of δ with the rate of the reaction with PhS-, the time course of the reaction between [Fe4S4Cl4]2- and L can be mapped out. In studies where L = ButNC this technique has allowed the detection of an intermediate {[Fe4S4Cl4(CNBut)]2-} which cannot be detected spectrophotometrically. In further studies, the substitution reactions of [Fe4S4Cl4]2- with PhS-, Et2NCS2-, or ButNC are all perturbed by the addition of Cl-. In all cases a common pathway for substitution is evident, but with Et2NCS2- an additional, slower pathway becomes apparent under conditions where the common pathway is completely inhibited by Cl-.
Author(s): Henderson RA; Dunford AJ
Publication type: Article
Publication status: Published
Journal: Inorganic Chemistry
Year: 2002
Volume: 41
Issue: 21
Pages: 5487-5494
ISSN (print): 0020-1669
ISSN (electronic): 1520-510X
Publisher: American Chemical Society
URL: http://dx.doi.org/10.1021/ic0202110
DOI: 10.1021/ic0202110
PubMed id: 12377044
Altmetrics provided by Altmetric
