Stabilization of Potent Co(II)-based Lewis Acids with Weakly Basic Ligands

Area of Science:

• Inorganic Chemistry
• Organometallic Chemistry
• Catalysis

Background:

• Pairing cations with weakly coordinating anions (WCAs) creates highly Lewis-acidic and reactive species.
• Excessive cation reactivity can lead to decomposition, hindering practical applications.
• Stabilizing metal centers is crucial for controlling reactivity and enabling isolation.

Purpose of the Study:

• To synthesize and characterize novel, stable Co(II)-WCA salts.
• To investigate the Lewis acidity and reactivity of these new complexes.
• To explore their potential as catalysts in Lewis acid-mediated reactions.

Main Methods:

• Synthesis of novel Co(II)-WCA salts using SO2, halogenated acetonitriles, and nitromethane as ligands.
• Comprehensive characterization: structural, magnetic, spectral (IR), and thermal stability.
• Density Functional Theory (DFT) calculations for structural and energetic insights.
• Synthesis and characterization of related Ag(I) complexes.

Main Results:

• Stable Co(II)-WCA complexes were successfully synthesized and characterized.
• The complexes exhibit high Lewis acidity, comparable to SbF5 in some cases.
• DFT calculations confirm the availability of the Co(II) center for substrate binding (e.g., olefins).
• Novel Ag(I) complexes were also synthesized and characterized.

Conclusions:

• The developed Co(II)-WCA complexes offer a balance of high Lewis acidity and stability.
• These complexes are promising candidates for catalytic applications in reactions requiring Lewis acids.
• The use of weakly bound ligands effectively mitigates excessive cation reactivity.