The homogeneous hydrogenation of carbon-carbon multiple bonds with heteronuclear platinum clusters

The heteronuclear platinum clusters Pt 2 CO 2 (CO) 8 (PPh 3 ) 2 and Pt(C 6 H 11 NC) 2 [Mo(CO) 3 (n 5 -C 5 H 5 )] 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 PtMo 2 cluster can be recovered unaltered from the reaction mixture, the Pt 2 CO 2 cluster undergoes rather complex molecular rearrangements, which take place under the catalytic conditions. Finally the Pt 2 CO 2 cluster, under well defined conditions, may act as a catalyst for the selective hydrogenation of diphenylacetylene to cis -stilbene.