Diiron ethanedithiolate complexes with acetate ester: Synthesis, characterization and electrochemical properties

A cross-metathesis approach for polymetallic [FeFe]-hydrogenase mimics

A method has been developed for synthesizing [FeFe]-H2ase mimics with diverse structures and properties, employing cross-metathesis of olefins. Vinylmetallocenes (5 and 6) and vinyl half-sandwich complexes (10 and 11) have been used as cross-metathesis partners with [FeFe]-H2ase mimics (4, 8, and 9) bearing a double bond in the moiety attached to the ADT-bridge nitrogen. Electrochemical studies of these complexes, encompassing metallocene-type (7a-b, 12a-b, and 13a-b) as well as half-sandwich derivatives (12c and 13c-d), have demonstrated that the introduction of a redox unit has a marginal impact on the reduction potential of these [FeFe]-H2ase mimics. The application of this cross-metathesis approach has allowed the synthesis of [FeFe]-H2ase mimics featuring an Ir(III) electrochemical antenna (16-18) as well as systems having an electron-donor-photosensitizer structure (ED-PS) (23). The electrocatalytic properties of these complexes have been elucidated through electrochemical studies.

The crystal structure of tris(carbonyl)-bis(carbonyl)-[μ-propane-1,2- dithiolato]-(benzyldiphenylphosphine)diiron (Fe—Fe), C27H23Fe2O5PS2

C27H23Fe2O5PS2, monoclinic, P21/c (no. 14), a = 11.3170(5) Å, b = 16.1774(8) Å, c = 15.2170(7) Å, β = 92.933(1)°, V = 2782.3(2) Å3, Z = 4, R gt (F) = 0.0537, wR ref(F 2) = 0.1636, T = 296(2) K.

Crystal structure of pentacarbonyl-(μ2-propane-1,3-dithiolato-κ4 S:S,S′:S′)-(diphenyl(o-tolyl)phosphine-κ1 P)diiron (Fe-Fe), C27H23Fe2O5PS2

C27H23Fe2O5PS2, monoclinic, P21/c (no. 14), a = 15.4423(7) Å, b = 9.8615(5) Å, c = 18.0727(8) Å, β = 90.0380(10)°, V = 2752.2(2) Å3, Z = 4, Rgt (F) = 0.0296, wRref (F 2) = 0.0703, T = 296(2) K.

The influence of phosphine ligand substituted [2Fe2S] model complexes as electro-catalyst on proton reduction

To probe the influence of phosphine ligand substitution on the well-known [2Fe2S] model, two new [FeFe]-hydrogenase model complexes with the phosphine ligands, PMe₃ or P(CH₃O)₃, were synthesized, such as μ-(SCH(CH₂CH₃)CH₂S)–Fe₂(CO)₅PMe₃1, and μ-(SCH(CH₂CH₃)CH₂S)–Fe₂(CO)₅P(CH₃O)₃2 Confirmation of structures was provided by FTIR, ¹H NMR, ¹³C NMR, ³¹P NMR, elemental analyses and single-crystal X-ray analysis. The crystal structure of complex 2 shows that the P(CH₃O)₃ ligand has less steric effect on the coordination geometry of the Fe atom than the PMe₃ ligand. In the presence of HOAc in CH₃CN solution, the hydrogen evolution overpotentials of complexes 1 and 2 were 0.91 V and 0.81 V, respectively. Comparatively, complex 2 produces hydrogen at an overpotential of 0.1 V, lower than that for complex 1. A further electrocatalytic study showed the maximum charges for 1 and 2 were 31.3 mC and 56.3 mC at −2.30 V for 10 min, respectively. These studies showed that the complexes 1 and 2 have the ability, as novel electrocatalysts, for catalysis of hydrogen production, and complex 2 has better electrocatalytic ability than complex 1.

To probe the influence of phosphine ligand substitution on the well-known [2Fe2S] model, two new [FeFe]-hydrogenase model complexes with the phosphine ligands, PMe₃ or P(CH₃O)₃, were synthesized.