Hydrogenation of CO2 at Room Temperature and Low Pressure with a Cobalt Tetraphosphine Catalyst.

Large-scale implementation of carbon neutral energy sources such as solar and wind will require the development of energy storage mechanisms. The hydrogenation of CO2 into formic acid or methanol could function as a means to store energy in a chemical bond. The catalyst reported here operates under low pressure, at room temperature, and in the presence of a base much milder (7 pKa units lower) than the previously reported CO2 hydrogenation catalyst, Co(dmpe)2H. The Co(I) tetraphosphine complex, [Co(L3)(CH3CN)]BF4, where L3 = 1,5-diphenyl-3,7-bis(diphenylphosphino)propyl-1,5-diaza-3,7-diphosphacyclooctane (0.31 mM), catalyzes CO2 hydrogenation with an initial turnover frequency of 150(20) h-1 at 25 °C, 1.7 atm of a 1:1 mixture of H2 and CO2, and 0.6 M 2-tert-butyl-1,1,3,3-tetramethylguanidine.