Issue 43, 2014

Large structural changes upon protonation of Fe4S4 clusters: the consequences for reactivity

Abstract

Density functional calculations reveal that protonation of a μ3-S in [Fe4S4X4]2− clusters (X = halide, thiolate, phenoxide) results in the breaking of one S–Fe bond (to >3 Å, from 2.3 Å). This creates a doubly-bridging SH ligand (μ3-SH is not stable), and a unique three-coordinated planar Fe atom. The under-coordination of this unique Fe atom is the basis of revised mechanisms for the acid-catalysed ligand substitution reactions in which substitution of X by PhS occurs at the unique Fe site by an indirect pathway involving initial displacement of X by acetonitrile (solvent), followed by displacement of coordinated acetonitrile by PhSH. When X = Cl or Br the rate of attack by PhSH is slower than the dissociation of X, and is the rate-determining step; in contrast, when X = SEt, SBut or OPh the rate of dissociation of XH is slower than attack by PhSH and is rate-determining for these clusters. A full and consistent interpretation of all kinetic data is presented including new explanations of many of the kinetic observations on the acid-catalysed substitution reactions of [Fe4S4X4]2− clusters. The proposed mechanisms are supported by density functional calculations of the structures of intermediates, and simulations of some of the steps. These findings are expected to have widespread ramifications for the reaction chemistry of both natural and synthetic clusters with the {Fe4S4} core.

Graphical abstract: Large structural changes upon protonation of Fe4S4 clusters: the consequences for reactivity

Supplementary files

Article information

Article type
Paper
Submitted
10 Jun 2014
Accepted
16 Jul 2014
First published
30 Jul 2014

Dalton Trans., 2014,43, 16213-16226

Author version available

Large structural changes upon protonation of Fe4S4 clusters: the consequences for reactivity

I. Dance and R. A. Henderson, Dalton Trans., 2014, 43, 16213 DOI: 10.1039/C4DT01687D

To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page.

If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given.

If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page.

Read more about how to correctly acknowledge RSC content.

Social activity

Spotlight

Advertisements