Palladium complexes triangular cluster

Arenes can also bridge tw o metals, as shown in Figure 2.35. In one example shown, the arene bridges and sandwiches two palladium atoms. The arene in the dinuclear nickel complex also bridges two metals. The arene in the osmium complex binds symmetrically to each of the three metal atoms on the triangular face of a cluster. This compound provides a molecular view of the chemisorption of benzene on a metal surface. ... 

Numerous palladium-osmium clusters have been prepared and characterized through the reaction of osmium carbonyl clusters with palladium(O) and palladium(ii) complexes. The simplest of these is probably (bipy)Pd 20s3(G0)i2, which is prepared from Os3(/i-H)2(GO)io and Pd(OAc)2(bipy). This cluster is made up of a triangular arrangement of Os3(GO)s, with two (/x-GO)2Pd(bipy) units attached to two of the osmium atoms (43, terminal osmium carbonyls omitted for clarity). Each palladium atom has one symmetrically bound and one semibridging carbonyl ligand associated with it (Pd-GO= 1.98(2) and 2.34(2) A). 

---