Diruthenium Catalyst for Hydrogen Production from Aqueous Formic Acid

Area of Science:

• Organometallic Chemistry
• Catalysis
• Green Chemistry

Background:

• Formic acid dehydrogenation is a key reaction for hydrogen storage and generation.
• Developing stable and highly active catalysts for this process is crucial for practical applications.

Purpose of the Study:

• To synthesize and characterize novel diruthenium complexes for catalytic formic acid dehydrogenation.
• To evaluate the catalytic performance, stability, and reaction mechanism of these complexes in water.

Main Methods:

• Synthesis of diruthenium complexes featuring a bridging bis-imidazole methane-based ligand (benztetraimd).
• Catalytic testing of formic acid dehydrogenation in water at 90 °C.
• In-depth mechanistic studies using mass spectrometry and nuclear magnetic resonance (NMR) spectroscopy.

Main Results:

• The diruthenium complex [{(η⁶-p-cymene)RuCl}₂(μ-κ²:κ²-benztetraimd)]²⁺ ([1-Cl]) exhibited exceptional turnover frequency (1993 h⁻¹) and stability (>60 days).
• Catalyst [1-Cl] demonstrated a high turnover number (93,200) in bulk-scale reactions.
• Mechanistic investigations identified key catalytic intermediates, including Ru-aqua, Ru-formato, and Ru-hydrido species.

Conclusions:

• The synthesized diruthenium complex [1-Cl] is a highly efficient and stable catalyst for formic acid dehydrogenation in water.
• The study provides valuable insights into the catalytic mechanism, highlighting the role of various ruthenium species.
• This work contributes to the development of sustainable hydrogen production technologies.