Mild and Selective Carbon Dioxide Hydroboration to Methoxyboranes Catalyzed by Mn(I) PNP Pincer Complexes

Abstract

AbstractWell‐defined Mn(I)‐PNP pincer‐type complexes were tested as non‐precious transition metal catalysts for the selective reduction of CO2 to boryl‐protected MeOH in the presence of hydroboranes (HBpin, 9‐BBN) and borates as Lewis acids (LA) additives. The best performance was obtained under mild reaction conditions (1 bar CO2, 60 °C) in the presence of the hydridocarbonyl complex [MnH(PNPNH–iPr)(CO)2] and B(OPh)3 as co‐catalyst. Preliminary mechanistic studies suggest that the initial activation step may occur by cationization of the metal center by the strong LA, and that both metal‐catalyzed and metal‐free steps are present in the overall catalytic system.