Cleavage of cluster iron-sulfide bonds in cyclophane-coordinated Fe n S m complexes

Reaction of the tri(μ-sulfido)triiron(iii) tris(β-diketiminate) cyclophane complex, Fe S L (1), or of the di(μ-sulfido)diiron(iii) complex Fe S HL (5), with the related tri(bromide)triiron(ii) complex Fe Br L (2) results in electron and ligand redistribution to yield the mixed-ligand multiiron complexes, including Fe Br SL (3) and Fe Br SHL (4). The cleavage and redistribution observed in these complexes is reminiscent of necessary Fe-S bond cleavage for substrate activation in nitrogenase enzymes, and provides a new perspective on the lability of Fe-S bonds in FeS clusters.