title: Unusual formation of a [NiSFe(2)(CO)(6)] cluster: a structural model for the inactive form of [NiFe] hydrogenase.
abstract: The synthesis and characterisation of the trinuclear Ni-Fe complex [Ni(L(2))SFe(2)(CO)(6)] (1) formed from the reaction of [Ni(L(1))] with Fe(3)(CO)(12) is described. The single-crystal X-ray structure of 1 shows Ni(ii) bound to three thioether R(2)-S donors and bridged by a sulfide (S(2-)) group to two Fe(CO)(3) units. undergoes a reversible one-electron reduction process at E(1/2) = -1.62 V vs. Fc(+)/Fc to generate 1 (-), which has been characterised by UV-vis and IR spectroelectrochemistry and by EPR spectroscopy. DFT calculations on 1and 1 (-) reveal electronic structures that are delocalised across the NiFe(2) core. The SOMO in 1 (-) possesses Ni-Fe and Fe-Fe anti-bonding character and lies approximately in the plane defined by the equilateral triangle of Ni and Fe atoms. It possesses d-orbital contributions of 18.5, 15.0 and 19.8% for the Ni(1), Fe(1) and Fe(2) atoms, respectively. The Ni-S(sulfide) bond length in 1 [2.1654(7) A] is identical to that for the bridging sulfide found in the oxidised inactive form of the [NiFe] hydrogenase from D. vulgaris (2.16 A). Thus, 1 provides a useful comparison for biological [NiFe] centres bridged by sulfide donors.
authors.affiliation: University of Nottingham, Nottingham, UKNG7 2RD.
authors.forename: Alessandro
authors.initials: A
authors.lastname: Perra
authors.forename: Qiang
authors.initials: Q
authors.lastname: Wang
authors.forename: Alexander J
authors.initials: AJ
authors.lastname: Blake
authors.forename: E Stephen
authors.initials: ES
authors.lastname: Davies
authors.forename: Jonathan
authors.initials: J
authors.lastname: McMaster
authors.forename: Claire
authors.initials: C
authors.lastname: Wilson
authors.forename: Martin
authors.initials: M
authors.lastname: Schröder
mesh_terms: D018360:Crystallography, X-Ray; D004563:Electrochemistry; D004578:Electron Spin Resonance Spectroscopy; D006864:Hydrogenase / Q000737:chemistry* / Q000378:metabolism; D007501:Iron / Q000737:chemistry*; D009532:Nickel / Q000737:chemistry*; D009942:Organometallic Compounds / Q000737:chemistry*; D013055:Spectrophotometry, Infrared
chemical_list: D009942:Organometallic Compounds; C030616:ferronickel; D009532:Nickel; D007501:Iron; C043296:nickel-iron hydrogenase; D006864:Hydrogenase