Syntheses and structures of cationic osmium bis(σ-B-H) borane complexes

Area of Science:

• Organometallic Chemistry
• Boron Chemistry
• Catalysis

Background:

• Transition metal (TM) σ-B-H borane/borate complexes are crucial for understanding B-H bond activation and catalysis.
• While neutral σ-B-H complexes are common, cationic examples are rare, limiting the scope of these fascinating compounds.

Purpose of the Study:

• To develop an efficient method for synthesizing rare cationic osmium bis(σ-B-H) borane complexes.
• To characterize the electronic and structural properties of these novel cationic species.

Main Methods:

• An efficient salt elimination and hydride removal strategy was employed for complex synthesis.
• Characterization involved spectroscopic methods and Atoms in Molecules (AIM) analysis.

Main Results:

• Novel cationic osmium bis(σ-B-H) borane complexes featuring the OsH(CO)(PCy₃)₂⁺ fragment were successfully synthesized.
• These complexes coordinate monoaryl borane ligands via two geminal σ-B-H bonds.
• AIM analyses revealed significant differences in the Os-H-H-B bonding regions between analyzed complexes.

Conclusions:

• The study presents an effective route to previously scarce cationic osmium σ-B-H complexes.
• The findings significantly enrich the known diversity of osmium σ-B-H complexes and their bonding characteristics.