Efficient CO₂ Insertion and Reduction Catalyzed by a Terminal Zinc Hydride Complex.

Area of Science:

• Organometallic Chemistry
• Catalysis
• Green Chemistry

Background:

• Carbon dioxide (CO2) utilization remains a significant challenge in sustainable chemistry.
• Development of efficient catalysts for CO2 transformation is crucial for mitigating environmental impact.
• Hydrosilylation offers a promising route for CO2 conversion into valuable organic compounds.

Purpose of the Study:

• To synthesize and characterize a novel terminal zinc hydride complex for CO2 hydrosilylation.
• To investigate the catalytic activity and selectivity of the complex in CO2 hydrosilylation reactions.
• To elucidate the reaction mechanism using spectroscopic and computational methods.

Main Methods:

• Synthesis and characterization of the zinc hydride complex [Tntm]ZnH (2).
• Catalytic hydrosilylation of CO2 with silanes at room temperature and elevated temperatures.
• Spectroscopic analysis (1H and 13C NMR) and single-crystal X-ray diffraction for complex characterization.
• Density Functional Theory (DFT) calculations to understand electronic structure and coordination preferences.

Main Results:

• The [Tntm]ZnH complex demonstrated efficient catalytic activity for CO2 hydrosilylation at room temperature.
• Selective formation of the monosilylated product (MeO)3SiO2CH was achieved with high turnover frequencies (TOF).
• The intermediate formate complex [Tntm]Zn(O2CH) (3) was quantitatively formed in the absence of silanes.
• DFT calculations indicated a highly electrophilic zinc center and a preferred kappa(3)-coordination mode of the ligand.

Conclusions:

• The terminal zinc hydride complex is a highly effective catalyst for CO2 hydrosilylation, operating under mild conditions.
• The catalyst's inherent electrophilicity drives selective monosilylation of CO2.
• The study provides mechanistic insights into the catalytic cycle and ligand behavior.