Group electron-deficient borane clusters

The chemistry of the electron-deficient boranes and carboranes which has indeed been employed as a useful model in the description of bonding in transition metal clusters appears to be a singular case among main group elements. From the point of view of the cluster chemistry, the properties of boron appear to meet with those of the transition metals. 

There are some interesting observations too concerning the structures of polyhedral molecules. Very often they are electron deficient in the sense that there are fewer than two electrons for each close contact. The heavy atoms forming the skeleton of the molecule may be either main group atoms (for example in the boranes and carboranes) or transition metal atoms (metal cluster compounds) or both (metallocarboranes). 50 shows the structures expected from Wade s rules for five atom polyhedral molecules with six, seven and eight pairs of skeletal electrons. There are a total of fifteen skeletal orbitals... 

In this Chapter, some of the different possibilities that Main Group Elements offer for building atomic conglomerates will be analyzed. In such a context examples of electron-deficient cluster species such as the clusters formed by the alkali metals and some complementary aspects of the chemistry of boranes and... 

---