Hydrogen activation by biomimetic diiron dithiolates

Area of Science:

• Organometallic Chemistry
• Coordination Chemistry
• Catalysis

Background:

• Iron complexes are valuable in catalysis.
• Understanding reactivity of metal-sulfur complexes with small molecules like H2 is crucial.
• Previous studies have explored related iron complexes, but their reactivity with H2 under pressure is less understood.

Purpose of the Study:

• To investigate the reactivity of iron-sulfur complexes with molecular hydrogen.
• To explore the role of different ligand environments, specifically azadithiolates, in H2 activation.
• To elucidate the mechanism of hydrogenation for these iron complexes.

Main Methods:

• Synthesis of thermally stable iron complexes with azadithiolate ligands.
• High-pressure hydrogenation reactions using molecular hydrogen (H2).
• Characterization of products using spectroscopic techniques and isotopic labeling (D2O).

Main Results:

• The azadithiolate iron complexes [Fe(2)(adtR)(CO)(3)(PMe(3))(dppv)](+) react with H2 under high pressure to yield the corresponding hydride complex.
• Related oxadithiolate and propanedithiolate complexes were found to be unreactive towards H2.
• Deuterium labeling studies using H2 and D2O confirmed the formation of both hydride and deuteride species, suggesting protic intermediates.

Conclusions:

• The amine functionality within the azadithiolate ligand plays a critical role in facilitating the heterolysis of molecular hydrogen.
• A proposed mechanism involves amine-assisted heterolysis followed by hydride isomerization.
• These findings offer insights into the activation of H2 by iron complexes and potential catalytic applications.