All-iron hydrogenase: synthesis, structure and properties of {2Fe3S}-assemblies related to the di-iron sub-site of the H-clusterElectronic supplementary information (ESI) available: crystal and structure refinement data for complexes 4a, 4b and 5a. See http://www.rsc.org/suppdata/dt/b2/b209690k/

Abstract

Tripodal dithiolate thioether ligands MeC(CH₂SH)₂CH₂SR (R = Me or Ph) provide a route to {2Fe3S}-complexes and syntheses are described. X-Ray crystal structures for two {2Fe3S}-pentacarbonyl derivatives and that for the first carbonyl cyanide are reported, together with temperature dependent ¹H-NMR, Mössbauer, FTIR and redox potential data. The NMR data establish fluctionality associated with inversion at the thioether sulfur in the carbonyl complexes. The Mössbauer data affirm that the coordination environment of the two iron atoms in a dicyanide bridging carbonyl intermediate are differentiated. Bridging carbonyl intermediates have been structurally and spectroscopically identified in resting and CO inhibited forms of the sub-site of all-iron hydrogenases; the observation of a thermally unstable {2Fe3S}-bridging carbonyl intermediate is discussed in this context.