Thiophene and Selenophene Binding at a Pd₃ Cluster Site

Area of Science:

• Organometallic Chemistry
• Coordination Chemistry
• Materials Science

Background:

• Understanding ligand coordination to metal clusters is crucial for catalysis.
• Palladium (Pd) clusters are vital in various catalytic applications.
• Thiophene and selenophene are important sulfur- and selenium-containing heterocycles.

Purpose of the Study:

• To investigate the triply bridging coordination of thiophene and selenophene to trinuclear metal cluster sites.
• To characterize the resulting metal cluster structures and their properties.
• To compare the binding affinities of different ligands at various palladium sites.

Main Methods:

• Synthesis of novel palladium-thiophene and palladium-selenophene complexes.
• X-ray crystallography for structural elucidation of metal clusters.
• Ligand binding studies to determine relative affinities.

Main Results:

• Observed triply bridging coordination of thiophene and selenophene at a trinuclear metal cluster.
• Formation of a unique spiro-type Pd5 cluster via selenophene coordination.
• Stable face-capping μ3-coordination of thiophene/selenophene on a Pd3 site supported by a cyclooctatetraene ligand.
• Pd3 site with cyclooctatetraene showed higher benzene binding affinity than thiophene.
• Pd2 site strongly favored thiophene over benzene.

Conclusions:

• Demonstrated novel coordination modes for thiophene and selenophene with palladium clusters.
• Highlighted the influence of supporting ligands on cluster structure and ligand binding selectivity.
• Provided insights into the design principles for metal-ligand interactions in catalysis.