Synthesis and properties of oligomers of iron–manganese carbonyl complexes with bridging disulfido ligands

The reactions of activated CpFeMn(CO)71a and Cp*FeMn(CO)71b, Cp=C5Me5 with thiirane yielded the new dimeric mixed metal disulfido complexes: [CpFeMn(CO)5(μ3-S2)]2 (2) and [Cp*FeMn(CO)5(μ3-S2)]2 (3). Compounds 2 and 3 both contain two triply bridging disulfido ligands. When heated at 40 °C, compound 2 was transformed into a trimeric compound Cp3Fe3Mn3(CO)15(μ3-S2)(μ4-S2)2, 4. Compound 4 contains three disulfido ligands, each of which has a different bridging coordination mode in the six atom metal cluster. There are three inequivalent CpFe(CO)2 groupings linked to a central Mn3(S2)3 core by the disulfido ligands. In solution, compound 4 exhibits a dynamical intramolecular exchange process that interconverts two of the three CpFe(CO)2 groups on the NMR timescale.