The Homogeneous Hydrogenation of Carbon--Carbon Multiple Bonds with Heteronuclear Platinum Clusters

The heteronuclear platinum clusters Pt₂Co₂(CO)₈(PPh₃)₂ and Pt(C₆H₁₁NC)₂[Mo(CO₃)(eta ⁵-C₅H₅)]₂ are poor catalysts for the hydrogenation of olefins and internal acetylenes, but they show a reasonable activity for the hydrogenation of terminal acetylenes. In this latter case the selectivity towards olefins is low. Whereas the PtMo₂ cluster can be recovered unaltered from the reaction mixture, the Pt₂Co₂ cluster undergoes rather complex molecular rearrangements, which take place under the catalytic conditions. Finally the Pt₂Co₂ cluster, under well defined conditions, may act as a catalyst for the selective hydrogenation of diphenylacetylene to cis-stilbene.