Iron Carbide-Sulfide Carbonyl Clusters.

Described is the preparation of the first iron carbide-sulfides. The cluster [Fe6C(CO)15(SO2)]2- ([2]2-), which is generated quantitatively from [Fe6C(CO)16]2- ([1]2-), was O-methylated to give the sulfinite [2Me]-. Demethoxylation of [2Me]- with BF3 gave the face-capped octahedral cluster Fe6C(CO)15(SO) (3). In solution, 3 spontaneously converted to the sulfide Fe6C(CO)16(S) (4), an edge-fused double cluster with Fe5C and Fe3S subunits. Although 4 undergoes 1e- reduction reversibly, 2e- reduction (or base hydrolysis) of 4 gives closo-[Fe6C(CO)14(S)]2- ([5]2-). The synthetic entries into the Fe6CS x manifold may underpin the preparation of active-site analogues of the FeMoco and FeVco cofactors.