Abstract
Addition of the bulky redox-active diphosphine 1,8-bis(diphenylphosphino)naphthalene (dppn) to [Fe2(CO)6(µ-edt)] (1) (edt = 1,2-ethanedithiolate) affords [Fe2(CO)4(κ2-dppn)(µ-edt)] (3) as the major product, together with small amounts of a P–C bond cleavage product [Fe2(CO)5{κ1-PPh2(1-C10H7)}(µ-edt)] (2). The redox properties of 3 have been examined by cyclic voltammetry and it has been tested as a proton-reduction catalyst. It undergoes a reversible reduction at E1/2 = −2.18 V and exhibits two overlapping reversible oxidations at E1/2 = −0.08 V and E1/2 = 0.04 V. DFT calculations show that while the Highest Occupied Molecular Orbital (HOMO) is metal-centred (Fe–Fe σ-bonding), the Lowest Unoccupied Molecular Orbital (LUMO) is primarily ligand-based, but also contains an antibonding Fe–Fe contribution, highlighting the redox-active nature of the diphosphine. It is readily protonated upon addition of strong acids and catalyzes the electrochemical reduction of protons at Ep = −2.00 V in the presence of CF3CO2H. The catalytic current indicates that it is one of the most efficient diiron electrocatalysts for the reduction of protons, albeit operating at quite a negative potential.
Highlights
Interest in dithiolate-bridged diiron complexes [1,2,3,4,5,6,7] continues since they closely resemble the two-iron unit of the active site (H-cluster) of [FeFe]-hydrogenases [8,9]
Both independent molecules are similar, consisting of a diiron framework coordinated by four carbonyls, a chelating significantly), consisting of a diiron coordinated by four carbonyls, chelating adppn, and an differ significantly), consisting offramework a diiron framework coordinated by four acarbonyls, chelating edt ligand, which bridges the diiron centre
The diiron-dithiolate [Fe2 (CO)4 (κ2 -dppn)(μ-edt)] (3) containing a chelating dppn ligand has been synthesized from the reaction between [Fe2 (CO)6 (μ-edt)] (1) and dppn, together with a side product [Fe2 (CO)5 {κ1 -PPh2 (1-C10 H7 )}(μ-edt)] (2) resulting from P–C bond cleavage
Summary
Interest in dithiolate-bridged diiron complexes [1,2,3,4,5,6,7] continues since they closely resemble the two-iron unit of the active site (H-cluster) of [FeFe]-hydrogenases [8,9]. Over the past 20 years, the synthesis, structural characterization, and redox properties of a diverse range of diiron-dithiolate complexes has been studied [1,2,3,4,5,6,7,10,11,12,13], most focusing on their role as electrocatalysts for proton-reduction [14,15], and in hydrogen oxidation [16,17,18,19,20,21,22]. [50], are are attractive attractive surrogates surrogatesofofthe thetetrairon tetraironsite sitedue duetotothe theavailability availabilityof ofa π*-orbital delocalised overover the ligand backbone. 2010, Schollhammer and co-workers reported studies on biomimetics containing these diphosphines are rare.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
