Mediators for hydrogenation of carbon monoxide: theoretical study of addition of H-2 to HCO+ in the presence of CO or H2O

Relevant parts of the potential energy surfaces of the title reaction syste ms (CH3O+, C2H3O2+, and CH5O2+) have been explored using quantum chemical m odels (MP2/6-31G(d,p) and G2). The results of the calculations demonstrate that the barrier for hydrogenation drops significantly when a third molecul e (CO or H2O) can act as a proton acceptor during the critical H-H bond het erolytic dissociation step, thereby avoiding the tight transition state fou nd for the direct reaction. (C) 2000 Elsevier Science B.V.