Carbon Dioxide Hydrosilylation Promoted by Cobalt Pincer Complexes

The addition of carbon dioxide to ((PNP)-P-tBu)CoH [(PNP)-P-tBu = 2,6-bis(di-tert-butylphosphinomethyl)pyridine] resulted in rapid insertion into the Co-H bond to form the corresponding kappa(1)-formate complex, which has been structurally characterized. Treatment of ((PNP)-P-tBu)CoH with PhSiH3 resulted in oxidative addition to form trans-((PNP)-P-ttbu)CoH2(SiH2Ph), which undergoes rapid exchange with excess free silane. With 0.5 mol % ((PNP)-P-tBu)CoH, the catalytic hydrosilylation of CO2 with PhSiH3 to a mixture of oligomers containing silyl formate, bis(silyl)acetyl, and silyl ether subunits has been observed.