RP-Bridged Metal Carbonyl Clusters: Synthesis,Properties, and Reactions

Metal carbonyl clusters possess a complicated chemistry that is only beginning to be understood. One of the main current goals in this area is thus an understanding of their reactivity. This article describes the syntheses and reactions of clusters that contain metal carbonyl fragments bridged by a main-group element. But what is the sense of making such clusters still more complicated by the incorporation of main-group elements? The example of μ₃-bridged carbonyl clusters will serve to show that the main-group element plays an important role in the study of reaction paths; it holds the metal carbonyl fragments together even when the bonds between them are broken in the course of a reaction. Trinuclear μ₃-bridged clusters prove to be small enough to allow the analysis of typical cluster reactions (such as the reversible breaking of metal-metal bonds) in terms of single reaction steps. They are also large enough to provide surprises by their multifaceted reactivity. It will be shown that a detailed study of trinuclear RX-bridged metal carbonyl clusters (X ? N, P, As, Sb, Bi)—a very small part of carbonyl cluster chemistry—can lead to a better understanding of the general reaction principles involved.