Transition metal clusters fluxionality

The vast majority of transition metal clusters contain carbonyl ligands, which have been shown in many cases to be fluxional on the metal skeleton of the cluster (40,41). Therefore, the most obvious reactions to be catalyzed by such clusters should be those involving carbon monoxide. In fact, catalytic carbonylations are frequently encountered with transition metal carbonyl cluster catalysts, but very often the carbonylation step is followed by a consecutive step, e.g., a hydrogenation step, to give an overall hydroformylation. Simple carbonylation reactions have nevertheless been observed for various structures. 

Structures and fluxional behaviour of transition metal cluster carbonyls. R. E. Benfield and B. F. G. Johnson, Transition Met. Chem. Weinheim, Ger.), 1981,6,131-144 (90). 

MM modeling of the soft PES of metal carbonyl clusters has been made possible by a local connectivity approach which, freeing metal-to-ligand connectivity while tightening cluster-to-ligand connectivity, has enabled the fluxionality of ligands to be taken into account it has been shown theoretically that intramolecular steric interactions alone fail to account for the ligand stereochemistry of transition metal carbonyl clusters. At present, in our BMCCs model, and perhaps in the real... 

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