Synergism in the Activity of the Mixed Oligoallene Complexes of Palladium and Group VIII Nonnoble Metals in the Hydrogenation of Dienes to Alkenes

The superadditivity of the catalytic properties of various bimetallic Pd–Ni, Pd–Co, and Pd–Fe complexes with oligodimethylallene ligands was studied. Palladium–nickel catalysts of an equimolar composition exhibited the highest activity. The complexes were studied by IR spectroscopy. Conceivable structures were proposed for the complexes. The main kinetic features of the isoprene hydrogenation reaction under the action of palladium and palladium–nickel systems were studied. A two-center mechanism, which takes into account the presence of properly arranged palladium and nickel atoms in the active center of the catalyst, was considered as a probable reason for the appearance of a synergistic effect.