Synthesis and Characterization of [Fe4S5Cp4][MoOCl (thf)]: A “Cubane” Type Cluster with One Penta-Coordinated Fe Site

Recent findings show that natural Fe-S clusters (1) are not confined to the by now well studied species having planar 2Fe-2S and cubane-type 4Fe-4S core units. This has triggered a series of synthetic efforts to obtain new polynuclear Fe/S geometries, where one of the Fe sites is different from the others in its coordination number and/or type of ligands (2). In this paper we report the preparation and properties of a new structural Fe-S cluster type. The X-rays analysis reveals a S22− ligand bonded to three of the Fe sites, and one Fe atom is pentacoordinated. Also, EPR and Moessbauer studies indicate the presence of a [3FeIII, 1FeII] oxidation state.