Zirconium-Nitrogen Intermolecular Frustrated Lewis Pairs

Area of Science:

• Organometallic Chemistry
• Catalysis
• Lewis Pair Chemistry

Background:

• Frustrated Lewis pairs (FLPs) are key to small molecule activation.
• Zirconocene complexes offer tunable steric and electronic properties.
• Nitrogen bases provide alternative Lewis base components for FLPs.

Purpose of the Study:

• To synthesize and characterize novel intermolecular transition metal FLPs.
• To investigate the influence of steric hindrance on FLP interactions.
• To explore the reactivity and catalytic applications of these FLPs.

Main Methods:

• Synthesis of zirconocene alkoxide complexes and nitrogen Lewis bases.
• Characterization using Nuclear Magnetic Resonance (NMR) spectroscopy, including DOSY NMR.
• Reactivity studies with small molecules (D2, CO2, THF, PhCCD) and catalytic dehydrocoupling.

Main Results:

• Successfully formed intermolecular FLPs from zirconocene alkoxides and various nitrogen bases.
• Demonstrated that increased steric bulk enhances FLP frustration.
• Observed dynamic interactions in FLPs via DOSY NMR.
• Showcased FLP reactivity including small molecule activation and catalytic dehydrocoupling of Me2NH·BH3.

Conclusions:

• Steric bulk and basicity are more critical than hard-soft acid-base interactions in tuning FLP behavior.
• Nitrogen-based FLPs offer a viable alternative to phosphine-based systems.
• These findings expand the scope of FLP chemistry and catalysis.