Polymer-Supported Tetranuclear Bimetallic Cluster Catalysts

Abstract

Supported metal clusters with unique structures have been prepared by phosphine-phosphine ligand exchange between the parent molecular metal clusters and phosphine-functionalized poly(styrene-divinylbenzene). The polymers incorporating clusters with open butterfly framework structures ([ClAuOs 3 (CO) 10 ([Ph 2 P- )] and [Co 2 Pt 2 (CO) 8 (Ph 2 P- ) 2 ]) were active catalysts for ethylene hydrogenation at 1 atm and temperatures ≤100°C, whereas polymers incorporating clusters with closed tetrahedral framework structures ([HAuOs 3 (CO) 10 (Ph 2 P- )] and [H 2 PtOs 3 (CO) 10 (Ph 2 P- ) 2 ]) had immeasurably low activity. It is inferred that the former metal clusters themselves provided the catalytic sites by virtue of their coordinative unsaturation, whereas metal-metal, or metal-ligand bond cleavage would be required for catalytic activity of the clusters with closed tetrahedral frameworks.