Olefin hydrogenation using diimine pyridine complexes of Co and Rh

Square-planar cobalt diimine pyridine complexes LCoR are active in the hydrogenation of monosubstituted and disubstituted olefins; sterically more hindered trisubstituted olefins do not react. Intermediate alkyl species of the hydrogenation cycle were detected. The mechanism was further investigated by EPR measurements and DFT calculations.