Subsite-differentiated analogs of native iron sulfide [4Fe-4S]2+ clusters: preparation of clusters with five- and six-coordinate subsites and modulation of redox potentials and charge distributions

The subsite-differentiated cluster [Fe 4 S 4 (LS 3 )Cl] 2− (LS 3 =1,3,5-tris((4,6-dimethyl-3-mercaptophenyl) thio)-2,4,6-tris(p-tolylthio) benzene(3-)) in Me 2 SO solution reacts with a variety of bidentate and tridentate ligands to afford the substituted clusters [Fe 4 S 4 (LS 3 )L'] z− . Some ten clusters of this type were prepared in order to examine the effects of cluster charge and coordination number at the unique subsite on relative stabilities of oxidation states and charge distributions as sensed by 57 Fe isomer shifts. This is the first comprehensive study of such effects with Fe 4 S 4 clusters