Synthetic Models for Nickel-Iron Hydrogenase Featuring Redox-Active Ligands

Area of Science:

• Bioinorganic Chemistry
• Organometallic Chemistry
• Catalysis

Background:

• Nickel-iron hydrogenase enzymes are crucial for reversible interconversion of protons, electrons, and dihydrogen.
• These enzymes utilize iron-sulfur clusters for electron relay to and from their active sites.

Purpose of the Study:

• To develop synthetic models of nickel-iron hydrogenase.
• To mimic the function of iron-sulfur cofactors using redox-active auxiliaries.
• To investigate catalytic activity and redox properties of novel nickel-iron complexes.

Main Methods:

• Synthesis of nickel-iron dithiolate complexes with varying diphosphine and ferrocenylphosphine ligands.
• Characterization of Ni^II(μ-H)Fe^IIFe and Ni^IIFe^IFe species.
• Evaluation of catalytic activity for hydrogen evolution and redox state analysis.

Main Results:

• Successful preparation of synthetic nickel-iron complexes mimicking hydrogenase active sites.
• The hydride species demonstrated catalytic activity for hydrogen evolution.
• Hydride-free complexes exhibited multiple stable redox states due to ferrocenyl group incorporation.

Conclusions:

• The synthetic models effectively replicate key features of nickel-iron hydrogenase.
• Redox-active ferrocenyl groups are crucial for achieving multiple redox states in the models.
• These advanced models offer insights into the mechanism of biological hydrogen conversion.