Fe4S4→ Fe3S4 Conversions: spectroscopic evidence for the generation of Fe3CoS4 clusters

The controlled aerobic oxidation of [Fe4S4(tibt)4]2–(tibt = SC6H2Pri3-2,4,6) generates, in the presence of CoCl2, the new [Fe3CoS4]2+ cluster species, which can also be quantitatively obtained by reaction of the linear trimer [Fe3S4(tibt)4]3– with CoCl2; this new mixed valence [Fe2+, 2Fe3+, Co2+] species, with an Stot= 1/2 ground state, was characterised by EPR and Mossbauer spectroscopy, magnetic susceptibility and cyclic voltammetry.