title: [Fe(4)S(4)](q) cubane clusters (q = 4+, 3+, 2+) with terminal amide ligands.
abstract: Bis(trimethylsilyl)amide-ligated iron-sulfur cubane clusters [Fe(4)(mu(3)-S)(4)(N{SiMe(3)}(2))(4)](z) (z = 0, 1-, 2-) are accessible by the reaction of FeCl(N{SiMe(3)}(2))(2)(THF) (1) with 1 equiv of NaSH (z = 0), followed by reduction with either 0.25 (z = 1-) or 1 equiv (z = 2-) of Na(2)S as needed. The anionic clusters are obtained as the sodium salts [Na(THF)(2)][Fe(4)S(4)(N{SiMe(3)}(2))(4)] and [Na(THF)(2)](2)[Fe(4)S(4)(N{SiMe(3)}(2))(4)]; in the solid state, these two clusters both possess a unique contact ion pair motif in which individual sodium ions each coordinate to a cluster core sulfide, an adjacent amide nitrogen, and two THF donors. The monoanionic cluster can also be prepared as the lithium salt [Li(THF)(4)][Fe(4)S(4)(N{SiMe(3)}(2))(4)] by the reaction of 1 with 1:0.5 LiCl/Li(2)S. The characterization of the three-membered redox series allows an analysis of redox trends, as well as a study of the effects of the amide donor environment on the [Fe(4)S(4)] core. Bis(trimethylsilyl)amide terminal ligation significantly stabilizes oxidized cluster redox states, permitting isolation of the uncommon [Fe(4)S(4)](3+) and unprecedented [Fe(4)S(4)](4+) weak-field cores.
authors.affiliation: Department of Chemistry, Princeton University, Princeton, New Jersey 08544 and Department of Chemistry, University of Waterloo, Waterloo, Ontario, Canada N2L 3G1.
authors.forename: Christopher R
authors.initials: CR
authors.lastname: Sharp
authors.forename: Jeremiah S
authors.initials: JS
authors.lastname: Duncan
authors.forename: Sonny C
authors.initials: SC
authors.lastname: Lee
mesh_terms: D000577:Amides / Q000737:chemistry*; D056831:Coordination Complexes / Q000138:chemical synthesis / Q000737:chemistry*; D018360:Crystallography, X-Ray; D007501:Iron / Q000737:chemistry*; D008024:Ligands; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D015394:Molecular Structure; D010084:Oxidation-Reduction; D013455:Sulfur / Q000737:chemistry*; D014961:X-Ray Diffraction
chemical_list: D000577:Amides; D056831:Coordination Complexes; D008024:Ligands; D013455:Sulfur; D007501:Iron