Main group-transition metal cluster element compounds

Main Group-Transition Metal Cluster Compounds of the Group 15 Elements... 

Current concepts in modem chemistry/Transition metal cluster chemistry/Main group-transition metal mixed clusters/Cluster compounds of main group elements/ Synthetic analogues of the active sites of iron-sulfur proteins... 

The simplest and also the commonest among main group-transition metal mixed compounds are those in which the main group element caps a triangular array of metal atoms in any triangular or more complex deltahedral metal cluster thus forming units of the type (jU3-E)M3. 

Metal Preferences. LVC s are formed mainly by transition metals to the right in the periodic table (especially elements in Group 8). This is in part due to the availability of d electrons that can be used in back-donation to the 7r-accepting ligands. Moreover, the formation of LVC s is not particularly "row-sensitive" by which I mean that the first-transition-series metals, Fe, Co and Ni, tend to form most of the same cluster compounds as their congeners, Ru, Rh, Pd and Os, Ir, Pt. 

Carbonyl Complexes of the Transition Metals Cluster Compounds Inorganometalhc Compounds Containing Transition Metal Main Group Elements Cyanide Complexes of the Transition Metals Dinuclear Organometallic Cluster Complexes Gold Inorganic Coordination Chemistry. 

Main group element clusters without ligands belong to another class of cluster compounds and can also be classified into discrete cluster ions and solid-state clusters. Some of their bonding properties are similar to those of the transition-metal clusters, and in addition to being important in their own right, information obtained from compounds such as Zintl phases is very useful for an overview of metal-metal bonding. 

Research on small transition-metal clusters was reviewed in a comprehensive way in 1986 [14] and again in 2002 (taking then in also lanthanide clusters) [15]. Moreover, small metal oxides and, less detailed, metal oxide clusters of the transition metals were recently reviewed [16]. Herein we restrict the discussion to some examples, most of them involving the matrix isolation technique this article is not a comprehensive overview of research in this field. Different from the three aforementioned review articles, our examples will also include main-group element compounds. 

The recent discovery of many metal complexes having t/2-H2 ligands or agostic C—H bonds has focused attention on a type of bonding that had hitherto seemed to be a domain of early main group elements and metal clusters three-center, two-electron bonds. As more and more examples are found, it has become obvious that such bonds are probably more widespread among transition metal compounds than had been commonly assumed and that it is about time to recognize the features the various species have in common. 

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