Formate-Catalyzed Selective Reduction of Carbon Dioxide to Formate Products Using Hydrosilanes

Formate salts were found to be active and selective homogeneous catalysts for the hydrosilylation of CO₂. Counter cations and solvents strongly affected their catalytic activity. The use of toluene as a solvent rendered the recyclable catalyst system. Lewis basic polar solvents such as N-methylpyrrolidone and dimethyl sulfoxide significantly accelerated the reaction. The turnover number approached up to 1800. Analyses of the Fourier-transform infrared spectroscopy and in situ ¹H nuclear magnetic resonance spectra suggested that the catalysis proceeds via electron donation from the solvent to hydrosilane, thereby accelerating the hydride transfer step.