TY - JOUR
T1 - Hydrogenase biomimetics with redox-active ligands
T2 - Synthesis, structure, and electrocatalytic studies on [Fe2(CO)4(κ2-dppn)(μ-edt)] (edt = ethanedithiolate; dppn = 1,8-bis(diphenylphosphino)naphthalene)
AU - Ghosh, Shishir
AU - Rana, Shahed
AU - Hollingsworth, Nathan
AU - Richmond, Michael G.
AU - Kabir, Shariff E.
AU - Hogarth, Graeme
PY - 2018/11/20
Y1 - 2018/11/20
N2 - 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)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.
AB - 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)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.
KW - Dithiolate
KW - Dppn
KW - Hydrogenase biomimetics
KW - Proton-reduction
KW - Redox-active
U2 - 10.3390/inorganics6040122
DO - 10.3390/inorganics6040122
M3 - Article
AN - SCOPUS:85058818331
SN - 2304-6740
VL - 6
SP - 1
EP - 14
JO - Inorganics
JF - Inorganics
IS - 4
M1 - 122
ER -