Efficient additive-free formic acid dehydrogenation with a NNN-ruthenium complex

Area of Science:

• Catalysis
• Organometallic Chemistry
• Green Chemistry

Background:

• Formic acid dehydrogenation is a key reaction for hydrogen production.
• Existing catalysts often require basic additives, complicating processes.
• Development of efficient, additive-free catalysts is crucial.

Purpose of the Study:

• To synthesize and characterize a new ruthenium complex for formic acid dehydrogenation.
• To investigate the catalytic activity and mechanism of the complex.
• To demonstrate additive-free high catalytic performance.

Main Methods:

• Synthesis of a ruthenium complex with a pyridylidene amine-based NNN ligand.
• Catalytic testing for formic acid dehydrogenation.
• Mechanistic studies using UV-vis and NMR spectroscopy, and gas evolution monitoring.

Main Results:

• The ruthenium complex functions as an effective catalyst precursor for formic acid dehydrogenation.
• High catalytic activity (TOF ~10,000 h⁻¹) was achieved without basic additives.
• The catalyst is air-stable but light-sensitive.
• Mechanistic studies revealed rapid, reversible protonation of the NNN ligand as the key activation step.

Conclusions:

• A novel, air-stable ruthenium complex enables efficient, additive-free formic acid dehydrogenation.
• The catalyst's activation mechanism involves reversible protonation of the NNN ligand.
• This development offers a promising pathway for sustainable hydrogen generation.