title: Tridentate thiolate ligands: application to the synthesis of the site-differentiated [4Fe-4S] cluster having a hydrosulfide ligand at the unique iron center.
abstract: We have designed new trithiols Temp(SH)(3) and Tefp(SH)(3) that can be synthesized conveniently in short steps and are useful for preparation of crystalline [3:1] site-differentiated [4Fe-4S] clusters suitable for X-ray structural analysis. The ethanethiolate clusters (PPh(4))(2)[Fe(4)S(4)(SEt)(TempS(3))] (4a) and (PPh(4))(2)[Fe(4)S(4)(SEt)(TefpS(3))] (4b) were prepared as precursors, and the unique iron sites were then selectively substituted. Upon reaction with H(2)S, (PPh(4))(2)[Fe(4)S(4)(SH)(TempS(3))] (6a) and (PPh(4))(2)[Fe(4)S(4)(SH)(TefpS(3))] (6b), which model the [4Fe-4S] cluster in the β subunit of (R)-2-hydroxyisocaproyl-CoA dehydratase, were synthesized. Clusters 6a and 6b were further converted to the sulfido-bridged double cubanes (PPh(4))(4)[{Fe(4)S(4)(TempS(3))}(2)(μ(2)-S)] (7a) and (PPh(4))(4)[{Fe(4)S(4)(TefpS(3))}(2)(μ(2)-S)] (7b), respectively, via intermolecular condensation with the release of H(2)S. Conversely, addition of H(2)S to 7a,b afforded the hydrosulfide clusters 6a,b. The molecular structures of the clusters reported herein were elucidated by X-ray crystallographic analysis. Their redox properties were investigated by cyclic voltammetry.
authors.affiliation: Research Center for Materials Science and Department of Chemistry, Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8602, Japan.
authors.forename: Tamaki
authors.initials: T
authors.lastname: Terada
authors.forename: Takuya
authors.initials: T
authors.lastname: Wakimoto
authors.forename: Tomohiko
authors.initials: T
authors.lastname: Nakamura
authors.forename: Kiyohisa
authors.initials: K
authors.lastname: Hirabayashi
authors.forename: Kaho
authors.initials: K
authors.lastname: Tanaka
authors.forename: Jichun
authors.initials: J
authors.lastname: Li
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Matsumoto
authors.forename: Kazuyuki
authors.initials: K
authors.lastname: Tatsumi
mesh_terms: D040761:Biomimetic Materials / Q000138:chemical synthesis / Q000737:chemistry*; D018360:Crystallography, X-Ray; D058085:Iron Compounds / Q000138:chemical synthesis / Q000737:chemistry*; D007506:Iron-Sulfur Proteins / Q000138:chemical synthesis / Q000737:chemistry*; D008024:Ligands; D008958:Models, Molecular; D010084:Oxidation-Reduction; D013438:Sulfhydryl Compounds / Q000138:chemical synthesis / Q000737:chemistry*; D013440:Sulfides / Q000138:chemical synthesis / Q000737:chemistry*
chemical_list: D058085:Iron Compounds; D007506:Iron-Sulfur Proteins; D008024:Ligands; D013438:Sulfhydryl Compounds; D013440:Sulfides