Hydrogenase biomimetics with redox-active ligands: Synthesis, structure, and electrocatalytic studies on [Fe2(CO)42-dppn)(μ-edt)] (edt = ethanedithiolate; dppn = 1,8-bis(diphenylphosphino)naphthalene)

Shishir Ghosh*, Shahed Rana, Nathan Hollingsworth, Michael G. Richmond, Shariff E. Kabir, Graeme Hogarth

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

10 Citations (Scopus)
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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)42-dppn)(μ-edt)] (3) as the major product, together with small amounts of a P-C bond cleavage product [Fe2(CO)5κ1-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.

Original languageEnglish
Article number122
Pages (from-to)1-14
Number of pages14
JournalInorganics
Volume6
Issue number4
Early online date20 Nov 2018
DOIs
Publication statusE-pub ahead of print - 20 Nov 2018

Keywords

  • Dithiolate
  • Dppn
  • Hydrogenase biomimetics
  • Proton-reduction
  • Redox-active

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