title: Nickel-iron dithiolates related to the deactivated [NiFe]-hydrogenases.
abstract: Described herein are preparations of synthetic models for the deactivated Ni(II)Fe(II) states of the [NiFe]-hydrogenases. Iodination of the S = ½ species [(dppe)Ni(pdt)Fe(CO)(3)](+) afforded the diamagnetic iodo complex [(dppe)Ni(pdt)IFe(CO)(3)](+). Crystallographic analysis of this species confirmed the presence of square-pyramidal Ni linked to an octahedral Fe centre. The NiFe separation of 3.018 Å indicated the absence of metal-metal bonding. This complex could be reduced to give (dppe)Ni(pdt)Fe(CO)(3) and, in the presence of iodide, decarbonylated to afford (dppe)Ni(pdt)FeI(2). Derivatives of the type [(diphosphine)Ni(dithiolate)XFe(CO)(2)L](+) (X = Cl, Br, I) were prepared by halogenation of mixed-valence precursors [(diphosphine)Ni(dithiolate)Fe(CO)(2)L](+) (diphosphine = dppe, dcpe; L = tertiary phosphine or CO). The Fe(CO)(2)(PR(3))-containing derivatives are more robust than the related tricarbonyl derivatives. Exploiting this greater stability, we characterised examples of chloride and bromide derivatives. Related fluorides could be prepared by F(-) abstraction from BF(4)(-). Spectroscopic evidence is presented for the hydroperoxide [(dppe)Ni(pdt)(OOH)Fe(CO)(2)L](+), which represents a model for the Ni-SU state.
authors.affiliation: School of Chemical Sciences, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA.
authors.forename: David
authors.initials: D
authors.lastname: Schilter
authors.forename: Thomas B
authors.initials: TB
authors.lastname: Rauchfuss
mesh_terms: D001952:Bridged-Ring Compounds / Q000737:chemistry; D056831:Coordination Complexes / Q000138:chemical synthesis / Q000737:chemistry; D018360:Crystallography, X-Ray; D005296:Ferrous Compounds / Q000737:chemistry*; D006864:Hydrogenase / Q000737:chemistry / Q000378:metabolism*; D008968:Molecular Conformation; D009532:Nickel / Q000737:chemistry*; D013438:Sulfhydryl Compounds / Q000737:chemistry*
chemical_list: D001952:Bridged-Ring Compounds; D056831:Coordination Complexes; D005296:Ferrous Compounds; D013438:Sulfhydryl Compounds; D009532:Nickel; C043296:nickel-iron hydrogenase; D006864:Hydrogenase