Macropolyhedral borane clusters

For a closo macropolyhedral borane cluster, the rule giving the required number of electron pairs is N = m + n. 

Half-sandwich complexes have also been reported with macropolyhedral boranes, but the Ni-borane bonding in these complexes does not involve 7r-interactions. For instance, reacting nickelocene with anti- > zz results in the elimination of CpH and formation of the 19-vertex conjuncto- xxwQXm anions [Bi8H2oNiCp] , 231 subtle differences in the reaction conditions lead to the oxidation of 231 to give 232. Structural studies of these compounds have shown that their overall structures consist of two edge-fused cluster subunits (a 10-vertex and a ////To-10-vertex)... 

Metal atoms have fewer valence electrons than orbitals available for bonding and in this they resemble boron. The consequences of this idea are examined and it is shown that many metals with electronegativities in the range 1.6-2.4 (B = 2.0) can subrogate boron atoms as vertices in polyhedral clusters. Such metalloboranes are often much more stable than the parent boranes or borane anions. Not only can metals mimic boron in known cluster geometries but the flexibility thus introduced can lead to novel and previously unsuspected cluster geometries. The construction of macropolyhedral clusters containing 17-20 vertices is also described. 

Macropolyhedral Condensed Boranes and Supra-icosahedral Clusters... 

---