A coordinatively unsaturated dinuclear iron(II) complex of bulky thiolates, [(TipS)Fe(μ-SDmp)] (1; Tip = 2,4,6- Pr C H , Dmp = 2,6-(mesityl) C H ), was synthesized from stepwise reactions of Fe{N(SiMe ) } with 1 equiv of HSDmp and then with 1 equiv of HSTip. Complex 1 was found to react with elemental sulfur (S ) in toluene to generate a new class of [8Fe-7S] cluster, [(DmpS)Fe S ] (μ-SDmp) (μ- STip)(μ -S) (2). The cluster 2 was also produced from one-pot reactions of Fe{N(SiMe ) } + HSDmp + HSTip + S (8:6:10:7/8) and Fe {N(SiMe ) } (M-STip) + HSDmp + S (8/3:16/3:7/8), where another [8Fe-7S] cluster, [(TipS)Fe S ] (μ-SDmp) {μ-N(SiMe ) }(μ -S) (3), was also found as a minor byproduct. In either of the clusters, two Fe S incomplete cubane units are connected by three anionic ligands, namely three thiolate S atoms for 2 or two thiolate S atoms and one amide N atom for 3, and one hexa-coordinate S atom resides at the center of the [8Fe-7S] core. They have a common Fe(II) Fe( ) oxidation states, and an S = 1/2 ground spin state was indicated by rhombic EPR signals at 10 K with g = 2.19, 2.07, and 1.96 for 2 and g = 2.13, 2.06, and 1.93 for 3. The structural relevance of clusters 2 and 3 to P-cluster, FeMo-co, and FeFe-co of nitrogenases is discussed. © 2007 American Chemical Society. 2 3 6 2 2 6 3 3 2 2 8 4 3 2 2 6 3 2 2 8 3 3 2 2 4 8 4 3 2 2 3 2 6 4 3 5 III 3 t