Single-Step Sulfur Insertions into Iron Carbide Carbonyl Clusters: Unlocking the Synthetic Door to FeMoco Analogues.

The one-step syntheses, X-ray structures, and spectroscopic characterization of synthetic iron clusters, bearing either inorganic sulfides or thiolate with interstitial carbide motifs, are reported. Treatment of iron carbide carbonyl clusters [Fen (μn -C)(CO)m ]x (n=5,6; m=15,16; x=0,-2) with electrophilic sulfur sources (S2 Cl2 , S8 ) results in the formation of several μ4 -S dimers of clusters, and moreover, iron-sulfide-(sulfocarbide) clusters. The core sulfocarbide unit {C-S}4- serves as a structural model for a proposed intermediate in the radical S-adenosyl-L-methionine biogenesis of the M-cluster. Furthermore, the electrophilic sulfur strategy has been extended to provide the first ever thiolato-iron-carbide complex: an analogous reaction with toluylsulfenyl chloride affords the cluster [Fe5 (μ5 -C)(SC7 H7 )(CO)13 ]- . The strategy described herein provides a breakthrough towards developing syntheses of biomimetic iron-sulfur-carbide clusters like FeMoco.