Simple ligand effects switch a hydrogenase mimic between H2 and O2 activation

Area of Science:

• Bioinorganic Chemistry
• Catalysis
• Biomimetic Chemistry

Background:

• Oxygen-tolerant [NiFe]hydrogenases are crucial enzymes with complex active sites.
• Understanding their mechanism requires robust biomimetic models.
• Previous models have limitations in mimicking oxygen tolerance.

Purpose of the Study:

• To develop a [NiRu] biomimetic system that mimics oxygen-tolerant [NiFe]hydrogenases.
• To investigate the role of electron donation and ligand effects in controlling H2 and O2 activation.
• To synthesize and characterize a biomimetic analogue of oxygen-bound species (OBS).

Main Methods:

• Synthesis of a [NiRu] complex.
• Ligand modification using hexamethylbenzene and pentamethylcyclopentadienyl.
• Oxygenation of a Ni-SIa model complex.
• Characterization using X-ray analysis, XPS, mass spectrometry, and NMR spectroscopy.

Main Results:

• Demonstrated switching between H2 and O2 activation via electron donation and ligand effects.
• Synthesized and directly observed a [NiRu]-peroxo species, a proposed OBS analogue.
• Fully characterized the [NiRu]-peroxo complex.
• The OBS analogue successfully oxidized p-hydroquinone and sodium borohydride.

Conclusions:

• The [NiRu] biomimetic system effectively mimics key functions of oxygen-tolerant [NiFe]hydrogenases.
• Ligand effects and electron donation are critical for controlling catalytic activity.
• The synthesized [NiRu]-peroxo species provides valuable insights into OBS structures and functions.