Hydrogenation of phenylacetylene catalyzed by a dihydridorhodium complex, [RhH2(Ph2N3)(PPh3)(2)]

The homogeneous hydrogenation of phenylacetylene homolog catalyzed by dihydrido(1,3-diphenyltriazenido)bis(triphenylphosphine)rhodium(III)(dihydridorhodium complex) was studied under a pressure of 1 atm hydrogen. The dihydridorhodium complex was active catalyst for the selective hydrogenation of phenylacetylene to styrene. On the other hand, internal alkynes are not hydrogenated. For the reduction of phenylacetylene in toluene, incleasing reaction temperature decreased catalytic activity of hydrogenation of phenylacetylene and the addition of triphenylphosphine or 1,3-diphenyltriazene leads decreasing in the catalytic activity. The results are discussed in terms of the mechanism of hydrogenation reaction.